Mechanism of Chronic Pain of Symptomatic Hip Osteoarthritis by Association of Its Distribution, Nociceptive, Neuropathic, Nociplastic, or Mixed Pain Screening, and the Prevalence of Lumbar Spinal Stenosis: A Cross-Sectional Study.

OBJECTIVES The pain of hip osteoarthritis is generally recognized as nociceptive in origin because of the local pathology. However, some patients with osteoarthritis experience a neuropathic pain component as an essential part of some nociplastic pain subtype. Here, we sought to examine the mechanism of chronic pain of symptomatic hip osteoarthritis by association of its distribution, complex pain mechanism screening, and the prevalence of lumbar spinal stenosis (LSS). METHODS We conducted a prospective cross-sectional study of 100 hips in 100 patients with symptomatic hip osteoarthritis in a chronic state. We examined all baseline clinical characteristics including clinical and functional score, location of pain and numbness, and pain score (PainDETECT questionnaire (PDQ) and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS)), and magnetic resonance imaging of the hip and lumbar spine. RESULTS The PDQ and LANSS revealed that 23% of the patients had a neuropathic pain component. There were 24 variations of the pain pattern. By contrast, the pain localized around the hip joint was only 15%. Pain distal to the thigh and any numbness was significantly more frequent in the group with neuropathic pain (P<0.001). LSS grade was not significantly different between patients with nociceptive pain and those with neuropathic pain. Pain score was significantly correlated with the pain in clinical and functional scores. DISCUSSION Among patients with symptomatic hip osteoarthritis, the distribution of pain was various, and about 23% of patients had neuropathic, nociplastic, or mixed pain as a possibility for somatosensory system disturbances.