A myofascial component of pain in knee osteoarthritis

Background Osteoarthritis (OA) is the most common cause of musculoskeletal pain and disability. The knee is the most common site of OA. Numerous studies have shown an inconsistency between patients' reports of pain and their radiographic findings. This inconsistency may be partially explained by the fact that a portion of the pain originates from the myofascial trigger points (MTrPs) located in the surrounding muscles. Aim To assess the role of myofascial pain in OA patients. Methods Critical review. PubMed, Google Scholar, Scopus, and PEDro databases were searched from inception until December 2016 for the following keywords: “myofascial pain”, “osteoarthritis”, “trigger points”, “knee” or any combination of these words. The reference lists of all articles retrieved were searched as well. Results The current review included two observational studies evaluating the prevalence of MTrPs in OA patients and six interventional studies describing the treatment of myofascial pain in OA patients. Data from two of the interventional studies also included an observational section. Conclusion The reviewed observational studies offered initial evidence as to the assumption that myofascial pain and the presence of MTrPs may play a role in pain and disability of knee OA. Because of the cross-sectional design of these studies, the causal relationships could not be established. Additional studies are needed to confirm this assumption as well as to clarify if MTrPs are a portion of OA etiology or that OA is the basis for MTrPs formation. Each interventional study elaborated on various myofascial treatment techniques. However, treatment focusing on MTrPs seems to be effective in reducing pain and improving function in OA patients. Due to the heterogeneity in treatment methods and outcome measures, it is difficult to attain a definite conclusion and therefore, additional high-quality randomized controlled trials are warranted.