Chronic pain in osteoarthritis of the hip is associated with selective cognitive impairment

Chronic pain of various origin is known to be associated with selective cognitive impairment. Osteoarthritis (OA) of the hip is one of the leading causes of chronic pain in the adult population, but its association with cognitive performance has not been evaluated. Here, we investigate the effect of chronic pain due to unilateral OA of one hip and no further source of chronic pain on cognitive performance.

A neuropsychological test battery, consisting of the Mini-Mental State Examination, Rey-Osterrieth complex figure test, Rivermead behavioural memory test, d2 test of attention, and F-A-S test was applied in 148 patients and 82 healthy pain-free control individuals. The influence of potentially confounding factors such as depression and anxiety was examined.

Patients with OA of the hip showed decreased performance in specific neuropsychological tests. Performance in verbal and visual short-term and long-term memory and selective attention tests was significantly poorer compared to healthy controls. Whereas the executive functions "updating", "set shifting", "response inhibition" and "reflection" appear intact, "problem solving" and "planning" were impaired. None of the confounders showed any influence on cognitive performance in both study groups.

We conclude that chronic pain secondary to end-stage hip OA is associated with selective cognitive impairment. Future studies are required to investigate the effect of total hip arthroplasty on cognitive performance.