BACKGROUND: Analyses of long-term results after mobile-bearing total ankle arthroplasty (TAA) in ankles with preoperative moderate to severe varus deformity with adequate sample sizes remain limited. Because preoperative...BACKGROUND: Analyses of long-term results after mobile-bearing total ankle arthroplasty (TAA) in ankles with preoperative moderate to severe varus deformity with adequate sample sizes remain limited. Because preoperative moderate to severe varus alignment may influence implant survival and functional outcomes, clarifying its long-term impact is important. QUESTIONS/PURPOSES: (1) Do the clinical and radiologic outcomes of mobile-bearing TAA differ between ankles with preoperative neutral alignment and those with moderate to severe varus alignment? (2) What are the 5- and 10-year prosthesis survivorship, survivorship free from any revision including polyethylene exchange, and survivorship free from any unplanned reoperation in each group after mobile-bearing TAA? (3) Did the incidence of asymmetric polyethylene wear differ between the groups? METHODS: Between September 2004 and May 2019, a single nondeveloper surgeon performed 417 TAAs. All procedures were performed using a single-design mobile-bearing device. The general indications for TAA were painful end-stage ankle arthritis. Of the 382 eligible ankles, 44% (168 ankles) were in patients with varus ankles (a preoperative coronal tibiotalar ankle ≥ 10° of varus) and 56% (214 ankles) were in neutral ankles (defined as < 10° of varus or valgus). Sixty-one percent (103 of 168) of the varus group and 61% (131 of 214) of the neutral group were available for follow-up with complete radiographic imaging and patient-reported outcome scores at a minimum of 5 years, and these patients were the focus of this retrospective, comparative study. The median (range) follow-up time was 123 months (60 to 230). The groups were similar with respect to age (63 versus 64 years; p = 0.34), gender (53% versus 44% men; p = 0.19), BMI (25.1 versus 25.5 kg/m2; p = 0.58), and follow-up duration (124 versus 116 months; p = 0.09). Although posttraumatic osteoarthritis was more common in the varus group and inflammatory arthritis in the neutral group, baseline demographic characteristics were otherwise comparable. Additional procedures to correct coronal alignment were performed at the discretion of the surgeon when necessary. Clinical outcomes were evaluated using VAS pain scores, Ankle Osteoarthritis Scale pain and disability subscores, as well as ankle ROM. Radiologic assessment included measurements of the postoperative coronal tibiotalar angle and development of asymmetric polyethylene inlay wear. CT scans with metal artifact reduction were performed to evaluate osteolysis. Survivorship was analyzed using the Kaplan-Meier method at 5 and 10 years for three endpoints: (1) revision or removal of a metal component, (2) revision of any component (including polyethylene exchange), and (3) any unplanned reoperation. RESULTS: There were no clinically important differences in patient-reported outcome scores between the neutral and varus groups at a minimum of 5-year follow-up. The varus group had greater preoperative varus deformity (3° ± 4° versus 18° ± 6°, mean difference 15° [95% confidence interval (CI) 14° to 17°]; p < 0.001). Postoperative coronal plane alignment differed between groups, with the varus group demonstrating 1° more residual varus (2° ± 2° versus 3° ± 2°, mean difference 1° [95% CI 0° to 1°]; p = 0.01). Survivorship free from metal component revision did not differ between the neutral and varus groups at a minimum of 10-year follow-up (93.7% [95% CI 89.9% to 99.4%] versus 94.2% [95% CI 89.8% to 98.9%]; p = 0.88). Survivorship free from all-kind revision (including polyethylene exchange) did not differ between the neutral and varus groups at a minimum of 10-year follow-up (68.7% [95% CI 60.3% to 78.3%] versus 75.1% [95% CI 66.3% to 85.1%]; p = 0.19). Survivorship free from any unplanned reoperation did not differ between the neutral and varus groups at a minimum of 10-year follow-up (63.4% [95% CI 54.8% to 73.3%] versus 63.1% [95% CI 53.6% to 74.3%]; p = 0.94). The varus group had a higher proportion of patients who developed asymmetric polyethylene inlay wear than did the neutral group (42% [43 of 103] versus 17% [22 of 131]; p < 0.001). CONCLUSION: In patients with moderate to severe preoperative varus deformity treated with this mobile-bearing TAA, we found no difference in patient-reported outcomes and implant survivorship compared with neutral ankles. However, varus ankles demonstrated a higher proportion of asymmetric polyethylene inlay wear, which may increase the risk of subsequent revision. Future studies should determine which patterns of varus deformity and residual malalignment are most strongly associated with edge-loading and how surgical correction strategies may mitigate this risk. LEVEL OF EVIDENCE: Level III, therapeutic study.
BACKGROUND: Osteoarticular allografts are used for knee reconstruction after tumor resection, but the number of these types of reconstruction has declined because of frequent complications and perceived better results wi...BACKGROUND: Osteoarticular allografts are used for knee reconstruction after tumor resection, but the number of these types of reconstruction has declined because of frequent complications and perceived better results with tumor endoprostheses. Failed osteoarticular allografts can be salvaged with megaprosthesis conversion, but it remains unclear whether the outcomes of the patients who undergo conversion differ from those of patients who have primary megaprosthesis reconstructions at the time of tumor resection. Also, there is lack of evidence on the comparison of implant survival. This study aimed to fill the gaps in our current knowledge about conversion megaprosthesis to inform patients and guide treatment accordingly. QUESTIONS/PURPOSES: (1) Did the survivorship free from revision or amputation differ between patients who initially received an osteoarticular allograft and underwent a conversion to a megaprosthesis and patients who underwent primary megaprosthesis reconstruction? (2) Did the groups differ in terms of Musculoskeletal Tumor Society-93 (MSTS-93) scores, knee flexion angle, and extensor lag? METHODS: Between January 1997 and December 2023, we treated 276 patients with megaprosthesis for bone sarcoma of the distal femur and proximal tibia, including patients who had a failed osteoarticular allograft in the distal femur or proximal tibia and were subsequently converted to megaprosthesis as well as patients who initially underwent megaprosthesis reconstruction. At our institution, initial patient selection for osteoarticular allograft reconstruction is influenced by several factors. Patients who were younger, had fewer comorbidities, and who would be more compliant with the follow-up protocol usually underwent osteoarticular allograft reconstruction for the initial resection procedure. All patients were followed up for at least 2 years after megaprosthesis reconstruction or until reoperation or death (mean ± SD follow-up time 10 ± 8 years). The patient cohort in the institutional database had 29 patients with conversion before the exclusion criteria were applied. Seven percent (2 of 29) of the patients underwent conversion with different implant systems and 14% (4 of 29) of the patients had insufficient follow-up. Seventy-nine percent (23 of 29) of the patients were eligible for final analysis. In the primary group, there were 247 patients before the exclusion criteria were applied. Twenty-one percent (52 of 247) of the patients underwent primary reconstruction with different implant systems, 6% (14 of 247) received uncemented stems, 2% (6 of 247) underwent extraarticular resection, and 1% (2 of 247) of the patients initially underwent allograft-prosthetic composite reconstruction. After the exclusion criteria were applied, 70% (173 of 247) of the patients were eligible. Of those patients, 20% (49 of 247) had insufficient follow-up. Fifty percent (124 of 247) of the patients were eligible for the final analysis. After 1:2 nearest-neighbor propensity score matching, 23 patients who underwent a conversion to endoprosthesis were compared with 46 patients who had a primary megaprosthesis implanted at the time of the tumor resection. Groups were matched for age, gender, BMI, diagnosis, tumor location, resection ratio, stem length, and stem diameter. After matching, osteosarcoma was the most common diagnosis for the conversion and primary groups (65% versus 70%, standardized mean difference [SMD] -0.09). Distal femur was the most common tumor location for the conversion and primary groups (70% versus 70%, SMD 0.00). We compared survivorship free from revision and survivorship free from amputation between patients with conversion and primary megaprostheses using competing risk analysis. Tumor recurrence and death were assessed as competing events for competing risk analysis. We then compared functional outcomes, including the MSTS-93 score, knee flexion angle, and extensor lag with the Welch t-test. Additionally, we performed a noninferiority test to evaluate whether patients with conversion had functional outcomes (MSTS-93 score, knee flexion angle, and extensor lag) not worse than the primary group with a 15% margin. In comparisons, MSTS-93 scores and knee flexion angles were regarded as clinically inferior in lower values, whereas extensor lag was regarded as clinically inferior in higher values. RESULTS: Survivorship free from revision did not differ between the conversion and primary groups at 5 years (79% [95% confidence interval (CI) 60% to 98%] versus 75% [95% CI 61% to 90%]) and at 15 years (37% [95% CI 6% to 67%] versus 49% [95% CI 25% to 73%]; p = 0.61). Survivorship free from amputations did not differ between the conversion and primary groups at 15 years (100% [95% CI 100% to 100%] versus 92% [95% CI 81% to 100%]; p = 0.29). Likewise, the conversion and primary groups did not differ in terms of MSTS-93 scores at mean ± SD 11 ± 8 years (23 ± 4 versus 25 ± 5, mean difference 1 [95% CI -1 to 4]; p = 0.17). The conversion and primary groups did not differ in terms of knee flexion angles at 11 ± 8 years (94° ± 24° versus 104° ± 19°; p = 0.17). The conversion and primary groups did not differ in terms of extensor lag at 11 ± 8 years (3° ± 3° versus 6° ± 9°; p = 0.21). The conversion and primary groups differed in terms of extensor lag in proximal tibia replacements (5° ± 4° versus 13° ± 12°; p = 0.01). Noninferiority was demonstrated for MSTS-93 scores and extensor lag for the conversion group. CONCLUSION: A conversion megaprosthesis yields outcomes no different than a primary megaprosthesis in terms implant survival, limb preservation, and functional outcomes. When limb salvage is feasible, a conversion megaprosthesis represents a reliable salvage option for failed osteoarticular allograft reconstruction. Our findings show that osteoarticular allografts around the knee continue to have a selective role as a time-buying strategy for younger patients with bone tumors without compromising future survival and outcomes. LEVEL OF EVIDENCE: Level III, therapeutic study.
Leopold VJ, Rakhra K, Spiker AM
… +6 more, Nepple JJ, Beck M, Karimijashni M, Poitras S, Beaulé PE, Grammatopoulos G
Clin Orthop Relat Res
· 2026 May · PMID 41926199
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BACKGROUND: The diagnosis of hip instability remains challenging because of its multifactorial etiology and the variability of imaging practices across institutions. Hip instability refers to a clinical condition of insu...BACKGROUND: The diagnosis of hip instability remains challenging because of its multifactorial etiology and the variability of imaging practices across institutions. Hip instability refers to a clinical condition of insufficient osseous and/or soft tissue constraint with abnormal femoral head motion and symptoms, which may occur along a morphologic spectrum that overlaps with-but is not synonymous with-developmental dysplasia of the hip. Although numerous imaging modalities and imaging parameters have been proposed, there is limited consensus on which are most relevant, how they should be measured, and what diagnostic thresholds best correlate with instability. To address this gap, a Delphi consensus study with an international panel of experts to establish standardized clinical statements for the diagnostic criteria of hip instability was conducted. QUESTIONS/PURPOSES: (1) What are the imaging modalities and protocols for investigating hip instability? (2) Which imaging parameters are most strongly associated with clinical hip instability? (3) What are the quantitative imaging thresholds for diagnosing hip instability? METHODS: A consensus study using a modified Delphi technique was conducted in accordance with the Accurate Consensus Reporting Document (ACCORD) guideline. Following a scoping review, 27 statements addressing imaging modalities and protocols (question 1), imaging parameters associated with hip instability (question 2), and quantitative imaging thresholds (question 3) were developed. These statements were evaluated by a multidisciplinary international expert panel during a structured consensus meeting, with two rounds of anonymous voting and consensus defined a priori as ≥ 75% agreement. Consensus was achieved for 81% (22 of 27) of statements. RESULTS: There was strong agreement that radiography (AP pelvis, false-profile, Dunn view) and MRI and CT constitute the foundational imaging modalities for the assessment of hip instability, whereas cartilage mapping techniques and dynamic ultrasound were considered adjunctive modalities with a more limited and evolving role. Radiographic measurements such as lateral center-edge angle (LCEA), anterior wall index (AWI), posterior wall index, and Tönnis angle reached consensus as key morphologic indicators. Several quantitative thresholds were endorsed. An LCEA of < 20° was considered diagnostic for hip dysplasia, a condition in which clinical hip instability is highly prevalent, whereas values between 20° and 25° were considered concerning for possible clinical hip instability. Additional thresholds included an AWI of < 0.30, PWI of < 0.8, and acetabular version < 5° or > 30°. In contrast, no consensus was reached for less-established imaging metrics such as the FEAR index, crescent sign, anterior capsule thickness, and dynamic femoral head translation. CONCLUSION: This international Delphi consensus defined core imaging approaches and threshold values for the evaluation of hip instability. Although agreement was reached on key morphometric parameters and diagnostic thresholds, a lack of consensus exists around newer soft tissue and dynamic measures, highlighting important areas for future research. CLINICAL RELEVANCE: In patients with suspected clinical hip instability, standard radiography should be used as the first-line imaging modality, followed by targeted use of CT and MRI to evaluate three-dimensional bony morphology and soft tissue stabilizers. Imaging findings should be interpreted within a stepwise, algorithmic framework that integrates clinical assessment with multiple complementary imaging parameters rather than relying on isolated measurements. Ultimately, accurate diagnosis of hip instability depends on the integration of findings from multiple modalities. Additionally, it must be recognized that hip instability may exist even in the absence of characteristic radiologic signs.
Bracken A, Whelehan S, Merghani K
… +2 more, Sheehan E, Feeley I
Clin Orthop Relat Res
· 2026 Jun · PMID 41915013
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BACKGROUND: Artificial intelligence (AI) and machine-learning (ML) technologies are increasingly being incorporated into orthopaedic medical devices, offering the potential to enhance surgical planning, intraoperative pr...BACKGROUND: Artificial intelligence (AI) and machine-learning (ML) technologies are increasingly being incorporated into orthopaedic medical devices, offering the potential to enhance surgical planning, intraoperative precision, and personalized care. The incorporation of AI into medical devices introduces unique risks and challenges that traditional regulatory pathways in the United States and European Union (EU) were not designed to address. Although the EU Artificial Intelligence Act is currently being implemented to provide a specific framework for AI medical device assessment, no equivalent directive exists in the United States. QUESTIONS/PURPOSES: In consideration of these evolving regulatory contexts, this study sought to address the following questions related to FDA-approved, AI/ML-enabled orthopaedic devices: (1) How often are FDA-approved, AI/ML-enabled orthopaedic devices also approved under the EU Medical Device Regulation (MDR)? (2) How often are AI/ML-enabled orthopaedic devices approved through the FDA 510(k) pathway using non-AI predicate devices? (3) How often do approved AI/ML-enabled orthopaedic devices have independent, peer-reviewed evidence supporting their use? (4) How often are the details of the training and validation datasets of these devices disclosed in publicly available regulatory documents? METHODS: A total of 37 AI/ML-enabled orthopaedic device approvals were identified from the FDA's list of 1017 AI/ML-enabled medical devices as of May 2025. Regulatory documents were analyzed to identify training and validation data sets and predicate devices. A predicate device is an existing legally marketed device that the FDA has previously approved; a manufacturer may claim that a new device is "substantially equivalent" to this approved device to obtain clearance through the 510(k) pathway. The availability of devices in the EU was assessed through the publicly available European Database on Medical Devices (EUDAMED) database and manufacturer websites. A systematic review of PubMed and manufacturer websites identified peer-reviewed evidence for each device. RESULTS: Our results showed that 38% (14 of 37) of AI/ML-enabled orthopaedic devices were approved for use in the EU, and devices were more frequently available in the United States first. All AI/ML-enabled orthopaedic devices approved by the FDA received regulatory clearance through the 510(k) pathway; most devices (62% [23 of 37]) were approved based on substantial equivalence to non-AI enabled devices. Independent peer-reviewed evidence was identified for 30% (11 of 37) of devices, with 67% (34 of 51) of published studies reporting manufacturer involvement. Information on training and validation datasets was disclosed in 57% (21 of 37) of 510(k) summaries, with dataset sizes ranging from 21 to 150,000 for training and 20 to 29,991 for validation. CONCLUSION: AI/ML-enabled orthopaedic devices have entered the market under existing regulatory frameworks in the United States and, at a slower pace, in the EU. Reliance on non-AI comparators and limited postmarket evaluation raises concerns regarding their long-term clinical reliability. CLINICAL RELEVANCE: As the level of patient risk under the current regulatory pathways remains uncertain, future research should compare AI/ML-enabled device recall rates across jurisdictions to assess whether AI-specific regulatory frameworks improve patient safety and device reliability.
Karimijashni M, Beaulé PE, Carsen S
… +7 more, Clohisy J, Sink E, Zaltz I, Grammatopoulos G, Pfalzgraf-Reny A, Bechiau C, Poitras S
Clin Orthop Relat Res
· 2026 May · PMID 41911001
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BACKGROUND: Although several clinical signs have been proposed for diagnosing atraumatic hip instability, the condition remains poorly defined because of the absence of standardized diagnostic criteria. To address this g...BACKGROUND: Although several clinical signs have been proposed for diagnosing atraumatic hip instability, the condition remains poorly defined because of the absence of standardized diagnostic criteria. To address this gap, a Delphi consensus study with an international panel of experts to establish standardized clinical statements for the diagnostic criteria of hip instability was conducted. QUESTIONS/PURPOSES: The objective was to reach consensus on the following questions: (1) What are typical presenting symptoms of hip instability? (2) What physical examination should be used to assess hip instability in patients presenting with symptoms of hip instability? (3) What risk factors are associated with patients presenting with symptomatic hip 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 were developed and sent to participants 1 week prior to the meeting. These statements were voted across two Delphi rounds during the meeting, with consensus defined as ≥ 75% agreement. RESULTS: Clinically, three physical examination tests, the abduction-hyperextension-external rotation (AB-HEER), prone instability, and anterior apprehension (HEER) tests, achieved consensus as clinically useful to assess hip instability. The flexion-abduction-external rotation (FABER) test and hip flexion + rotation arc of 200° did not reach consensus. Symptomatically, consensus was reached on patients reporting anterior hip pain during daily activities such as sitting, squatting, or participating in sports; mechanical symptoms such as popping, clicking, or grinding; and subjective sensations of looseness or instability. Female sex and hip dysplasia were agreed upon as key risk factors associated with atraumatic hip instability. Younger age as a potential risk factor did not reach consensus. CONCLUSION: Individual physical examination tests assess different components of hip instability. As such, the use of a combination of tests alongside consideration of symptoms and relevant risk factors has been suggested to enhance diagnostic specificity and produce higher assessment accuracy. Also, further research is warranted to assess other psychometric properties of these tests to develop a comprehensive diagnostic framework for atraumatic hip instability. CLINICAL RELEVANCE: By outlining key symptoms, recommended physical examination maneuvers, and associated risk factors, this study supports a more standardized and reproducible approach to evaluate hip instability in clinical practice. These findings can inform clinical algorithms, enhance diagnostic accuracy, and reduce variability in both research protocols and clinical practice.