Pain in knee OA is likely a heterogenous, multifactorial phenomenon that involves not only the disease process but also elements specific to patient psychosocial make-up and pain neurophysiology (Andrew et al., 2013). However, pain in OA of the knee is presumed to arise from a combination of the following mechanisms (Joern et al., 2010):
- Osteophytic periosteal elevation
- Vascular congestion of subchondral bone, leading to increased intraosseous pressure
- Fatigue in muscles that cross the joint
- Overall joint shortening
- Joint effusion and stretching of the joint capsule
- Torn menisci
- Inflammation of the joint
- Muscle spasm
- Rough or crunchy sensation
- Central pain sensitization
- Psychosocial factors