Evaluation Of Femoral, Acetabular and Global Offset Restoration Following Hip Spacer Implantation in Staged Total Hip Arthroplasty

Evaluation Of Femoral, Acetabular and Global Offset Restoration Following Hip Spacer Implantation in Staged Total Hip Arthroplasty | 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 Evaluation Of Femoral, Acetabular and Global Offset Restoration Following Hip Spacer Implantation in Staged Total Hip Arthroplasty Luca Cavagnaro, Emilio Ferrari, Valentina Providenti, Vito Marciante, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8182860/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 9 You are reading this latest preprint version Abstract Introduction The primary aim of this study is to evaluate the restoration of biomechanical parameters of the hip—specifically leg length discrepancy (LLD), femoral offset (FO), acetabular offset (AO), and global offset (GO)—following implantation of a specific type of articulating hip spacer during the first stage of a two-stage revision for PJI. A secondary objective is to assess the correlation between variations in offset parameters and the rate of interstage mechanical complications Materials and Methods We retrospectively reviewed all patients undergoing staged revision with a specific articulating spacer between 2020 and 2022 at a single institution. Harris Hip Scores, Oxford Hip Scores, and Visual Analogue Scales for pain were obtained at different time points. Radiographic analysis included LLD, FO, AO and GO measurements on the affected (spacer and post-reimplantation) and the contralateral side. Complications were recorded during the interstage and post-reimplantation period. Results Forthy-seven patients (47 hips), were enrolled. The mean follow-up was 25.3 months. Clinical outcomes showed significant improvement from pre-operative visit to interim period and at the last follow-up (p < 0.01). No statistically significant differences for FO, AO and GO between contralateral and spacer side were observed. LLD before reimplantation was 10.1 ± 7.5 mm. GO increases of 4 ± 3.2 mm at final follow-up (p < 0.05) with a final LLD of 5.6 ± 4.9 mm. Six complications (12.8%) occurred during the interstage period: 4 spacer dislocations (8.5%) and 2 intraoperative femoral peri-spacer fractures (4.3%). . Comparison between stable and dislocated spacers showed statistically significant differences for mean ΔFO (p = 0.02) and ΔGO (p = 0.04). Conclusion The articulated spacer assessed in this study, especially when used in combination with a custom-made acetabular component, enabled adequate restoration of the main biomechanical parameters of the hip. Offset parameters reduction correlates with spacer dislocation rate. Hip Revision PJI Spacer Two-stage Complication Figures Figure 1 Figure 2 Figure 3 Introduction The number of total hip arthroplasties (THAs) performed worldwide is steadily increasing, and, consequently, the demand for revision procedures is expected to rise as well [ 1 – 4 ]. Periprosthetic joint infection (PJI) remains one of the leading causes of hip prosthesis failure, frequently requiring revision surgery [ 5 ]. While the one-stage revision approach has shown promising outcomes with good eradication rates in selected cases [ 6 ], the two-stage revision procedure continues to be considered the gold standard in many clinical scenarios due to its long-term optimal results [ 7 ]. In the first stage of the two-stage protocol, the use of articulating antibiotic-loaded spacers is the standard of care. These spacers offer several advantages: they help preserve joint function, reduce scar tissue formation—which facilitates the second stage reimplantation—and provide high local concentrations of antibiotics [ 8 , 9 ]. Nevertheless, spacer use is not without complications. Reported mechanical complication rates, such as spacer dislocation, spacer fracture, perispacer fracture, and periprosthetic osteolysis, vary widely in the literature, ranging from 0% to 92% [ 10 ]. Several factors have been associated with an increased risk of spacer-related mechanical complications, including the presence of femoral or acetabular bone loss, inadequate femoral engagement, abductor muscle deficiency, and suboptimal spacer design or positioning [ 11 – 13 ]. Among these, restoration of key biomechanical parameters—particularly leg length discrepancy (LLD) and offset—has been increasingly recognized as a potentially modifiable risk factor. In particular, failure to restore femoral offset has been implicated as a contributor to instability and mechanical failure, although a clear consensus is still lacking [ 14 , 15 ].The primary aim of this study is to evaluate the restoration of biomechanical parameters of the hip—specifically leg length discrepancy (LLD), femoral offset (FO), acetabular offset (AO), and global offset (GO)—following implantation of a specific type of articulating hip spacer during the first stage of a two-stage revision for PJI. A secondary objective is to assess the correlation between variations in offset parameters and the rate of interstage mechanical complications. Materials and Methods A retrospective analysis was conducted on patients treated with staged revision for chronic hip PJI from January 2020 to December 2022. All data have been prospectively collected by our Istitutional Arthroplasty Register and retrospectively analyzed. The Institutional Review Board (IRB) approved this single center study (no. 007/2025). Written and informed consent was obtained from all the included participants. All procedures were conducted according to Declaration of Helsinki. All patients undergoing a two-stage hip revision with a specific articulating spacer (G21 - SpaceFlex Hip) coupled with a handmade acetabular spacer during the study period were enrolled. Patients revised with different kind of spacer or that were managed with interim Girdlestone procedure were excluded. PJI diagnosis was made according to the 2018 International Consensus Meeting (ICM) criteria [ 16 ]. Main demographic (age, sex, diagnosis, affected side, body mass index (BMI), comorbidities, smoke status, previous surgical procedures) and surgical data (surgical time, surgical approach, acetabular and femoral bone loss, stem and acetabular spacer size, time of the interstage period, the need of a lateral window at the first stage and final prosthetic implant type) were recorded. Patients were classified according to systemic host grade McPherson staging system [ 17 ]. Acetabular and femoral bone defects were classified radiographically before surgery and confirmed during surgery according to the classification of Paprosky et al. [ 18 , 19 ]. Clinical and radiographic evaluation Clinical and radiographic evaluation were scheduled as follows: before the first stage, 6 week after the first stage, one, three and six months after the second stage and once per year thereafter Clinical assessment included physical examination, the Visual Analogue Scale (VAS), the Harris Hip Score (HHS), and the Oxford Hip Score (OHS), and these were used to evaluate subjective and objective hip function. Radiographic analysis included LLD, FO, AO and GO measurements on the affected (spacer and post-reimplantation) and the contralateral side as well as osseointegration, loosening, radiolucent lines, osteolysis, stem subsidence, malposition, and heterotopic ossification after final prosthetic reimplantation. Heterotopic ossifications were classified according to Brooker grade [ 20 ]. Stem subsidence was defined as femoral stem distal migration greater than 2 mm seen on the last AP radiograph in comparison to the immediately postoperative imaging [ 21 ]. Radiolucency lines and osteolysis areas were reported and evaluated according to the Charnely-DeLee and Gruen method [ 22 , 23 ] on the acetabular and femoral side, respectively. Radiographic analysis was performed on standard anteroposterior (AP) radiographs taken postoperatively with the patient in supine position and both legs in 15° internal rotation. The X-ray beam was centered on the symphysis pubis. All measurements were taken twice, at different time points, on digital AP radiographs of the pelvis by the same author (VM), who was not involved in index surgery. Recorded values were the average of the two measurements. Radiological distances (LLD, AO, FO and GO) were measured by using Carestream Imageview software. FO was defined as the perpendicular distance from the center of rotation of the femoral head to the anatomical femoral axis [ 24 ]. AO was defined as the perpendicular distance from the center of rotation of the femoral head to a line passing through the medial edge of the ipsilateral teardrop, perpendicular to the line through the inferior margins of the ischial tuberosities [ 25 ]. GO was defined as the sum of FO and AO [ 26 ]. Limb length (LL) was defined as the distance between the medial apex of the ipsilateral lesser trochanter and the line passing through the lower margins of the ischial tuberosity (Fig. 1 ). We measured AO, LL and FO on both the operated and contralateral sides. Differences were defined as follows: ΔGO = spacer GO – contralateral GO ΔFO = spacer FO – contralateral FO ΔAO = spacer AO – contralateral AO LLD = spacer LL – contralateral LL FO and AO were also assessed after reimplantation. Increase in offset measurements were expressed as positive values, while negative values defined offset reduction. Complications were recorded during the interstage and post-reimplantation period. Radiographs were assessed by two orthopaedic fellows (EF, VP). Surgical technique All patients underwent a two-stage procedure for hip PJI via a posterolateral approach. Preoperative digital templating (Fig. 2 ) with spacer templates was routinely performed to estimate size and head dimensions, though final sizing was determined intraoperatively after broaching the femoral canal and assessing bone loss. Scar tissue, sinus tracts, and abscesses were excised. In the first stage, the prosthesis was explanted and a G21 Spaceflex hip spacer (G21 S.r.l., Modena, Italy) was implanted. Before antibiotic administration, at least five microbiological samples were collected while prosthetic components were sent for sonication. For stem extraction, an extended lateral cortical window was performed if needed. After final intraoperative confirmation of spacer size, the G21 Spaceflex spacer was intraoperatively molded. It consists of a titanium core coated with gentamicin-loaded cement. Available options include three sizes of stem (10, 13 and 15) three possible lengths (140, 170, 210 mm) and 4 head sizes (48, 52, 56 and 60 mm). Acetabular spacers were handmade intraoperatively by molding a cement cup 2 mm larger than the spacer head [ 27 ] (Fig. 3 ). Low-viscosity G3A cement (G21 S.r.l., Modena, Italy) was used for molding the spacer, while PALACOS G® gentamicin cement (Heraeus Medical GmbH, Hamburg, Germany) was used for fixing the devices. If needed, specific antibiotics were added to cement spacer according to preoperative microbiological data. Both acetabular and femoral spacers were loosely cemented to avoid excessive cement infiltration into cancellous bone. During reimplantation and after removal of the mobile antibiotic-loaded spacer, a new, accurate surgical debridement was performed. At least 5 intraoperative samples were collected, and spacer was sent for sonication. According to the size and shape of bone deficiency, the senior surgeon decided the best technique to address the bone defect and the final components. Postoperative course After first stage, partial weight-bearing with a walker or crutches started on the second post-operative day after removal of the surgical drain and was continued for the whole interstage period. Standard venous thromboembolism prophylaxis with enoxaparin and compression stockings was prescribed at least for 45 days. In agreement with the infectious disease team, a 6-weeks specific antibiotic course was administered (intravenous for 2 weeks and oral administration for 4 weeks if possible, according to microbiological data). After the second stage, physiotherapy started with mobilization on the first postoperative day. Ambulation was allowed with partial weight-bearing the second day after surgery. Standard venous thromboembolism prophylaxis with enoxaparin and compression stockings was prescribed at least for 35 days. An intravenous specific antibiotic course was administered until intraoperative microbiological results were attained and continued thereafter if necessary. Statistical analysis Continuous variables were reported as mean ± standard deviation (SD) and compared using paired or unpaired Student t test. Categorical variables were expressed as the number of cases and percentage and compared using chi-squared or Fisher’s exact tests. For all the analyzed data, a two-tailed, p value < 0.05 was considered statistically significant. For radiological parameters, interobserver reliability was evaluated with the Cohen’s kappa coefficient. We defined as re-operation any kind of surgery that involved the hip joint after the index procedure without removing the fixed prosthetic component. Conversely, revision was considered as any surgical procedure that required fixed component removal for any reason. Spacer revision was defined as any procedure performed on the affected hip during the interstage time. We defined septic recurrence as each new infection or positive culture at reimplantation with isolation of the original infecting organism. Statistical analysis was carried out with the XLSTAT and Excel statistical software. Results Overall, 47 patients (47 hips), who met all inclusion/ exclusion criteria, were identified to be suitable to be enrolled in this study. All patients had a minimum follow-up of one year and none was lost during this time. The mean follow-up duration was 25.3 months. The mean age at surgery was 63.1 ± 11.4 years. Thirty patients were male (63.8%) and seventeen females (36.2%). The mean BMI was 26.2 ± 5.3. Excluding the index revision, patients had undergone an average of 2.3 ± 1.8 previous surgeries. Relevant comorbidities are summarized in Table 1. In all cases, chronic hip PJI was the indication for revision THA. Table 2 shows microbiological findings. The mean interstage period duration was 16.6 ± 11.1 weeks. Twelve (25.5%) patients required a femoral lateral window for stem extraction. Main surgical data along with femoral and acetabular bone defects distribution are potted in Table 3. According to spacer size, most of the included patient (55.3%) received a size 10 stem, 19 patients were implanted with a size 13 stem and only 2 had a size 15 spacer. Thirty-nine had a 48 mm spacer head; 52- and 56-mm heads were used in 4 patients each. Spacer length of 210 mm and 140 mm were employed in 29 (61.7%) and 17 (36.2%) of cases, respectively. Spacer features are showed in Table 4. Clinical and radiological analysis The mean HHS and OHS improved significantly from 29.7 ± 9.3 and 18.4 ± 10.6 pre-operatively to 72.6 ± 7.8 and 31.6 ± 3.3 before reimplantation and, 84.1 ± 8.9 and 39.4 ± 4.0, respectively, at the last follow-up (p < 0.01). On average, VAS decreased from 8.4 ± 2.1 pre-operatively to 1.1 ± 1.2 at the last evaluation (p < 0.01). Seven patients walked with crutches and 3 had mild limping at final follow up. Mean differences for FO, AO and GO between contralateral and spacer side were 0.4 ± 9.9, − 2.7 ± 6.0 and − 2.3 ± 7.7 mm, respectively with no statistically significant differences for the observed values (Table 5). LLD before reimplantation was 10.1 ± 7.5 mm. We observed a significantly mean increase of GO of 4 ± 3.2 mm at final follow-up (p < 0.05) with a final LLD of 5.6 ± 4.9 mm. No case of migration, loosening, or stem subsidence were observed at the last follow-up radiographic analysis. Two cases (4.3%) showed incomplete and not progressive < 2 mm radiolucent lines on Gruen zone 1. Heterotopic ossifications (2 Brooker type 2 and 1 Brooker type 3) were observed in 3 patients (6.4%). No dislocations were reported during the post-reimplantation period. For radiological parameters, very good (≥ 90%) Cohen’s kappa inter-rater agreement was found. Complications Six complications (12.8%) occurred during the interstage period (Table 6): 4 spacer dislocations (8.5%) and 2 intraoperative femoral peri-spacer fractures (4.3%) during the first step. No cases of spacer fracture, postoperative peri-spacer fracture or spacer revision for persistent infection were reported. Two dislocations were managed with spacer revision, 1 underwent a close reduction with no subsequent relapse and 1 patient was managed with final prothesis reimplantation. Comparison between stable and dislocated spacers showed statistically significant differences for mean ΔFO (p = 0.02) and ΔGO (p = 0.04), no significant differences were detected for other commonly involved parameters affecting dislocation (Table 7). Four (8.5%) of the included patients reported complications, including 1 septic recurrence (2.1%), 1 new prosthetic infection (2.1%) managed with a repeated two stage procedure, and 2 positive intra-operative microbiological cultures managed with specific suppressive therapy for three months with good outcome. The overall final implant survival rate was 95.7% at final follow-up. Discussion The primary objective of this study was to assess the ability of the G21 Spaceflex articulating spacer to restore key hip biomechanical parameters—FO, AO and GO, as well as leg length—in patients undergoing staged revision for periprosthetic hip infection. The findings demonstrate that, in most cases, the spacer provided satisfactory restoration of these parameters, thereby offering a reliable interim reconstruction during the first stage of revision. A significant observation emerged when comparing patients who sustained spacer dislocation with those who did not. Patients with dislocation exhibited a statistically significant reduction in femoral and global offset, whereas no significant differences were detected in other parameters commonly associated with instability. These results support the hypothesis that inadequate restoration of offset contributes to soft-tissue imbalance and reduced joint stability, ultimately increasing the risk of spacer dislocation. This association aligns with prior reports emphasizing the central role of offset and soft-tissue tension in maintaining stability during staged revision procedures [ 28 , 29 ]. The present findings are consistent with the literature, which underscores the challenges of achieving optimal biomechanics with prefabricated spacers [ 13 , 15 ]. Most commercially available spacers provide a fixed neck–shaft angle and a single offset option, limiting their adaptability to the broad anatomical variability encountered in revision settings [ 11 ]. These inherent constraints have been previously associated with suboptimal joint biomechanics and instability. Despite these limitations, the spacer used in this study—particularly when combined with a custom-made acetabular component—achieved satisfactory restoration of offset and limb length in the majority of patients. This suggests that the combined use of modular or custom acetabular elements may mitigate some of the intrinsic limitations of standard femoral spacers and improve biomechanical reconstruction [ 27 , 28 ]. Mechanical complications of hip spacers, particularly dislocation, remain a major concern, with reported rates ranging from 0% to 92.3% in the literature [ 10 ]. Risk factors for spacer dislocation include poor patient compliance, inadequate spacer femoral engagement, undersized spacer head, large acetabular bone defects, decreased leg length and muscular insufficiency [ 12 ]. Spacer geometry is also critical: Leunig et al. found that higher neck-to-head ratios increased dislocation risk, while insufficient intramedullary anchorage (< 22 ± 33 mm) was associated with failure [ 29 ]. Jones at al retrospectively reviewed 185 patients treated for hip PJI with antibiotic cement spacers between 2004 and 2014. Dislocation occurred in 9% and was significantly associated with reduced femoral offset of > 5 mm and increased bone loss. The authors concluded that spacer design, acetabular and femoral bone loss, and offset restoration were significantly associated with perioperative complications. Nonetheless, Molinas et al. [ 30 ] reported that lateral femoral offset (LFO) and modified vertical femoral offset (MVFO) did not modify dislocation rate. Although the mean LFO reduction on the spacer side was 8 mm, the same parameter for MVFO was only 1.2 mm. This minimal offset reduction explained the non-statistical correlation between offset reduction and dislocation rate. In order to improve spacer geometry, several techniques have been proposed. PROSTALAC (prosthesis of antibiotic-loaded acrylic cement, DePuy Synthes, Warsaw, IN, USA) was initially developed for septic hip revision and consists of a metal femoral stem and a polyethylene acetabular liner [ 31 ]. In a 10- to 15-year follow-up study, 99 PJI patients using the PROSTALAC hip spacer attained an 89% long-term treatment success rate [ 32 ] however, the availability of PROSTALAC is limited, and it is currently not approved for use in many countries. Custom-made articulating spacers (CUMARS) system the Exeter Universal Femoral stem (Stryker, Mahwah, NJ, USA) and a polyethylene acetabular liner [ 33 ]. It is comparable to PROSTALAC, but its components are more common and readily available. Recently, CUMARS was reported to be associated with good interstage functionality, easier removal, and excellent infection control [ 34 ] but polyethylene can act as a substrate for infection relapse with a possible increase of failures. Moreover, this procedure is burdened by considerable costs. The post-reimplantation biomechanical analysis showed good restoration of offset and leg length parameters with no dislocations during the follow-up period. This underlines a proper restoration of hip anatomy when compared to the preoperative contralateral side. This goal should be achieved only with proper preoperative planning and intraoperative accurate component positioning considering the first stage non only a debridement phase but the first step of hip reconstruction. This study has several limitations. Its retrospective design, although based on prospectively collected data, may introduce selection bias and prevents definitive causal inference. A second limitation is that, although 47 patients were included, only 4 dislocation were recorded, limiting the possibility to make clear estimations. Furthermore, the lack of a control group limits comparative interpretation, and the limited follow-up does not allow evaluation of long-term mechanical or functional outcomes. Finally, we measured the biomechanical parameters on the AP x-ray while some authors argued that CT-scans are more accurate [ 35 ]. CT scans were not routinely used to control patients in the interim period. In order to minimize measurement errors, we standardize x-ray protocol and all measurements were taken twice at different time points. Nevertheless, the present work also has notable strengths, including a consecutive and homogeneous patient series, a uniform surgical approach performed by a single surgeon, and the absence of dropouts, all of which enhance the reliability and consistency of the data. Conclusions The articulated spacer assessed in this study, especially when used in combination with a custom-made acetabular component, enabled adequate restoration of the main biomechanical parameters of the hip in most patients undergoing two-stage revision for infection. It should be considered a safe and effective interim solution for staged hip revision providing good clinical and functional outcomes in the interstage period. Offset parameters reduction correlates with spacer dislocation rate. The association between insufficient offset restoration and spacer dislocation highlights the importance of meticulous preoperative planning and accurate component positioning to reduce mechanical complications during the interim stage. These findings may contribute to improving the management strategies for periprosthetic hip infection and optimizing patient outcomes. Declarations Author Contribution All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Valentina Providenti, Emilio Ferrari and Vito Marciante. The first draft of the manuscript was written by Luca Cavagnaro and Giuliana Carrega and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. References Shichman I, Askew N, Habibi A, Nherera L, Macaulay W, Seyler T, Schwarzkopf R (20239 Projections and Epidemiology of Revision Hip and Knee Arthroplasty in the United States to 2040–2060. 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AJR Am J Roentgenol 180(6):1701–1706 Biring GS, Kostamo T, Garbuz DS, Masri BA, Duncan CP (2009) Two-stage revision arthroplasty of the hip for infection using an interim articulated Prostalac hip spacer: a 10- to 15-year follow-up study. J Bone Joint Surg Br 91(11):1431–1437 Tsung JD, Rohrsheim JA, Whitehouse SL, Wilson MJ, Howell JR (2014) Management of periprosthetic joint infection after total hip arthroplasty using a custom-made articulating spacer (CUMARS); the Exeter experience. J Arthroplasty 29(9):1813–1818 Quayle J, Barakat A, Klasan A, Mittal A, Stott P (2022) External validation study of hip peri-prosthetic joint infection with cemented custom-made articulating spacer (CUMARS). Hip Int 32(3):379–385 Pasquier G, Ducharne G, Ali ES, Giraud F, Mouttet A, Durante E (2010) Total hip arthroplasty offset measurement: is C T scan the most accurate option? Orthop Traumatol Surg Res Jun 96(4):367–375 Tables Table 1 to 7 are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Table1.docx Table2.docx Table3.docx Table4.docx Table5.docx Table6.docx Table7.docx Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 08 Feb, 2026 Reviews received at journal 08 Feb, 2026 Reviewers agreed at journal 27 Jan, 2026 Reviews received at journal 28 Dec, 2025 Reviewers agreed at journal 22 Dec, 2025 Reviewers invited by journal 04 Dec, 2025 Editor assigned by journal 25 Nov, 2025 Submission checks completed at journal 25 Nov, 2025 First submitted to journal 22 Nov, 2025 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. 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Cavagnaro","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABA0lEQVRIiWNgGAWjYBACPlRuxX85EHXgAR4tbKjcM8zGYC0JRGthbGNObAAx8GqRSH744UfNYXn56OZnHz6cYUufH3b4IdAWOzndBlxa0owle44dNtx455jxzBkVPLkbb6cZALUkG5sdwKUlh0GagS2NceOMBGNmnjMSuRtnJ4C0HEjchlsL82+Gf2n2G2ekf2bmbTNIN5yd/oGQFjZpxjabxPkSOcZALQkJ8tI5BGzheWZm2dtnk7xBIqeYccaZA4YbpHMKDiQY4PYLP3vy4xs/vknYzp+RvpnhQ8UBefnZ6Zs/fKiwk8OlBQ4MDqAwDAgoBwH5BnTGKBgFo2AUjAIoAAABa19ps8Wz9AAAAABJRU5ErkJggg==","orcid":"","institution":"Joint Replacement Unit / Bone Infection Unit (MIOS) – Ospedale Santa Maria di Misericordia","correspondingAuthor":true,"prefix":"","firstName":"Luca","middleName":"","lastName":"Cavagnaro","suffix":""},{"id":556394338,"identity":"d2b42f82-41ef-46b0-a586-be55d0c46786","order_by":1,"name":"Emilio Ferrari","email":"","orcid":"","institution":"Joint Replacement Unit / Bone Infection Unit (MIOS) – Ospedale Santa Maria di Misericordia","correspondingAuthor":false,"prefix":"","firstName":"Emilio","middleName":"","lastName":"Ferrari","suffix":""},{"id":556394339,"identity":"096a3944-2d14-4506-bb1c-6b057513d187","order_by":2,"name":"Valentina Providenti","email":"","orcid":"","institution":"Joint Replacement Unit / Bone Infection Unit (MIOS) – Ospedale Santa Maria di Misericordia","correspondingAuthor":false,"prefix":"","firstName":"Valentina","middleName":"","lastName":"Providenti","suffix":""},{"id":556394340,"identity":"fd45b5d8-f9ca-42d1-9ebf-a4e3a2eccd63","order_by":3,"name":"Vito Marciante","email":"","orcid":"","institution":"Clinica Ortopedica - Policlinico San Martino","correspondingAuthor":false,"prefix":"","firstName":"Vito","middleName":"","lastName":"Marciante","suffix":""},{"id":556394341,"identity":"86d79eae-6d6d-443f-8a3c-9da00f62fffe","order_by":4,"name":"Giuliana Carrega","email":"","orcid":"","institution":"Joint Replacement Unit / Bone Infection Unit (MIOS) – Ospedale Santa Maria di Misericordia","correspondingAuthor":false,"prefix":"","firstName":"Giuliana","middleName":"","lastName":"Carrega","suffix":""},{"id":556394342,"identity":"77c25bda-c35c-4c2e-9451-7fc7c757fbf5","order_by":5,"name":"Matteo Formica","email":"","orcid":"","institution":"Clinica Ortopedica - Policlinico San Martino","correspondingAuthor":false,"prefix":"","firstName":"Matteo","middleName":"","lastName":"Formica","suffix":""}],"badges":[],"createdAt":"2025-11-23 00:53:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8182860/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8182860/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":97894944,"identity":"e416ad60-23ea-40cc-8070-afe70b6babd5","added_by":"auto","created_at":"2025-12-10 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15:34:46","extension":"xml","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":82853,"visible":true,"origin":"","legend":"","description":"","filename":"547366d3b10a4d4686330ffb4cd038181enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/60bd955470d4200ee10c67d5.xml"},{"id":97895791,"identity":"08c2c98a-663e-43b0-8442-bee9c9be2097","added_by":"auto","created_at":"2025-12-10 15:34:56","extension":"xml","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":79168,"visible":true,"origin":"","legend":"","description":"","filename":"547366d3b10a4d4686330ffb4cd038181structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/c55caf10e4cff8f64d4c904b.xml"},{"id":97895687,"identity":"b8dbc7ab-cf93-4f7c-82db-25d3402f57f4","added_by":"auto","created_at":"2025-12-10 15:34:42","extension":"html","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":89165,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/dbc79d194fad70b46ece3a5e.html"},{"id":97720931,"identity":"ebc78203-5a31-4c96-bb65-e8b0eca4a5de","added_by":"auto","created_at":"2025-12-08 15:37:24","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":63764,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurements of the hip biomechanical radiographic parameters. \u003cem\u003eAO: acetabular offset; FO: femoral offset; LL: leg length.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/72c8dc53865c6d4c5a8f26fa.jpg"},{"id":97720935,"identity":"77a39252-3a69-4075-8cac-31e3c20ada6a","added_by":"auto","created_at":"2025-12-08 15:37:24","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":33789,"visible":true,"origin":"","legend":"\u003cp\u003ePreoperative planning of spacer implantation in right hip PJI.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/1dc975c70874ef5441fc4b5d.jpg"},{"id":97895542,"identity":"49873b04-7c37-4f48-93bd-8988e91860b3","added_by":"auto","created_at":"2025-12-10 15:34:25","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":90998,"visible":true,"origin":"","legend":"\u003cp\u003eG21 Spaceflex hip spacer coupled with a custom made acetabular spacer.\u003c/p\u003e","description":"","filename":"Figure3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/09782a08f9a383b083e7048c.jpeg"},{"id":97902731,"identity":"93596519-3ad8-486f-a29d-be26f01ebce5","added_by":"auto","created_at":"2025-12-10 15:53:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":636214,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/1b3a0ea3-9f3e-4506-a33f-652df7e2155d.pdf"},{"id":97720932,"identity":"c26ecc27-3782-4c30-a898-6d4ba6b802bd","added_by":"auto","created_at":"2025-12-08 15:37:24","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":29028,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/77fe2b2ada2952640a577755.docx"},{"id":97895920,"identity":"d1647be0-b4ef-4dab-8545-8e9c90a638bd","added_by":"auto","created_at":"2025-12-10 15:35:23","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":12567,"visible":true,"origin":"","legend":"","description":"","filename":"Table2.docx","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/74fea30e4579c89c53b981f5.docx"},{"id":97720936,"identity":"efe5f2c0-b75e-426b-b754-7ee7272d4239","added_by":"auto","created_at":"2025-12-08 15:37:24","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":12641,"visible":true,"origin":"","legend":"","description":"","filename":"Table3.docx","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/86cd6fd2e4d6144e3ef0a80a.docx"},{"id":97720941,"identity":"f8b57754-0fd4-4605-b209-9e91bc467ec9","added_by":"auto","created_at":"2025-12-08 15:37:24","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":12542,"visible":true,"origin":"","legend":"","description":"","filename":"Table4.docx","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/9d854e0a4c8ddbed697942e0.docx"},{"id":97720943,"identity":"75784dcf-c40f-425b-b76a-979e53987a02","added_by":"auto","created_at":"2025-12-08 15:37:24","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":12879,"visible":true,"origin":"","legend":"","description":"","filename":"Table5.docx","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/b67cc8de549a27bcb4e538a5.docx"},{"id":97720944,"identity":"edeaf6b9-34ea-4f0f-9414-7d0356390fa5","added_by":"auto","created_at":"2025-12-08 15:37:24","extension":"docx","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":12365,"visible":true,"origin":"","legend":"","description":"","filename":"Table6.docx","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/c19f7305a75bf3fb05657054.docx"},{"id":97720948,"identity":"82837650-d2ab-420b-a7dd-b9828ec449b8","added_by":"auto","created_at":"2025-12-08 15:37:24","extension":"docx","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":13188,"visible":true,"origin":"","legend":"","description":"","filename":"Table7.docx","url":"https://assets-eu.researchsquare.com/files/rs-8182860/v1/3dde5d3e0b35b12ba17a9e1c.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eEvaluation Of Femoral, Acetabular and Global Offset Restoration Following Hip Spacer Implantation in Staged Total Hip Arthroplasty\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe number of total hip arthroplasties (THAs) performed worldwide is steadily increasing, and, consequently, the demand for revision procedures is expected to rise as well [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Periprosthetic joint infection (PJI) remains one of the leading causes of hip prosthesis failure, frequently requiring revision surgery [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. While the one-stage revision approach has shown promising outcomes with good eradication rates in selected cases [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], the two-stage revision procedure continues to be considered the gold standard in many clinical scenarios due to its long-term optimal results [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In the first stage of the two-stage protocol, the use of articulating antibiotic-loaded spacers is the standard of care. These spacers offer several advantages: they help preserve joint function, reduce scar tissue formation\u0026mdash;which facilitates the second stage reimplantation\u0026mdash;and provide high local concentrations of antibiotics [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Nevertheless, spacer use is not without complications. Reported mechanical complication rates, such as spacer dislocation, spacer fracture, perispacer fracture, and periprosthetic osteolysis, vary widely in the literature, ranging from 0% to 92% [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Several factors have been associated with an increased risk of spacer-related mechanical complications, including the presence of femoral or acetabular bone loss, inadequate femoral engagement, abductor muscle deficiency, and suboptimal spacer design or positioning [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Among these, restoration of key biomechanical parameters\u0026mdash;particularly leg length discrepancy (LLD) and offset\u0026mdash;has been increasingly recognized as a potentially modifiable risk factor. In particular, failure to restore femoral offset has been implicated as a contributor to instability and mechanical failure, although a clear consensus is still lacking [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].The primary aim of this study is to evaluate the restoration of biomechanical parameters of the hip\u0026mdash;specifically leg length discrepancy (LLD), femoral offset (FO), acetabular offset (AO), and global offset (GO)\u0026mdash;following implantation of a specific type of articulating hip spacer during the first stage of a two-stage revision for PJI. A secondary objective is to assess the correlation between variations in offset parameters and the rate of interstage mechanical complications.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eA retrospective analysis was conducted on patients treated with staged revision for chronic hip PJI from January 2020 to December 2022. All data have been prospectively collected by our Istitutional Arthroplasty Register and retrospectively analyzed. The Institutional Review Board (IRB) approved this single center study (no. 007/2025). Written and informed consent was obtained from all the included participants. All procedures were conducted according to Declaration of Helsinki. All patients undergoing a two-stage hip revision with a specific articulating spacer (G21 - SpaceFlex Hip) coupled with a handmade acetabular spacer during the study period were enrolled. Patients revised with different kind of spacer or that were managed with interim Girdlestone procedure were excluded. PJI diagnosis was made according to the 2018 International Consensus Meeting (ICM) criteria [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Main demographic (age, sex, diagnosis, affected side, body mass index (BMI), comorbidities, smoke status, previous surgical procedures) and surgical data (surgical time, surgical approach, acetabular and femoral bone loss, stem and acetabular spacer size, time of the interstage period, the need of a lateral window at the first stage and final prosthetic implant type) were recorded. Patients were classified according to systemic host grade McPherson staging system [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Acetabular and femoral bone defects were classified radiographically before surgery and confirmed during surgery according to the classification of Paprosky et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eClinical and radiographic evaluation\u003c/h2\u003e\u003cp\u003eClinical and radiographic evaluation were scheduled as follows: before the first stage, 6 week after the first stage, one, three and six months after the second stage and once per year thereafter Clinical assessment included physical examination, the Visual Analogue Scale (VAS), the Harris Hip Score (HHS), and the Oxford Hip Score (OHS), and these were used to evaluate subjective and objective hip function. Radiographic analysis included LLD, FO, AO and GO measurements on the affected (spacer and post-reimplantation) and the contralateral side as well as osseointegration, loosening, radiolucent lines, osteolysis, stem subsidence, malposition, and heterotopic ossification after final prosthetic reimplantation. Heterotopic ossifications were classified according to Brooker grade [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Stem subsidence was defined as femoral stem distal migration greater than 2 mm seen on the last AP radiograph in comparison to the immediately postoperative imaging [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Radiolucency lines and osteolysis areas were reported and evaluated according to the Charnely-DeLee and Gruen method [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] on the acetabular and femoral side, respectively. Radiographic analysis was performed on standard anteroposterior (AP) radiographs taken postoperatively with the patient in supine position and both legs in 15\u0026deg; internal rotation. The X-ray beam was centered on the symphysis pubis. All measurements were taken twice, at different time points, on digital AP radiographs of the pelvis by the same author (VM), who was not involved in index surgery. Recorded values were the average of the two measurements. Radiological distances (LLD, AO, FO and GO) were measured by using Carestream Imageview software. FO was defined as the perpendicular distance from the center of rotation of the femoral head to the anatomical femoral axis [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. AO was defined as the perpendicular distance from the center of rotation of the femoral head to a line passing through the medial edge of the ipsilateral teardrop, perpendicular to the line through the inferior margins of the ischial tuberosities [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. GO was defined as the sum of FO and AO [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Limb length (LL) was defined as the distance between the medial apex of the ipsilateral lesser trochanter and the line passing through the lower margins of the ischial tuberosity (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eWe measured AO, LL and FO on both the operated and contralateral sides. Differences were defined as follows:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e ΔGO\u0026thinsp;=\u0026thinsp;spacer GO \u0026ndash; contralateral GO\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e ΔFO\u0026thinsp;=\u0026thinsp;spacer FO \u0026ndash; contralateral FO\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e ΔAO\u0026thinsp;=\u0026thinsp;spacer AO \u0026ndash; contralateral AO\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e LLD\u0026thinsp;=\u0026thinsp;spacer LL \u0026ndash; contralateral LL\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eFO and AO were also assessed after reimplantation. Increase in offset measurements were expressed as positive values, while negative values defined offset reduction.\u003c/p\u003e\u003cp\u003eComplications were recorded during the interstage and post-reimplantation period. Radiographs were assessed by two orthopaedic fellows (EF, VP).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSurgical technique\u003c/h3\u003e\n\u003cp\u003eAll patients underwent a two-stage procedure for hip PJI via a posterolateral approach. Preoperative digital templating (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) with spacer templates was routinely performed to estimate size and head dimensions, though final sizing was determined intraoperatively after broaching the femoral canal and assessing bone loss.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eScar tissue, sinus tracts, and abscesses were excised. In the first stage, the prosthesis was explanted and a G21 Spaceflex hip spacer (G21 S.r.l., Modena, Italy) was implanted. Before antibiotic administration, at least five microbiological samples were collected while prosthetic components were sent for sonication.\u003c/p\u003e\u003cp\u003eFor stem extraction, an extended lateral cortical window was performed if needed. After final intraoperative confirmation of spacer size, the G21 Spaceflex spacer was intraoperatively molded. It consists of a titanium core coated with gentamicin-loaded cement. Available options include three sizes of stem (10, 13 and 15) three possible lengths (140, 170, 210 mm) and 4 head sizes (48, 52, 56 and 60 mm). Acetabular spacers were handmade intraoperatively by molding a cement cup 2 mm larger than the spacer head [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Low-viscosity G3A cement (G21 S.r.l., Modena, Italy) was used for molding the spacer, while PALACOS G\u0026reg; gentamicin cement (Heraeus Medical GmbH, Hamburg, Germany) was used for fixing the devices. If needed, specific antibiotics were added to cement spacer according to preoperative microbiological data. Both acetabular and femoral spacers were loosely cemented to avoid excessive cement infiltration into cancellous bone. During reimplantation and after removal of the mobile antibiotic-loaded spacer, a new, accurate surgical debridement was performed. At least 5 intraoperative samples were collected, and spacer was sent for sonication. According to the size and shape of bone deficiency, the senior surgeon decided the best technique to address the bone defect and the final components.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003ePostoperative course\u003c/h3\u003e\n\u003cp\u003eAfter first stage, partial weight-bearing with a walker or crutches started on the second post-operative day after removal of the surgical drain and was continued for the whole interstage period. Standard venous thromboembolism prophylaxis with enoxaparin and compression stockings was prescribed at least for 45 days. In agreement with the infectious disease team, a 6-weeks specific antibiotic course was administered (intravenous for 2 weeks and oral administration for 4 weeks if possible, according to microbiological data). After the second stage, physiotherapy started with mobilization on the first postoperative day. Ambulation was allowed with partial weight-bearing the second day after surgery. Standard venous thromboembolism prophylaxis with enoxaparin and compression stockings was prescribed at least for 35 days. An intravenous specific antibiotic course was administered until intraoperative microbiological results were attained and continued thereafter if necessary.\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eContinuous variables were reported as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) and compared using paired or unpaired Student t test. Categorical variables were expressed as the number of cases and percentage and compared using chi-squared or Fisher\u0026rsquo;s exact tests. For all the analyzed data, a two-tailed, p value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. For radiological parameters, interobserver reliability was evaluated with the Cohen\u0026rsquo;s kappa coefficient. We defined as re-operation any kind of surgery that involved the hip joint after the index procedure without removing the fixed prosthetic component. Conversely, revision was considered as any surgical procedure that required fixed component removal for any reason. Spacer revision was defined as any procedure performed on the affected hip during the interstage time. We defined septic recurrence as each new infection or positive culture at reimplantation with isolation of the original infecting organism. Statistical analysis was carried out with the XLSTAT and Excel statistical software.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eOverall, 47 patients (47 hips), who met all inclusion/ exclusion criteria, were identified to be suitable to be enrolled in this study. All patients had a minimum follow-up of one year and none was lost during this time. The mean follow-up duration was 25.3 months. The mean age at surgery was 63.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.4 years. Thirty patients were male (63.8%) and seventeen females (36.2%). The mean BMI was 26.2\u0026thinsp;\u0026plusmn;\u0026thinsp;5.3. Excluding the index revision, patients had undergone an average of 2.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8 previous surgeries. Relevant comorbidities are summarized in Table\u0026nbsp;1. In all cases, chronic hip PJI was the indication for revision THA. Table\u0026nbsp;2 shows microbiological findings. The mean interstage period duration was 16.6\u0026thinsp;\u0026plusmn;\u0026thinsp;11.1 weeks. Twelve (25.5%) patients required a femoral lateral window for stem extraction. Main surgical data along with femoral and acetabular bone defects distribution are potted in Table\u0026nbsp;3. According to spacer size, most of the included patient (55.3%) received a size 10 stem, 19 patients were implanted with a size 13 stem and only 2 had a size 15 spacer. Thirty-nine had a 48 mm spacer head; 52- and 56-mm heads were used in 4 patients each. Spacer length of 210 mm and 140 mm were employed in 29 (61.7%) and 17 (36.2%) of cases, respectively. Spacer features are showed in Table\u0026nbsp;4.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eClinical and radiological analysis\u003c/h2\u003e\u003cp\u003eThe mean HHS and OHS improved significantly from 29.7\u0026thinsp;\u0026plusmn;\u0026thinsp;9.3 and 18.4\u0026thinsp;\u0026plusmn;\u0026thinsp;10.6 pre-operatively to 72.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8 and 31.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3 before reimplantation and, 84.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9 and 39.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0, respectively, at the last follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). On average, VAS decreased from 8.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 pre-operatively to 1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2 at the last evaluation (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). Seven patients walked with crutches and 3 had mild limping at final follow up. Mean differences for FO, AO and GO between contralateral and spacer side were 0.4\u0026thinsp;\u0026plusmn;\u0026thinsp;9.9, \u0026minus;\u0026thinsp;2.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0 and \u0026minus;\u0026thinsp;2.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7 mm, respectively with no statistically significant differences for the observed values (Table\u0026nbsp;5). LLD before reimplantation was 10.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.5 mm. We observed a significantly mean increase of GO of 4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2 mm at final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) with a final LLD of 5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9 mm. No case of migration, loosening, or stem subsidence were observed at the last follow-up radiographic analysis. Two cases (4.3%) showed incomplete and not progressive\u0026thinsp;\u0026lt;\u0026thinsp;2 mm radiolucent lines on Gruen zone 1. Heterotopic ossifications (2 Brooker type 2 and 1 Brooker type 3) were observed in 3 patients (6.4%). No dislocations were reported during the post-reimplantation period. For radiological parameters, very good (\u0026ge;\u0026thinsp;90%) Cohen\u0026rsquo;s kappa inter-rater agreement was found.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eComplications\u003c/h3\u003e\n\u003cp\u003eSix complications (12.8%) occurred during the interstage period (Table\u0026nbsp;6): 4 spacer dislocations (8.5%) and 2 intraoperative femoral peri-spacer fractures (4.3%) during the first step. No cases of spacer fracture, postoperative peri-spacer fracture or spacer revision for persistent infection were reported. Two dislocations were managed with spacer revision, 1 underwent a close reduction with no subsequent relapse and 1 patient was managed with final prothesis reimplantation. Comparison between stable and dislocated spacers showed statistically significant differences for mean ΔFO (p\u0026thinsp;=\u0026thinsp;0.02) and ΔGO (p\u0026thinsp;=\u0026thinsp;0.04), no significant differences were detected for other commonly involved parameters affecting dislocation (Table\u0026nbsp;7). Four (8.5%) of the included patients reported complications, including 1 septic recurrence (2.1%), 1 new prosthetic infection (2.1%) managed with a repeated two stage procedure, and 2 positive intra-operative microbiological cultures managed with specific suppressive therapy for three months with good outcome. The overall final implant survival rate was 95.7% at final follow-up.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe primary objective of this study was to assess the ability of the G21 Spaceflex articulating spacer to restore key hip biomechanical parameters\u0026mdash;FO, AO and GO, as well as leg length\u0026mdash;in patients undergoing staged revision for periprosthetic hip infection. The findings demonstrate that, in most cases, the spacer provided satisfactory restoration of these parameters, thereby offering a reliable interim reconstruction during the first stage of revision.\u003c/p\u003e\u003cp\u003eA significant observation emerged when comparing patients who sustained spacer dislocation with those who did not. Patients with dislocation exhibited a statistically significant reduction in femoral and global offset, whereas no significant differences were detected in other parameters commonly associated with instability. These results support the hypothesis that inadequate restoration of offset contributes to soft-tissue imbalance and reduced joint stability, ultimately increasing the risk of spacer dislocation. This association aligns with prior reports emphasizing the central role of offset and soft-tissue tension in maintaining stability during staged revision procedures [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. The present findings are consistent with the literature, which underscores the challenges of achieving optimal biomechanics with prefabricated spacers [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Most commercially available spacers provide a fixed neck\u0026ndash;shaft angle and a single offset option, limiting their adaptability to the broad anatomical variability encountered in revision settings [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. These inherent constraints have been previously associated with suboptimal joint biomechanics and instability. Despite these limitations, the spacer used in this study\u0026mdash;particularly when combined with a custom-made acetabular component\u0026mdash;achieved satisfactory restoration of offset and limb length in the majority of patients. This suggests that the combined use of modular or custom acetabular elements may mitigate some of the intrinsic limitations of standard femoral spacers and improve biomechanical reconstruction [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMechanical complications of hip spacers, particularly dislocation, remain a major concern, with reported rates ranging from 0% to 92.3% in the literature [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Risk factors for spacer dislocation include poor patient compliance, inadequate spacer femoral engagement, undersized spacer head, large acetabular bone defects, decreased leg length and muscular insufficiency [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eSpacer geometry is also critical: Leunig et al. found that higher neck-to-head ratios increased dislocation risk, while insufficient intramedullary anchorage (\u0026lt;\u0026thinsp;22\u0026thinsp;\u0026plusmn;\u0026thinsp;33 mm) was associated with failure [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Jones at al retrospectively reviewed 185 patients treated for hip PJI with antibiotic cement spacers between 2004 and 2014. Dislocation occurred in 9% and was significantly associated with reduced femoral offset of \u0026gt;\u0026thinsp;5 mm and increased bone loss. The authors concluded that spacer design, acetabular and femoral bone loss, and offset restoration were significantly associated with perioperative complications. Nonetheless, Molinas et al. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] reported that lateral femoral offset (LFO) and modified vertical femoral offset (MVFO) did not modify dislocation rate. Although the mean LFO reduction on the spacer side was 8 mm, the same parameter for MVFO was only 1.2 mm. This minimal offset reduction explained the non-statistical correlation between offset reduction and dislocation rate. In order to improve spacer geometry, several techniques have been proposed. PROSTALAC (prosthesis of antibiotic-loaded acrylic cement, DePuy Synthes, Warsaw, IN, USA) was initially developed for septic hip revision and consists of a metal femoral stem and a polyethylene acetabular liner [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. In a 10- to 15-year follow-up study, 99 PJI patients using the PROSTALAC hip spacer attained an 89% long-term treatment success rate [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] however, the availability of PROSTALAC is limited, and it is currently not approved for use in many countries. Custom-made articulating spacers (CUMARS) system the Exeter Universal Femoral stem (Stryker, Mahwah, NJ, USA) and a polyethylene acetabular liner [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. It is comparable to PROSTALAC, but its components are more common and readily available. Recently, CUMARS was reported to be associated with good interstage functionality, easier removal, and excellent infection control [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] but polyethylene can act as a substrate for infection relapse with a possible increase of failures. Moreover, this procedure is burdened by considerable costs.\u003c/p\u003e\u003cp\u003eThe post-reimplantation biomechanical analysis showed good restoration of offset and leg length parameters with no dislocations during the follow-up period. This underlines a proper restoration of hip anatomy when compared to the preoperative contralateral side. This goal should be achieved only with proper preoperative planning and intraoperative accurate component positioning considering the first stage non only a debridement phase but the first step of hip reconstruction.\u003c/p\u003e\u003cp\u003eThis study has several limitations. Its retrospective design, although based on prospectively collected data, may introduce selection bias and prevents definitive causal inference. A second limitation is that, although 47 patients were included, only 4 dislocation were recorded, limiting the possibility to make clear estimations. Furthermore, the lack of a control group limits comparative interpretation, and the limited follow-up does not allow evaluation of long-term mechanical or functional outcomes. Finally, we measured the biomechanical parameters on the AP x-ray while some authors argued that CT-scans are more accurate [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. CT scans were not routinely used to control patients in the interim period. In order to minimize measurement errors, we standardize x-ray protocol and all measurements were taken twice at different time points. Nevertheless, the present work also has notable strengths, including a consecutive and homogeneous patient series, a uniform surgical approach performed by a single surgeon, and the absence of dropouts, all of which enhance the reliability and consistency of the data.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe articulated spacer assessed in this study, especially when used in combination with a custom-made acetabular component, enabled adequate restoration of the main biomechanical parameters of the hip in most patients undergoing two-stage revision for infection. It should be considered a safe and effective interim solution for staged hip revision providing good clinical and functional outcomes in the interstage period. Offset parameters reduction correlates with spacer dislocation rate. The association between insufficient offset restoration and spacer dislocation highlights the importance of meticulous preoperative planning and accurate component positioning to reduce mechanical complications during the interim stage. These findings may contribute to improving the management strategies for periprosthetic hip infection and optimizing patient outcomes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Valentina Providenti, Emilio Ferrari and Vito Marciante. The first draft of the manuscript was written by Luca Cavagnaro and Giuliana Carrega and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eShichman I, Askew N, Habibi A, Nherera L, Macaulay W, Seyler T, Schwarzkopf R (20239 Projections and Epidemiology of Revision Hip and Knee Arthroplasty in the United States to 2040\u0026ndash;2060. Arthroplast Today May 30;21:101152\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSchwartz AM, Farley KX, Guild GN, Bradbury TL Jr. (2020) Projections and Epidemiology of Revision Hip and Knee Arthroplasty in the United States to 2030. J Arthroplasty Jun 35(6S):S79\u0026ndash;S85\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChiarlone F, Cavagnaro L, Zanirato A, Alessio Mazzola M, Lovisolo S, Mosconi L, Felli L, Burastero G (2020) Cup-on-cup technique: a reliable management solution for severe acetabular bone loss in revision total hip replacement. Hip Int Sep 30(1suppl):12\u0026ndash;18\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChiarlone F, Zanirato A, Cavagnaro L, Alessio-Mazzola M, Felli L, Burastero G (2020) Acetabular custom-made implants for severe acetabular bone defect in revision total hip arthroplasty: a systematic review of the literature. Arch Orthop Trauma Surg Mar 140(3):415\u0026ndash;424\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDale H, Fenstad AM, Hallan G, Overgaard S, Pedersen AB, Hailer NP, K\u0026auml;rrholm J, Rolfson O, Eskelinen A, M\u0026auml;kel\u0026auml; KT, Furnes O (20239 Increasing risk of revision due to infection after primary total hip arthroplasty: results from the Nordic Arthroplasty Register Association. Acta Orthop Jun 27;94:307\u0026ndash;315\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNguyen M, Sukeik M, Zahar A, Nizam I, Haddad FS (2016) One-stage Exchange Arthroplasty for Periprosthetic Hip and Knee Joint Infections. Open Orthop J Nov 30:10:646\u0026ndash;653\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCarrega G, Casalino-Finocchio G, Cavagnaro L, Felli L, Riccio G, Burastero G (2020) Long-term outcome of prosthetic joint infections treated with two-stage revision. Acta Orthop Belg Mar; 86(1):10\u0026ndash;16\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSporer SM (2020) Spacer Design Options and Consideration for Periprosthetic Joint Infection. J Arthroplasty Mar 35(3S):S31\u0026ndash;S34\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTseng J, Oladipo VA, Acu\u0026ntilde;a AJ, Jones CM, Tsintolas J, Levine BR (2024) Evaluating Modern Spacer Options and Outcomes in Revision Hip Arthroplasty. 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Int J Med Sci Sep 3(5):274\u0026ndash;279\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBarreira P, Leite P, Neves P, Soares D, Sousa R (2015) Preventing mechanical complications of hip spacer implantation: technical tips and pearls. Acta Orthop Belg Jun; 81(2):344\u0026ndash;348\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eErivan R, Lecointe T, Villatte G, Mulliez A, Descamps S, Boisgard S (2018) Complications with cement spacers in 2-stage treatment of periprosthetic joint infection on total hip replacement. Orthop Traumatol Surg Res May 104(3):333\u0026ndash;339\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKipp JO, Lamm M, S\u0026oslash;balle K, Jakobsen SS (2019) Periprosthetic hip infection treated with two-stage stage-one Select Spacer- complication rate and restoration of anatomy. J Orthop Sep 11:18:138\u0026ndash;142\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eParvizi J, Tan TL, Goswami K, Higuera C, Della Valle C, Chen AF, Shohat N (2018) The 2018 Definition of Periprosthetic Hip and Knee Infection: An Evidence-Based and Validated Criteria. J Arthroplasty May 33(5):1309\u0026ndash;1314e2\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCoughlan A, Taylor F (2020) Classifications in Brief: The McPherson Classification of Periprosthetic Infection. Clin Orthop Relat Res Apr 478(4):903\u0026ndash;908\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePaprosky WG, Perona PG, Lawrence JM (1994) Acetabular defect classification and surgical reconstruction in revision arthroplasty. A 6-year follow-up evaluation. J Arthroplast 9(1):33\u0026ndash;44\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDella Valle CJ, Paprosky WG (2004) The femur in revision total hip arthroplasty evaluation and classification. Clin Orthop Relat Res 420:55\u0026ndash;62\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHug KT, Alton TB, Gee AO (2015) Classifications in brief: Brooker classification of heterotopic ossification after total hip arthroplasty. Clin Orthop Relat Res 473(6):2154\u0026ndash;2157\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEspehaug B, Havelin LI, Engesaeter LB, Vollset SE, Langeland N (1995) Early revision among 12,179 hip prostheses. A comparison of 10 different brands reported to the Norwegian Arthroplasty register, 1987\u0026ndash;1993. Acta Orthop Scand 66(6):487\u0026ndash;493\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDeLee JG, Charnley J (1976) Radiological demarcation of cemented sockets in total hip replacement. Clin Orthop Relat Res (121):20\u0026ndash;3228\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGruen TA, McNeice GM, Amstutz HC (1979) Modes of failure of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop Relat Res (141):17\u0026ndash;27\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWarnock J, Hill J, Humphreys L, Gallagher N, Napier R, Beverland D (2019) Independent restoration of femoral and acetabular height reduces limb length discrepancy and improves reported outcome following total hiparthroplasty. J Orthop 16(6):483\u0026ndash;488\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eClement ND, Patrick-Patel S, MacDonald R, Breusch D SJ (2016) Total hip replacement: increasing femoral offset improves functional outcome. Acta Orthop Trauma Surg 136(9):1317\u0026ndash;1323\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAl-Amiry B, Mahmood S, Krupic F, Sayed-Noor A (2017) Leg lengthening and femoral-offset reduction after total hip arthroplasty: where is the problem -stem or cup positioning? Acta Radiol 58(9):1125\u0026ndash;1131\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBurastero G, Basso M, Carrega G et al (2016) Acetabular Spacers in 2-Stage Hip Revision: Is it Worth it? A Single-Centre Retrospective Study. HIP Int 27(2):187\u0026ndash;192. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.5301/hipint.5000446\u003c/span\u003e\u003cspan address=\"10.5301/hipint.5000446\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLausmann C, Citak M, Hessling U, Wolff M, Gehrke T, Suero EM, Zahar A (2018) Preliminary results of a novel spacer technique in the management of septic revision hip arthroplasty. Arch Orthop Trauma Surg Nov 138(11):1617\u0026ndash;1622\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLeunig M, Chosa E, Speck M, Ganz R (1998) A cement spacer for two-stage revision of infected implants of the hip joint. Int Orthop 22(4):209\u0026ndash;214\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMolinas I, Garcia-Oltra E, Fern\u0026aacute;ndez-Valencia JA, Tomas X, Gal- lart X, Riba J et al (2017) Relationship between femoral off-set and dislocation in preformed antibiotic-loaded cement spacers (Spacer-G\u0026reg;). Hip Int 27(5):494\u0026ndash;499\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGee R, Munk PL, Keogh C, Nicolaou S, Masri B, Marchinkow LO, Ellis J, Chan LP (2003) Radiography of the PROSTALAC (prosthesis with antibiotic-loaded acrylic cement) orthopedic implant. AJR Am J Roentgenol 180(6):1701\u0026ndash;1706\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBiring GS, Kostamo T, Garbuz DS, Masri BA, Duncan CP (2009) Two-stage revision arthroplasty of the hip for infection using an interim articulated Prostalac hip spacer: a 10- to 15-year follow-up study. J Bone Joint Surg Br 91(11):1431\u0026ndash;1437\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTsung JD, Rohrsheim JA, Whitehouse SL, Wilson MJ, Howell JR (2014) Management of periprosthetic joint infection after total hip arthroplasty using a custom-made articulating spacer (CUMARS); the Exeter experience. J Arthroplasty 29(9):1813\u0026ndash;1818\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eQuayle J, Barakat A, Klasan A, Mittal A, Stott P (2022) External validation study of hip peri-prosthetic joint infection with cemented custom-made articulating spacer (CUMARS). Hip Int 32(3):379\u0026ndash;385\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePasquier G, Ducharne G, Ali ES, Giraud F, Mouttet A, Durante E (2010) Total hip arthroplasty offset measurement: is C T scan the most accurate option? Orthop Traumatol Surg Res Jun 96(4):367\u0026ndash;375\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1 to 7 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"archives-of-orthopaedic-and-trauma-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aots","sideBox":"Learn more about [Archives of Orthopaedic and Trauma Surgery](http://link.springer.com/journal/402)","snPcode":"402","submissionUrl":"https://submission.springernature.com/new-submission/402/3","title":"Archives of Orthopaedic and Trauma Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":" Hip, Revision, PJI, Spacer, Two-stage, Complication","lastPublishedDoi":"10.21203/rs.3.rs-8182860/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8182860/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIntroduction The primary aim of this study is to evaluate the restoration of biomechanical parameters of the hip—specifically leg length discrepancy (LLD), femoral offset (FO), acetabular offset (AO), and global offset (GO)—following implantation of a specific type of articulating hip spacer during the first stage of a two-stage revision for PJI. A secondary objective is to assess the correlation between variations in offset parameters and the rate of interstage mechanical complications\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMaterials and\u0026nbsp;Methods We retrospectively reviewed all patients undergoing staged revision with a specific articulating spacer between 2020 and 2022 at a single institution. Harris Hip Scores, Oxford Hip Scores, and Visual Analogue Scales for pain were obtained at different time points. Radiographic analysis included LLD, FO, AO and GO measurements on the affected (spacer and post-reimplantation) and the contralateral side. Complications were recorded during the interstage and post-reimplantation period.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eResults Forthy-seven patients (47 hips), were enrolled. The mean follow-up was 25.3 months. Clinical outcomes showed significant improvement from pre-operative visit to interim period and at the last follow-up (p \u0026lt; 0.01). No statistically significant differences for FO, AO and GO between contralateral and spacer side were observed. LLD before reimplantation was 10.1 ± 7.5 mm. GO increases of 4 ± 3.2 mm at final follow-up (p \u0026lt; 0.05) with a final LLD of 5.6 ± 4.9 mm. Six complications (12.8%) occurred during the interstage period: 4 spacer dislocations (8.5%) and 2 intraoperative femoral peri-spacer fractures (4.3%). . Comparison between stable and dislocated spacers showed statistically significant differences for mean ΔFO (p = 0.02) and ΔGO (p = 0.04).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eConclusion The articulated spacer assessed in this study, especially when used in combination with a custom-made acetabular component, enabled adequate restoration of the main biomechanical parameters of the hip. Offset parameters reduction correlates with spacer dislocation rate.\u003c/p\u003e","manuscriptTitle":"Evaluation Of Femoral, Acetabular and Global Offset Restoration Following Hip Spacer Implantation in Staged Total Hip Arthroplasty","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-08 15:37:20","doi":"10.21203/rs.3.rs-8182860/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-08T20:53:03+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-08T20:21:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"300290065321483942128689525206041876508","date":"2026-01-28T02:26:43+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-28T19:19:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"325676707923832251977592608298718924094","date":"2025-12-22T19:35:37+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-04T22:00:24+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-25T07:42:00+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-11-25T07:41:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"Archives of Orthopaedic and Trauma Surgery","date":"2025-11-23T00:39:46+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"archives-of-orthopaedic-and-trauma-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aots","sideBox":"Learn more about [Archives of Orthopaedic and Trauma Surgery](http://link.springer.com/journal/402)","snPcode":"402","submissionUrl":"https://submission.springernature.com/new-submission/402/3","title":"Archives of Orthopaedic and Trauma Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"cc6bb74d-d525-4d97-8e5d-055d41a5cb8f","owner":[],"postedDate":"December 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-05T14:10:17+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-08 15:37:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8182860","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8182860","identity":"rs-8182860","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}