Comparison of methods for evaluating soft tissue balance in robotic-assisted total knee arthroplasty: A cadaveric study.

Abstract

Robotic-assisted total knee arthroplasty (TKA) can simulate postoperative soft tissue balance based on three-dimensional positional information for the prosthesis and preoperative soft tissue balance data. However, the accuracy of soft tissue balance data obtained during robotic-assisted TKA is unclear. This study aimed to compare the reproducibility of three different assessment methods for soft tissue balance in robotic-assisted TKA and to examine the influence of examiner experience. Seven fresh-frozen cadavers were used. Three examiners assessed the medial and lateral gaps by applying a continuous varus/valgus load to the knee throughout the full range of motion using an image-free system (Navio). Soft tissue balance was evaluated by applying mild manual stress (mild group), maximum manual stress (max group), and a Z-retractor (Z group). Each examiner performed the procedure twice, and intra-rater and inter-rater reliability was evaluated using the intraclass correlation coefficient (ICC). In medial gap assessment, the ICCs for intra-rater reliability ranged from 0.88 to 0.95 in the mild group, 0.89 to 0.94 in the max group, and 0.89 to 0.95 in the Z group, with respective ICCs of 0.88, 0.88, and 0.92 for inter-rater reliability. In lateral gap assessment, the ICCs for intra-rater reliability ranged from 0.37 to 0.66 in the mild group, 0.33 to 0.86 in the max group, and 0.62 to 0.96 in the Z group, with respective ICCs of 0.41, 0.24, and 0.57 for inter-rater reliability. Intra-rater and inter-rater reliability was high for the medial gap assessment but lower for the lateral gap assessment.