Wagner M, Anderson AE, Parisien A
… +7 more, Belzile ÉL, Ng KCG, Safran MR, Karimijashni M, Poitras S, Grammatopoulos G, Beaulé PE
Clin Orthop Relat Res
· 2026 May · PMID 41910967
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BACKGROUND: Native hip instability encompasses a spectrum of abnormal pathomechanics under physiological loading and is associated with pain, dysfunction, and soft tissue damage. The condition spans a continuum-from deve...BACKGROUND: Native hip instability encompasses a spectrum of abnormal pathomechanics under physiological loading and is associated with pain, dysfunction, and soft tissue damage. The condition spans a continuum-from developmental hip dysplasia to femoroacetabular impingement and even instability in the absence of bony deformities, as can be the case in patients with connective tissue disorders or soft tissue deficiencies. Despite advances in understanding this condition, biomechanical definitions, thresholds, and metrics remain inconsistent. We therefore sought to conduct a meeting with an international panel of experts to map available evidence on the biomechanical features of native hip instability, to identify knowledge gaps, and to explore whether current biomechanical metrics can reliably differentiate various degrees of severity of instability. QUESTIONS/PURPOSES: In this scoping review and structured consensus document, we asked: (1) What are the biomechanical or pathomechanical features of native hip instability? (2) What are the biomechanical metrics of hip instability? (3) Can biomechanical metrics differentiate between hip microinstability versus conventional (bony) instability? METHODS: A consensus study using the modified Delphi technique was conducted in accordance with the Accurate Consensus Reporting Document (ACCORD) guideline. The consensus meeting was held during the 15th Symposium on Joint Preserving and Minimally Invasive Surgery of the Hip, which took place in Québec City, Québec, Canada, in June 2025. The process involved a multidisciplinary steering committee and a diverse panel of 100 international participants representing 13 countries. Following a rapid scoping review, statements related to biomechanical or pathomechanical features of native hip instability and metrics of hip instability and hip microinstability were developed and sent to participants 1 week prior to the meeting. Participants voted on these statements across two Delphi rounds during the meeting, with consensus defined as ≥ 75% agreement. RESULTS: The anatomic features of instability were identified as follows: bony morphology, static soft tissue stabilizers of the labrum and joint capsule, and muscles as dynamic stabilizers. Reported metrics for instability included femoral head translation, with translation < 3 mm considered normal by consensus. There was insufficient evidence to differentiate between microinstability (ligamentous) and conventional (structural bony) instability. CONCLUSION: Biomechanically, native hip instability is characterized by an unpredictable femoral head path of motion influenced by bony morphology, capsulolabral integrity, and muscular stabilization. Femoral head translation was the most consistently supported metric, with translation < 3 mm considered physiological by consensus. Current biomechanical methods do not allow reliable differentiation between microinstability and structural instability. Standardized, reproducible in vivo measurements of three-dimensional hip motion are needed to establish clinically meaningful thresholds and guide patient care. CLINICAL RELEVANCE: Clinically, this study sets a biomechanical benchmark defining native hip instability, enabling researchers to better distinguish between physiological laxity and pathologic instability. By defining biomechanical features of hip instability-most notably femoral head translation > 3 mm-this work contributes to a more standardized approach for defining joint stability, integrating bony morphology, capsulolabral integrity, and muscular stabilization. Such biomechanical insights guide surgical decision-making regarding capsular management and soft tissue repair and inform targeted rehabilitation strategies aimed at restoring hip stability.
Clin Orthop Relat Res
· 2026 Mar · PMID 41910634
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BACKGROUND: Cementing a new liner into a well-fixed acetabular cup with a deficient locking mechanism has been reported as a viable option, but concerns remain regarding complications such as dislocation and late looseni...BACKGROUND: Cementing a new liner into a well-fixed acetabular cup with a deficient locking mechanism has been reported as a viable option, but concerns remain regarding complications such as dislocation and late loosening. QUESTIONS/PURPOSES: What were the (1) durability of the cement-liner interface, (2) patient-reported outcome scores and complications, and (3) survivorship free from revision after liner cementation into a single acetabular cup design (Harris-Galante II, Zimmer) when the cup's locking mechanism was found to be deficient? METHODS: Between May 2006 and January 2015, two surgeons performed 76 revision procedures with retention of the metallic shell by cementing a new polyethylene liner into the existing shell. During that time, this procedure was used when the acetabular shell was well fixed but the locking mechanism was found to be deficient, or when a compatible liner was unavailable. When the native locking mechanism appeared intact, liner exchange was performed using the original locking mechanism without cementation. All patients treated with this procedure were considered potentially eligible for inclusion in this retrospective study. Of those, 9% (7 of 76) were excluded because they had a shell other than the Harris-Galante II cup, which was the focus of this study. An additional 16% (12 of 76) were lost prior to the minimum study follow-up of 10 years or had incomplete data sets, leaving 75% (57 of 76) for analysis. In patients who underwent bilateral procedures, the hip operated on first was selected for analysis to avoid nonindependence of observations, resulting in a final cohort of 51 patients. A highly crosslinked polyethylene liner was used in all procedures. The mean ± SD patient age at revision surgery was 57 ± 12 years, and the median (range) follow-up was 14 years (10 to 18), with all patients having a minimum 10-year follow-up. Fifty-one percent (26 of 51) of the patients were men. Clinical outcomes and complications were assessed using medical records and radiographs. Implant survivorship was estimated using the Kaplan-Meier method at 10 and 15 years with 95% confidence intervals (CIs), using acetabular cup revision as the endpoint. RESULTS: The cement-liner interface remained intact throughout follow-up. The mean ± SD Harris hip score improved from 74 ± 21 to 88 ± 11 (p < 0.001), and the WOMAC score also improved from 79 ± 13 to 59 ± 14 (p < 0.001), whereas both the SF-12 mental and physical component summary scores did not improve. Complications occurred in 39% (20 of 51) of patients, including posterior dislocation, late cup loosening, new osteolysis, and periprosthetic femoral fracture. Kaplan-Meier survivorship free from acetabular cup revision was 88% (95% CI 80% to 98%) at 10 years and 77% (95% CI 66% to 90%) at 15 years. CONCLUSION: The results of this study suggest that liner cementation into Harris-Galante II shells (Zimmer) resulted in frequent complications and lower survivorship than we expected, and given that 16% (12 of 76) of the patients were lost to follow-up, our findings may have underestimated the risk of complications. Therefore, surgeons should exercise caution when considering isolated liner cementation, particularly given the high rates of dislocation and late shell loosening, and patients should be counseled thoroughly regarding these risks. LEVEL OF EVIDENCE: Level IV, therapeutic study.
Poursalehian M, Sahebi M, Tajvidi M
… +4 more, Sabaghian A, Asgari AM, Tabaie SA, Hoveidaei AH
Clin Orthop Relat Res
· 2026 Mar · PMID 41910627
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BACKGROUND: RCTs are a key block in the evidence pyramid, but their quality relies on detailed, consistent reporting, and one best-practice standard is prospective registration. Prospective trial registration was intende...BACKGROUND: RCTs are a key block in the evidence pyramid, but their quality relies on detailed, consistent reporting, and one best-practice standard is prospective registration. Prospective trial registration was intended to reduce publication bias, and adherence to a prespecified protocol helps limit bias from selective reporting; any protocol or end point changes should be transparently documented and justified. However, the degree to which articles published in the leading journals on orthopaedic surgery comply with this best-practice standard has, to our knowledge, not been evaluated. QUESTIONS/PURPOSES: (1) Do RCTs published in leading, general-interest orthopaedic surgery journals comply with best practices regarding prospective clinical trial registration? (2) Do major discrepancies exist between registered protocols and published orthopaedic RCTs? (3) Are there specific study types that are more likely to demonstrate discrepancies? METHODS: A review was performed on RCTs published in the top five general-interest orthopaedic surgery journals, based on the 2022 scientific journal rankings (from SciMago): Journal of Bone and Joint Surgery, Bone and Joint Journal, Clinical Orthopaedics and Related Research®, Journal of the American Academy of Orthopaedic Surgeons (JAAOS), and Acta Orthopaedica. During the study period, all journals maintained editorial policies requiring prospective clinical trial registration as a condition of consideration for publication except for JAAOS. A systematic search on PubMed retrieved 705 potential publications, of which 324 RCTs fulfilled the inclusion criteria. For each trial, nine essential elements from the 24-item WHO minimum data set were extracted and compared between the published article and its trial registry entry, focusing on health condition, intervention, sample size, outcomes, and eligibility criteria. To answer our first question regarding compliance, we audited each article to identify the presence of a registry code. For our second question, we performed a side-by-side comparison of nine essential elements from the WHO trial registration data set (including primary outcomes, sample size, and eligibility criteria) to identify discrepancies between the registry and the final publication. Finally, to address our third question, we used chi-square tests to determine whether study characteristics, such as country of origin or subspecialty, were associated with higher rates of reporting shifts. RESULTS: Most orthopaedic RCTs published in leading journals complied with registration standards, with 95% (309 of 324) having an identifiable registry entry. However, 2% (8 of 324) were published without any registry identifier or justification for its absence, and 2% (7 of 324) were identified as long-term follow-up visits that did not have unique prospective entries. Major discrepancies between registered protocols and published manuscripts were frequent. Discrepancies in the sample size occurred in 33% (102 of 309) of trials. Discrepancies in the primary outcome occurred in 25% (78 of 309) of trials. Discrepancies in the secondary outcome occurred in 60% (185 of 309) of trials. Discrepancies in the inclusion criteria occurred in 33% (102 of 309) of trials. Discrepancies in the exclusion criteria occurred in 53% (165 of 309) of trials. Trials conducted in the United States or as multicenter international collaborations were more likely to update their final results in the registry compared with single-country trials conducted outside the US (37% versus 10%; p < 0.001). No other study characteristics, including publication year or subspecialty, were associated with the presence of reporting discrepancies. CONCLUSION: Prospective registration has become the standard for RCTs in high-impact orthopaedic journals. However, our findings suggest that a gap still exists between having a registry and the accuracy of the information contained within it. These findings suggest that registration is often treated as a procedural requirement rather than a rigorous commitment to a fixed study protocol. CLINICAL RELEVANCE: The orthopaedic research community should adopt stricter standards for trial registration, reporting, and verification of registry entries to reduce undisclosed protocol changes and improve confidence in published evidence.
Olerud F, Garland A, Dahl AW
… +2 more, Hailer NP, Wolf O
Clin Orthop Relat Res
· 2026 Jul · PMID 41879276
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BACKGROUND: Acute TKA has been proposed as an alternative to open reduction and internal fixation for complex tibial plateau fractures in patients who are older and who have compromised bone quality. The alternative is a...BACKGROUND: Acute TKA has been proposed as an alternative to open reduction and internal fixation for complex tibial plateau fractures in patients who are older and who have compromised bone quality. The alternative is a delayed TKA after primary fracture management with an unfavorable outcome. However, the long-term outcomes and risk for reoperation after acute TKA compared with delayed TKA for fracture sequelae remain unclear. QUESTIONS/PURPOSES: When comparing acute TKA (< 3 months after injury) for tibial plateau fracture with delayed TKA for fracture sequelae, we asked: (1) Do the risks of reoperation or revision for any cause differ? (2) Do the risks of reoperation or revision for infection differ? (3) Do the risks of reoperation or revision for loosening differ? METHODS: Data for all TKAs performed between 2014 and 2023 with the indication of acute tibial plateau fracture (n = 152) or fracture sequelae (n = 950) were extracted from the Swedish Arthroplasty Register. Patients who underwent TKA for acute tibial plateau fractures were older (73 versus 66 years), more often women (78% [118 of 152] versus 57% [539 of 950]), had lower BMI (26.7 versus 27.9 kg/m 2 ), and received constrained or hinged implants more frequently (59% [89 of 152] versus 33% [311 of 950]). Reoperations were identified in the Swedish Arthroplasty Register through subsequent procedures on the index knee and classified as reoperations (where the implant remained in situ) or revisions (with exchange, addition, or removal of components). When bilateral procedures occurred within the study period, only the first TKA was retained to ensure independence of observations. Loss to follow-up because of emigration or incomplete revision reporting was expected to be minimal, as the Swedish Arthroplasty Register captures approximately 98% of primary TKAs and 94% of revisions nationally. We estimated the cumulative event probability of secondary procedures using the Kaplan-Meier method and used logistic regression models to estimate adjusted ORs for (1) any reoperation or revision, (2) infection-related procedures, and (3) loosening-related procedures, adjusting for age, gender, and BMI. Because implant type reflects the underlying clinical situation and cannot be reliably adjusted for, it was reported descriptively. RESULTS: During follow-up, 7% (78 of 1102) of patients underwent a reoperation and 5% (60 of 1102) of patients underwent a revision. At 5 years, the cumulative event probability of any revision was 8% (95% confidence interval [CI] 2% to 14%) for acute TKA and 5% (95% CI 4% to 7%) for delayed TKA (p = 0.41). For reoperations, the cumulative event probability at 5 years was 9% (95% CI 3% to 15%) for acute TKA and 7% (95% CI 5% to 9%) in the delayed TKA group (p = 0.26). After adjusting for age, gender, and BMI, there was no difference between groups in odds for any reoperation (OR 0.76 [95% CI 0.38 to 1.5]; p = 0.43) or any revision (OR 0.68 [95% CI 0.31 to 1.5]; p = 0.32). Infections accounted for 9% (1 of 11) of reoperations for acute TKAs and 40% (27 of 67) of delayed TKAs. At 5 years, the cumulative event probability of reoperation or revision due to infection was 2% (95% CI 0% to 5%) for acute TKA and 3% (95% CI 2% to 4%) for delayed TKA (p = 0.06). There was no difference in the adjusted odds of infection-related reoperation (OR 3.7 [95% CI 0.48 to 28]; p = 0.21) or infection-related revision (OR 3.0 [95% CI 0.40 to 23]; p = 0.28). Loosening accounted for 27% (3 of 11) of revisions after acute TKAs and 9% (6 of 67) after delayed TKAs. At 5 years, the cumulative event probability of loosening-related revision was 2.9% (95% CI 0% to 7.1%) for acute TKAs and 0.6% (95% CI 0.1% to 1.2%) for delayed TKAs (p = 0.50). The adjusted odds of loosening-related revision were lower for delayed TKAs (OR 0.21 [95% CI 0.05 to 0.97]; p = 0.045). CONCLUSION: The timing and pattern of revision differ between the two investigated groups, with delayed TKAs undergoing unplanned reoperation or revision earlier and with a higher proportion of infection-related revisions, whereas acute TKAs underwent reoperation or revision later and with a higher proportion of revisions for mechanical loosening. In the absence of large prospective trials, future observational work should include evaluation of pre- and postoperative radiographs and patient-reported outcomes, to determine which patients may benefit from acute TKA for tibial plateau fracture. LEVEL OF EVIDENCE: Level III, therapeutic study.
Clin Orthop Relat Res
· 2026 Jun · PMID 41879248
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BACKGROUND: Rotationplasty is a surgical procedure primarily used for malignant bone tumors around the knee when conventional limb salvage is not feasible because of tumor extent or patient preference. The procedure repu...BACKGROUND: Rotationplasty is a surgical procedure primarily used for malignant bone tumors around the knee when conventional limb salvage is not feasible because of tumor extent or patient preference. The procedure repurposes the ankle to function as a pseudo knee. While early outcomes are generally good, long-term gait performance in adulthood has not been well described. QUESTIONS/PURPOSES: This study addresses the following questions about patient outcomes 20 years or more after rotationplasty: (1) What are the walking speed and energy cost as well as the spatiotemporal and gait parameters compared with a control group without lower limb diseases? (2) How are walking speed and energy cost related to age, follow-up duration, and gait parameters? (3) Does thigh-shank length discrepancy correlate with the energy cost of walking and gait parameters? METHODS: Between 1980 and 2002, a total of 70 patients underwent rotationplasty (all Winkelmann Type A1) at two centers in Amsterdam. Of these, 37% (26) died, 4% (3) underwent amputation, and 9% (6) could not be traced. Of the remaining 35 patients, 6% (2) lived abroad, 9% (3) declined participation, and 3% (1) had a nonfitting prosthesis, leaving 83% (29 of 35) of patients available for evaluation at a median (IQR) follow-up time of 33 years (29 to 35). Rotationplasty was performed for osteosarcoma in 76% (22 of 29) of patients, Ewing sarcoma in 7% (2), other malignancies in 10% (3), hemangioma in 3% (1), and femoral deficiency in 3% (1), all by a single orthopaedic surgeon. This cohort included 52% (15 of 29) male and 48% (14 of 29) female patients. The control group, obtained from the institutional normative database, included 38 participants for analyses of the energy cost of walking and 27 participants for analyses of gait without lower limb diseases or systemic conditions affecting gait or energy cost, and was comparable with the rotationplasty group in age, sex, and BMI. Function was evaluated by walking speed, energy cost of walking, and gait parameters for spatiotemporal kinematics and kinetics and compared with the same parameters for the control group. Furthermore, outcomes were compared between patients with and without measurable thigh-shank length discrepancy. Statistical analyses included independent t-tests, statistical parametric mapping, and Pearson correlations. RESULTS: Compared with the control group, patients after rotationplasty walked slower (mean ± SD 1.2 ± 0.2 versus 1.4 ± 0.1 m/s, mean difference -0.2 [95% confidence interval (CI) -0.3 to -0.1]; p < 0.001) with a higher energy cost (4.4 ± 0.7 versus 3.5 ± 0.4 J/kg/m, mean difference 0.9 [95% CI 0.6 to 1.2]; p < 0.001). Cadence was lower (100 ± 7 versus 108 ± 7 steps per minute, mean difference -8 [95% CI -11 to -4]; p < 0.001) and stride length shorter (1.4 ± 0.2 versus 1.5 ± 0.1 m, mean difference -0.1 [95% CI -0.2 to -0.1]; p = 0.01). The double-support phase from the contralateral leg to the rotationplasty leg was longer (at 13.1% ± 1.9% versus 11.8% ± 1.2% of the gait cycle, mean difference 1.4% [95% CI 0.5% to 2.3%]; p = 0.003). Statistically significant differences were observed at specific phases of the gait cycle: Patients with rotationplasty lacked knee flexion during loading response and midstance, whereas the intact leg showed increased ankle dorsiflexion and greater knee and hip flexion during stance, accompanied by increased ground-reaction force in loading response and push-off. Walking speed increased very strongly as cadence increased (r = 0.7 [95% CI 0.6 to 0.8]; p < 0.001) and increased moderately as stride length increased (r = 0.3 [95% CI 0.1 to 0.5]; p < 0.01). As walking speed increased, walking energy cost decreased moderately (r = -0.4 [95% CI -0.6 to -0.2]; p < 0.001). With the numbers available, no associations were found between thigh-shank length discrepancy and walking speed, energy cost, joint angles, or joint moments. CONCLUSION: More than two decades after rotationplasty, patients demonstrated lower walking speed and higher energy cost of walking than the control group, which is expected given the magnitude of the procedure. Compared with previous reports, the energy cost was not higher at longer follow-up and approached normal values, exceeding those typically observed after transfemoral amputation. Although the absence of knee flexion during stance was associated with compensatory strategies, mainly in the contralateral limb, overall gait performance remained functional, with preserved pseudo knee mechanics. No differences were observed between patients with and without thigh-shank length discrepancy, providing no clear guidance for surgical length-correction strategies. Despite biomechanical deviations from normal gait, long-term function after rotationplasty appears durable and energy efficient, which can help clinicians to counsel patients on realistic expectations and functional potential. Further studies comparing rotationplasty with transfemoral amputation and limb-salvage surgery are warranted to better inform shared decision-making. LEVEL OF EVIDENCE: Level III, therapeutic study.
Clin Orthop Relat Res
· 2026 Mar · PMID 41805647
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BACKGROUND: Functional reconstruction after resection of malignant pelvic tumors involving zones I + II ± IV remains a major challenge in orthopaedic oncology. Conventional hip transposition can reduce prosthesis-related...BACKGROUND: Functional reconstruction after resection of malignant pelvic tumors involving zones I + II ± IV remains a major challenge in orthopaedic oncology. Conventional hip transposition can reduce prosthesis-related complications, but it is often associated with limb shortening and femoral head malrotation. We propose a modified hip transposition technique-femoral lengthening and retroversion hip transposition with a customized three-dimensionally (3D) printed femoral prosthesis-to address deficiencies in limb length, femoral head positioning, and fixation stability, and we evaluate its effectiveness in reducing complications and improving functional outcomes. QUESTIONS/PURPOSES: In the context of a small, initial patient series, we asked: (1) What was the postoperative functional outcome, as assessed by Musculoskeletal Tumor Society 1993 (MSTS-93) score, after reconstruction using this technique? (2) What were the frequency and nature of complications associated with the method? (3) How well was limb length restored at a minimum follow-up of 3 years? METHODS: Between January 2019 and December 2021, a total of 49 patients underwent resection and reconstruction for pelvic zone I + II ± IV tumors. Of these, 18% (9) received the modified hip transposition with a customized 3D-printed femoral lengthening and retroversion prosthesis. This approach was selected for patients in whom sufficient proximal femur was preserved to allow controlled osteotomy and femoral lengthening, who were unsuitable for standard hemipelvic endoprosthetic reconstruction because of extensive bone or soft tissue defects, who had histologically confirmed primary malignant or aggressive pelvic tumors, and who were expected to have long-term survival without distant metastasis. The remaining 82% (40) of patients treated during the same period underwent alternative reconstruction strategies, including hemipelvic endoprosthetic reconstruction, external hemipelvectomy, or conventional hip transposition. No patients were lost to follow-up. Three patients died of pulmonary metastases during follow-up and were included in the analysis with their actual follow-up durations. The six surviving patients had a median (range) follow-up time of 43 months (37 to 50). Among the nine patients included in this study, three were male and six were female, with a median (range) age of 55 years (19 to 73). At final follow-up, functional outcomes were assessed using the MSTS-93 score, complications were recorded and categorized, and limb-length discrepancy (LLD) was measured radiographically. RESULTS: The six surviving patients achieved a median (range) MSTS-93 score of 24 (21 to 27) with minimal or no pain. Four patients used a cane for ambulation, and two walked independently. Two patients experienced delayed wound healing, which resolved with dressing changes; no prosthetic infections or mechanical failures occurred. Median (range) postoperative LLD was 1.0 cm (0.5 to 2.0) after intraoperative prosthesis adjustment. CONCLUSION: This modified hip transposition technique utilizing patient-specific osteotomy guides and a 3D-printed femoral lengthening and retroversion prosthesis allowed adjustment of limb length and femoral rotation in this small series, with minimal postoperative LLD and no major complications observed. Larger studies with longer follow-up times will be needed to confirm the feasibility and functional benefit of this method as a valuable complement to existing reconstructive options, particularly for patients with extensive soft tissue defects and high functional demands. LEVEL OF EVIDENCE: Level IV, therapeutic study.