Fractures in Oxford unicompartmental knee arthroplasty are associated with medial positioning of the femoral component - A retrospective cohort study

a. Purpose: This study aimed to evaluate the relationship between femoral component positioning and the incidence of periprosthetic fractures in Oxford unicompartmental knee arthroplasty (UKA), as well as the effects of component size and preoperative coronal lower limb alignment on fracture risk. b. Methods: A retrospective single-center study was conducted, including 1,642 cases of medial UKA performed between July 2015 and December 2022. Patients with symptomatic isolated medial knee osteoarthritis meeting specific selection criteria underwent surgery using either press-fit or cemented fixation based on individual bone quality. Radiographic evaluations were performed preoperatively and postoperatively to assess component positioning and alignment. Statistical analyses included the Mann-Whitney U test, Wilcoxon test, and Pearson's chi-squared test to compare fracture and non-fracture groups. c. Results: Out of 1,642 cases, 15 (0.9%) experienced a tibial periprosthetic fracture. These fractures were significantly associated with medial positioning of the femoral component and smaller component sizes. The fracture group had a higher mean age (74.3 +/- 6.2 years) and a higher percentage of females (80%) compared to the non-fracture group. No significant differences were observed in Body Mass Index (BMI) or preoperative coronal alignment between the groups. d. Conclusion: Medial positioning of the femoral component and smaller component sizes in Oxford UKA are associated with an increased risk of tibial periprosthetic fractures. Accurate implant positioning is crucial to minimize fracture risk and improve clinical out-comes. These findings underscore the importance of precise surgical techniques and may inform future guidelines for UKA procedures. Trial registration: This study was retrospectively registered and ethical approval was waived by the local ethical committee (No. 22-0990KB). (c) 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).