Decision-making in unicompartmental knee arthroplasty using radiological parameters in South Asian populations

Background: Many patients who visit orthopedic surgeons mainly complained of knee pain, which is often diagnosed as osteoarthritis affecting the medial compartment, whereas the lateral compartment and patello-femoral joint remain relatively unaffected.

AIM: This study aimed to establish criteria for patient selection and validate an evidence-based approach for selecting candidates for unicompartmental knee arthroplasty (UKA). Key considerations in patient selection for UKA include identifying the presence of bone-on-bone osteoarthritis in the medial compartment, ensuring a functionally normal anterior cruciate ligament, maintaining full-thickness cartilage in the lateral compartment, verifying a functionally normal medial collateral ligament, and confirming the absence of severe damage lateral to the patello-femoral joint.

MATERIALS AND METHODS: From a consecutive cohort of 390 patients with medial knee pain, preoperative radiographs of bilateral knee including anteroposterior/lateral/Rosenberg/20° valgus stress views were collected, and results were tabulated. Patients were categorized into appropriate groups. The suitability for UKA was determined based on the Oxford radiological decision aid, history, examination, and radiographic assessment including stress radiographs.

RESULTS: The Oxford radiological decision aid demonstrated 92% sensitivity and 88% specificity. According to the radiographic assessment, 49% of the knees were considered suitable for Oxford UKA (OUKA), whereas 51% were deemed unsuitable. Among the 51 knees identified as unsuitable for OUKA, 40% did not meet one radiographic criterion, 38% did not meet two criteria, 22% did not meet three criteria, and <1% did not meet four criteria.

CONCLUSION: The Oxford radiographic decision aid safely and reliably identifies the appropriate patients for meniscal-bearing UKA and achieves good results in this population. The widespread use of this radiological decision aid should improve the results of UKA.