Quadriceps weakness in osteoarthritis.

Involvement of the quadriceps muscle group in knee osteoarthritis is receiving increasing research interest. The motor and sensory functions of muscle are intimately linked, and deficits in the sensorimotor functions of the quadriceps have been identified and proposed as possible factors in the pathogenesis of knee osteoarthritis or as consequences of the disease. Weakness of the quadriceps as a clinical feature of knee osteoarthritis has been well recognized for some time, but causes for this weakness and its significance as a determinant of the patient's disability is only now being investigated. Rehabilitation regimens that increase quadriceps weakness also effect improvements in the patient's disability, but the length and cost most of these research regimens would be impractical in the clinical setting. More clinically practicable rehabilitation regimens need to be devised that could be implemented in the community, if the management of this chronic, prevalent condition is to be managed effectively and cost-effectively.