Clinical utility of markerless motion capture for kinematic evaluation of sit-to-stand during 30s-CST at one year post total knee arthroplasty: a retrospective study

Abstract

Abstract Background Although the importance of kinematic evaluation of the sit-to-stand (STS) test of total knee arthroplasty (TKA) patients is clear, there have been no reports analyzing STS during the 30-second chair sit-up test (30s-CST) with a focus on kinematic characteristics. This study aimed to demonstrate the clinical utility of kinematic analysis of STS during the 30s-CST by classifying STS into subgroups based on kinematic parameters, and to determine whether differences in clinical outcomes are expressed as differences in clinical outcomes. Methods The subjects were all patients who underwent unilateral TKA due to osteoarthritis of the knee and were followed up for one year postoperatively. Forty-eight kinematic parameters were calculated using markerless motion capture by cutting STS at the 30s-CST. The principal components of the kinematic parameters were extracted and grouped by kinematic characteristics based on the principal component scores. Clinical significance was examined by testing whether differences in patient-reported outcome measures (PROMs) were observed. Results Five principal components were extracted from the 48 kinematic parameters of STS and classified into three subgroups (SGs) according to their kinematic characteristics. It was suggested that SG2, with kinematic characteristics similar to the momentum transfer strategy shown in previous studies, performed better in PROMs and, in particular, may be significantly closer to obtaining the “forgotten joint”, which is considered the ultimate goal after TKA. Conclusions Clinical outcomes differed according to kinematic differences in STS, suggesting that kinematic analysis of STS in 30s-CST may be useful in clinical practice. Trial registration: This study was approved by the Medical Ethical Committee of the Tokyo Women’s Medical University (approval number: 5628 on May 21, 2021).