Patient-reported outcome measures following individualised TKA are not affected by the degree of preoperative coronal varus or valgus laxity.

Abstract

To determine whether there is a correlation between preoperative coronal varus or valgus laxity and patient-reported outcome measures (PROMs) 2 years after individualised total knee arthroplasty (TKA). Records of 150 consecutive patients who received individualised TKA were retrospectively analysed, and 126 with complete pre- and postoperative data were included. Preoperative coronal varus and valgus stress radiographs (15 N load) were taken using a telos stress device with the knee in 5°-10° of flexion. Varus stress angles were positive if the joint opened on the lateral side, and valgus stress angles were positive if the joint opened on the medial side. The sum of varus and valgus stress angles indicated total joint laxity. During surgery, cases that required tibial recuts to balance the joint were recorded. Patients completed three PROMs and rated their satisfaction. Correlations between laxity and PROMs were evaluated using Pearson's correlation. Stress radiographs revealed varus stress angles of 6.3° ± 3.5° (range, -4.5° to 14.1°), valgus stress angles of 0.1° ± 3.7° (range, -8.0° to 10.9°), and the sum of the varus and valgus stress angle of 6.4° ± 3.3° (range, 0.1° to 17.1°). There were no correlations between laxity and PROMs: r < 0.160 for varus stress angle, r < 0.180 for valgus stress angle and r < 0.160 for the sum of stress angles. There were no statistically significant or clinically relevant differences in PROMs between knees without and those with tibial recuts. Preoperative coronal varus or valgus laxity was not correlated with PROMs following individualised TKA at a minimum 2-year follow-up. Individualised TKA with personalised alignment enables adequate accommodation of a broad spectrum of preoperative coronal varus-valgus laxities. Level IV.