Effect of strength exercises in patients with knee OA.

Effects of progressive resistance strength training on knee biomechanics during single leg step-up in persons with mild knee osteoarthritis.
McQuade, K. and de Oliveira, A. Clinical Biomechanics, 2011; 26: 741 – 748.
http://www.ncbi.nlm.nih.gov/pubmed/21514018

Strength training is one of the most recommended treatment approaches in patients with knee OA. It has been considered to protect the knee from increased load and stress and therefore improve knee function and decrease pain. These improvements have been attributed to several factors and alternations in knee biomechanics have been one of them. According to some authors, it might be due to the fact that strengthened muscles are more able to stabilize and reduce stress placed on the knee joint. The main objective of this study was to explore whether changing strength alone in primary knee extensors and flexors would cause knee joint sagittal and frontal plane moments to be altered during a common functional task.

Subjects participated in an individually supervised training program 3 times a week for eight weeks consisting of progressive resistive exercises for knee extensors and knee flexors. Pre and post outcome measures were surface electromyography, knee joint biomechanics; (net joint moments, net knee internal forces) and self-report measures of knee pain and function.
Results showed that the scores in the KOOS scales were higher at the post-intervention time, reflecting an improvement in pain, symptoms, activities of daily life, quality of life, stiffness, and function. No significant post intervention differences were observed in regards to muscle co-contraction activation and knee joint biomechanics. Authors concluded that patients self-report functional and psychosocial improvements associated with strength training, might not be directly related to alteration in knee joint biomechanics and/or muscles co-contraction pattern.
Despite the results, this study proves strength exercises to be an effective treatment approach in decreasing pain and improving knee function in patients with knee OA, which is in agreement with literature. Do you incorporate strength exercises in rehabilitation of patients with knee OA? Which muscles are you focused on mostly?
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