Patients with anteromedial osteoarthritis achieve the greatest improvement in patient reported outcome after total knee arthroplasty

The osteoarthritic (OA) disease pattern of the knee is one of the determinants for choice of arthroplasty concept when knee replacement is indicated, but whether the disease pattern has a direct effect on postoperative outcome has not previously been investigated. The aim was to investigate if different OA disease patterns have an effect on postoperative outcome after receiving total knee arthroplasty (TKA). 472 patients with pre- and 1-year postoperative patient reported outcome measures (PROMs) undergoing TKA surgery were retrospectively identified and classification of the OA disease pattern was made on preoperative radiographs. Measured resection was the universal technical approach. The key findings showed greater improvement in mean PROMs for anteromedial OA (AMOA) compared with other OA disease patterns; 3.1 points (95% CI 1.4–4.7, p < 0.001) in Oxford Knee score, 11.7 points (95% CI 0.9–22.5, p = 0.034) in Forgotten Joint score and 0.08 points (95% CI 0.02–0.14, p = 0.007) in EQ 5D score. Similar results were observed when comparing AMOA with AMOA that had only partial thickness cartilage loss (AMOA-PTCL). Patients with AMOA achieve greater improvement in PROMs after TKA surgery when using measured resection compared with other OA disease patterns. This finding has important implications for reporting, risk stratification and interpretation in TKA outcome studies, including randomized trials, why further investigation of the topic is of highly relevance.