Effects of Strengthening the Core and Hip Stabilizers in Knee Osteoarthritis: A Systematic Review

Knee osteoarthritis (OA) is one of the most common causes of knee pain and disability in older adults. The pain and functional limitations associated with knee joint OA can result in weakness not only around the knee joint but also in the proximal regions, including the hip and trunk. The objectives of the current systematic review was to evaluate the effects of strengthening core and/or hip muscles on the functional status of individuals with knee OA. A systematic approach, following the Preferred Reporting Items for Systematic Review (PRISMA) guidelines, was used to search four electronic databases (PubMed, CINAHL, PEDro, and the Cochrane Library registry of studies) for studies published from 2015 to 2023. The methodological quality of the identified randomized controlled trials (RCTs) was assessed using the PEDro scale. A total of 580 studies were identified, however, only 10 RCTs matched the eligibility criteria and were included in the review, that focused on the strengthening the core and/or hip in individuals with knee OA. Out of these 10 studies, two studies specifically examined the effects of core muscle strengthening, while the remaining eight studies investigated the impact of strengthening exercises that targeted hip muscles in individuals with knee OA. Current evidence suggests that incorporating core and hip muscle strengthening in the rehabilitation of individuals with knee OA has beneficial effects. However, it is noteworthy that none of the researchers assessed the quality of core muscle contractions in their studies. Despite the positive findings regarding the benefits of strengthening exercises for the core and hip muscles, the lack of evaluation of core muscle contraction quality highlights a potential research gap in understanding the comprehensive effects of these exercises on knee OA rehabilitation.