Non-union Treatment in the arm, wrist, and fingers: A Multicenter Retrospective Study Contrasting Conventional Treatment with the Allogeneic Cortical Bone Screw (Shark Screw®)

Non-union Treatment in the arm, wrist, and fingers: A Multicenter Retrospective Study Contrasting Conventional Treatment with the Allogeneic Cortical Bone Screw (Shark Screw®) | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Non-union Treatment in the arm, wrist, and fingers: A Multicenter Retrospective Study Contrasting Conventional Treatment with the Allogeneic Cortical Bone Screw (Shark Screw®) Elisabeth Huber, Gerd Jakob, Wolfgang Palle, Gudrun H. Borchert, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4562491/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Introduction: The cause of pseudarthrosis is the interaction of various biological and biomechanical factors with systemic and local interactions. Successful therapy consists of a combination of optimizing mechanical stability and activating biological factors. The conventional method for treating non-union is debridement and stabilization with metal hardware. But it leads to complications and a potential second operation for hardware removal. The human allogeneic cortical bone screw (Shark Screw®) provides a close contact between allograft and host bone, which is required for revascularisation and bone healing. The Shark Screw® merges human cortical bone properties with screw stability, addressing non-union surgery principles by integrating mechanical and biological aspects. Material and Methods: The retrospective-multi-center study included 31 patients, 11treated with the conventional method(metal hardware ± graft) and 20 patients with the Shark Screw® (±graft). Patient demographics, non-union location, autograft and/or allograft use, follow-up time, complications, union-rate, time-to-union and time-to-return to work were recorded. Results: Follow-up was 17 months in the conventional group and 12 months in the Shark Screw® group. The union rate was 72.7% in the conventional group and 95.0% in the Shark Screw® group. Time to union was significantly shorter in the Shark Screw® group with 12 weeks in comparison to 39 weeks in the conventional group. Conclusion The Shark Screw® presents a reliable option for treating non-unions in the shoulder, forearm, hand, and fingers. It demonstrates a low complication rate. The human allogeneic cortical bone screw (Shark Screw®) combines both stability and biology with a single transplant. The socioeconomic effect is another advantage using the Shark Screw®. Level of evidence: III non-union shoulder arm wrist and finger human allogeneic cortical bone screw (Shark Screw®) time to union metal hardware removal socio-economic effect Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Physiological fracture healing is a biological outstanding achievement. It can be disturbed by many factors [ 1 ]. The cause of non-union seems to be an interaction of various biological and biomechanical factors with systemic and local interactions [1; 2]. Regarding local causes, unsuitable or faulty stabilization, possibly with long periods of reduced loading, pronounced soft tissue damage, reduced blood supply in the affected region and traumatic or iatrogenic destruction of the periosteum, former radiation and infection are considered to be permissive for failure of the fracture to heal [1; 2]. Gagnon et al. [ 3 ] summarize in their recent review that: ”Every non-union case is different in terms of bone defect, biology, mechanical stability, surgical technique and host factors…We might never see a level 1, high powered and robust study defining the efficacy, safety profile and cost-effectiveness”[ 3 ] because of the different procedures necessary to overcome non-union. Non-union results in prolonged pain and reduced functionality [ 4 ]. Socioeconomic costs are caused by the complex operation treatment strategies [ 4 – 7 ]. Therefore, successful therapy often consists of a combination of optimizing mechanical stability and activating biological factors [1; 7; 8]. For the biological activation of fracture healing the application of autologous cancellous bone is often used [2; 9–11], but its limited availability and the high donor site morbidity [9; 11] is a great disadvantage. The site of non-union can be augmented with bone graft. Allografts are an alternative and perform as autografts [9; 12]. The conventional method for treating non-union is the debridement of the non-union and the stabilization with metal plates and screws. But metal hardware leads to complications and a potential second operation for hardware removal. Complication rates between 30–60% are reported after total wrist arthrodesis and a re-operation rate between 19–64% [ 13 ]. Nwosu et al. describe in their recent review 3–31%[ 14 ] hardware related complications. Hardware removal was recorded between 6.8% after volar locking plate fixation of distal radius fractures in adults [ 14 ] up to 77% after arthrodesis for primary osteoarthritis of the trapezio-metacarpal joint [ 15 – 18 ]. Avoiding hardware removal and donor site morbidity while obtaining comparable results as with conventional methods would decrease economic burden and the higher risk for the patient. The non-union rate in the shoulder is reported with 5% [ 19 ]. Non-union in long bones is recorded up to 30% [ 1 ]. Vanderkarr et al. [ 20 ] describe a 7.2% non-union rate for the humerus. In the forearm non-unions are reported to be between 0–60% [10; 21–23]. Non-union rates are described with 4% for the radius, with 7% for the ulna [ 2 ] and with 11% for the hand [ 8 ]. For the scaphoid, non-unions are reported between 0% and 18% and in some cases up to 63% [11; 24–27]. Treating scaphoid non-union arthroscopically with autograft from the distal radius and 4 pins resulted in 93.5% union [ 28 ]. Dislocated fractures, in particular seem to be prone to non-union [6; 29; 30]. Displaced scaphoid fractures are at risk for nonunion due to a variety of factors, including interfragmentary instability, retrograde vascular supply, and lack of soft tissue attachments on a largely cartilaginous surface [30; 31]. Non-union after arthrodesis of the proximal interphalangeal joint of the finger is reported with 3.9% using the compression screw and 8.6% after interosseous wiring [ 32 ]. Fractures with severe soft tissue trauma are also at increased risk of non-union [ 20 ]. To avoid progression to arthrosis of the scaphoid there are 3 major aims: restauration of the form of the scaphoid, restauration of the carpal alignment and bony consolidation of the scaphoid [ 25 ]. Despite improvement in surgical procedures treating non-union, there is no consensus over the optimal treatment option. For certain age groups Mills at al. [ 33 ] described a non-union rate up to 9% and 80 non-unions per 1000 fractures in the shoulder per year for the age group between 35–45 years [ 33 ]. This is mainly true for male patients, for female patients an increase in the incidence is reported with age [8; 34]. Using the human allogeneic cortical bone screw (Shark Screw®) is a new option to treat non-unions[ 7 ]. The cortical bone screw provides a close contact between allograft and host bone, which is required for revascularisation and healing as described by Basile et al. [ 35 ] and confirmed by Brcic for the allogeneic cortical bone screw [ 36 ]. It is described that (metal) screw fixation disrupts the internal vascularity [37; 38] more than a K-wire and hence reduces the potential benefits of vascular grafts [ 37 ]. Perren et al. [ 38 ] describes that a plate used for e.g. radius fixation inhibits the blood reaching or leaving the bone. This complication is avoided by using the cortical bone screw because vascularization is not disrupted. The success of the graft may also depend on the quality of the bone bed from which most of the revascularization arises [36; 39]. The processing, preservation and sterilization (via irradiation or chemically sterilized) of allograft bone may influence its biophysical and general biological properties [ 39 ]. The goal of using bone allograft is to initiate a healing response from the host bed that will produce new bone at the host-graft interface and within the porous body of the graft material [ 39 ]. The mechanical stability of the graft is of vital importance [ 39 ] and is given by the design of the Shark Screw® as a set screw. For the human allogeneic cortical bone screw this process was shown after 10 weeks [ 36 ]. Recent publications show that, when using the Shark Screw, the union rate is between 94–100% for fracture treatment, arthrodesis and non-union [ 40 – 43 ] and thus similar to union rates with conventional methods. The multicentred retrospective data analysis presented here aims to compare the outcome of non-union treatment with 1) conventional methods (metal crews/plates/nails ± graft and 2) the human allogeneic cortical bone screw (Shark Screw®) in upper extremities. We recorded patient demographics, follow up time, union rate, time to union, time to return to work, complications, and percentage of hardware removal. We collected data from clavicula, humerus, radius, ulna, the scaphoid, and the finger joints. Material and Methods Approval from the local Institutional Review Boards (IRBs) was received before the study's commencement, and the reference numbers are as follows: 1146/2023 (Ethik-Kommission of the Johannes Keppler University Linz), and M2023-25 (Ethik-Kommission Kärnten). The study was conducted in accordance with the Declaration of Helsinki. Informed consent to participate was waved by the institutional review boards. Study design and patient population This study was designed as a retrospective multicentred study. Clinical and radiographic data were collected from the medical charts of 31 patients who underwent non-union surgery on the shoulder, arm, and fingers between 2016 and 2022. The specific treatment method for non-union was not a selection criterion. Our study included a total of 31 patients, with 11 patients (37%) in the conventional treatment group and 20 patients (64%) in the Shark Screw® group. Patient demographics are presented in Table 1 . Table 1 Patient Data Conventional treatment (metal hardware ± graft) Shark Screw® treatment (Shark Screw® ± metal plate) Number of patients Mean ± SD Number of patients Mean± SD Number of patients 11 - 20 - Age [years] 11 40.8 ± 19.9 20 54.8 ± 15.7* BMI [kg/m²] 11 25.1 ± 6.4 20 25.1 ± 4.7 Gender [male/female] 6/5 - 10/10 - Smoker [yes/no] 5/6 - 5/15 - Comorbidities [yes/no] 4/7 - 9/11 - Non-union revision following: Surgical fracture treatment Elective surgery (arthrodesis, osteotomy) Conservative fracture treatment 3 1 7 - - - 8 7 5 - - - Aseptic/septic 10/1 - 20/0 - *p = 0.03909 vs . conventional group Patients from two treatment groups were evaluated: the conventional treatment involving metal hardware (screws/plates) ) with or without bone graft (Table 2 ), and the Shark Screw® procedure. Table 2 Localization of Pseudarthrosis Anatomic localization of non-union Conventional treatment (metal hardware ± graft) Shark Screw® treatment (Shark Screw® ± metal plate) Number of patients 11 20 Shoulder Clavicular 3 1 Shoulder (Latarjet) 0 1 Arm Humerus 1 3 Ulna 1 1 Radius 1 1 Hand Scapho-Trapezo-Trapezoidal (STT) 0 1 Wrist 0 1 Repetitive Strain Injury (RSI) 1 0 Scaphoid 3 4 Finger PIP3 1 0 DIP1 CP 0 3 DIP2,3,4 0 1 DIP2,3,5 0 1 MCP 2 0 2 The comorbidities included Diabetes Mellitus Type II, COPD, mutilating chronic polyarthritis, arterial hypertension, adeno carcinoma, (allergic) asthma bronchial, Lupus erythematosus, osteoporosis, foramen ovale, deep vein thrombosis, varicose, benign prostatic hyperplasia. Inclusion Criteria To be eligible for inclusion in the study, patients were required to have at least one follow-up visit at least 6 months post-surgery or until bone healing was documented. These cases encompassed non-union after elective procedures (arthrodesis and osteotomy), after surgical fracture treatment, and after conservative fracture treatment (Table 1 ). Exclusion Criteria We excluded non-unions related to tumour-related cases. Surgical procedures Surgical procedures vary with location of the non-union. For using the cortical bone screw surgical procedures were described before for different locations [ 40 ] of the hand, for scaphoid fractures [ 42 ], and for distal interphalangeal joint arthrodesis [ 43 ]. We recorded the following parameter: Non-union location for revision (Table 2 ), autograft and allograft use, follow up time, complications, union rate, time to union and time to return to work (Table 3 ). Table 3 Clinical Data and Outcome Conventional treatment (metal hardware ± graft) Shark Screw® treatment (Shark Screw® ± metal plate) Number of patients Mean ± SD/% Number of patients Mean ± SD/% Number of patients 11 - 20 - metal hardware use additional to Shark Screw® metal left in from previous surgery 11 (per definition) - - - - - - 2 (1xprothesis) 2 - - - Autograft use Iliac crest Medial femoral condylar span (MFC) Lateral femoral condylar span (LFC) Allograft use DBM putty cortical span 2 2 2 0 0 - - - - - - - - 7 1 - - - - - Follow up [weeks] 11 71.0 ± 41.0 20 50.5 ± 36.4 & Complications [yes/no][%] 4/7 36.4 1/19* 5.0 Metal hardware removal [%] 7 63.6 1 % *** 5.0 Bony union rate [%] Partial union [%] Non-union [%] 8 1 2 72.7 9.1 18.2 19 1 0 95.0 5.0 0.0 Time to Union [weeks] 8 38.8 ± 26.3 19 12.4 ± 5.4**** Return to work [weeks] 10 25.3 ± 16.3 20 12.0 ± 5.5** & p = 0.16055; *p = 0.02311; **p = 0.00238; % Hardware removal from previous surgery; ***p = 0.000357; ****p = 0.000247 Complications We defined non-union and partial union after 6 months, osteonecrosis, screw loosening or screw breakage as a complication. Statistics Data are presented as mean ± SD. Due to the non-Gaussian distribution of the data, non-parametric Kruskal–Wallis ANOVA was used for calculating significant differences in quantitative values. Ordinal values were evaluated with contingency tables using Fisher’s exact test for significance. A p-value 0.8. All statistical analyses were performed using Origin Pro statistical software (OriginPro, version 2023; OriginLab Corporation, Northampton, MA). Results Patient average age was 41 years in the conventional group and 55 years in the Shark Screw® group, this difference was statistically significant (p = 0.03909). Patients average BMI was 25 kg/m². In the conventional group and in the Shark Screw® group were smoker, 45% and 25%, respectively. 52% were male patients (Table 1 ). Except for age, patient demographics were not significant different between the conventional group and the Shark Screw® group (Table 1 ). Patients in the Shark Screw group were significantly older. For the conventional group in 4 cases metal screws were used, in 3 cases plates, in 2 cases K-wires, 1 mini-fixateur and in 1 case a prothesis was placed. In the Shark Screw® group in 1 case the metal hardware was left in. Autograft was used only in the conventional group in 6 cases (Table 3 ). Allograft was not used in the conventional group but in 8 cases (DBM putty (7 cases) and one cortical span) in the Shark Screw® group. Follow up was 17 months in the conventional group and 12 months in the Shark Screw® group. The union rate was 72.7% (8 of the 11 patients) in the conventional group and 95.0% (19 of the 20 patients) in the Shark Screw® group. Time to union was significantly shorter in the Shark Screw® group with 12 weeks in comparison to 39 weeks in the conventional group (p = 0.000247). Smoking delayed union in the conventional group, but it did not reach statistical significance, but not in the Shark Screw® group (data not shown). There was an earlier return to work for the Shark Screw® group, with 12 weeks for the Shark Screw® group and 25 weeks for the conventional group (p = 0.00238). Complications were low in both groups with 4 in the conventional group (2 non-unions, one of them with osteonecrosis, 1 partial union and 1 screw loosening) and 1 in the Shark Screw® group (partial union). Non-unions were recorded in patients with an age of 35 and 59 years, whereas patients obtaining only partial unions were older (55 years and 78 years). All patients with non-unions or only partial unions were non-smokers. Except for the 59-year-old patient (Lupus erythematosus) in the conventional group, none of the patients with complications had co-morbidities at the time of surgery. Metal removal in the conventional group was performed in 7 of the 11 patients (64%) compared to 1 patient (5%) in the Shark Screw® group. The one patient in the Shark Screw® group had metal hardware from a previous surgery, which was left in place during revision surgery, but removed later. A failed thumb IP-arthrodesis of a 72-year-old patient with chronic polyarthritis is depicted in Fig. 1 a-c and was treated with 1 Shark Screw®, union was recorded after 12 weeks and the Shark Screw® totally remodeled into host bone after 21 months (Fig. 1 c). The revision after a failed arthrodesis of a middle finger with a metal screw of a 63 years-old patient is shown in Fig. 1 d-i for the left hand and in Fig. 1 j-o for the right hand. The X-ray after the first treatment is presented in Fig. 1 d-e. Even hardware removal did not lead to union 31 months after surgery. For revision one Shark Screw was placed (Fig. 1 f-g) and union was obtained after 26 weeks. 36 months after revision surgery the Shark Screw® is nearly totally remodelled (Fig. 1 h-i). The treatment of a non-union of a middle finger of the right hand is presented in Fig. 1 l-q: The Herberden Osteoarthrosis was bridged with a 3 mm metal screw in the first attempt (Fig. 1 j-k), even after 21 months no union was recorded (Fig. 1 l-m). Revision was performed with one 3.5 mm Shark Screw®. Starting the consolidation is visible 6 weeks after revision (Fig. 1 n-o). totally remodelled. j-o: The middle finger of the right hand. j-k: The Herberden osteoarthrosis was bridged with a 3 mm metal screw in the first attempt, l-m; even after 21 months no union was recorded. Revision was performed with one 3.5 mm Shark Screw®. n-o: Starting the consolidation is visible 6 weeks after revision A 31-year-old patient with a non-union of the scaphoid is presented in Fig. 2 a-g. Revision was performed with 1 Shark Screw® (Fig. 2 b). Union was obtained after 8 weeks (Fig. 2 c). After 35 months the Shark Screw® is totally remodeled into host bone (Fig. 2 d). An 82-years-old patient was treated with 2 Shark Screws® (Fig. 2 f) to overcome the non-union (Fig. 2 e) of the scaphoid-trapezoid-trapezium-arthrodesis. Union was detected 8 weeks after revision surgery. 14 months after revision the Shark Screw® is not any more visible (Fig. 2 g). In Fig. 2 h-l we present the non-union obtained for the scaphoid after conventional treatment even though autograft was used. Figure 2 h pre-revision X-ray. Figure 2 i intraoperative fluoroscopy using a vascularized femur condylar span which was attached to the aorta radialis. The span was stabilized with 4 K-wires. 12 weeks after surgery is presented in Fig. 2 j with the non-union still visible. Shock-wave therapy did not improve the situation after 8 month (Fig. 2 k). Five years after revision, the necrosis of the proximal pole is visible, but the patient is nearly pain-free (Fig. 2 l). A 59-year-old patient was treated for non-union after using a humerus nail after a fall at home (Fig. 3 ), 10 months after initial surgery non-union was recorded (Fig. 3 a). For revision, non-union debridement was performed, the nail was removed and replaced with a 9-hole plate. Non-union was additionally bridged with 2 Shark Screws®. Four weeks after revision the Shark Screws® are still well visible and union not yet observed (Fig. 3 b). Eight weeks after revision (Fig. 3 c) remodelling is visible in part of the former non-union area. Union was recorded 12 weeks after revision surgery. Figure 3 d shows union and full remodelling of the Shark Screws® 1-year post-revision. A radius-non-union in a 39-year-old patient is shown in Fig. 3 e-k. As the former radius plate was bent, the radius was shortened in relation to the ulna (Fig. 3 e-f). During the revision operation, the plate on the radius was replaced and the radius was restored to its original length. The resulting bone defect was filled with an allogeneic cortical block and DBM putty. In addition, the bone defect was stabilized and bridged with 2 Shark Screws®(Fig. 3 g-h). Union was obtained after 12 weeks; Metal hardware was removed 1 year after revision surgery (Fig. 3 i-k). The nonunion of the epicondyle of the lateral humerus of an 80-year-old patient is presented in Fig. 4 . Pre-revision X-ray and CT scan are shown in Fig. 4 a-b. Non-union was treated with 3 Shark Screws® (Fig. 4 c) and union was observed after 10 weeks. Figure 4 d represents the X-ray after 4 months and 21 months after revision the Shark Screws® are totally remodelled into host bone (Fig. 4 e). A humerus shaft non-union of a 40-year-old patient is depicted in Fig. 5 a-f. The nail was left in, but the non-union was bridged with 3 Shark Screws® (Fig. 5 c-d). Union was recorded after 7 weeks. 8 months after revision the Shark Screws® were remodeled to host bone and are not any more visible (Fig. 5 e and ). A failed Laterjet in a 35-year-old patient was treated with 1 Shark Screw® (Fig. 5 g-i). The metal screws were taken off (Fig. 5 g). No debridement of the non-union was performed, only the bone bed was prepared for the Shark Screw® (drilling and thread cutting). 1 Shark Screw® was used for revision (Fig. 5 h). Union was observed 2 months after surgery. 4 months after surgery the Shark Screw® is totally remodelled into host bone (Fig. 5 i). In Fig. 6 a-d we show the revision of the non-union of a clavicula of a 64-year-old patient. Former metal hardware (Fig. 6 a-b) was removed in the same session and 2 Shark Screws® were used for revision. Union was obtained 12 weeks after revision (Fig. 6 c). 15 months after revision bone union is visible and the Shark Screws® are totally remodelled into host bone. In Fig. 6 e-g we present the case of non-union union after osteomyelitis of a 52-year-old patient after a fall at home. The fracture was anatomically reduced after pseudoarthrosis removal, insertion of microvascular pedicled MFC spans and bridging osteosynthesis with a 10-hole lateral clavicle plate (Arthrex, Naples, FL, USA, Fig. 6 f). With complete union 1 year after revision (Fig. 6 g). A case of a non-union of a scaphoid fracture with conservative treatment (Fig. 7 a) is shown in Fig. 7 a-e. Revision was performed using Linscheid maneuver, correction of Humpback deformity, using an autologous iliac crest cortical bone span and a Herbert Screw (Fig. 7 b). Figure 7 c shows the X-ray after 2 months. Union was observed 6 months after surgery (Fig. 7 d). Metal hardware was removed 1 year later. Figure 7 e shows an X-ray 18 months post revision. Pseudoarthrosis after scaphoid fracture in the middle third after surgical treatment with angle stable Medartis scaphoid plate (1.5 mm) is presented in Fig. 7 f-h. Revision was performed including metal removal (Fig. 7 f), elimination of the humpback deformity and pseudoarthrosis bridging with one 3.5 mm Shark Screw®. Figure 7 g represents the case 6 weeks after revision surgery. Two years after revision we recorded increasing callus formation, the pseudoarthrosis is still visible centrally, the Shark Screw® is now completely resorbed, the fracture is not yet completely united (Fig. 7 h). Discussion The most important finding of this study is, that surgical treatment of non-union with the human allogeneic cortical bone screw (Shark Screw®) outperformed conventional treatment (metal hardware) with a 95% bone healing rate with a shorter time to union (26 weeks earlier) and a faster return to work (13 weeks earlier). The Shark Screw® group had fewer complications, with only one cases of partial union recorded, which occurred after scaphoid revision surgery. An advantage of the Shark Screw® is its avoidance of metal components, which may further cause problems. In 2 cases the metal hardware from previous surgeries was left in, in 1 case the old metal hardware was replaced with new metal hardware and in 1 case an ulna head prothesis was used additionally to the Shark Screws® used. It is possible to combine the human allogeneic cortical bone screw with metal hardware. The use of the Shark Screw® avoids donor site morbidity and improves bone healing. The non-union-rate depends on the location of the fracture and is reported to be the highest in the shoulder, followed by the upper arm and the forearm and is lowest in the hand [ 33 ]. In contrast Reeh et al. describes that the hand has the highest probability for non-union [ 8 ]. Non-union is described in the humerus with 7.2% [ 20 ] − 9%[34; 44] and for non-union treatment in the humerus with 16% [ 3 ], in the ulna with 7% [ 44 ] and 5%[ 44 ] in the radius. We recorded non-union in the ulna and in the scaphoid and partial union again in the ulna and in the scaphoid, which confirms the literature. Union rates for revision of scaphoid non-union were reported with 50%-100% [11; 25; 28; 30; 42; 45–47]. Millrose et al. [ 32 ] describes a non-union rate between 3.6% and 8.6% for PIP joint arthrodesis depending on the technique used. The union rate in our cohort was 73% and 95% in the conventional group and in the Shark Screw® group, respectively. In the conventional group we had 1 non-union and 1 partial union in the ulna. Additional, in the conventional group there was 1 non-union in the pole fraction of the scaphoid, which is known to show higher non-union rates than for waist or distal fractures of the scaphoid [42; 47]. In the Shark Screw® group we did not have any non-union. The partial union in the Shark Screw® group was recorded in one case of scaphoid (waist fraction) non-union-revision. Time to union for the clavicula after non-union was reported with 3–8 weeks [ 48 ]. Literature reports treating forearm non-unions with allograft resulted in union after 102 days (14 weeks) and after 117 days (17 weeks) for the autograft group, when using plates and nails [ 12 ]. For the forearm 6 months were described for the time to union [ 10 ]. Time to union was 3.8 months without bone grafting [ 26 ]. After non-union revision time to union is described after 3–4 months [28; 42]. Others report 15 months until union was obtained for scaphoid fractures [ 47 ]. We could observe a significant shorter time to union in the Shark Screw® group (12.4 weeks), which was on the shorter end of the results described in the literature. Time to union in the conventional group was longer (39 weeks), with 2 patients (both smokers) having extremely long time to union (74 and 78 weeks). But still this value is in the range described in the literature [ 47 ]. The complication rate using the conventional methods is reported to be between 4 and 33% for major complications [11; 49] and up to 44% including minor complications [ 49 ]. Lari et al. [ 50 ] reported in his review article a complication rate of 14% after distal radius fractures involving the volar rim. In our study we recorded 4 complications (36%) in the conventional group, 2 non-unions, 1 partial union and 1 case of screw loosening. In the Shark Screw® group there was only 1 complication (5%) of a partial union which confirms reports in the literature [ 51 ]. The hardware removal rates were reported with 7.5% [ 52 ], 20% [ 11 ], 22% [ 50 ] and 65% [ 17 ]. Removal of internal fixation is described with an incidence of 1.92/100000 person years and 20,385 cases between 2007–2019 [ 8 ]. In our patient cohort the hardware removal rate was 63.6% in the conventional group and 5% (1 patient) in the Shark Screw® group which was significant different (p = 0.000794). The one patient in the Shark Screw® group had hardware from previous surgeries, which were left in place during revision. Rolo et al. [ 12 ] reported a return to work after 9.4 months in the allograft group and 12.6 months in the autograft group when using metal plates for treating forearm non-unions [ 12 ]. These results described are longer than observed in our study. After 4-corner fusion using bioabsorbable plates, return to work was described with 4.5 months [ 53 ] which is longer than our values in the Shark Screw® group but shorter than in our conventional group. After fixation of scaphoid fractures with staples, return to work was described with 10 weeks [ 52 ], which is similar to our observation in the Shark Screw® group, but primary fractures and non-unions were not separately analyzed. In our cohort, the return to work was 13 weeks earlier in the Shark Screw® group (12 weeks) than in the conventional group (25 weeks), which was statistically significant (p = 0.00238). Further studies should be performed to support this findings. Non-union is described more in male patients aged between 30 and 50 years [8; 44], which may be attributed to more high energy trauma [ 5 ]. This was not true in our cohort. There were 2 male and 2 female in the group of partial union and non-union. Reeh et al. [ 8 ] describes that male patients under 30 years are at the highest risk for non-union, whereas for female the risk of nonunion increases with age. The latter statement was true for our patient cohort, because the 2 oldest patients with non-union/partial union were female, the male patients with non-union/partial union were younger (35 and 55 years). We can confirm the middle age group for higher rates of non-unions in male (35 years) and the higher age in female (59 years), whereas the patients with partial unions were older (55 and 78 years). Ekegren et al. [ 34 ] describes that patients between the age of 55–64 years are more than twice as likely to be resubmitted to the hospital for non-union than younger, which confirms our findings. An interesting observation in our study is that 32% of the patients which were treated for non-union, were smoker, whereas in the general European public around 20% are smoker, with 28% in Turkey and, 11% in the United States. Especially in the conventional group the percentage of smoker was high (45%). We could not detect that time to union was significantly delayed for smokers [ 54 ]. The incidence of non-union in the upper arm and forearm is described with 1.3/100,000 [8; 55], and for the hand with 2.9–3.08/100,000 [8; 55]. This sums up to 5,824 − 13,798 patients per year in Europe. Walter et al. [ 55 ] describes a re-imbursement for nonunion revision between €2900 (hand) and €5095 (forearm). We obtained a reduction of the non-union rate by 22% (p = 0.12096). Because this difference was not significant, we would use a reduction of 10% for our calculations. When using the human allogeneic cortical bone screw the number of non-unions could be reduced by at least 10% (700 patients). Calculating with €4000 per reimbursement this accumulates to €2,800,000 per year for the health system in Europe. Additionally, there would be savings because there is no need for hardware removal (as described by Reeh et al. [ 8 ]) and the savings for the patient for lost wages. Conclusion In conclusion, the Shark Screw® presents a reliable option for treating non-unions in the shoulder, forearm, hand, and fingers. It demonstrates a low complication rate. The human allogeneic cortical bone screw (Shark Screw®) combines both stability and biology with a single transplant. This dual functionality is unmatched by any other material, particularly one that integrates seamlessly with the host bone in accordance with its biology. As Elliott et al. [ 56 ] describes: the tissue that forms in and around a fracture should be considered a specific functional entity [ 56 ]. This ‘bone-healing unit’ produces a physiological response to its biological and mechanical environment, which leads to the normal healing of bone[ 56 ] which was confirmed for the human allogeneic cortical bone screw [ 36 ]. The Shark Screw® forms a bone healing unit with the surrounding tissue which is in constant exchange with the host tissue. The presented data show that the use of the human allogeneic cortical bone screw (Shark Screw®) alone or in combination with (remaining) metal hardware results in shorter time to union and earlier return to work after non-union revision surgery compared to the conventional treatment. The potential for cost savings (reduction in non-union rate and reduction in hardware removal after healing) favors utilization of the Shark Screw® for the revision of a non-union. Further studies have to be performed to underline these findings. Limitation of the study The retrospective design of the study is a limitation. The involvement of multiple surgeons led to variations in surgical protocols, therefore they are not described in detail in this study. Due to the positive impression after the first treatments with the human allogeneic cortical bone screw the treatment with the conventional methods was more and more diminished and thus the groups do not have similar patient numbers. Additionally the patients in the conventional group are significantly younger, which should be kept in mind when interpreting the data. Declarations Competing Interests Klaus Pastl is one of the CEOs of Surgebright GmbH, Wolfgang Palle received a travel grant from Surgebright and support for attending a workshop, all other authors do not have any conflict of interest for the reported study. Funding: no funding Author Contribution E.H., K.P., G.H.B.: Conceptualization and methodology; K.P., E.H., W.P.G.J.: Surgery; G.H.B., K.P., E.H.: formal analysis and investigation; G.H.B., K.P., E.H.: Writing original draft preparation. All authors reviewed the manuscript. Acknowledgement: non Ethical approval : Approval from the local Institutional Review Boards (IRBs) was received before the study's commencement, and the reference numbers are as follows: 1146/2023 (Ethik-Kommission of the Johannes Keppler University Linz), and M2023-25 (Ethik-Kommission Kärnten). The study was conducted in accordance with the Declaration of Helsinki. Consent to Participate: Informed consent to participate was waved by the institutional review boards (Ethik-Kommission of the Johannes Keppler University Linz and Ethik-Kommission Kärnten due to the retrospective data analysis and was not obtained. Conflict of Interest: Klaus Pastl is one of the CEOs of Surgebright GmbH, Wolfgang Palle received a travel grant from Surgebright and support for attending a workshop, all other authors do not have any conflict of interest for the reported study. Generative AI We did not use generative AI for any part of the manuscript. Submission declaration The manuscript has not been published previously and is not under consideration for publication elsewhere. Its publication is approved by all authors and tacitly or explicitly by the responsible authorities where the work was carried out, and that, if accepted, it will not be published elsewhere in the same form, in English or in any other language, including electronically without the written consent of the copyright holder. Data Availability Data is provided as supplemental information References Moghaddam-Alvandi A, Zimmermann G, Büchler A, et al. [Results of nonunion treatment with bone morphogenetic protein 7 (BMP-7)]. 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A systematic review of mechanical stabilization by screw fixation without bone grafting in the management of stable scaphoid non-union. J Clin Orthop trauma. 2021;17:112–7. Van Nest D, Ilyas AM. (2022) Scaphoid Nonunion: A Review of Surgical Strategies. Orthopedics:1–8. Burnier M, Loisel F, Ardouin L, et al. Treatment of scaphoid nonunion by arthroscopic cancellous bone grafting. Volume 109. Orthopaedics & traumatology, surgery & research; 2023. p. 103665. 8s. Moog P, Cerny MK, Schmauss D, Betzl J, Löw S, Erne H. (2020) [Osteophyte-induced impingement reduces range of motion in humpback deformity of incorrectly healed scaphoid reconstruction]. Unfallchirurg. Yarar-Schlickewei S, Frosch KH, Schlickewei C. [Scaphoid pseudarthrosis without circulatory disorder: Management and standard procedure for primary treatment]. Unfallchirurg. 2019;122(3):191–9. Dodds SD, Halim A. Scaphoid Plate Fixation and Volar Carpal Artery Vascularized Bone Graft for Recalcitrant Scaphoid Nonunions. 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Comparison of the results of percutaneous and open screw fixation in the treatment of scaphoid nonunion fractures. Eur Rev Med Pharmacol Sci. 2022;26(24):9204–11. Braun KFHM, Biberthaler P. Definition, Risikofaktoren und Klassifikationsmodelle von Pseudarthrosen. Op-Journal. 2019;35(03):217–24. Villani F, Uribe-Echevarria B, Vaienti L. Distal interphalangeal joint arthrodesis for degenerative osteoarthritis with compression screw: results in 102 digits. J Hand Surg Am. 2012;37(7):1330–4. Lari A, Nouri A, Alherz M, Prada C. Operative treatment of distal radius fractures involving the volar rim-A systematic review of outcomes and complications. Eur J Orthop Surg Traumatol; 2023. Andre C, Coursier R, Saab M et al. (2023) Functional and radiologic outcomes of non-displaced scaphoid waist fractures in adolescents approaching skeletal maturity: comparison between conservative treatment and percutaneous screw fixation. Orthopaedics & traumatology, surgery & research: OTSR:103636. Dunn J, Kusnezov N, Fares A, Mitchell J, Pirela-Cruz M. The Scaphoid Staple: A Systematic Review. Hand (N Y). 2017;12(3):236–41. Zenke Y, Oshige T, Menuki K, et al. Four-corner fusion method using a bioabsorbable plate for scapholunate advanced collapse and scaphoid nonunion advanced collapse wrists: a case series study. BMC Musculoskelet Disord. 2020;21(1):683. Waters TL, Collins LK, Cole MW, et al. The Snuffbox: The Effect of Smokeless Tobacco Use on Scaphoid Fracture Healing. J Am Acad Orthop Surg; 2023. Walter N, Hierl K, Brochhausen C, Alt V, Rupp M. The epidemiology and direct healthcare costs of aseptic nonunions in Germany - a descriptive report. Bone Joint Res. 2022;11(8):541–7. Elliott DS, Newman KJ, Forward DP et al. (2016) A unified theory of bone healing and nonunion: BHN theory. Bone Joint J, 98–b(7):884–891. Additional Declarations Competing interest reported. Klaus Pastl is one of the CEOs of Surgebright GmbH, Wolfgang Palle received a travel grant from Surgebright and support for attending a workshop, all other authors do not have any conflict of interest for the reported study. Supplementary Files TableS1upperextremities.xlsx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4562491","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":315513416,"identity":"2052a9fb-55e8-4bf9-ac30-7693ea95f140","order_by":0,"name":"Elisabeth Huber","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIiWNgGAWjYDACdsYGBiBiMGDgYWAG8uUYDrCx4dfCDNEiAdNiDNVigEcLECNrSWwgpIWfmbn5w88dNnXmDLzHpAsq7qX3HW9Le8BQ8wenFslmxjbJ3jNpEpYNfGnSM84U5848c+y4AcMx3LYYHGZsY+BtOyxhcIDHTJq3LSF3w430NgkGNtxa7A8zNn/82/YfquVfQroBWMs/PLYAQwxo+AGoloaEBIMbacckGNtwa5EAOkxa9kyy5IbDPMbWM44lGAL9kiaR2GeMUwt/e/vjj2932PEbHO8xvF1QkyDPd7zNTOLDNzmcWhCAGZmTQISGUTAKRsEoGAW4AQARClEbu3nPIQAAAABJRU5ErkJggg==","orcid":"","institution":"DOKH Friesach","correspondingAuthor":true,"prefix":"","firstName":"Elisabeth","middleName":"","lastName":"Huber","suffix":""},{"id":315513417,"identity":"b46c6bc4-b00d-4a71-bc88-9d93d51334fd","order_by":1,"name":"Gerd Jakob","email":"","orcid":"","institution":"Landeskrankenhaus Villach","correspondingAuthor":false,"prefix":"","firstName":"Gerd","middleName":"","lastName":"Jakob","suffix":""},{"id":315513418,"identity":"117f95c2-6728-4542-8329-e38dd5068e2d","order_by":2,"name":"Wolfgang Palle","email":"","orcid":"","institution":"DOKH Friesach","correspondingAuthor":false,"prefix":"","firstName":"Wolfgang","middleName":"","lastName":"Palle","suffix":""},{"id":315513419,"identity":"2be4e47f-62ce-4cc4-8b3b-cf8c221a7f52","order_by":3,"name":"Gudrun H. Borchert","email":"","orcid":"","institution":"Dr. Borchert Medical Information Management","correspondingAuthor":false,"prefix":"","firstName":"Gudrun","middleName":"H.","lastName":"Borchert","suffix":""},{"id":315513420,"identity":"5b7b6f9f-0cb5-4a56-8757-79754090f182","order_by":4,"name":"Klaus Pastl","email":"","orcid":"","institution":"Klinik Diakonissen Linz","correspondingAuthor":false,"prefix":"","firstName":"Klaus","middleName":"","lastName":"Pastl","suffix":""}],"badges":[],"createdAt":"2024-06-11 08:30:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4562491/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4562491/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":60201657,"identity":"5f303490-a6f4-4ccb-a7aa-4b6f5aea9802","added_by":"auto","created_at":"2024-07-13 02:50:38","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":696798,"visible":true,"origin":"","legend":"\u003cp\u003eA failed thumb IP-arthrodesis of a 72-year-old female with chronic polyarthritis is depicted. a: presurgical X-ray; b: the patient was treated with 1 Shark Screw®; union was recorded after 12 weeks and c: the Shark Screw® totally remodeled into host bone after 21 months. d-i: The revision after a failed arthrodesis of the middle finger in both hands with a metal screw of a 63 years-old female, d-i left hand. d-e: The X-ray after the first treatment. Even hardware removal did not lead to union 31 months after surgery. f-g: For revision one Shark Screw was paced and union was obtained after 26 weeks. h-i: 36 months after surgery the Shark Screw® is nearly\u003c/p\u003e\n\u003cp\u003etotally remodelled. j-o: The middle finger of the right hand. j-k: The Herberden osteoarthrosis was bridged with a 3 mm metal screw in the first attempt, l-m; even after 21 months no union was recorded. Revision was performed with one 3.5 mm Shark Screw®. n-o: Starting the consolidation is visible 6 weeks after revision\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/e67535e945fa9896e6cfb242.png"},{"id":60201656,"identity":"6c3db358-4e3a-4410-9d98-40aeea9e5698","added_by":"auto","created_at":"2024-07-13 02:50:38","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":708867,"visible":true,"origin":"","legend":"\u003cp\u003ea-d: A 31-year-old male with a non-union of the scaphoid. a: presurgical X-ray; b: The patient was treated with 1 Shark Screw®. Union was obtained after 8 weeks. c-d: After 35 months the Shark Screw® is totally remodeled into host bone. e-g: An 82-years-old female was treated to overcome the non-union of the scaphoid-trapezoid-trapezium-arthrodesis. E: pre-revision X-ray; f: the metal screw was removed, and the patient was treated with 2 Shark Screws®, union was detected 8 weeks after revision surgery. g: 14 months after revision the Shark Screw® is not any more visible. h-l: non-union of the scaphoid after conventional treatment even though autograft was used. h: pre-revision X-ray. i: intraoperative fluoroscopy using a vascularized femur condylar span which was attached to the aorta radialis. The span was stabilized with 4 K-wires. j: 12 weeks after surgery with the non-union still visible. k: Shock-wave therapy did not improve the situation after 8 month. l: Five years after revision the necrosis of the proximal pole is visible, but the patient is nearly pain-free\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/10dcf9bbd997f77eff3519ab.png"},{"id":60201114,"identity":"d8a2175f-36fa-4eb9-8475-b8de56621f48","added_by":"auto","created_at":"2024-07-13 02:42:38","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":411625,"visible":true,"origin":"","legend":"\u003cp\u003ea-d: 59-year-old patient after non-union treatment after a fall at home: a: first surgery was performed with a humerus nail T2 (Stryker) 10 months after this surgery no union was obtained. Revision was performed with a 9-hole plate and one 4 mm and one 4.5 mm Shark Screw®; b: 4 weeks after revision; c: 8 weeks after revision, remodeling is visible. Union recorded 12 weeks post-revision; d: 1-year post-revision the Shark Screws® are totally remodelled. A radius-non-union in a 39-year-old male is shown. e-f: pre-revision X-rays. As the former radius plate was bent, the radius was shortened in relation to the ulna. During the revision operation, the plate on the radius was replaced and the radius was restored to its original length. The resulting bone defect was filled with an allogeneic cortical block and DBM putty. In addition, the bone defect was stabilized and bridged with 2 Shark Screws®. g-h: post-surgery X-rays; Union was obtained after 12 weeks. i-j: Before metal hardware removal 1 year after revision surgery; k: After metal removal\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/889a0c4b6665b55d768381dd.png"},{"id":60201121,"identity":"e09672b2-51e4-48ac-b2c5-2e87a8dd0b77","added_by":"auto","created_at":"2024-07-13 02:42:38","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":682352,"visible":true,"origin":"","legend":"\u003cp\u003eThe nonunion of the epicondyle of the lateral humerus of an 80-year-old male. a: presurgical X-ray; b: pre-surgical CT; c: Non-union was treated with 3 Shark Screws®. Union was observed after 10 weeks. d: 4 months after surgery; e: 21 months after revision the Shark Screws® are totally remodelled into host bone\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/611e0c6897d5bf070fd5bcd3.png"},{"id":60201120,"identity":"e9f8a687-4f94-4cad-94b5-25d3ed3ca503","added_by":"auto","created_at":"2024-07-13 02:42:38","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":491501,"visible":true,"origin":"","legend":"\u003cp\u003eA humerus shaft non-union of a 40-year-old male (a-f). a-b: presurgical X-rays; c-d: The nail was left in, but the non-union was bridged with 3 Shark Screws®, post-surgical X-rays; Union was recorded after 7 weeks. e-f: 8 months after revision the Shark Screws® were remodeled to host bone and are not any more visible. g-i: A failed Laterjet in a 35-year-old male G: pre-surgical X-ray; h: The metal screws were taken off and preparation of the bone bed for the Shark Screw® was performed (drilling and thread cutting). 1 Shark Screw® was used for revision. Union was observed 2 months after surgery. i: X-ray 4 months after surgery the Shark Screw® is nearly remodelled into host bone\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/24aa7761beedaa6a3bf28b05.png"},{"id":60201117,"identity":"df827300-fb51-4e5e-8fb6-5cf542856498","added_by":"auto","created_at":"2024-07-13 02:42:38","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":536955,"visible":true,"origin":"","legend":"\u003cp\u003ea-d: the revision of the non-union of a clavicula of a 64-year-old female. a-b: CT-scans: The former metal hardware was removed in the same session. c: 2 Shark Screws® were used for revision. 12 weeks after revision bone union was recorded; d: After 15 months the Shark Screw® ist totally remodelled into host bone. e-g: case of non-union after osteomyelitis of a 52-year-old male after a fall at home. E: presurgical X-ray; f: The fracture was anatomically reduced after pseudoarthrosis removal, insertion of a microvascular pedicled MFC spans and bridging osteosynthesis with a 10-hole lateral clavicle plate (Arthrex, Naples, FL, USA). g: complete union 1 year after revision\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/cc55a6579e6f6f7e1cf7aa3e.png"},{"id":60201658,"identity":"84956842-f0ed-4345-90bd-da1a160a6f49","added_by":"auto","created_at":"2024-07-13 02:50:38","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":766795,"visible":true,"origin":"","legend":"\u003cp\u003ea-e: The case of a non-union of a scaphoid fracture with conservative treatment. a: pre-surgical X-ray; b: interoperative fluoroscopy, Revision was performed using Linscheid maneuver, correction of Humpback deformity, using an autologous iliac crest cortical bone span and a Herbert Screw. c: X-ray 2 months after revision; d: Union was observed 6 months after surgery. Metal hardware was removed 1 year later. e: X-ray 18 months post revision. f-h: A case of 55-year-old-male with partial union after revision surgery in the Shark Screw® group. f: Pseudoarthrosis after scaphoid fracture in the middle third after initial surgical treatment with angle stable Medartis scaphoid plate (1.5 mm). Revision was performed including metal removal, elimination of the humpback deformity and pseudoarthrosis bridging with one 3.5 mm Shark Screw®. g: 6 weeks after revision surgery. h: Two years after revision we recorded increasing callus formation, the pseudoarthrosis is still visible centrally, the Shark Screw® is now completely resorbed, the fracture is not yet completely united\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/173ea3d4c26e5573aa434990.png"},{"id":79158074,"identity":"367d9293-1704-4479-b619-1bac2c927389","added_by":"auto","created_at":"2025-03-25 06:47:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7661241,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/630571f7-1640-4245-9130-e0d6a27fc879.pdf"},{"id":60201116,"identity":"4b728d7c-680b-437e-a953-b2d524b9050b","added_by":"auto","created_at":"2024-07-13 02:42:38","extension":"xlsx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":18960,"visible":true,"origin":"","legend":"","description":"","filename":"TableS1upperextremities.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-4562491/v1/657d6daad8170ec6d6401c35.xlsx"}],"financialInterests":"Competing interest reported. Klaus Pastl is one of the CEOs of Surgebright GmbH, Wolfgang Palle received a travel grant from Surgebright and support for attending a workshop, all other authors do not have any conflict of interest for the reported study.","formattedTitle":"Non-union Treatment in the arm, wrist, and fingers: A Multicenter Retrospective Study Contrasting Conventional Treatment with the Allogeneic Cortical Bone Screw (Shark Screw®)","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePhysiological fracture healing is a biological outstanding achievement. It can be disturbed by many factors [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The cause of non-union seems to be an interaction of various biological and biomechanical factors with systemic and local interactions [1; 2]. Regarding local causes, unsuitable or faulty stabilization, possibly with long periods of reduced loading, pronounced soft tissue damage, reduced blood supply in the affected region and traumatic or iatrogenic destruction of the periosteum, former radiation and infection are considered to be permissive for failure of the fracture to heal [1; 2]. Gagnon et al. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] summarize in their recent review that: \u0026rdquo;Every non-union case is different in terms of bone defect, biology, mechanical stability, surgical technique and host factors\u0026hellip;We might never see a level 1, high powered and robust study defining the efficacy, safety profile and cost-effectiveness\u0026rdquo;[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] because of the different procedures necessary to overcome non-union. Non-union results in prolonged pain and reduced functionality [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Socioeconomic costs are caused by the complex operation treatment strategies [\u003cspan additionalcitationids=\"CR5 CR6\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Therefore, successful therapy often consists of a combination of optimizing mechanical stability and activating biological factors [1; 7; 8]. For the biological activation of fracture healing the application of autologous cancellous bone is often used [2; 9\u0026ndash;11], but its limited availability and the high donor site morbidity [9; 11] is a great disadvantage. The site of non-union can be augmented with bone graft. Allografts are an alternative and perform as autografts [9; 12]. The conventional method for treating non-union is the debridement of the non-union and the stabilization with metal plates and screws. But metal hardware leads to complications and a potential second operation for hardware removal. Complication rates between 30\u0026ndash;60% are reported after total wrist arthrodesis and a re-operation rate between 19\u0026ndash;64% [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Nwosu et al. describe in their recent review 3\u0026ndash;31%[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] hardware related complications. Hardware removal was recorded between 6.8% after volar locking plate fixation of distal radius fractures in adults [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] up to 77% after arthrodesis for primary osteoarthritis of the trapezio-metacarpal joint [\u003cspan additionalcitationids=\"CR16 CR17\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Avoiding hardware removal and donor site morbidity while obtaining comparable results as with conventional methods would decrease economic burden and the higher risk for the patient.\u003c/p\u003e \u003cp\u003eThe non-union rate in the shoulder is reported with 5% [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Non-union in long bones is recorded up to 30% [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Vanderkarr et al. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] describe a 7.2% non-union rate for the humerus. In the forearm non-unions are reported to be between 0\u0026ndash;60% [10; 21\u0026ndash;23]. Non-union rates are described with 4% for the radius, with 7% for the ulna [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] and with 11% for the hand [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. For the scaphoid, non-unions are reported between 0% and 18% and in some cases up to 63% [11; 24\u0026ndash;27]. Treating scaphoid non-union arthroscopically with autograft from the distal radius and 4 pins resulted in 93.5% union [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Dislocated fractures, in particular seem to be prone to non-union [6; 29; 30]. Displaced scaphoid fractures are at risk for nonunion due to a variety of factors, including interfragmentary instability, retrograde vascular supply, and lack of soft tissue attachments on a largely cartilaginous surface [30; 31]. Non-union after arthrodesis of the proximal interphalangeal joint of the finger is reported with 3.9% using the compression screw and 8.6% after interosseous wiring [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Fractures with severe soft tissue trauma are also at increased risk of non-union [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo avoid progression to arthrosis of the scaphoid there are 3 major aims: restauration of the form of the scaphoid, restauration of the carpal alignment and bony consolidation of the scaphoid [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Despite improvement in surgical procedures treating non-union, there is no consensus over the optimal treatment option.\u003c/p\u003e \u003cp\u003eFor certain age groups Mills at al. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] described a non-union rate up to 9% and 80 non-unions per 1000 fractures in the shoulder per year for the age group between 35\u0026ndash;45 years [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. This is mainly true for male patients, for female patients an increase in the incidence is reported with age [8; 34].\u003c/p\u003e \u003cp\u003eUsing the human allogeneic cortical bone screw (Shark Screw\u0026reg;) is a new option to treat non-unions[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The cortical bone screw provides a close contact between allograft and host bone, which is required for revascularisation and healing as described by Basile et al. [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] and confirmed by Brcic for the allogeneic cortical bone screw [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. It is described that (metal) screw fixation disrupts the internal vascularity [37; 38] more than a K-wire and hence reduces the potential benefits of vascular grafts [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Perren et al. [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e] describes that a plate used for e.g. radius fixation inhibits the blood reaching or leaving the bone. This complication is avoided by using the cortical bone screw because vascularization is not disrupted. The success of the graft may also depend on the quality of the bone bed from which most of the revascularization arises [36; 39]. The processing, preservation and sterilization (via irradiation or chemically sterilized) of allograft bone may influence its biophysical and general biological properties [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The goal of using bone allograft is to initiate a healing response from the host bed that will produce new bone at the host-graft interface and within the porous body of the graft material [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The mechanical stability of the graft is of vital importance [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] and is given by the design of the Shark Screw\u0026reg; as a set screw. For the human allogeneic cortical bone screw this process was shown after 10 weeks [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Recent publications show that, when using the Shark Screw, the union rate is between 94\u0026ndash;100% for fracture treatment, arthrodesis and non-union [\u003cspan additionalcitationids=\"CR41 CR42\" citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e] and thus similar to union rates with conventional methods.\u003c/p\u003e \u003cp\u003eThe multicentred retrospective data analysis presented here aims to compare the outcome of non-union treatment with 1) conventional methods (metal crews/plates/nails\u0026thinsp;\u0026plusmn;\u0026thinsp;graft and 2) the human allogeneic cortical bone screw (Shark Screw\u0026reg;) in upper extremities. We recorded patient demographics, follow up time, union rate, time to union, time to return to work, complications, and percentage of hardware removal. We collected data from clavicula, humerus, radius, ulna, the scaphoid, and the finger joints.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cp\u003eApproval from the local Institutional Review Boards (IRBs) was received before the study's commencement, and the reference numbers are as follows: 1146/2023 (Ethik-Kommission of the Johannes Keppler University Linz), and M2023-25 (Ethik-Kommission K\u0026auml;rnten). The study was conducted in accordance with the Declaration of Helsinki. Informed consent to participate was waved by the institutional review boards.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and patient population\u003c/h2\u003e \u003cp\u003eThis study was designed as a retrospective multicentred study. Clinical and radiographic data were collected from the medical charts of 31 patients who underwent non-union surgery on the shoulder, arm, and fingers between 2016 and 2022.\u003c/p\u003e \u003cp\u003eThe specific treatment method for non-union was not a selection criterion. Our study included a total of 31 patients, with 11 patients (37%) in the conventional treatment group and 20 patients (64%) in the Shark Screw\u0026reg; group. Patient demographics are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePatient Data\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eConventional treatment\u003c/p\u003e \u003cp\u003e(metal hardware\u0026thinsp;\u0026plusmn;\u0026thinsp;graft)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eShark Screw\u0026reg; treatment\u003c/p\u003e \u003cp\u003e(Shark Screw\u0026reg; \u0026plusmn; metal plate)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNumber of patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean \u0026plusmn; SD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNumber of patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMean\u0026plusmn; SD\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge [years]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40.8\u0026thinsp;\u0026plusmn;\u0026thinsp;19.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e54.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.7*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI [kg/m\u0026sup2;]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.1\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e25.1\u0026thinsp;\u0026plusmn;\u0026thinsp;4.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender [male/female]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6/5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10/10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoker [yes/no]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5/6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5/15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComorbidities [yes/no]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4/7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9/11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-union revision following:\u003c/p\u003e \u003cp\u003eSurgical fracture treatment\u003c/p\u003e \u003cp\u003eElective surgery (arthrodesis, osteotomy)\u003c/p\u003e \u003cp\u003eConservative fracture treatment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003cp\u003e7\u003c/p\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAseptic/septic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10/1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20/0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*p\u0026thinsp;=\u0026thinsp;0.03909 \u003cem\u003evs\u003c/em\u003e. conventional group\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ePatients from two treatment groups were evaluated: the conventional treatment involving metal hardware (screws/plates) ) with or without bone graft (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), and the Shark Screw\u0026reg; procedure.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLocalization of Pseudarthrosis\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAnatomic localization of non-union\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eConventional treatment (metal hardware\u0026thinsp;\u0026plusmn;\u0026thinsp;graft)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eShark Screw\u0026reg; treatment (Shark Screw\u0026reg; \u0026plusmn; metal plate)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNumber of patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eShoulder\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eClavicular\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eShoulder (Latarjet)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHumerus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUlna\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRadius\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHand\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eScapho-Trapezo-Trapezoidal (STT)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWrist\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRepetitive Strain Injury (RSI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eScaphoid\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFinger\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePIP3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDIP1 CP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDIP2,3,4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDIP2,3,5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMCP 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe comorbidities included Diabetes Mellitus Type II, COPD, mutilating chronic polyarthritis, arterial hypertension, adeno carcinoma, (allergic) asthma bronchial, Lupus erythematosus, osteoporosis, foramen ovale, deep vein thrombosis, varicose, benign prostatic hyperplasia.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eInclusion Criteria\u003c/h2\u003e \u003cp\u003eTo be eligible for inclusion in the study, patients were required to have at least one follow-up visit at least 6 months post-surgery or until bone healing was documented. These cases encompassed non-union after elective procedures (arthrodesis and osteotomy), after surgical fracture treatment, and after conservative fracture treatment (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eExclusion Criteria\u003c/h2\u003e \u003cp\u003eWe excluded non-unions related to tumour-related cases.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eSurgical procedures\u003c/h2\u003e \u003cp\u003eSurgical procedures vary with location of the non-union. For using the cortical bone screw surgical procedures were described before for different locations [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e] of the hand, for scaphoid fractures [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e], and for distal interphalangeal joint arthrodesis [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWe recorded the following parameter: Non-union location for revision (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), autograft and allograft use, follow up time, complications, union rate, time to union and time to return to work (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical Data and Outcome\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c6\" namest=\"c3\"\u003e \u003cp\u003eConventional treatment\u003c/p\u003e \u003cp\u003e(metal hardware\u0026thinsp;\u0026plusmn;\u0026thinsp;graft)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c10\" namest=\"c7\"\u003e \u003cp\u003eShark Screw\u0026reg; treatment\u003c/p\u003e \u003cp\u003e(Shark Screw\u0026reg; \u0026plusmn; metal plate)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eNumber of patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD/%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eNumber of patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD/%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of patients\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emetal hardware use\u003c/p\u003e \u003cp\u003eadditional to Shark Screw\u0026reg;\u003c/p\u003e \u003cp\u003emetal left in from previous surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e11 \u003cem\u003e(per definition)\u003c/em\u003e\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e2 (1xprothesis)\u003c/p\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAutograft use\u003c/p\u003e \u003cp\u003eIliac crest\u003c/p\u003e \u003cp\u003eMedial femoral condylar span (MFC)\u003c/p\u003e \u003cp\u003eLateral femoral condylar span (LFC)\u003c/p\u003e \u003cp\u003eAllograft use\u003c/p\u003e \u003cp\u003eDBM putty\u003c/p\u003e \u003cp\u003ecortical span\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003cp\u003e2\u003c/p\u003e \u003cp\u003e2\u003c/p\u003e \u003cp\u003e0\u003c/p\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e7\u003c/p\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFollow up [weeks]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e71.0\u0026thinsp;\u0026plusmn;\u0026thinsp;41.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e50.5\u0026thinsp;\u0026plusmn;\u0026thinsp;36.4\u003csup\u003e\u0026amp;\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplications [yes/no][%]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e4/7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e36.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e1/19*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e5.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMetal hardware removal [%]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e63.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e1\u003csup\u003e%\u003c/sup\u003e***\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e5.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBony union rate [%]\u003c/p\u003e \u003cp\u003ePartial union [%]\u003c/p\u003e \u003cp\u003eNon-union [%]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e72.7\u003c/p\u003e \u003cp\u003e9.1\u003c/p\u003e \u003cp\u003e18.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e19\u003c/p\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e95.0\u003c/p\u003e \u003cp\u003e5.0\u003c/p\u003e \u003cp\u003e0.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime to Union [weeks]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e38.8\u0026thinsp;\u0026plusmn;\u0026thinsp;26.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e12.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.4****\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eReturn to work [weeks]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e25.3\u0026thinsp;\u0026plusmn;\u0026thinsp;16.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e12.0\u0026thinsp;\u0026plusmn;\u0026thinsp;5.5**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c10\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"10\"\u003e\u003csup\u003e\u0026amp;\u003c/sup\u003ep\u0026thinsp;=\u0026thinsp;0.16055; *p\u0026thinsp;=\u0026thinsp;0.02311; **p\u0026thinsp;=\u0026thinsp;0.00238; \u003csup\u003e%\u003c/sup\u003eHardware removal from previous surgery; ***p\u0026thinsp;=\u0026thinsp;0.000357; ****p\u0026thinsp;=\u0026thinsp;0.000247\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eComplications\u003c/h2\u003e \u003cp\u003eWe defined non-union and partial union after 6 months, osteonecrosis, screw loosening or screw breakage as a complication.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistics\u003c/h2\u003e \u003cp\u003eData are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD. Due to the non-Gaussian distribution of the data, non-parametric Kruskal\u0026ndash;Wallis ANOVA was used for calculating significant differences in quantitative values. Ordinal values were evaluated with contingency tables using Fisher\u0026rsquo;s exact test for significance. A p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 is considered to be significant with a power\u0026thinsp;\u0026gt;\u0026thinsp;0.8. All statistical analyses were performed using Origin Pro statistical software (OriginPro, version 2023; OriginLab Corporation, Northampton, MA).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003ePatient average age was 41 years in the conventional group and 55 years in the Shark Screw\u0026reg; group, this difference was statistically significant (p\u0026thinsp;=\u0026thinsp;0.03909). Patients average BMI was 25 kg/m\u0026sup2;. In the conventional group and in the Shark Screw\u0026reg; group were smoker, 45% and 25%, respectively. 52% were male patients (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eExcept for age, patient demographics were not significant different between the conventional group and the Shark Screw\u0026reg; group (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Patients in the Shark Screw group were significantly older.\u003c/p\u003e \u003cp\u003eFor the conventional group in 4 cases metal screws were used, in 3 cases plates, in 2 cases K-wires, 1 mini-fixateur and in 1 case a prothesis was placed. In the Shark Screw\u0026reg; group in 1 case the metal hardware was left in. Autograft was used only in the conventional group in 6 cases (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Allograft was not used in the conventional group but in 8 cases (DBM putty (7 cases) and one cortical span) in the Shark Screw\u0026reg; group.\u003c/p\u003e \u003cp\u003eFollow up was 17 months in the conventional group and 12 months in the Shark Screw\u0026reg; group.\u003c/p\u003e \u003cp\u003eThe union rate was 72.7% (8 of the 11 patients) in the conventional group and 95.0% (19 of the 20 patients) in the Shark Screw\u0026reg; group. Time to union was significantly shorter in the Shark Screw\u0026reg; group with 12 weeks in comparison to 39 weeks in the conventional group (p\u0026thinsp;=\u0026thinsp;0.000247). Smoking delayed union in the conventional group, but it did not reach statistical significance, but not in the Shark Screw\u0026reg; group (data not shown). There was an earlier return to work for the Shark Screw\u0026reg; group, with 12 weeks for the Shark Screw\u0026reg; group and 25 weeks for the conventional group (p\u0026thinsp;=\u0026thinsp;0.00238).\u003c/p\u003e \u003cp\u003eComplications were low in both groups with 4 in the conventional group (2 non-unions, one of them with osteonecrosis, 1 partial union and 1 screw loosening) and 1 in the Shark Screw\u0026reg; group (partial union). Non-unions were recorded in patients with an age of 35 and 59 years, whereas patients obtaining only partial unions were older (55 years and 78 years). All patients with non-unions or only partial unions were non-smokers. Except for the 59-year-old patient (Lupus erythematosus) in the conventional group, none of the patients with complications had co-morbidities at the time of surgery. Metal removal in the conventional group was performed in 7 of the 11 patients (64%) compared to 1 patient (5%) in the Shark Screw\u0026reg; group. The one patient in the Shark Screw\u0026reg; group had metal hardware from a previous surgery, which was left in place during revision surgery, but removed later.\u003c/p\u003e \u003cp\u003eA failed thumb IP-arthrodesis of a 72-year-old patient with chronic polyarthritis is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea-c and was treated with 1 Shark Screw\u0026reg;, union was recorded after 12 weeks and the Shark Screw\u0026reg; totally remodeled into host bone after 21 months (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). The revision after a failed arthrodesis of a middle finger with a metal screw of a 63 years-old patient is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed-i for the left hand and in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ej-o for the right hand. The X-ray after the first treatment is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed-e. Even hardware removal did not lead to union 31 months after surgery. For revision one Shark Screw was placed (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef-g) and union was obtained after 26 weeks. 36 months after revision surgery the Shark Screw\u0026reg; is nearly totally remodelled (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eh-i). The treatment of a non-union of a middle finger of the right hand is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003el-q: The Herberden Osteoarthrosis was bridged with a 3 mm metal screw in the first attempt (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ej-k), even after 21 months no union was recorded (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003el-m). Revision was performed with one 3.5 mm Shark Screw\u0026reg;. Starting the consolidation is visible 6 weeks after revision (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003en-o).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003etotally remodelled. j-o: The middle finger of the right hand. j-k: The Herberden osteoarthrosis was bridged with a 3 mm metal screw in the first attempt, l-m; even after 21 months no union was recorded. Revision was performed with one 3.5 mm Shark Screw\u0026reg;. n-o: Starting the consolidation is visible 6 weeks after revision\u003c/p\u003e \u003cp\u003eA 31-year-old patient with a non-union of the scaphoid is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea-g. Revision was performed with 1 Shark Screw\u0026reg; (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). Union was obtained after 8 weeks (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). After 35 months the Shark Screw\u0026reg; is totally remodeled into host bone (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). An 82-years-old patient was treated with 2 Shark Screws\u0026reg; (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef) to overcome the non-union (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee) of the scaphoid-trapezoid-trapezium-arthrodesis. Union was detected 8 weeks after revision surgery. 14 months after revision the Shark Screw\u0026reg; is not any more visible (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eg). In Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eh-l we present the non-union obtained for the scaphoid after conventional treatment even though autograft was used. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eh pre-revision X-ray. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ei intraoperative fluoroscopy using a vascularized femur condylar span which was attached to the aorta radialis. The span was stabilized with 4 K-wires. 12 weeks after surgery is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ej with the non-union still visible. Shock-wave therapy did not improve the situation after 8 month (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ek). Five years after revision, the necrosis of the proximal pole is visible, but the patient is nearly pain-free (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003el).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eA 59-year-old patient was treated for non-union after using a humerus nail after a fall at home (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), 10 months after initial surgery non-union was recorded (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). For revision, non-union debridement was performed, the nail was removed and replaced with a 9-hole plate. Non-union was additionally bridged with 2 Shark Screws\u0026reg;. Four weeks after revision the Shark Screws\u0026reg; are still well visible and union not yet observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). Eight weeks after revision (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec) remodelling is visible in part of the former non-union area. Union was recorded 12 weeks after revision surgery. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed shows union and full remodelling of the Shark Screws\u0026reg; 1-year post-revision. A radius-non-union in a 39-year-old patient is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee-k. As the former radius plate was bent, the radius was shortened in relation to the ulna (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee-f). During the revision operation, the plate on the radius was replaced and the radius was restored to its original length. The resulting bone defect was filled with an allogeneic cortical block and DBM putty. In addition, the bone defect was stabilized and bridged with 2 Shark Screws\u0026reg;(Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg-h). Union was obtained after 12 weeks; Metal hardware was removed 1 year after revision surgery (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ei-k).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe nonunion of the epicondyle of the lateral humerus of an 80-year-old patient is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Pre-revision X-ray and CT scan are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea-b. Non-union was treated with 3 Shark Screws\u0026reg; (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec) and union was observed after 10 weeks. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed represents the X-ray after 4 months and 21 months after revision the Shark Screws\u0026reg; are totally remodelled into host bone (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eA humerus shaft non-union of a 40-year-old patient is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea-f. The nail was left in, but the non-union was bridged with 3 Shark Screws\u0026reg; (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec-d). Union was recorded after 7 weeks. 8 months after revision the Shark Screws\u0026reg; were remodeled to host bone and are not any more visible (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ee and ). A failed Laterjet in a 35-year-old patient was treated with 1 Shark Screw\u0026reg; (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eg-i). The metal screws were taken off (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eg). No debridement of the non-union was performed, only the bone bed was prepared for the Shark Screw\u0026reg; (drilling and thread cutting). 1 Shark Screw\u0026reg; was used for revision (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eh). Union was observed 2 months after surgery. 4 months after surgery the Shark Screw\u0026reg; is totally remodelled into host bone (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ei).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea-d we show the revision of the non-union of a clavicula of a 64-year-old patient. Former metal hardware (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea-b) was removed in the same session and 2 Shark Screws\u0026reg; were used for revision. Union was obtained 12 weeks after revision (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec). 15 months after revision bone union is visible and the Shark Screws\u0026reg; are totally remodelled into host bone. In Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ee-g we present the case of non-union union after osteomyelitis of a 52-year-old patient after a fall at home. The fracture was anatomically reduced after pseudoarthrosis removal, insertion of microvascular pedicled MFC spans and bridging osteosynthesis with a 10-hole lateral clavicle plate (Arthrex, Naples, FL, USA, Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ef). With complete union 1 year after revision (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eg).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eA case of a non-union of a scaphoid fracture with conservative treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea) is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea-e. Revision was performed using Linscheid maneuver, correction of Humpback deformity, using an autologous iliac crest cortical bone span and a Herbert Screw (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb). Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec shows the X-ray after 2 months. Union was observed 6 months after surgery (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ed). Metal hardware was removed 1 year later. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ee shows an X-ray 18 months post revision. Pseudoarthrosis after scaphoid fracture in the middle third after surgical treatment with angle stable Medartis scaphoid plate (1.5 mm) is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ef-h. Revision was performed including metal removal (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ef), elimination of the humpback deformity and pseudoarthrosis bridging with one 3.5 mm Shark Screw\u0026reg;. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eg represents the case 6 weeks after revision surgery. Two years after revision we recorded increasing callus formation, the pseudoarthrosis is still visible centrally, the Shark Screw\u0026reg; is now completely resorbed, the fracture is not yet completely united (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eh).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe most important finding of this study is, that surgical treatment of non-union with the human allogeneic cortical bone screw (Shark Screw\u0026reg;) outperformed conventional treatment (metal hardware) with a 95% bone healing rate with a shorter time to union (26 weeks earlier) and a faster return to work (13 weeks earlier). The Shark Screw\u0026reg; group had fewer complications, with only one cases of partial union recorded, which occurred after scaphoid revision surgery. An advantage of the Shark Screw\u0026reg; is its avoidance of metal components, which may further cause problems. In 2 cases the metal hardware from previous surgeries was left in, in 1 case the old metal hardware was replaced with new metal hardware and in 1 case an ulna head prothesis was used additionally to the Shark Screws\u0026reg; used. It is possible to combine the human allogeneic cortical bone screw with metal hardware. The use of the Shark Screw\u0026reg; avoids donor site morbidity and improves bone healing.\u003c/p\u003e \u003cp\u003eThe non-union-rate depends on the location of the fracture and is reported to be the highest in the shoulder, followed by the upper arm and the forearm and is lowest in the hand [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. In contrast Reeh et al. describes that the hand has the highest probability for non-union [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Non-union is described in the humerus with 7.2% [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] \u0026minus;\u0026thinsp;9%[34; 44] and for non-union treatment in the humerus with 16% [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], in the ulna with 7% [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e] and 5%[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e] in the radius. We recorded non-union in the ulna and in the scaphoid and partial union again in the ulna and in the scaphoid, which confirms the literature. Union rates for revision of scaphoid non-union were reported with 50%-100% [11; 25; 28; 30; 42; 45\u0026ndash;47]. Millrose et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] describes a non-union rate between 3.6% and 8.6% for PIP joint arthrodesis depending on the technique used. The union rate in our cohort was 73% and 95% in the conventional group and in the Shark Screw\u0026reg; group, respectively. In the conventional group we had 1 non-union and 1 partial union in the ulna. Additional, in the conventional group there was 1 non-union in the pole fraction of the scaphoid, which is known to show higher non-union rates than for waist or distal fractures of the scaphoid [42; 47]. In the Shark Screw\u0026reg; group we did not have any non-union. The partial union in the Shark Screw\u0026reg; group was recorded in one case of scaphoid (waist fraction) non-union-revision.\u003c/p\u003e \u003cp\u003eTime to union for the clavicula after non-union was reported with 3\u0026ndash;8 weeks [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Literature reports treating forearm non-unions with allograft resulted in union after 102 days (14 weeks) and after 117 days (17 weeks) for the autograft group, when using plates and nails [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. For the forearm 6 months were described for the time to union [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Time to union was 3.8 months without bone grafting [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. After non-union revision time to union is described after 3\u0026ndash;4 months [28; 42]. Others report 15 months until union was obtained for scaphoid fractures [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. We could observe a significant shorter time to union in the Shark Screw\u0026reg; group (12.4 weeks), which was on the shorter end of the results described in the literature. Time to union in the conventional group was longer (39 weeks), with 2 patients (both smokers) having extremely long time to union (74 and 78 weeks). But still this value is in the range described in the literature [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe complication rate using the conventional methods is reported to be between 4 and 33% for major complications [11; 49] and up to 44% including minor complications [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]. Lari et al. [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e] reported in his review article a complication rate of 14% after distal radius fractures involving the volar rim. In our study we recorded 4 complications (36%) in the conventional group, 2 non-unions, 1 partial union and 1 case of screw loosening. In the Shark Screw\u0026reg; group there was only 1 complication (5%) of a partial union which confirms reports in the literature [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe hardware removal rates were reported with 7.5% [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e], 20% [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], 22% [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e] and 65% [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Removal of internal fixation is described with an incidence of 1.92/100000 person years and 20,385 cases between 2007\u0026ndash;2019 [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. In our patient cohort the hardware removal rate was 63.6% in the conventional group and 5% (1 patient) in the Shark Screw\u0026reg; group which was significant different (p\u0026thinsp;=\u0026thinsp;0.000794). The one patient in the Shark Screw\u0026reg; group had hardware from previous surgeries, which were left in place during revision.\u003c/p\u003e \u003cp\u003eRolo et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] reported a return to work after 9.4 months in the allograft group and 12.6 months in the autograft group when using metal plates for treating forearm non-unions [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. These results described are longer than observed in our study. After 4-corner fusion using bioabsorbable plates, return to work was described with 4.5 months [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e] which is longer than our values in the Shark Screw\u0026reg; group but shorter than in our conventional group. After fixation of scaphoid fractures with staples, return to work was described with 10 weeks [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e], which is similar to our observation in the Shark Screw\u0026reg; group, but primary fractures and non-unions were not separately analyzed. In our cohort, the return to work was 13 weeks earlier in the Shark Screw\u0026reg; group (12 weeks) than in the conventional group (25 weeks), which was statistically significant (p\u0026thinsp;=\u0026thinsp;0.00238). Further studies should be performed to support this findings.\u003c/p\u003e \u003cp\u003eNon-union is described more in male patients aged between 30 and 50 years [8; 44], which may be attributed to more high energy trauma [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This was not true in our cohort. There were 2 male and 2 female in the group of partial union and non-union. Reeh et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] describes that male patients under 30 years are at the highest risk for non-union, whereas for female the risk of nonunion increases with age. The latter statement was true for our patient cohort, because the 2 oldest patients with non-union/partial union were female, the male patients with non-union/partial union were younger (35 and 55 years). We can confirm the middle age group for higher rates of non-unions in male (35 years) and the higher age in female (59 years), whereas the patients with partial unions were older (55 and 78 years). Ekegren et al. [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] describes that patients between the age of 55\u0026ndash;64 years are more than twice as likely to be resubmitted to the hospital for non-union than younger, which confirms our findings.\u003c/p\u003e \u003cp\u003eAn interesting observation in our study is that 32% of the patients which were treated for non-union, were smoker, whereas in the general European public around 20% are smoker, with 28% in Turkey and, 11% in the United States. Especially in the conventional group the percentage of smoker was high (45%). We could not detect that time to union was significantly delayed for smokers [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe incidence of non-union in the upper arm and forearm is described with 1.3/100,000 [8; 55], and for the hand with 2.9\u0026ndash;3.08/100,000 [8; 55]. This sums up to 5,824\u0026thinsp;\u0026minus;\u0026thinsp;13,798 patients per year in Europe. Walter et al. [\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e] describes a re-imbursement for nonunion revision between \u0026euro;2900 (hand) and \u0026euro;5095 (forearm). We obtained a reduction of the non-union rate by 22% (p\u0026thinsp;=\u0026thinsp;0.12096). Because this difference was not significant, we would use a reduction of 10% for our calculations. When using the human allogeneic cortical bone screw the number of non-unions could be reduced by at least 10% (700 patients). Calculating with \u0026euro;4000 per reimbursement this accumulates to \u0026euro;2,800,000 per year for the health system in Europe. Additionally, there would be savings because there is no need for hardware removal (as described by Reeh et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]) and the savings for the patient for lost wages.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, the Shark Screw\u0026reg; presents a reliable option for treating non-unions in the shoulder, forearm, hand, and fingers. It demonstrates a low complication rate. The human allogeneic cortical bone screw (Shark Screw\u0026reg;) combines both stability and biology with a single transplant. This dual functionality is unmatched by any other material, particularly one that integrates seamlessly with the host bone in accordance with its biology. As Elliott et al. [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e] describes: the tissue that forms in and around a fracture should be considered a specific functional entity [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. This \u0026lsquo;bone-healing unit\u0026rsquo; produces a physiological response to its biological and mechanical environment, which leads to the normal healing of bone[\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e] which was confirmed for the human allogeneic cortical bone screw [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. The Shark Screw\u0026reg; forms a bone healing unit with the surrounding tissue which is in constant exchange with the host tissue. The presented data show that the use of the human allogeneic cortical bone screw (Shark Screw\u0026reg;) alone or in combination with (remaining) metal hardware results in shorter time to union and earlier return to work after non-union revision surgery compared to the conventional treatment. The potential for cost savings (reduction in non-union rate and reduction in hardware removal after healing) favors utilization of the Shark Screw\u0026reg; for the revision of a non-union. Further studies have to be performed to underline these findings.\u003c/p\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eLimitation of the study\u003c/h2\u003e \u003cp\u003eThe retrospective design of the study is a limitation. The involvement of multiple surgeons led to variations in surgical protocols, therefore they are not described in detail in this study. Due to the positive impression after the first treatments with the human allogeneic cortical bone screw the treatment with the conventional methods was more and more diminished and thus the groups do not have similar patient numbers. Additionally the patients in the conventional group are significantly younger, which should be kept in mind when interpreting the data.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003cp\u003eKlaus Pastl is one of the CEOs of Surgebright GmbH, Wolfgang Palle received a travel grant from Surgebright and support for attending a workshop, all other authors do not have any conflict of interest for the reported study.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eno funding\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eE.H., K.P., G.H.B.: Conceptualization and methodology; K.P., E.H., W.P.G.J.: Surgery; G.H.B., K.P., E.H.: formal analysis and investigation; G.H.B., K.P., E.H.: Writing original draft preparation. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement:\u003c/h2\u003e \u003cp\u003enon\u003c/p\u003e \u003cp\u003e \u003cstrong\u003e \u003cb\u003eEthical approval\u003c/b\u003e:\u003c/strong\u003e \u003cp\u003e Approval from the local Institutional Review Boards (IRBs) was received before the study's commencement, and the reference numbers are as follows: 1146/2023 (Ethik-Kommission of the Johannes Keppler University Linz), and M2023-25 (Ethik-Kommission K\u0026auml;rnten). The study was conducted in accordance with the Declaration of Helsinki.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to Participate:\u003c/strong\u003e \u003cp\u003eInformed consent to participate was waved by the institutional review boards (Ethik-Kommission of the Johannes Keppler University Linz and Ethik-Kommission K\u0026auml;rnten due to the retrospective data analysis and was not obtained.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConflict of Interest:\u003c/strong\u003e \u003cp\u003eKlaus Pastl is one of the CEOs of Surgebright GmbH, Wolfgang Palle received a travel grant from Surgebright and support for attending a workshop, all other authors do not have any conflict of interest for the reported study.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eGenerative AI\u003c/strong\u003e \u003cp\u003eWe did not use generative AI for any part of the manuscript.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSubmission declaration\u003c/strong\u003e \u003cp\u003eThe manuscript has not been published previously and is not under consideration for publication elsewhere. Its publication is approved by all authors and tacitly or explicitly by the responsible authorities where the work was carried out, and that, if accepted, it will not be published elsewhere in the same form, in English or in any other language, including electronically without the written consent of the copyright holder.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData is provided as supplemental information\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMoghaddam-Alvandi A, Zimmermann G, B\u0026uuml;chler A, et al. [Results of nonunion treatment with bone morphogenetic protein 7 (BMP-7)]. Unfallchirurg. 2012;115(6):518\u0026ndash;26.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEvers SCD, Wahler A, Theodora. M\u0026ouml;glichkeiten der vaskularisierten Knochentransplantationen bei Defektpseudarthrosen an ausgew\u0026auml;hlten Beispielen der oberen Extremit\u0026auml;t. 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A human, allogeneic cortical bone screw for distal interphalangeal joint (DIP) arthrodesis: a retrospective cohort study with at least 10 months follow-up. Arch Orthop Trauma Surg; 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmidmaier G, Moghaddam A. [Long Bone Nonunion]. Z Orthop Unfall. 2015;153(6):659\u0026ndash;74. quiz 675\u0026thinsp;\u0026ndash;\u0026thinsp;656.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eReigstad O, Thorkildsen R, Grimsgaard C, Melhuus K, R\u0026oslash;kkum M. Examination and treatment of scaphoid fractures and pseudarthrosis. Tidsskr Nor Laegeforen. 2015;135(12\u0026ndash;13):1138\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAsmus A, Lautenbach M, Schacher B, Kim S, Eisenschenk A. [Scaphoid pseudarthrosis: Indications for avascular iliac crest or radius bone grafts]. 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Operative treatment of distal radius fractures involving the volar rim-A systematic review of outcomes and complications. Eur J Orthop Surg Traumatol; 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAndre C, Coursier R, Saab M et al. (2023) Functional and radiologic outcomes of non-displaced scaphoid waist fractures in adolescents approaching skeletal maturity: comparison between conservative treatment and percutaneous screw fixation. Orthopaedics \u0026amp; traumatology, surgery \u0026amp; research: OTSR:103636.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDunn J, Kusnezov N, Fares A, Mitchell J, Pirela-Cruz M. The Scaphoid Staple: A Systematic Review. Hand (N Y). 2017;12(3):236\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZenke Y, Oshige T, Menuki K, et al. Four-corner fusion method using a bioabsorbable plate for scapholunate advanced collapse and scaphoid nonunion advanced collapse wrists: a case series study. BMC Musculoskelet Disord. 2020;21(1):683.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWaters TL, Collins LK, Cole MW, et al. The Snuffbox: The Effect of Smokeless Tobacco Use on Scaphoid Fracture Healing. J Am Acad Orthop Surg; 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWalter N, Hierl K, Brochhausen C, Alt V, Rupp M. The epidemiology and direct healthcare costs of aseptic nonunions in Germany - a descriptive report. Bone Joint Res. 2022;11(8):541\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElliott DS, Newman KJ, Forward DP et al. (2016) A unified theory of bone healing and nonunion: BHN theory. Bone Joint J, 98\u0026ndash;b(7):884\u0026ndash;891.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"non-union, shoulder, arm, wrist and finger, human allogeneic cortical bone screw (Shark Screw®), time to union, metal hardware removal, socio-economic effect","lastPublishedDoi":"10.21203/rs.3.rs-4562491/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4562491/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Introduction:\nThe cause of pseudarthrosis is the interaction of various biological and biomechanical factors with systemic and local interactions. Successful therapy consists of a combination of optimizing mechanical stability and activating biological factors. The conventional method for treating non-union is debridement and stabilization with metal hardware. But it leads to complications and a potential second operation for hardware removal. The human allogeneic cortical bone screw (Shark Screw®) provides a close contact between allograft and host bone, which is required for revascularisation and bone healing. The Shark Screw® merges human cortical bone properties with screw stability, addressing non-union surgery principles by integrating mechanical and biological aspects.\nMaterial and Methods: The retrospective-multi-center study included 31 patients, 11treated with the conventional method(metal hardware ± graft) and 20 patients with the Shark Screw® (±graft). Patient demographics, non-union location, autograft and/or allograft use, follow-up time, complications, union-rate, time-to-union and time-to-return to work were recorded.\nResults: Follow-up was 17 months in the conventional group and 12 months in the Shark Screw® group. The union rate was 72.7% in the conventional group and 95.0% in the Shark Screw® group. Time to union was significantly shorter in the Shark Screw® group with 12 weeks in comparison to 39 weeks in the conventional group. Conclusion The Shark Screw® presents a reliable option for treating non-unions in the shoulder, forearm, hand, and fingers. It demonstrates a low complication rate. The human allogeneic cortical bone screw (Shark Screw®) combines both stability and biology with a single transplant. The socioeconomic effect is another advantage using the Shark Screw®. Level of evidence: III","manuscriptTitle":"Non-union Treatment in the arm, wrist, and fingers: A Multicenter Retrospective Study Contrasting Conventional Treatment with the Allogeneic Cortical Bone Screw (Shark Screw®)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-13 02:42:33","doi":"10.21203/rs.3.rs-4562491/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"58a9ffd4-fc4c-4d2a-b847-702ddb259082","owner":[],"postedDate":"July 13th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-03-25T06:38:55+00:00","versionOfRecord":[],"versionCreatedAt":"2024-07-13 02:42:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4562491","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4562491","identity":"rs-4562491","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}