Osteoarthritis is a neurological disease – an hypothesis

OBJECTIVE: This commentary aims to summarise the importance of the joint nervous system in maintaining joint homeostasis and the role of nerves in contributing to degenerative diseases such as osteoarthritis (OA). METHODS: Pertinent scientific literature was evaluated and summarised to form the hypothesis that OA is a neurological disease. RESULTS: Joint nerves regulate a constant blood supply to maintain joint homeostasis and sustain tissue health; however, in OA this neurovascular control system is compromised and joint tissue integrity declines. Similarly, a decrease in joint proprioceptors and nociceptors with age and during arthritis interferes with position sense and pain transmission so that the body is unable to correct abnormal loading and this alteration in joint biomechanics can lead to joint destruction. Finally, brain morphology and activity are altered in OA patients but can be rectified by total joint replacement. CONCLUSIONS: Joints possess a complex nervous system that controls multiple physiological functions such as tissue blood flow, position sense, and pain. Damage or dysfunction of the joint nervous system can affect joint health and promote degenerative diseases such as OA. Drugs that are used to treat neurological diseases such as epilepsy and depression have been found to be effective at ameliorating the symptoms of OA. Thus, in addition to age, obesity, joint instability, and sex, neuronal impairment could be considered an additional risk factor for the development and pathogenesis of OA.