Can We Predict Poor Outcomes for Arthroscopic Partial Meniscectomy?

Commentary Arthroscopic partial meniscectomy (APM) continues to be one of the most commonly performed procedures in orthopaedic surgery. This continues to be the case despite several randomized prospective studies calling into question the utility of APM compared with nonoperative management1. There is no question that there are patients who have degenerative meniscal tears and present with primarily mechanical symptoms who do benefit from APM. Unfortunately, there are also patients who have poor outcomes after APM. The challenge for orthopaedic surgeons is to determine which patients will have poor outcomes and advise them that APM surgery is probably not the proper course of treatment of them. Often, clinicians rely on factors such as age, body mass index, and arthritis grade to differentiate between the 2 groups. The study by Moore et al. reports interesting correlations between synovial fluid markers obtained at the time of APM and long-term outcomes, namely conversion to total knee arthroplasty (TKA) and validated patient-reported outcomes (PROs). I also found the use of an unsupervised machine learning algorithm in the study particularly interesting. The algorithm created 2 cohorts based on cytokine concentrations, those with a “pro-inflammatory phenotype” and an “anti-inflammatory phenotype.” The authors concluded that these phenotypes can predict PROs and conversion to TKA at long-term follow-up after APM. The shortcoming of the data presented in this study is that the synovial fluid was collected at the time of surgery. The next logical step is to utilize the 2 phenotypes identified in this study as part of the clinical decision-making process for patients being considered for APM. Performing this analysis in the clinic is certainly feasible, as evidenced by the work of Cole et al.2. In that study, the authors collected synovial fluid samples at the time of hyaluronic acid and platelet-rich plasma injection therapy and afterward. They concluded that there was a trend toward decreases over time in the levels of 2 pro-inflammatory cytokines. Injection therapy is often part of the management for patients with symptomatic meniscal tears prior to surgery. The phenotypes determined by Moore et al. have the potential to determine which patients may be better served by continued nonoperative management. Investigators continue to look for ways to alter the degenerative processes that lead to end-stage arthritis of the knee. Of the 2 phenotypes identified by Moore et al. on the basis of an analysis of synovial fluid cytokines, one progressed toward end-stage arthritis more quickly than the other phenotype. Ultimately, that and other data may be used to develop pharmacologic strategies to slow the steady progression of degenerative arthritis in the millions of patients affected by this condition.