The complexity of pain around the knee in patients with osteoarthritis.

Osteoarthritis of the knee is a common joint disease that can cause substantial pain and disability. The manifestation of pain, however, is highly variable and has a poor correlation to plain radiographs. The source of pain in gonarthrosis is elusive. Pain receptors have been found in the synovium, ligaments, capsule, subchondral bone and surrounding tissues with the exception of articular cartilage. The perception of pain is regulated at the spinal and cortical level and is often influenced by psychosocial conditions. There is no definitive treatment modality to relieve the pain and surgery does not necessarily guarantee improvement. Understanding and careful clinical assessment of the sore osteoarthritic knee together with better imaging such as magnetic resonance may improve treatment strategies.