Frequency of soft-tissue releases and their effect on patient reported outcomes in robotic-assisted TKA.

Abstract

Soft tissue releases are often required to correct deformity and achieve balance in total knee arthroplasty (TKA). However, releasing soft tissues can be subjective, highly variable and is perceived as an ‘art’ in TKA. The objective of this study was to compare the rate of soft tissue release required to achieve a balanced knee in tibial-first gap- balancing versus conventional, measured resection TKA, and its effect on outcomes.Soft tissue releases were documented and reviewed in 1256 robotic-assisted gap- balancing and 85 robotic-assisted measured-resection TKAs. Knees were stratified by coronal deformity (varus: >2° varus; valgus: >2° valgus). Rates of releases were compared between the two groups and literature. A subset of these patients were also enrolled in a prospective study. KOOS outcomes were captured pre-operatively and at 6M post TKA.The frequency of soft tissue release was significantly lower in the robotic gap- balancing group, with 21% of knees requiring release versus 40% (p=0.001) in the robotic measured resection group and 67% (p<0.001) for conventional measured resection. Pre-operative KOOS scores were similar between groups, however 6M scores showed a significant improvement in QOL, Sports and Symptoms scores in knees not released.Robotic assisted TKA with predictive gap balancing was found to reduce the number of releases across all coronal angles compared to conventional instruments. Furthermore, performing a soft tissue release rather than bone resection to achieve balance, correlated with worse outcomes. Further research is required to understand when imbalance should be corrected with bone resection adjustment versus soft tissue release.