Medial Abrasion Syndrome:  A Neglected Cause of Persistent Pain After Knee Arthroplasty

Abstract Background: Persistent postoperative pain (PPOP) has detracted from some otherwise successful knee arthroplasties. This study investigated medial abrasion syndrome (MAS) as a cause of PPOP after knee arthroplasty and presented the technique and outcome of arthroscopic medial release (AMR) procedure to treat such patients. Methods: In a one-year period, the author performed unicompartmental or total knee arthroplasty (the UKA or TKA group) that also eliminated MAS on 196 knees of 150 patients at advanced stages of knee osteoarthritis (OA). During the same year, 16 knees of 16 patients with unknown causes of PPOP after knee arthroplasty were referred to the author for the AMR procedure (the AMR group). Subjective satisfaction, Knee Society Score (KSS), and Knee injury and Osteoarthritis Outcome Score (KOOS) evaluations were used for outcome study.Results: All 166 patients were followed up for more than 3 years (mean: 3.7 years, 3.1-4.2) for outcome study. All knees receiving arthroplasty showed pathologic medial plicae of various severities at the time of arthroplasty. Only 2 patients suffered PPOP: one was a neglected tibial plateau fracture with residual varus deformity after UKA and the other was a late infection after TKA and received revision. The satisfactory rate was 98.8% in the UKA group, 99.1% in the TKA group, and 100% in the AMR group. The Knee Society scores and all subscales of KOOS were statistically improved in all groups.Conclusion: MAS is a cause of pain in patients who have received knee arthroplasty, and MAS should be managed before wound closure to ensure a successful knee arthroplasty. PPOP after knee arthroplasty can be caused by MAS, which can be managed by AMR.