Mechanical factors contributing to pain in knee OA.

Mechanical factors relate to pain in knee osteoarthritis.

Maly M., Costigan P., Olney S. Clinical Biomechanics; 2008, 23, 796 – 805.

http://www.ncbi.nlm.nih.gov/pubmed/18346827

Literature provides evidence that people with knee osteoarthritis, experience pain mostly due to psychosocial factors and damage/deterioration of articular and periarticular structures. Also, abnormal mechanical factors such as knee alignment, body size or muscle strength might play role in triggering pain due to facilitation of tissue degradation. However, there seems to be lack of research conducted on mechanical factors contributing to pain experience in people suffering from knee OA. Thus, authors conducted the study to find whether certain mechanical factors could explain variance in pain intensity among people with medial knee OA. Factors included in the analysis were: varus–valgus alignment, body size, strength, adduction – abduction range of motion, knee flexion–extension range of motion and the knee adduction moment. Sample was composed of 54 participants with mean age of 68.5 years (range 50 – 87).

Findings indicated that pain intensity was significantly related to BMI and to dynamic range of flexion–extension movement during gait. There was no significant association observed between pain and other factors analyzed. Authors found out that patients with greater flexion–extension knee range of motion by 5° had less pain intensity reported in the WOMAC scale. Given that, authors believe that, implementation of physical therapy exercise and/or methods to increase dynamic knee flexion – extension ROM could reduce pain in OA patients. Participants with lower BMI by 2kg/m² also reported lower pain scores. This finding support generally accepted notion that obese patient with knee OA should benefit from weight loss.

What are your experiences in treating patients with knee OA? Do you really find it beneficial to encourage patients to lose weight? How does it relate to their pain intensity? What kind of methods/ exercises do you incorporate in your practice to increase dynamic knee flexion – extension ROM?
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