The opening wedge approach to high tibial osteotomy (HTO) is perceived to have some advantages relative to the closing wedge approach but it may be associated with delayed and nonunions. Because nonunions evolve over months, it would be advantageous to be able to identify risk factors for and early predictors of nonunion after medial opening wedge HTO. We sought to determine whether (1) preoperatively identifiable patient factors, including tobacco use, body mass index > 30 kg/m², and degree of correction, are associated with nonunion, and (2) a modified Radiographic Union Score for Tibial Fractures (RUST) score, taken at 6 weeks and 3 months, would be predictive for delayed or nonunion after medial opening wedge HTO. The medical records and radiographs of 185 patients, 21 bilateral cases, treated with a medial open wedge HTO using the TomoFix^® device were retrospectively evaluated. For all patients, demographic data regarding risk factors were collected from their records. Diagnosis for delayed or nonunion was already done earlier for standard medical care by the orthopaedic surgeon based on clinical and radiographic grounds. For the retrospective radiographic evaluation, a modified RUST score was used in which each tibial cortex is scored by one observer. Logistic regression analysis was used to identify preoperative and postoperative predictive factors for developing delayed or nonunion. In the series, a total of 19 patients (9.2%) developed clinically delayed/nonunion of whom 10 patients (4.9%) developed a nonunion. Smoking was identified as a risk factor for developing delayed/nonunion (19% for smokers versus 5.4% for nonsmokers; p = 0.005; odds ratio, 4.1; 95% confidence interval, 1.5–10.7). By contrast, body mass index, lateral cortical hinge fracture, age, infection, and degree of correction were not risk factors. Patients with delayed/nonunion had lower RUST scores at all time points when a radiograph was taken compared with the total study group. The RUST score at 6 weeks and 3 months after surgery and the use of tobacco were identified as predictive factors for development of delayed union and nonunion after open wedge HTO. Based on these results, we now actively try to stop patients from smoking and these data are helpful in doing that. The RUST score may be of use to identify which patients are at risk for developing a delayed union so that interventions may be offered earlier in the course of care. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Femoral component rotation from a total knee prosthesis can be determined by either a measured resection technique or a balanced gap technique. With the balanced gap implantation technique, femoral component rotation can vary freely within the restrictions produced by soft tissue structures. Because internal rotation might cause patella problems, the effect of ligament releases on femoral component rotation in a prospective clinical study was studied. Femoral component rotation was measured intraoperatively with a tensor applied in flexion at 150 N in 87 knees. Great interpatient variability was found; femoral component rotation, reference from the posterior condyles, ranged from −4° to 13°. There was no difference in femoral component rotation of knees with or without ligament releases in extension. However, knees with major medial release had less external femoral component rotation than knees with minor lateral releases. Preoperative alignment had no influence on femoral component rotation. The use of the balanced gap implantation technique theoretically will result in a balanced flexion gap, but the amount of femoral component rotation will be variable owing to patient variability and variation in ligament releases. Level of Evidence: Level II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Opening remarks: These guidelines are the result of discussions within a diverse group of RSA researchers. They were approved in December 2023 by the board and selected members of the International Radiostereometry Society to update the guidelines by Valstar et al. [1]. By adhering to these guidelines, RSA studies will become more transparent and consistent in execution, presentation, reporting, and interpretation. Both authors and reviewers of scientific papers using RSA may use these guidelines, summarized in the Checklist, as a reference. Deviations from these guidelines should have the underlying rationale stated.

The third generation of total wrist arthroplasty (TWA) was designed to solve the early loosening problem, but there have been few long-term follow-ups. We present the outcome of the biaxial total wrist prosthesis (no longer available) after 5-8 years of follow-up. 40 biaxial wrist prostheses were implanted uncemented in 36 patients with rheumatoid arthritis. 32 wrists were followed clinically and radiographically. 7 prostheses had been revised at median 21 (8-71) months; 1 patient died from an unrelated cause. Mean follow-up of the remaining 32 wrists was 6 (5-8) years. Kaplan-Meier survival analysis was performed with revision defined as failure. Survival after 7 years was 81% (95% CI: 64-91). There were 31 complications. 22 wrists showed radiographic loosening. Range of motion improved, except for pronation. The mean DASH score improved and the median postoperative pain score (from 0 to 10) was 0 (0-6) at rest and 0 (0-7) during activity. One quarter of the prostheses had been revised and radiographic loosening had occurred in two thirds of the cases. Radiographic and clinical follow-up is therefore necessary for patients with this implant.

Background A dual mobility cup has the theoretic potential to improve stability in primary total hip arthroplasty (THA) and mid-term cohort results are favorable. We hypothesized that use of a new-generation dual mobility cup in revision arthroplasty prevents dislocation in patients with a history of recurrent dislocation of the THA. Materials and methods We performed a retrospective cohort study of patients receiving an isolated acetabular revision with a dual mobility cup for recurrent dislocation of the prosthesis with a minimum follow-up of 1 year. Kaplan–Meier survival analyses were performed with dislocation as a primary endpoint and re-revision for any reason as a secondary endpoint. Results Forty-nine consecutive patients (50 hips) were included; none of the patients was lost to follow-up. The median follow-up was 29 months (range 12–66 months). Two patients died from unrelated causes. Survival after 56 months was 100 % based on dislocation and 93 % (95 % CI 79–98 %) based on re-revision for any reason. Radiologic analysis revealed no osteolysis or radiolucent lines around the acetabular component during the follow-up period. Conclusion The dual mobility cup is an efficient solution for instability of THA with a favorable implant survival at 56 months. Level of evidence Level 4, retrospective case series.