Surgical procedures may contribute to nerve damage and pain in knee osteoarthritis
Valdes AM, Suokas AK, Doherty SA, Jenkins W, Doherty MD. History of knee surgery is associated with higher prevalence of neuropathic pain-like symptoms in patients with severe osteoarthritis of the knee. Seminars in Arthritis and Rheumatism 2013. Seminars in Arthritis and Rheumatism Vol. 41, Issue 4, Pages 568-575.
Key findings and importance of study
Causes of pain from osteoarthritis (OA) are diverse and poorly understood. This study found that symptoms that are similar to pain from nerve damage are common among patients with severe knee OA and that in some patients such pain may arise from nerves damaged during surgery to repair the knee. This research is important because it contributes to more precise identification and targeting of pain in the management of knee OA.
Background
Pain from OA can be caused by different factors including joint damage, inflammation and increased pain sensitivity due to the development of chronic pain. In addition, many people with OA experience "neuropathic-like" pain e.g. burning pain or numbness, typically associated with nerve damage. Although such symptoms may be caused by osteoarthritis, alternative explanations include nerve damage from knee surgery or knee injury.
Aim of the study
We wanted to examine whether knee OA patients with a history of previous knee surgery or knee injury are more likely to suffer neuropathic-like pain. The surgical procedures included in the study were: 1) arthroscopy (keyhole surgery to diagnose and repair joint damage); 2) ligament repair (repair of the band tissue that runs diagonally through the middle of the knee); and 3) meniscectomy (removal or repair of tissue between the bones of the knee joint). Knee injury was define as physical injury caused, for example, by accident.
How the study was carried out
Patients with knee OA aged 40 or older were recruited from hospital clinics and asked to complete a set of questionnaires about pain, stiffness, function, sleep, tiredness and quality of life. They were also asked about previous knee injury from trauma. Knee x-rays were examined to grade the severity of osteoarthritis. Associations between pain, severity of OA and patient characteristics were investigated using a statistical method called regression analysis.
What the study found
We found that one-third of patients with severe painful knee OA suffered from neuropathic-like pain. Further, this group of patients reported worse pain, stiffness, function, quality of life, sleep and tiredness. A key finding was that patients with a history of previous knee surgery (mainly arthroscopic surgery) were significantly more likely to suffer neuropathic-like pain. No similar association was found for a history of knee injury.
Significance of the study to arthritis research
This study improves our general understanding of the risk factors that contribute to pain severity in patients with arthritis. If confirmed in independent studies, the findings suggest that arthroscopic procedures may potentially cause harm in terms of producing neuropathic pain in a proportion of patients with knee OA.