Aims. The aim of the study was to apply 3D measurements for fracture displacement in minimally to moderately displaced acetabular fractures treated nonoperatively, and to evaluate whether this measurement can be used to estimate the likelihood of conversion to total hip arthroplasty (THA) at follow-up. Methods. A multicentre, cross-sectional study was performed on 144 patients who were treated nonoperatively for an acetabular fracture in four level 1 trauma centres between January 2000 and December 2020. For each patient, fracture displacement was measured on CT-based 3D models. The 3D gap area represents fracture displacement (mm. 2. ) between all fracture fragments. A receiver operating characteristic curve was generated to determine a 3D gap area threshold representing the optimal sensitivity and specificity to predict conversion to THA. Native hip survival was reported using Kaplan-Meier curves. Predictors of conversion to THA were determined using Cox regression analysis. Results. Of 144 patients, 18 (12%) received a THA. The median 3D gap area of the complete study cohort was 692 mm. 2. (IQR 216 to 1,400). Native hip survival in patients with a gap area threshold ≤ 1,171 or > 1,171 mm. 2. differed at one-year (98% vs 85%), two-year (96% vs 77%), and five-year follow-up (92% vs 73%). 3D gap area > 1,171 mm. 2. (hazard ratio (HR) 4.3; 95% CI 1.7 to 11.0) and the presence of osteoarthritis grade 2 or higher (HR 3.1; 95% CI 1.2 to 7.8) independently predicted the likelihood of conversion to THA during follow-up. Conclusion. For nonoperatively treated acetabular fractures, introducing 3D gap area assessment to measure fracture displacement offers a promising approach for assessing the risk of conversion to THA. With the introduction of (semi-)automatic segmentation and measurement techniques, or their implementation into commercially available software, this 3D gap area measurement can serve as an addition to the Letournel classification and an alternative to traditional 2D gap and step-off measurements, improving accuracy, reproducibility, and applicability in clinical decision-making. Cite this article: Bone Joint J 2025;107-B(2):204–212

Introduction. High Tibial Osteotomy has become an increasingly popular management option for patients with painful medial compartment osteoarthritis. The Fujisawa method used to calculate the angle of correction is well-documented but there have been no studies to look at the reliability and accuracy of web-based systems to calculate this angle. Patients and Methods. Patients undergoing valgus high tibial osteotomy between October 2004 and February 2010 who had full-length lower-limb views on the Picture Archiving and Communications System (PACS). The Fujisawa angle and length of osteotomy were calculated by the surgeon and two Orthopaedic registrars who had been appropriately trained. Results. Thirty X-rays were reviewed in 28 patients. Mean difference between measurements was 0.43 mm (SD 2.45) There was a statistically significant correlation between all three raters (P < 0.001). The greatest correlation was between the Consultant and the more senior trainee (r=0.86) with the lowest correlation between the Consultant and the more junior trainee (r=0.70). Concordance correlation coefficient between raters varied from 0.81 to 0.63. Bland-Altman plot of agreement between the Consultant and senior trainee was excellent showing only two values lying outside 1.96 SD. Discussion. Comparison of measurements between raters showed increased accuracy with greater experience of the measurement technique. Despite this we show high correlation between raters with measurement accuracy of all raters found within clinically acceptable limits (< 1mm). Conclusion. Measurement of tibial osteotomy using the fujisawa method on a web-based X-ray interpretation system is accurate and reliable

Introduction. Total leg muscle function in hip OA patients is not well studied. We used a test-retest protocol to evaluate the reproducibility of single- and multi-joint peak muscle torque and rapid torque development in a group of 40–65 yr old hip patients. Both peak torque and torque development are outcome measures associated with functional performance during activities of daily living. Material and Methods. Patients: Twenty patients (age 55.5±3.3, BMI 27.6±4.8) who underwent total hip arthroplasty participated in this study. Reliability: We used the intra-class correlation (ICC) and within subject coefficients of variation (CVws) to evaluate reliability. Agreement: Relative Bland-Altman 95% limits of agreements (LOA) and smallest detectable difference (SDD) were calculated and used for evaluation of measurement accuracy. Parameters: Maximal muscle strength (peak torque, Nm) and rate of torque development (Nm•sec-1) for affected (AF) and non-affected (NA) side were measured during unilateral knee extension-flexion (seated), hip extension-flexion, and hip adduction-abduction (standing), respectively. Contractile RTD100, 200, peak was derived as the average slope of the torque-time curve (torque/time) at 0–100, 0–200 and 0 peak relative to onset of contraction. Protocol: After 5 min level walking at self-selected and maximum speeds each muscle group was tested using 1–2 sub-maximal contraction efforts followed by 3 maximal contractions 4s duration. Statistics: The variance components were estimated using STATA12, with muscle function and occasion as independent variable and patients as random factor, using the restricted maximum likelihood method (=0.05). Results. For all exercises and sides, the ICC's for peak torque were good (0.81–0.96) with CVws ranging from 5.0–10.8%. Similar good ICC's were observed for RTD200 on the non-affected side (0.83–0.93), whereas most exercises (4/6) on the affected side showed moderate to good ICC (0.72–0.82). We found moderate CVws for RTD200 with 12.8–18.7% and 10.3–18.9%, affected and non-affected, respectively. With few exceptions the ICC's and CVws for RTD100 were moderate to poor on the affected side but good to moderate on the non-affected side. The SDD's for peak torque ranged from 14.9 Nm to 39.0 Nm, equal to relative LOA of 13.9–23.8%. For RTD200, the SDD's were 77–257 Nm•sec-1 and 29.2–86.2%, absolute and relative, respectively. With few exceptions interventions measuring RTD100 and RTDpeak would have to find changes exceeding 60% for them to be statistical significant. Conclusions. Our novel set-up for lower limb isometric muscle testing showed overall good reproducibility for peak torque, moderate for RTD200, while poor for RTD100 and RTDpeak. The results for peak torque and RTD200 are promising for defining relevant changes in muscle function in future longitudinal clinical trials in this patient group