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Influence of total knee arthroplasty alignment on soft tissue balance and pivot patterns: a randomized controlled trial of kinematic versus mechanical alignment.

S. Barroso-Rosa, P. Ismailidis, K. Doma, A. Grant, P. McEwen, M. Wilkinson, B. Parkinson

Journal of Arthroplasty, 2025

9 citations

Abstract

BACKGROUND

Over the last decade alternative alignment techniques in primary total knee arthroplasty (TKA) have been developed in the hope to allow knee prostheses to better replicate normal knee kinematics and improve clinical outcomes. The purpose of this study was to quantify prosthesis soft tissue balance and pivot patterns based on a restricted kinematic (KA) or mechanical alignment (MA) surgical technique.

METHODS

A total of 109 primary cruciate retaining TKAs were randomized to either a mechanical or kinematic alignment technique. Medial and lateral compartmental pressures and contact point patterns were quantified at 10, 45, and 90 degrees of flexion using an insert pressure sensor.

RESULTS

A significantly greater proportion of KA knees were balanced through a full range of motion (ROM) after the initial bone resections (61 KA versus 12% MA, P < 0.001) and the differences were significant at all positions of ROM. For the unbalanced prostheses, the MA knees required significantly more soft tissue releases (P = 0.008) and bone alignment adjustments (P < 0.001). The initial and final rollback pivot patterns were not significantly different between techniques (initial P = 0.29, final P = 0.29). The primary driving factor for the pivot patterns was not alignment, but instead the differential pressure between the medial and lateral compartments at 45 and 90 degrees flexion (450P < 0.001, 900P < 0.001), with the knee pivoting on the tighter compartment in flexion.…

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Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design.

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