The biomechanical and functional outcomes of autologous chondrocyte implantation for articular cartilage defects of the knee: A systematic review

Purpose: Autologous chondrocyte implantation (ACI) is primarily performed in active, young patients to treat knee pain and functional limitations resulting from articular carti-lage injury. Nevertheless, the functional outcomes of ACI remain poorly understood. This systematic review aimed to evaluate the biomechanical and functional outcomes of ACI.Methods: Ovid MEDLINE, Embase, and Web of Science were systematically searched using the terms 'Knee OR Knee joint AND Autologous chondrocyte implantation OR ACI'. Inclusion and exclusion criteria were used to screen publications by title, abstract, and full text. Study quality and bias were assessed by two reviewers. Means and standard devia-tions of all collected variables were calculated and presented in the review. PROSPERO ID: CRD42021238768.Results: Nineteen articles including 20 ACI cohorts were included. In general, the average range of motion (ROM) improved with clinical (>5 & DEG;) and statistical significance (p < 0.05) postoperatively: 130.5 & PLUSMN; 14.8 & DEG; to 136.1 & PLUSMN; 10.2 & DEG;. Knee strength significantly improved within the first two postoperative years but remained poorer than control groups at final follow-up. No statistical differences were found between ACI and control groups in their ability to perform functional activities like the 6-minute walk test.Conclusion: Knee range of motion generally improved following ACI. Although, some stud-ies reported that knee strengths remained significantly poorer than healthy controls, par-ticularly >2-years postoperatively, implying that longer-term strength training may benefit patients. However, the volume of research and current level of evidence remain low, thus further research is required to better understand the impact of ACI on knee function and guide future rehabilitative protocols.& COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).