Summary

Better short term outcomes for kinematic compared to mechanical TKA

Abstract

Introduction

While mechanical alignment total knee arthroplasty (TKA) has long been the conventional surgical technique in patients with advanced osteoarthritis, kinematic alignment TKA has emerged as a promising alternative, designed to restore the knee’s native pre-arthritic anatomy. Since superiority of either technique remain inconclusive, we aimed to compare immediate and short-term postoperative outcomes of kinematic versus mechanical alignment TKA.

Methods

This prospective cohort study was conducted at a tertiary care centre between January 2020 and August 2022, enrolling kinematic and mechanical alignment TKA patients. Outcomes were assessed during hospitalization and at 14 days postoperatively. Data collected included patient-reported outcome measures (PROMs), functional performance evaluations, pain scores, discharge disposition and hospital length of stay. Both univariate and multivariate regression analyses were conducted, adjusting for potential confounders.

Results

The study included 103 patients, with 77 in the kinematic alignment TKA group and 26 in the mechanical alignment TKA group. Patients in the kinematic alignment TKA group demonstrated statistically significant better postoperative outcomes compared to those in the mechanical alignment TKA group. Kinematic alignment TKA patients demonstrated superior functional performance on the Timed Up and Go test immediately postoperatively (mean difference = 23.9 seconds, p=0.014), had shorter mean hospital stay (mean difference = 0.8 days, p=0.034), and were more frequently discharged home rather than to a rehabilitation facility (odds ratio = 3.5, p=0.001). Short-term PROMs also favoured the Kinematic alignment TKA group, showing statistically significant higher scores in the Oxford Knee Score, short form-12 Mental Component Summary, and the Knee Injury and Osteoarthritis Outcome Score Symptoms subscale.

Conclusions

Kinematic alignment TKA offers superior immediate and short-term outcomes compared to mechanical alignment TKA, with benefits in functional recovery, hospitalization duration, and discharge disposition. This evidence supports kinematic alignment TKA as a viable alternative, aiding in patient and surgeon decision-making.