Medial unicompartmental knee arthroplasty: short-term outcomes of a prospective continuous series (SOFCOT–SFHG 2025 symposium)
Medial unicompartmental knee arthroplasty (UKA) is an appealing option for disabling medial femorotibial osteoarthritis, with reported clinical outcomes superior to those of total knee arthroplasty. Renewed interest in the procedure, driven by new technologies, appears to be broadening the classical Kozinn selection criteria. This study, conducted under the auspices of the SFHG and reported at the SOFCOT 2025 Symposium, aimed to describe current patient selection, to evaluate clinical and radiological outcomes, and to analyse the potential influence of robotics, navigation, and patient-specific instrumentation (PSI).
Methods: Ten centres prospectively enrolled 487 consecutive medial UKAs between September 2023 and July 2024, with data collected via the RENACOT registry. Selection criteria, preoperative functional and radiological parameters, operative technique, fixation mode, and one-year outcomes were analysed. Conventional instrumentation was used in 35% of cases, navigation in 5%, PSI in 10%, and robotic assistance in 50%.
Results: Only 61% of patients met the classical Kozinn criteria; 29% were “borderline” and 10% presented with at least one potential contraindication. At one year, 88.7% of patients reported improvement, with preoperative functional status identified as the principal prognostic factor. BMI showed a moderate negative correlation with functional outcome, whereas age, sex, comorbidities, and preoperative radiological parameters had no significant influence. The mean postoperative hip-knee-ankle angle was 176.5°, with a mean varus correction of 3.3°. Positioning-assistance technologies did not yield superior implant positioning compared with conventional instrumentation, although conventional techniques appeared less effective at reducing an excessive preoperative tibial slope. The one-year revision rate was 3.37%, and 6.74% of patients experienced unexplained pain. Female sex, vascular comorbidity, and cemented fixation were statistically associated with failure.
Conclusions: Patient selection for medial UKA is evolving beyond the classical Kozinn criteria, and short-term outcomes are encouraging. Longer follow-up is required to assess the impact of broadened indications and the value of positioning-assistance technologies.
