Medial unicompartmental knee replacement is a viable treatment option after failed high tibial osteotomy: a systematic review

Purpose: It is debatable whether or not previous high tibial osteotomy (HTO) has negative effects on the results of subsequent medial unicompartmental knee replacement (UKR). The purpose of this study is to report, through a systematic review of the literature, the outcomes of medial UKR after failed HTO. It was hypothesized that this procedure would be safe and effective in providing satisfactory postoperative functional outcomes. Methods: A systematic review was performed by searching Pubmed/MEDLINE, Embase and CINAHL. Only studies in English pertaining to all levels of evidence reporting on subjects undergoing UKR following HTO were considered. Review articles and expert opinion or editorial pieces were excluded. Outcomes of interest included indications, surgical technique and associated procedures, type of prosthesis, clinical and functional outcomes, rate of complications, revision surgery and failure rate. Results: Overall, six studies met all the inclusion criteria for this review. All were published between 2006 and 2021. The search resulted in one prospective comparative study, four retrospective comparative cohort studies, and one retrospective cohort study. Average follow-up periods ranged from 1 to 13 years. From these studies, 115 patients (117 knees) were identified. Overall, most studies reported satisfying postoperative clinical and functional outcomes. Implant survivorship ranged from 66 to 97.6%. In 15 patients, revision surgery was performed due to persistent pain. Conclusions: Medial UKR performed after failed HTO appears as a feasible procedure providing satisfying outcomes and limited complications in most cases. Further prospective comparative studies reporting long-term outcomes are needed, as high-level studies on this topic are lacking.