Central sensitization may be responsible for joint pain in hip osteoarthritis (OA) patients with severe pain regardless of less severe joint deformity, a study in The Journal of Pain Research concluded. With the recent revelation of central sensitization as the culprit behind pain in OA, the study authors- Takafumi Hattori et al. aimed to assess the possible connection of radiologic severity or central sensitization in the clinical presentation of hip OA with different degrees of joint deformity.

Keeping in mind pain severity, 39 patients with hip OA were divided into two groups: (i) strong/severe group with numerical rating scale (NRS) ≥ 6) and, (ii) mild/moderate group with NRS< 6. The Kellgren-Lawrence (K-L) and minimum joint space width (mJSW) scale were used to assess the radiologic severity of OA. The difference of radiologic evaluation and quantitative sensory testing (QST) results between each group was examined.

No major difference in the K-L scale and mJSW between both groups was found. Patients in the strong/severe pain group exhibited elevated levels of temporal summation of pain (TSP) and a drop in pressure pain threshold (PPT) at hip and leg compared to the other group. Additionally, NRS was considerably negatively associated with PPT and positively associated with TSP, but not with the mJSW and K-L scale.

Although the radiologic severity was not substantially different between the groups, however, a noteworthy difference in central sensitization characterized by QST was found, the study authors noted.