A new method to measure ligament balancing in total knee arthroplasty: Laxity measurements in 100 knees

Abstract

Background: Ligament balancing is considered a prerequisite for good function and survival in total knee arthroplasty (TKA). However, there is no consensus on how to measure ligament balance intra-operatively and the degree of stability obtained after different balancing techniques is not clarified. Purpose: This study presents a new method to measure ligament balancing in TKA and reports on the results of a try-out of this method and its inter-observer reliability. Methods: After the implantation of the prosthesis, spatulas of different thickness were used to measure medial and lateral condylar lift-off in flexion and extension in 70 ligament- balanced knees and in 30 knees were ligament balancing was considered unnecessary. Inter-observer reliability for the new method was estimated and the degree of medial-lateral symmetry in extension and in flexion, and the equality of the extension gaps and flexion gaps were calculated. Results: The method was feasible in all operated knees, and found to be very reliable (intraclass correlation coefficient = 0.88). We found no statistically significant difference in condylar lift-off between the ligament-balanced and the non ligament-balanced group, however, there was a tendency to more outliers in flexion in the ligamentbalanced group. Conclusions: Our method for measuring ligament balance is reliable and provides valuable information in assessing laxity intra-operatively. This method may be a useful tool in further research on the relationship between ligament balance, function and survival of TKA. © The Author(s) 2012.