Aims: To seek consensus on the principles and criteria necessary to develop a CT-based bone defect classification (BDC) for revision knee arthroplasty. Methods: A three-round structured Delphi study was conducted. First, five interviews were held with international knee revision experts to support the development of 29 statements. Two consecutive rounds of Delphi survey statements were distributed among 56 international knee revision experts in the first round, and to 37 in the second round. Consensus (≥ 80% agreement) was sought on the statements covering bone defect definitions, imaging, and zonal assessment. Results: A total of 37 experts responded to the first survey round, and 34 also completed the second round. Consensus was reached on 93% of the statements after both survey rounds. Experts agreed that a BDC should guide both surgical planning and implant selection, and that CT imaging improves knee revision bone defect assessment. Consensus was also reached on the definition of a bone defect. While anatomical zones (epiphysis, metaphysis, diaphysis) were considered important for inclusion in a BDC, the results showed no consensus on which landmarks define these anatomical zones. Conclusion: The expert panel indicated that CT evaluation and distinct assessment of anatomical zones are essential in a (new) BDC, although no consensus was reached on the definition of those anatomical zones. Moreover, a CT-based BDC should be useful for guiding surgical planning and implant selection. Cite this article: Bone Jt Open 2026;7(10):1272–1279.
Aims: Radiostereometric analysis (RSA) is the gold standard for migration analysis of orthopaedic implants, but CT-based RSA has shown comparable results in an increasing number of joints. In this study, we compared the method in an uncemented medial pivot tibial implant. Our primary outcome measure was maximum total point motion (MTPM). Secondary measures were segmental and feature point migration parameters, range of motion (ROM), Forgotten Joint Score (FJS-12), Knee Injury and Osteoarthritis Score (KOOS), effective radiation doses, and time usage. Methods: A total of 31 patients were prospectively included to receive an uncemented medial pivot knee implant using mechanical alignment (MA) with conventional instruments. Migrations were measured up to 24 months with marker-based RSA, model-based RSA, and CT-based RSA. Clinical data were measured using a goniometer and patient-reported outcome measures ((PROMs); FJS-12 and KOOS). Results: Migrations at 24 months for MTPM showed a mean of 1.09 mm (95% CI 0.78 to 1.40) for marker-based RSA, 1.17 mm (95% CI 0.85 to 1.49) for model-based RSA, and 0.74 mm (95% CI 0.45 to 1.04) for CT-based RSA. MTPM for CT-based RSA was lower than both RSA methods (p < 0.001). Differences increased between the methods at all timepoints, but migrations stabilized for all methods. Time usage (min:sec) for performing RSA radiographs was 17:02 and 4:10 for CT. FJS-12 score increased from 12.3 at baseline to 70.4 at 24 months; and KOOS increased for all sub-scales. ROM increased by 12.4° (95% CI 5.6 to 19.3). Conclusion: For clinical importance, the uncemented GMK Sphere shows a stable migration pattern using all methods and can therefore be considered safe. CT-based RSA shows lower migration values of an uncemented medial pivot tibial implant up to 24 months compared with conventional RSA. Cite this article: Bone Jt Open 2026;7(10):1330–1341.
Aims: Early postoperative wound problems following major joint arthroplasty (MJA) are common, yet comprehensive guidelines for superficial surgical site infections (SSIs) are lacking. This study aimed to explore healthcare professionals’ views and management strategies for early wound problems after MJA. Methods: A national cross-sectional online survey was distributed to orthopaedic surgeons, microbiologists, general practitioners, physiotherapists, and nursing staff involved in MJA care. The survey explored perceptions of wound problems, along with diagnostic and management approaches, and sought to identify any evidence gaps. Results were reported with descriptive statistics. Results: Of 111 respondents (51% orthopaedic surgeons), 90% were involved in managing early MJA wound problems. Most (94.6%) considered early wound problems serious. Skin reactions (32.4%) and superficial wound infections (28.8%) were the most frequently cited causes. Respondents generally believed superficial infections could not be clinically distinguished from deep infections, but could be managed with oral antibiotics in primary care. However, a need for further evidence was expressed, particularly regarding diagnostic utility, intervention thresholds, and clear guidelines to differentiate superficial from deep infections. Common superficial infection signs included red skin and localized swelling, while deep infections were thought to present with fever and deep pain. Conclusion: Healthcare professionals recognize the seriousness of early postoperative wound problems, frequently encountering skin reactions and superficial SSIs. While superficial infections are often managed nonoperatively, there is a clear demand for high-level evidence and comprehensive guidelines to improve differentiation and management. This should ultimately enhance patient outcomes, reduce the time to correct diagnosis and management, and limit the need for unnecessary treatments and associated complications. Cite this article: Bone Jt Open 2026;7(10):1384–1391.
Aims: The outcome of late-detected developmental dysplasia and dislocation of the hip (DDH) deteriorates with the length of follow-up. The aims of this study were to explore the rate of total hip arthroplasty (THA) with follow-up to patient age 60 to 76 years, and to define risk factors for THA. Methods: Inclusion criteria were patient age at diagnosis < three years, closed reduction, and no acetabular procedures. A total of 114 patients (147 hips) met these criteria: 98 females and 16 males with a mean age of 1.4 years (0.4 to 2.7). Residual acetabular dysplasia was defined as centre-edge (CE) angle < 20° at skeletal maturity. Information on THA was obtained from the Norwegian Arthroplasty Register. Results: Overall, 39% of the hips (n = 54) had residual dysplasia at skeletal maturity, with a mean CE angle of 14.9° (7° to 19°). In total, 52 hips (35%) had undergone THA at a mean patient age of 53.2 years (33 to 71). Risk factors for THA were residual acetabular dysplasia and severe degree of avascular necrosis. Kaplan-Meier survival analysis, with THA as the endpoint, showed survival rates of 95% in hips without residual acetabular dysplasia at patient age 50 years and 76% at 70 years. In hips with residual dysplasia, the survival rate was 83% at age 50 years and 41% at 70 years. The estimated mean survival time was significantly lower in hips with residual dysplasia than in hips without dysplasia (62.6 years vs 71.4 years; p < 0.001). Conclusion: The long-term outcome was very good in hips with no residual dysplasia at skeletal maturity. Only 24% of such hips had undergone THA at patient age 70 years. Dysplastic hips showed markedly worse outcomes, with a THA rate of 59% at 70 years. Routine concurrent pelvic osteotomy at the time of reduction in children < three years at diagnosis is hardly indicated. Cite this article: Bone Jt Open 2026;7(10):1261–1268.
