Clinical outcome of Bio-Tenodesis Screw Versus Bone Tunnel Fixation of Flexor Hallucis Longus Tendon Transfers to the Calcaneus in chronic Achilles tendon rupture: Retrospective Cohort Study

Clinical outcome of Bio-Tenodesis Screw Versus Bone Tunnel Fixation of Flexor Hallucis Longus Tendon Transfers to the Calcaneus in chronic Achilles tendon rupture: Retrospective Cohort Study | 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 Clinical outcome of Bio-Tenodesis Screw Versus Bone Tunnel Fixation of Flexor Hallucis Longus Tendon Transfers to the Calcaneus in chronic Achilles tendon rupture: Retrospective Cohort Study Morteza Gholipour, Seyed Mehdi Hosseini Khameneh, Fatemeh Abbasi, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7445334/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 BACKGROUND : Due to the decrease in performance of patients and the lack of return to previous activity in patients with chronic Achilles tendon rupture (CATR), the treatment is surgery in most cases. Our main aim in this study is to compare the clinical results and postoperative complications of the Flexor halluces tendon (FHL) fixation technique with bio tenodesis screw (BTS) versus the bone tunnel (BT) technique in the calcaneus bone. METHODS : A retrospective cohort study in which patients were treated with two different FHL tendon fixation techniques, from September 2018 to September 2023.The evaluation included demographic information, complications (infection and dehiscence of the wound at the surgical site and re-rupture and sural nerve damage and deep vein thrombosis), duration of surgery, length of surgical incision. The Achilles Tendon Total Rupture Score (ATRS), and the American Orthopedic Foot and Ankle Society (AOFAS) scores of the patients at the 3th, 6 th and 12 th months of follow-up. RESULTS : The mean age of all patients in this cohort study was 34.7±1. The mean age (P=0.24), gender distribution (P=0.76), and body mass index (P=0.25) were similar for both groups. The mean operation time (group A: 63.9±7.6vs. group B: 57.1±7.8, P=0.86) and mean surgical incision length (group A: 18.2±3.4 vs. group B: 14.4±4.5, P=0.51) was not statistical difference between two groups.There was no statistical difference between groups regarding functional results at 3th (ATRS: group A: 79.4±5.7 vs. group B: 81.4±5.8, (P=0.87), and AOFAS: group A: 77.9±9. vs. group B: 81.6±7.9, (P=0.67)) and 6th months (ATRS: group A: 78.8±7.8 vs. group B: 83.5±5.9, (P=0.16), and AOFAS:group A: 83.3±5.4 vs. group B: 82.6±6, (P=0.54)). There was statistical difference between groups regarding functional results at 12th (ATRS: group A: 82.89±9.4 vs. group B: 83.84±6.6, (P=0.028), and AOFAS:group A: 81.51±8.9 vs. group B: 85.34±5.2, (P=0.01)). We observed four postoperative complications (13.6%) in groupA. two patients (6.8%) had a re-rupture, one patient (3.4%) had sural nerve injury and one patient (3.4%)superfacial infection. There were two complications (7.6%) in group B. one patient (3.8%) had re-rupture,and one patient (3.8%) had dehiscense of incision.(P:0.43) CONCLUSION : FHL tendon fixation to the calcaneus bone with the bio-tenodesis screw technique was a less invasive method and had good clinical results in long-term follow-up than the bone tunnel technique. Bio-Tenodesis Screw Bone Tunnel Fixation Flexor Hallucis Longus Tendon Transfers Calcaneus chronic Achilles tendon rupture Cohort Study Figures Figure 1 Figure 2 Introduction The Achilles tendon (AT) is the largest and strongest tendon in the human body, and with a prevalence of 31 in 100,000 cases in adults, it is the most common tendon injury of the lower limb [1, 2].Ruptures of this tendon usually occur in a relatively hypo vascular area (2 to 6 cm above the calcaneus joint).Tendon rupture is not diagnosed in about 27% of patients in acute stages, which ultimately leads to functional disability of patients [3–6].If there is a delay of more than four weeks in the diagnosis, it is considered chronic and it is associated with degrees of fibrosis and tendon defects[7–9].CATR is associated with a degree of weakness in walking, climbing or descending stairs, and the inability to perform ankle plantar flexion. In case of incorrect treatment, it can lead to complications, such as: permanent chronic pain, poor wound healing and re-rupture of the tendon[10] .The treatment of CATR is more difficult due to the shortness of the tendon, decreased blood supply to the fibrotic area, and the defect after tendon debridement, and the only definitive treatment is surgery [11].End-to-end direct repair (V-Y plasty) is usually not possible due to the significant defect that exists after the removal of the fibrotic tendon tissue. Therefore, in most cases, tendon transfer is needed for reconstruction [12]. Many studies have reported satisfactory results of FHL tendon transfer in the treatment of CATR [13, 14].This method was first described by Hansen et al. in 1991[3] .The FHL tendon theoretically offers several advantages for use in Achilles tendon repair compared to other tendon transfers. First, this tendon is 1.4 times stronger than the peroneus brevis muscle (PB) and twice as strong as the FHL muscle[15] .Second, it contracts simultaneously with the gastrocnemius-soleus muscle, and its pulling force is in the same direction as the AT. Thirdly, due to its anatomical proximity to the AT, it is possible to easily remove it from a single incision .Controversy exists in identifying the best method to achieve FHL tendon transfer for AT rupture .Different techniques have been reported for the fixation of the FHL tendon. However, no studies have been published comparing the clinical outcomes and complications between the interference screw and bone tunnel fixation techniques .Furthermore, only a few biomechanical studies have compared the structural variables between these two techniques in cadaver specimens.[16–18] (1Therefore, our aim in this study was to compare the clinical outcome of the treatment of CATR using two techniques of FHL tendon fixation. Materials and methods This retrospective cohort study, after the approval of the ethics committee of Shahid Beheshti University of Medical Sciences, was investigated among patients with a definitive diagnosis of CATR between September 2018 and 2023.In this study 55 people aged between 20 and 60 years, with complaints of progressive pain in the back of the leg and limitation of plantar flexion of the foot since about ≥ 3 months, who had visited the orthopedic clinic after the positive result of the Simmonds-Thompson test[19] and confirmed Magnetic resonance imaging (MRI) .Exclusion criteria of the study included: acute tendon rupture, patients with cerebral palsy and polio, patients with short Achilles tendon, history of previous surgery, and diabetic patients. After matching, the patients were divided into 2 groups A and B in terms of clinical conditions.Table 1 . Group A (n = 29) was fixed by passing the FHL tendon to the tran-sosseus from the calcaneus bone and group B (n = 26) was fixed perpendicularly to the calcaneus bone with an absorbable interference screw .All patients were subjected to color Doppler ultrasound for the presence of deep vein thrombosis .All patients were treated with enoxaparin 40 mg subcutaneously for 4 weeks .All patients underwent spinal block anesthesia .All surgical procedures were performed on patients by two orthopedic surgeon .Clinical results were evaluated using AOFAS- hindfoot score[20],Table 2 and ATRS score system[21], three months, six months and twelve months after surgery .The duration of surgery was evaluated from the start of anesthesia to the transfer of the patient to recovery .The length of the surgical incision was measured in centimeters with a sterile ruler .Surgical complications including (surgical site infection, tendon re-rupture, wound dehiscence, deep vein thrombosis and sural nerve injury ) were evaluated during the first 3 months[22, 23]. The sural nerve injury was diagnosed with electromyography studies. The results were presented as mean ± standard deviation (SD) for quantitative variables and were summarized by absolute frequencies and percentages for categorical variables. Categorical variables were compared using chi-square test. Quantitative variables were also compared with t test. For the statistical analysis, the statistical software SPSS version 16.0 for windows (SPSS Inc., Chicago, IL) was used. Surgical technique : For all patients, a incision was made to the Achilles insertion site behind the calcaneus, lateral to the Achilles tendon with a posterior midline approach .After exploration, the AT defect was touched and found, then under the debridement of the fibrotic piece to the healthy place of the tendon, the 2 healthy ends of the tendon were prepared by the Krackow suture method with FiberWire® Suture 2 (Arthrex).Then, a sharp incision was made to the fascia and deep compartment, and the FHL muscle was exposed, and the plantar flexion and dorsi flexion of the big toe and the FHL tendon were confirmed. After suturing the skin, a short leg cast at 15 degrees of plantar flexion was taken for four weeks. For group A, a longitudinal incision was made in the medial part of the foot, and the tendon of the FHL tendon was cut in the position of full plantar flexion at the location of the master knot of Henry, by releasing the common sheet with the long flexor muscles of the toes (Fig. 1A, 2A).Then, the tendon was stretched from the posterior region, and the FHL tendon was trans-osseous from the rim from medial to lateral in the calcaneus bone (Fig. 3A). In the neutral dorsiflexion position, the FHL tendon was sutured at the base of the Achilles tendon junction (Fig. 4A) and then strengthened by the distal remnants of the AT. Group B, the FHL tendon was cut at its maximum length in the position of full plantar flexion of the ankle from inside the sheath in the medial part of the ankle (Fig. 1B).Then vertically, with a reamer the diameter of the FHL tendon, a hole was created in front of the Achilles tendon junction in the tuberosity region (Fig. 2B).After passing the tendon with a nylon tape from inside the channel towards the heel, the tendon was fixed with a bio-absorbable screw (Fig. 3B). Finally, the two ends of the Achilles tendon were augmented into the tendon.(Fig. 4B). Results The average age of all patients in this study was 34.7 ± 1. There was no significant difference between the two groups in terms of mean age, gender distribution, body mass index and side of injury (P:0.238, P:0.76, P:0.249, P:0.56). There was no significant difference length of the surgical incision and the duration of the surgery between the patients of group B and A. (Table 1 )Clinical results were followed up in a twelve-month period (Table 2 ). No significant difference was found between group B and group A in terms of ATRS score and AOFAS hind foot score in the third and sixth months of follow-up, but in the twelfth month of follow-up, group B patients had a higher functional score than group A in ATRS score and AOFAS hind foot score showed. (Table 2 )In group B, one case (3.8%) of wound dehiscence was seen and one case (3.8%) of re-rupture was reported in the eighth month. In group A patients, one case (3.4%) of wound dehiscence, one case(3.4%) of superficial wound infection, one case (3.4%) of Sural nerve damage, and two cases (6.8%) of re-rupture were reported (third and sixth months). No evidence of DVT was reported from the patients. There was no significant difference between the two groups in terms of complications after surgery (P: 0.7). (Chart 1 ) Table 1 Demographic characteristics/Surgical Data of the patients (N = 55) Variable Group A (N = 29) Group B (N = 26) *p-value Age(years) 35.55 ± 11 33.76 ± 10.1 0.24 Gender Male Female 18(62%) 11(38%) 16(61.5%) 10(38.5%) 0.76 BMI (kg/m²) 28.06 ± 5.9 27.42 ± 5 0.25 Side Left Right 17(59%) 12(41%) 13(50%) 13(50%) 0.56 Operation duration (minute) 63.9 ± 7.6 57.1 ± 7.8 0.86 Surgical incision length (median; range) 18.2 ± 3.4 14.4 ± 4.5 0.51 *P values of 0.05 or less are considered statically significant Table 2 Functional outcome of patients according to type of fixation of FHL tendon Variable Group A(N = 29) Group B(N = 26) *P-value AOFAS-score(third month) 77.9 ± 9 81.6 ± 7.9 0.67 AOFAS-score(sixth month) 83.3 ± 5.4 82.6 ± 6 0.54 AOFAS-score(twelfth month) 81.51 ± 8.9 85.34 ± 5.2 0.01 ATR score(third month) 79.4 ± 5.7 81.4 ± 5.8 0.87 ATR score(sixth month) 78.8 ± 7.8 83.5 ± 5.9 0.16 ATR score (twelfth month) 82.89 ± 9.4 83.84 ± 6.6 0.02 *P values of 0.05 or less are considered statically significant Discussion Currently, various techniques for the treatment of CATR have been reported in various studies.Various methods such as: V-Y advancement tendon flap, local tendon transfer (PB transfer or FHLtransfer), free tendon graft are now used to treat CATR[24–27]. In 2024, Guidline The basis of the Gap length and the defect in the AT for the treatment of patients with chronic rupture has been published[28], but a single standard method was not introduced and there are also differences among surgeons regarding treatment techniques.We used the FHL tendon transfer technique for patients due to the lack of integrity at both ends of the Achilles tendon (gap between 2–6 cm). The FHL tendon transfer method was described for the first time by Hansen et al. in 1991 [14]. The use of FHL transfer is used as the gold standard technique in irreparable AT tears for several reasons: the axis of action is in the direction of the Achilles tendon., is one of the strongest tendons of the ankle, it has simultaneous activity in the gait phase with the gastrocnemius muscle, and harvesting does not cause a disturbance in the dynamic and static performance of the ankle [3, 4]. In a study by Xudong Miao et al[5] showed that the harvest of the FHL tendon from the posterior channel of the foot (foot in full plantar flexion) to reconstruct the CATR had good clinical results. In the present study, our aim was to focus on the clinical results of the patients and comparison the results of two different techniques of FHL transfer fixation in the calcaneus bone. We evaluated the clinical results of the patients based on the criteria of AOFAS hindfoot score and ATRS score system in a period of 12 months. Our results showed that there was no significant difference between group A and B patients during the first six months, but in the 12th month follow-up, group B patients had better clinical results. Several studies confirm our results. Based on a study by Hatem Elsayed Ahmed Elgohary et al[29] in 2016 on 19 patients CATR showed that the treatment of CATR with FHL tendon transfer technique and gastrocnemius muscle release is associated with better clinical results and does not lead to big toe dysfunction. In a systematic review and meta-analysis study conducted in 2019 showed that augmentation with FHL tendon transfer, AOFAS hindfoot score was better with a reduction in complications[29]. Several cadaver studies have been conducted to investigate the function of the FHL tendon based on the fixation technique. In a biomechanical study conducted on a cadaver in 2017 by George T. Liu et al[30], it showed that the BTS group, tension force is significant, but there is no change in the ultimate strength and peak stress and failure pressure between two fixation techniques of FHL to the calcaneus bone. In another study conducted by E. Benca et al [15, 17]on 24 cadavers, showed that BTS fixtion can be a less invasive method and has a similar biomechanical behavior compared to fixation through the BT technique. B. Christian Balldin et al[17] showed in the biomechanical analysis between the FHL fixation technique with screw and BT, that the BTS method creates similar biomechanical properties to restore function in patients with CATR, but due to being a single incision. BTS technique not disrupting the natural connection between FHL and Flexor Digitorum Longus tendons and is a good alternative. The results of our study showed that fixation of the FHL tendon with screws can be done using one approach and does not have long operation time. In various studies that use screw fixation technique, the findings of our study are confirmed[16, 31, 32]. In a study conducted by Aniruddha Pendse et al[33] in 2019 on 17 patients with chronic Achilles rupture, it was shown that FHL tendon transfer with A single incision technique is a reliable, safe and ideal method for elderly patients with AT insufficiency and diseases. Also, Hossam Abubeih et al [34] showed that FHL transfer with a single incision for CATR, has increased patient satisfaction and excellent clinical results. In a study conducted by Xudong Miao et al[10], it was shown that harvesting the FHL tendon from the posterior channel of the foot (foot in full plantar flexion) for the reconstruction of CATR has good clinical results. Our study had several limitations. 1) Our study was conducted retrospectively. 2) The number of samples in our study was small and the average follow-up time was short, but these parameters were similar to the parameters of the reported studies[17, 35]. 3) Despite the evaluation of patients by two surgeons, interobserver or intraobserver evaluation was not possible. The remarkable feature of our study was that it was the first study in this field. In addition, short time follow-up results were included in our study. Conclusion In recent years, due to the significant disturbance in ankle function, the use of FHL tendon transfer technique has increased for the treatment of patients with CATR. The findings of this study showed that the FHL tendon fixation technique with BTS has better functional results in It is long-term and the procedure is less invasive than the BT method, but it is not the preferred method. Declarations Ethics approval and consent to participate: This study was approved by the Research Ethics Committee of Shahid Beheshti University of Medical Sciences (IR.SBMU.RETECH.REC.1399.1244). Written informed consent was obtained from all participants prior to inclusion in the study. Consent for publication: Not applicable. Clinical trial number Not applicable. Competing interests: The authors declare no competing interests. Funding: No funding was received for this study. Author Contribution F. Abbasi, M.gholipour, M.H. Khameneh and S. Bonakdar wrote the main manuscript. F. Abbasi and M.gholipour prepared the figures and tables.All authors reviewed the manuscript. Availability of data and materials: Available from the corresponding author upon reasonable request. References Egger, A.C. and M.J. Berkowitz, Achilles tendon injuries. Current reviews in musculoskeletal medicine, 2017. 10 : p. 72–80. 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Kankate, Reconstruction of chronic achilles tendon ruptures in elderly patients, with vascularized flexor hallucis longus tendon transfer using single incision technique. Acta Orthop Belg, 2019. 85 (1): p. 137–143. Abubeih, H., et al., Flexor hallucis longus transfer clinical outcome through a single incision for chronic Achilles tendon rupture. International orthopaedics, 2018. 42 : p. 2699–2704. Subaşı, İ.Ö., et al., A clinical comparison of two different surgical techniques in the treatment of acute Achilles tendon ruptures: Limited-open approach vs. percutaneous approach. Turkish Journal of Trauma & Emergency Surgery, 2023. 29 (8): p. 935. Chart Chart 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files floatimage3.png Chart 1: Complication of patients according to type of fixation of FHL tendon 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-7445334","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":513091055,"identity":"dc61d08f-99ee-4516-b22b-4404c57484a6","order_by":0,"name":"Morteza Gholipour","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABIklEQVRIie3Pz0rDMBzA8YRCegn2mtENX6GjsNO0r9IQyKk3LxNlTgrdZWfJwYfYKe6YUugueYBCL1ZfwCHCdhHbIcw/rXgUzPeQwI/fBxIATKY/mCMAVOHHSbCep/f1jY86CCkAOBDVHFozryGog3jkffFAinBEmruTuLFS1WpM726y/PlpMj2GC8XPX6LTPgJW9VC0kH4eKqo5vS05E0qjYWxf5+VAsvphyPej72RYRJ6iSUaFG/kgTTBMsOJlT1o1wchtId5n8kqCBQlHZz159Vsy86ioCdzIrJOQgu//4guXM6DzkC2xZi6Ua4ys9r84gqXVbjUeCJdlYHI5PVna83SzkxeBY8fVYwvZB2dfBhbenx3rrQRuf9g2mUymf9cb7n5tWXmqogkAAAAASUVORK5CYII=","orcid":"","institution":"Shahid Beheshti University of Medical Sciences","correspondingAuthor":true,"prefix":"","firstName":"Morteza","middleName":"","lastName":"Gholipour","suffix":""},{"id":513091056,"identity":"06481f3a-6fc9-44c1-b59d-c20314d221db","order_by":1,"name":"Seyed Mehdi Hosseini Khameneh","email":"","orcid":"","institution":"Shahid Beheshti University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Seyed","middleName":"Mehdi Hosseini","lastName":"Khameneh","suffix":""},{"id":513091057,"identity":"b3ff7215-3c56-4311-b37c-061712d82200","order_by":2,"name":"Fatemeh Abbasi","email":"","orcid":"","institution":"Shahid Beheshti University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Fatemeh","middleName":"","lastName":"Abbasi","suffix":""},{"id":513091058,"identity":"4b08b249-1302-4903-950f-a8b450ca80de","order_by":3,"name":"Sona Bonakdar","email":"","orcid":"","institution":"Shahid Beheshti University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Sona","middleName":"","lastName":"Bonakdar","suffix":""}],"badges":[],"createdAt":"2025-08-24 09:38:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7445334/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7445334/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91196334,"identity":"807f6e6a-4cba-47e9-96cf-73e6a0ef82bd","added_by":"auto","created_at":"2025-09-12 15:02:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":755440,"visible":true,"origin":"","legend":"\u003cp\u003eFigure A: trans-osseous fixation(1A:a longitudinal incision was made in the medial part of the foot, and the tendon of the FHL tendon was cut in the position of full plantar flexion at the location of the master knot of Henry.2A: by releasing the common sheet with the long flexor muscles of the toes.3A: FHL tendon was trans-osseous from the rim from medial to lateral in the calcaneus bone . 4A:the neutral dorsiflexion position, the FHL tendon was sutured at the base of the Achilles tendon junction and agmentation by the distal remnants of the AT)\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7445334/v1/5322619a41fdbf30d48dae4b.png"},{"id":91196336,"identity":"6f4eb414-b75e-49f8-863f-ac36dbfe5ed6","added_by":"auto","created_at":"2025-09-12 15:02:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":915215,"visible":true,"origin":"","legend":"\u003cp\u003eFigure B: bio-tenodesis screw fixation(1B: FHL tendon was cut to its maximum length through the medial ankle canal. Then, a V-Y gastrocnemius tendonoplasty was performed. A guide pin was placed anterior to the Achilles insertion..2B: The Achilles tendon was punctured with a 6 mm reamer cannula anterior to the insertion. 3B:After passing the FHL tendon with a nylon tape \u0026nbsp;from inside the channel towards the heel, the FHL tendon was fixed with a bio-absorbable screw(6mm*25mm) .4B: The two ends of the Achilles tendon were augmented to the two ends of the FHL tendon.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7445334/v1/3f5ab9a1572e5b02dac58271.png"},{"id":104567945,"identity":"9b3e607c-61dc-4fc7-b1bc-007f1dbe3f85","added_by":"auto","created_at":"2026-03-13 11:56:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2205731,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7445334/v1/ff0d0873-37bd-4637-b18a-33a1a8323977.pdf"},{"id":91197765,"identity":"b540ce92-2c50-4330-ac09-fb05e715a00e","added_by":"auto","created_at":"2025-09-12 15:10:16","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":12202,"visible":true,"origin":"","legend":"\u003cp\u003eChart 1: Complication of patients according to type of fixation of FHL tendon\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7445334/v1/0fc489db51e04765de234a73.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Clinical outcome of Bio-Tenodesis Screw Versus Bone Tunnel Fixation of Flexor Hallucis Longus Tendon Transfers to the Calcaneus in chronic Achilles tendon rupture: Retrospective Cohort Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe Achilles tendon (AT) is the largest and strongest tendon in the human body, and with a prevalence of 31 in 100,000 cases in adults, it is the most common tendon injury of the lower limb [1, 2].Ruptures of this tendon usually occur in a relatively hypo vascular area (2 to 6 cm above the calcaneus joint).Tendon rupture is not diagnosed in about 27% of patients in acute stages, which ultimately leads to functional disability of patients [3\u0026ndash;6].If there is a delay of more than four weeks in the diagnosis, it is considered chronic and it is associated with degrees of fibrosis and tendon defects[7\u0026ndash;9].CATR is associated with a degree of weakness in walking, climbing or descending stairs, and the inability to perform ankle plantar flexion.\u003c/p\u003e\u003cp\u003eIn case of incorrect treatment, it can lead to complications, such as: permanent chronic pain, poor wound healing and re-rupture of the tendon[10] .The treatment of CATR is more difficult due to the shortness of the tendon, decreased blood supply to the fibrotic area, and the defect after tendon debridement, and the only definitive treatment is surgery [11].End-to-end direct repair (V-Y plasty) is usually not possible due to the significant defect that exists after the removal of the fibrotic tendon tissue. Therefore, in most cases, tendon transfer is needed for reconstruction [12].\u003c/p\u003e\u003cp\u003eMany studies have reported satisfactory results of FHL tendon transfer in the treatment of CATR [13, 14].This method was first described by Hansen et al. in 1991[3] .The FHL tendon theoretically offers several advantages for use in Achilles tendon repair compared to other tendon transfers. First, this tendon is 1.4 times stronger than the peroneus brevis muscle (PB) and twice as strong as the FHL muscle[15] .Second, it contracts simultaneously with the gastrocnemius-soleus muscle, and its pulling force is in the same direction as the AT. Thirdly, due to its anatomical proximity to the AT, it is possible to easily remove it from a single incision .Controversy exists in identifying the best method to achieve FHL tendon transfer for AT rupture .Different techniques have been reported for the fixation of the FHL tendon. However, no studies have been published comparing the clinical outcomes and complications between the interference screw and bone tunnel fixation techniques .Furthermore, only a few biomechanical studies have compared the structural variables between these two techniques in cadaver specimens.[16\u0026ndash;18] (1Therefore, our aim in this study was to compare the clinical outcome of the treatment of CATR using two techniques of FHL tendon fixation.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003eThis retrospective cohort study, after the approval of the ethics committee of Shahid Beheshti University of Medical Sciences, was investigated among patients with a definitive diagnosis of CATR between September 2018 and 2023.In this study 55 people aged between 20 and 60 years, with complaints of progressive pain in the back of the leg and limitation of plantar flexion of the foot since about\u0026thinsp;\u0026ge;\u0026thinsp;3 months, who had visited the orthopedic clinic after the positive result of the Simmonds-Thompson test[19] and confirmed Magnetic resonance imaging (MRI) .Exclusion criteria of the study included: acute tendon rupture, patients with cerebral palsy and polio, patients with short Achilles tendon, history of previous surgery, and diabetic patients. After matching, the patients were divided into 2 groups A and B in terms of clinical conditions.Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Group A (n\u0026thinsp;=\u0026thinsp;29) was fixed by passing the FHL tendon to the tran-sosseus from the calcaneus bone and group B (n\u0026thinsp;=\u0026thinsp;26) was fixed perpendicularly to the calcaneus bone with an absorbable interference screw .All patients were subjected to color Doppler ultrasound for the presence of deep vein thrombosis .All patients were treated with enoxaparin 40 mg subcutaneously for 4 weeks .All patients underwent spinal block anesthesia .All surgical procedures were performed on patients by two orthopedic surgeon .Clinical results were evaluated using AOFAS- hindfoot score[20],Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and ATRS score system[21], three months, six months and twelve months after surgery .The duration of surgery was evaluated from the start of anesthesia to the transfer of the patient to recovery .The length of the surgical incision was measured in centimeters with a sterile ruler .Surgical complications including (surgical site infection, tendon re-rupture, wound dehiscence, deep vein thrombosis and sural nerve injury ) were evaluated during the first 3 months[22, 23]. The sural nerve injury was diagnosed with electromyography studies.\u003c/p\u003e\u003cp\u003eThe results were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) for quantitative variables and were summarized by absolute frequencies and percentages for categorical variables. Categorical variables were compared using chi-square test. Quantitative variables were also compared with t test. For the statistical analysis, the statistical software SPSS version 16.0 for windows (SPSS Inc., Chicago, IL) was used.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e\u003cb\u003eSurgical technique\u003c/b\u003e:\u003c/h2\u003e\u003cp\u003eFor all patients, a incision was made to the Achilles insertion site behind the calcaneus, lateral to the Achilles tendon with a posterior midline approach .After exploration, the AT defect was touched and found, then under the debridement of the fibrotic piece to the healthy place of the tendon, the 2 healthy ends of the tendon were prepared by the Krackow suture method with FiberWire\u0026reg; Suture 2 (Arthrex).Then, a sharp incision was made to the fascia and deep compartment, and the FHL muscle was exposed, and the plantar flexion and dorsi flexion of the big toe and the FHL tendon were confirmed. After suturing the skin, a short leg cast at 15 degrees of plantar flexion was taken for four weeks.\u003c/p\u003e\u003cp\u003eFor group A, a longitudinal incision was made in the medial part of the foot, and the tendon of the FHL tendon was cut in the position of full plantar flexion at the location of the master knot of Henry, by releasing the common sheet with the long flexor muscles of the toes (Fig.\u0026nbsp;1A, 2A).Then, the tendon was stretched from the posterior region, and the FHL tendon was trans-osseous from the rim from medial to lateral in the calcaneus bone (Fig.\u0026nbsp;3A). In the neutral dorsiflexion position, the FHL tendon was sutured at the base of the Achilles tendon junction (Fig.\u0026nbsp;4A) and then strengthened by the distal remnants of the AT.\u003c/p\u003e\u003cp\u003eGroup B, the FHL tendon was cut at its maximum length in the position of full plantar flexion of the ankle from inside the sheath in the medial part of the ankle (Fig.\u0026nbsp;1B).Then vertically, with a reamer the diameter of the FHL tendon, a hole was created in front of the Achilles tendon junction in the tuberosity region (Fig.\u0026nbsp;2B).After passing the tendon with a nylon tape from inside the channel towards the heel, the tendon was fixed with a bio-absorbable screw (Fig.\u0026nbsp;3B). Finally, the two ends of the Achilles tendon were augmented into the tendon.(Fig.\u0026nbsp;4B).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe average age of all patients in this study was 34.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1. There was no significant difference between the two groups in terms of mean age, gender distribution, body mass index and side of injury (P:0.238, P:0.76, P:0.249, P:0.56). There was no significant difference length of the surgical incision and the duration of the surgery between the patients of group B and A. (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)Clinical results were followed up in a twelve-month period (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). No significant difference was found between group B and group A in terms of ATRS score and AOFAS hind foot score in the third and sixth months of follow-up, but in the twelfth month of follow-up, group B patients had a higher functional score than group A in ATRS score and AOFAS hind foot score showed. (Table\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)In group B, one case (3.8%) of wound dehiscence was seen and one case (3.8%) of re-rupture was reported in the eighth month. In group A patients, one case (3.4%) of wound dehiscence, one case(3.4%) of superficial wound infection, one case (3.4%) of Sural nerve damage, and two cases (6.8%) of re-rupture were reported (third and sixth months). No evidence of DVT was reported from the patients. There was no significant difference between the two groups in terms of complications after surgery (P: 0.7). (Chart \u003cspan refid=\"Str1\" 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\u003eDemographic characteristics/Surgical Data of the patients (N\u0026thinsp;=\u0026thinsp;55)\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=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" 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\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGroup A (N\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGroup B (N\u0026thinsp;=\u0026thinsp;26)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e*p-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge(years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e35.55\u0026thinsp;\u0026plusmn;\u0026thinsp;11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e33.76\u0026thinsp;\u0026plusmn;\u0026thinsp;10.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGender\u003c/p\u003e\u003cp\u003eMale\u003c/p\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18(62%)\u003c/p\u003e\u003cp\u003e11(38%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16(61.5%)\u003c/p\u003e\u003cp\u003e10(38.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.76\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=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e28.06\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e27.42\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSide\u003c/p\u003e\u003cp\u003eLeft\u003c/p\u003e\u003cp\u003eRight\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17(59%)\u003c/p\u003e\u003cp\u003e12(41%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13(50%)\u003c/p\u003e\u003cp\u003e13(50%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.56\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperation duration (minute)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e63.9\u0026thinsp;\u0026plusmn;\u0026thinsp;7.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e57.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.86\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSurgical incision length (median; range)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e18.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e14.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.51\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003e*P values of 0.05 or less are considered statically significant\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\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\u003eFunctional outcome of patients according to type of fixation of FHL tendon\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=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" 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\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGroup A(N\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGroup B(N\u0026thinsp;=\u0026thinsp;26)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e*P-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAOFAS-score(third month)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e77.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e81.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.67\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAOFAS-score(sixth month)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e83.3\u0026thinsp;\u0026plusmn;\u0026thinsp;5.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e82.6\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.54\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAOFAS-score(twelfth month)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e81.51\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e85.34\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eATR score(third month)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e79.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e81.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.87\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eATR score(sixth month)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e78.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e83.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eATR score (twelfth month)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e82.89\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e83.84\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.02\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003e*P values of 0.05 or less are considered statically significant\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eCurrently, various techniques for the treatment of CATR have been reported in various studies.Various methods such as: V-Y advancement tendon flap, local tendon transfer (PB transfer or FHLtransfer), free tendon graft are now used to treat CATR[24\u0026ndash;27]. In 2024, Guidline The basis of the Gap length and the defect in the AT for the treatment of patients with chronic rupture has been published[28], but a single standard method was not introduced and there are also differences among surgeons regarding treatment techniques.We used the FHL tendon transfer technique for patients due to the lack of integrity at both ends of the Achilles tendon (gap between 2\u0026ndash;6 cm). The FHL tendon transfer method was described for the first time by Hansen et al. in 1991 [14]. The use of FHL transfer is used as the gold standard technique in irreparable AT tears for several reasons: the axis of action is in the direction of the Achilles tendon., is one of the strongest tendons of the ankle, it has simultaneous activity in the gait phase with the gastrocnemius muscle, and harvesting does not cause a disturbance in the dynamic and static performance of the ankle [3, 4]. In a study by Xudong Miao et al[5] showed that the harvest of the FHL tendon from the posterior channel of the foot (foot in full plantar flexion) to reconstruct the CATR had good clinical results.\u003c/p\u003e\u003cp\u003eIn the present study, our aim was to focus on the clinical results of the patients and comparison the results of two different techniques of FHL transfer fixation in the calcaneus bone. We evaluated the clinical results of the patients based on the criteria of AOFAS hindfoot score and ATRS score system in a period of 12 months. Our results showed that there was no significant difference between group A and B patients during the first six months, but in the 12th month follow-up, group B patients had better clinical results. Several studies confirm our results. Based on a study by Hatem Elsayed Ahmed Elgohary et al[29] in 2016 on 19 patients CATR showed that the treatment of CATR with FHL tendon transfer technique and gastrocnemius muscle release is associated with better clinical results and does not lead to big toe dysfunction. In a systematic review and meta-analysis study conducted in 2019 showed that augmentation with FHL tendon transfer, AOFAS hindfoot score was better with a reduction in complications[29].\u003c/p\u003e\u003cp\u003eSeveral cadaver studies have been conducted to investigate the function of the FHL tendon based on the fixation technique. In a biomechanical study conducted on a cadaver in 2017 by George T. Liu et al[30], it showed that the BTS group, tension force is significant, but there is no change in the ultimate strength and peak stress and failure pressure between two fixation techniques of FHL to the calcaneus bone. In another study conducted by E. Benca et al [15, 17]on 24 cadavers, showed that BTS fixtion can be a less invasive method and has a similar biomechanical behavior compared to fixation through the BT technique. B. Christian Balldin et al[17] showed in the biomechanical analysis between the FHL fixation technique with screw and BT, that the BTS method creates similar biomechanical properties to restore function in patients with CATR, but due to being a single incision. BTS technique not disrupting the natural connection between FHL and Flexor Digitorum Longus tendons and is a good alternative.\u003c/p\u003e\u003cp\u003eThe results of our study showed that fixation of the FHL tendon with screws can be done using one approach and does not have long operation time. In various studies that use screw fixation technique, the findings of our study are confirmed[16, 31, 32]. In a study conducted by Aniruddha Pendse et al[33] in 2019 on 17 patients with chronic Achilles rupture, it was shown that FHL tendon transfer with A single incision technique is a reliable, safe and ideal method for elderly patients with AT insufficiency and diseases. Also, Hossam Abubeih et al [34] showed that FHL transfer with a single incision for CATR, has increased patient satisfaction and excellent clinical results. In a study conducted by Xudong Miao et al[10], it was shown that harvesting the FHL tendon from the posterior channel of the foot (foot in full plantar flexion) for the reconstruction of CATR has good clinical results.\u003c/p\u003e\u003cp\u003eOur study had several limitations. 1) Our study was conducted retrospectively. 2) The number of samples in our study was small and the average follow-up time was short, but these parameters were similar to the parameters of the reported studies[17, 35]. 3) Despite the evaluation of patients by two surgeons, interobserver or intraobserver evaluation was not possible. The remarkable feature of our study was that it was the first study in this field. In addition, short time follow-up results were included in our study.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn recent years, due to the significant disturbance in ankle function, the use of FHL tendon transfer technique has increased for the treatment of patients with CATR. The findings of this study showed that the FHL tendon fixation technique with BTS has better functional results in It is long-term and the procedure is less invasive than the BT method, but it is not the preferred method.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e\u003cp\u003e This study was approved by the Research Ethics Committee of Shahid Beheshti University of Medical Sciences (IR.SBMU.RETECH.REC.1399.1244). Written informed consent was obtained from all participants prior to inclusion in the study.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConsent for publication:\u003c/strong\u003e\u003cp\u003eNot applicable.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eClinical trial number\u003c/strong\u003e\u003cp\u003eNot applicable.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003ch2\u003eCompeting interests:\u003c/h2\u003e\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e\u003cp\u003eNo funding was received for this study.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eF. Abbasi, M.gholipour, M.H. Khameneh and S. Bonakdar wrote the main manuscript. F. Abbasi and M.gholipour prepared the figures and tables.All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAvailability of data and materials:\u003c/h2\u003e\u003cp\u003eAvailable from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eEgger, A.C. and M.J. Berkowitz, \u003cem\u003eAchilles tendon injuries.\u003c/em\u003e Current reviews in musculoskeletal medicine, 2017. \u003cstrong\u003e10\u003c/strong\u003e: p. 72\u0026ndash;80.\u003c/li\u003e\n\u003cli\u003eGanestam, A., et al., \u003cem\u003eIncreasing incidence of acute Achilles tendon rupture and a noticeable decline in surgical treatment from 1994 to 2013. A nationwide registry study of 33,160 patients.\u003c/em\u003e Knee surgery, sports traumatology, arthroscopy, 2016. \u003cstrong\u003e24\u003c/strong\u003e: p. 3730\u0026ndash;3737.\u003c/li\u003e\n\u003cli\u003eYeoman, T.F., M.J. Brown, and A. Pillai, \u003cem\u003eEarly post-operative results of neglected tendo-Achilles rupture reconstruction using short flexor hallucis longus tendon transfer: a prospective review.\u003c/em\u003e The Foot, 2012. \u003cstrong\u003e22\u003c/strong\u003e(3): p. 219\u0026ndash;223.\u003c/li\u003e\n\u003cli\u003eLeppilahti, J., J. Puranen, and S. Orava, \u003cem\u003eIncidence of Achilles tendon rupture.\u003c/em\u003e Acta Orthopaedica Scandinavica, 1996. \u003cstrong\u003e67\u003c/strong\u003e(3): p. 277\u0026ndash;279.\u003c/li\u003e\n\u003cli\u003eWegrzyn, J., et al., \u003cem\u003eChronic Achilles tendon rupture reconstruction using a modified flexor hallucis longus transfer.\u003c/em\u003e International orthopaedics, 2010. \u003cstrong\u003e34\u003c/strong\u003e: p. 1187\u0026ndash;1192.\u003c/li\u003e\n\u003cli\u003eReddy, S.S., et al., \u003cem\u003eSurgical treatment for chronic disease and disorders of the Achilles tendon.\u003c/em\u003e JAAOS-Journal of the American Academy of Orthopaedic Surgeons, 2009. \u003cstrong\u003e17\u003c/strong\u003e(1): p. 3\u0026ndash;14.\u003c/li\u003e\n\u003cli\u003eMaffulli, N. and A. 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Sung, \u003cem\u003eSurgical reconstruction of chronic Achilles tendon ruptures using various methods.\u003c/em\u003e Orthopedics, 2012. \u003cstrong\u003e35\u003c/strong\u003e(2): p. e213-e218.\u003c/li\u003e\n\u003cli\u003e Panchbhavi, V.K., \u003cem\u003eChronic Achilles tendon repair with flexor hallucis longus tendon harvested using a minimally invasive technique.\u003c/em\u003e Techniques in Foot \u0026amp; Ankle Surgery, 2007. \u003cstrong\u003e6\u003c/strong\u003e(2): p. 123\u0026ndash;129.\u003c/li\u003e\n\u003cli\u003e Ahmad, J., K. Jones, and S.M. Raikin, \u003cem\u003eTreatment of chronic Achilles tendon ruptures with large defects.\u003c/em\u003e Foot \u0026amp; ankle specialist, 2016. \u003cstrong\u003e9\u003c/strong\u003e(5): p. 400\u0026ndash;408.\u003c/li\u003e\n\u003cli\u003e Hansen, S.T., \u003cem\u003eTrauma to the heel cord.\u003c/em\u003e Disorders of the Foot and Ankle, 1991. \u003cstrong\u003e3\u003c/strong\u003e: p. 2355\u0026ndash;2360.\u003c/li\u003e\n\u003cli\u003e Liu, G.T., et al., \u003cem\u003eA biomechanical analysis of interference screw versus bone tunnel fixation of flexor hallucis longus tendon transfers to the calcaneus.\u003c/em\u003e The Journal of Foot and Ankle Surgery, 2017. \u003cstrong\u003e56\u003c/strong\u003e(4): p. 813\u0026ndash;816.\u003c/li\u003e\n\u003cli\u003e Balldin, B.C., et al. \u003cem\u003eBiomechanical cadaveric analysis of biotenodesis screw versus bone tunnel fixation methods in flexor hallucis longus transfers\u003c/em\u003e. in \u003cem\u003eSummer Bioengineering Conference\u003c/em\u003e. 2013. American Society of Mechanical Engineers.\u003c/li\u003e\n\u003cli\u003e Benca, E., et al., \u003cem\u003eBiomechanical evaluation of two methods of fixation of a flexor hallucis longus tendon graft.\u003c/em\u003e The Bone \u0026amp; Joint Journal, 2018. \u003cstrong\u003e100\u003c/strong\u003e(9): p. 1175\u0026ndash;1181.\u003c/li\u003e\n\u003cli\u003e Bishnoi, A. and M. Bhatia, \u003cem\u003eCurrent Concepts in Acute Achilles Tendon Injury.\u003c/em\u003e Journal of Foot and Ankle Surgery (Asia Pacific), 2022. \u003cstrong\u003e9\u003c/strong\u003e(3): p. 130\u0026ndash;134.\u003c/li\u003e\n\u003cli\u003e Van Lieshout, E.M., et al., \u003cem\u003eAmerican Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score: a study protocol for the translation and validation of the Dutch language version.\u003c/em\u003e BMJ open, 2017. \u003cstrong\u003e7\u003c/strong\u003e(2): p. e012884.\u003c/li\u003e\n\u003cli\u003e Ansari, N.N., et al., \u003cem\u003eCross-cultural adaptation and validation of Persian Achilles tendon Total Rupture Score.\u003c/em\u003e Knee surgery, sports traumatology, arthroscopy, 2016. \u003cstrong\u003e24\u003c/strong\u003e(4): p. 1372\u0026ndash;1380.\u003c/li\u003e\n\u003cli\u003e Nilsson, N., \u003cem\u003eChronic Achilles tendon rupture-surgical reconstruction and post-operative outcomes\u003c/em\u003e. 2023.\u003c/li\u003e\n\u003cli\u003e Shoap, S., et al., \u003cem\u003eRerupture and wound complications following Achilles tendon repair: A systematic review.\u003c/em\u003e Journal of Orthopaedic Research\u0026reg;, 2023. \u003cstrong\u003e41\u003c/strong\u003e(4): p. 845\u0026ndash;851.\u003c/li\u003e\n\u003cli\u003e Adukia, V., et al., \u003cem\u003eSurgical treatment of chronic achilles tendon rupture: An anatomical consideration of various autograft options.\u003c/em\u003e Journal of Orthopaedics, 2023.\u003c/li\u003e\n\u003cli\u003e Mahajan, R.H. and R.B. Dalal, \u003cem\u003eFlexor hallucis longus tendon transfer for reconstruction of chronically ruptured Achilles tendons.\u003c/em\u003e Journal of Orthopaedic Surgery, 2009. \u003cstrong\u003e17\u003c/strong\u003e(2): p. 194\u0026ndash;198.\u003c/li\u003e\n\u003cli\u003e Lin, Y.j., X.j. Duan, and L. Yang, \u003cem\u003eV-Y tendon plasty for reconstruction of chronic Achilles tendon rupture: a medium‐term and long‐term follow‐up.\u003c/em\u003e Orthopaedic Surgery, 2019. \u003cstrong\u003e11\u003c/strong\u003e(1): p. 109\u0026ndash;116.\u003c/li\u003e\n\u003cli\u003e Koh, D., et al., \u003cem\u003eFlexor hallucis longus transfer versus turndown flaps augmented with flexor hallucis longus transfer in the repair of chronic Achilles tendon rupture.\u003c/em\u003e Foot and Ankle Surgery, 2019. \u003cstrong\u003e25\u003c/strong\u003e(2): p. 221\u0026ndash;225.\u003c/li\u003e\n\u003cli\u003e Gon\u0026ccedil;alves, S., R. Caetano, and N. Corte-Real, \u003cem\u003eSalvage flexor hallucis longus transfer for a failed Achilles repair: endoscopic technique.\u003c/em\u003e Arthroscopy techniques, 2015. \u003cstrong\u003e4\u003c/strong\u003e(5): p. e411-e416.\u003c/li\u003e\n\u003cli\u003e Feng, S.-M., et al., \u003cem\u003eSurgical management of chronic Achilles tendon rupture: evidence-based guidelines.\u003c/em\u003e Journal of Orthopaedic Surgery and Research, 2024. \u003cstrong\u003e19\u003c/strong\u003e(1): p. 1\u0026ndash;13.\u003c/li\u003e\n\u003cli\u003e Elgohary, H.E.A. and N.A. Elmoghazy, \u003cem\u003eCombined flexor hallucis longus tendon transfer and gastrocnemius recession for reconstruction of gapped chronic Achilles tendon ruptures.\u003c/em\u003e Injury, 2016. \u003cstrong\u003e47\u003c/strong\u003e(12): p. 2833\u0026ndash;2837.\u003c/li\u003e\n\u003cli\u003e Apinun, J., et al., \u003cem\u003eClinical outcomes of chronic Achilles tendon rupture treated with flexor hallucis longus grafting and flexor hallucis longus grafting plus additional augmentation: a meta-analysis.\u003c/em\u003e Foot and Ankle Surgery, 2020. \u003cstrong\u003e26\u003c/strong\u003e(7): p. 717\u0026ndash;722.\u003c/li\u003e\n\u003cli\u003e Tay, D., et al., \u003cem\u003eChronic Achilles tendon rupture treated with two turndown flaps and flexor hallucis longus augmentation\u0026mdash;two-year clinical outcome.\u003c/em\u003e Annals Academy of Medicine Singapore, 2010. \u003cstrong\u003e39\u003c/strong\u003e(1): p. 58.\u003c/li\u003e\n\u003cli\u003e Elias, I., et al., \u003cem\u003eReconstruction for missed or neglected Achilles tendon rupture with VY lengthening and flexor hallucis longus tendon transfer through one incision.\u003c/em\u003e Foot \u0026amp; ankle international, 2007. \u003cstrong\u003e28\u003c/strong\u003e(12): p. 1238\u0026ndash;1248.\u003c/li\u003e\n\u003cli\u003e Pendse, A. and R. Kankate, \u003cem\u003eReconstruction of chronic achilles tendon ruptures in elderly patients, with vascularized flexor hallucis longus tendon transfer using single incision technique.\u003c/em\u003e Acta Orthop Belg, 2019. \u003cstrong\u003e85\u003c/strong\u003e(1): p. 137\u0026ndash;143.\u003c/li\u003e\n\u003cli\u003e Abubeih, H., et al., \u003cem\u003eFlexor hallucis longus transfer clinical outcome through a single incision for chronic Achilles tendon rupture.\u003c/em\u003e International orthopaedics, 2018. \u003cstrong\u003e42\u003c/strong\u003e: p. 2699\u0026ndash;2704.\u003c/li\u003e\n\u003cli\u003e Subaşı, İ.\u0026Ouml;., et al., \u003cem\u003eA clinical comparison of two different surgical techniques in the treatment of acute Achilles tendon ruptures: Limited-open approach vs. percutaneous approach.\u003c/em\u003e Turkish Journal of Trauma \u0026amp; Emergency Surgery, 2023. \u003cstrong\u003e29\u003c/strong\u003e(8): p. 935.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Chart","content":"\u003cp\u003eChart 1 is available in the Supplementary Files section.\u003c/p\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":"Bio-Tenodesis Screw, Bone Tunnel Fixation, Flexor Hallucis Longus, Tendon Transfers Calcaneus, chronic Achilles tendon rupture, Cohort Study","lastPublishedDoi":"10.21203/rs.3.rs-7445334/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7445334/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBACKGROUND\u003c/strong\u003e: Due to the decrease in performance of patients and the lack of return to previous activity in patients with chronic Achilles tendon rupture (CATR), the treatment is surgery in most cases. Our main aim in this study is to compare the clinical results and postoperative complications of the Flexor halluces tendon (FHL) fixation technique with bio tenodesis screw (BTS) versus the bone tunnel (BT) technique in the calcaneus bone.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMETHODS\u003c/strong\u003e: A retrospective cohort study in which patients were treated with two different FHL tendon fixation techniques, from September 2018 to September 2023.The evaluation included demographic information, complications (infection and dehiscence of the wound at the surgical site and re-rupture and sural nerve damage and deep vein thrombosis), duration of surgery, length of surgical incision. The Achilles Tendon Total Rupture Score (ATRS), and the American Orthopedic Foot and Ankle Society (AOFAS) scores of the patients at the 3th, 6\u003csup\u003e \u003c/sup\u003eth and 12\u003csup\u003e \u003c/sup\u003eth months of follow-up.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRESULTS\u003c/strong\u003e: \u0026nbsp;The mean age of all patients in this cohort study was 34.7±1. The mean age (P=0.24), gender distribution (P=0.76), and body mass index (P=0.25) were similar for both groups. The mean operation time (group A: 63.9±7.6vs. group B: 57.1±7.8, P=0.86) and mean surgical incision length (group A: 18.2±3.4 vs. group B: 14.4±4.5, P=0.51) was not statistical difference between two groups.There was no statistical difference between groups regarding functional results at 3th (ATRS: group A: 79.4±5.7 vs. group B: 81.4±5.8, (P=0.87), and AOFAS: group A: 77.9±9. vs. group B: 81.6±7.9, (P=0.67)) and 6th months (ATRS: group A: 78.8±7.8 vs. group B: 83.5±5.9, (P=0.16), and AOFAS:group A: 83.3±5.4 vs. group B: 82.6±6, (P=0.54)). There was statistical difference between groups regarding functional results at 12th (ATRS: group A: 82.89±9.4 vs. group B: 83.84±6.6, (P=0.028), and AOFAS:group A: 81.51±8.9 vs. group B: 85.34±5.2, (P=0.01)). We observed four postoperative complications (13.6%) in groupA. two patients (6.8%) had a re-rupture, one patient (3.4%) had sural nerve injury and one patient (3.4%)superfacial infection. There were two complications (7.6%) in group B. one patient (3.8%) had re-rupture,and one patient (3.8%) had dehiscense of incision.(P:0.43)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCONCLUSION\u003c/strong\u003e: FHL tendon fixation to the calcaneus bone with the bio-tenodesis screw technique was a less invasive method and had good clinical results in long-term follow-up than the bone tunnel technique.\u003c/p\u003e","manuscriptTitle":"Clinical outcome of Bio-Tenodesis Screw Versus Bone Tunnel Fixation of Flexor Hallucis Longus Tendon Transfers to the Calcaneus in chronic Achilles tendon rupture: Retrospective Cohort Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-12 15:02:11","doi":"10.21203/rs.3.rs-7445334/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":"4970434f-e3f1-4b97-a52d-95579c7f56b9","owner":[],"postedDate":"September 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-13T11:55:19+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-12 15:02:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7445334","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7445334","identity":"rs-7445334","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}