Somatosensory processing is altered in people with hip osteoarthritis compared to controls: A cross-sectional study

With knee osteoarthritis (OA), measures of mechanical and thermal pain sensitivity relate to both pain severity and treatment outcomes, and lower limb left/right judgement is impaired. However, little is known about these somatosensory variables in people with hip OA.

Our cross-sectional study aimed to explore the differences in sensitivity to noxious mechanical and thermal stimuli, and lower limb left/right judgement, in people with hip OA compared to matched controls without hip OA.

Demographic variables and self-reported hip-related disability were collected using an online survey, while physical function was assessed in person using standardised procedures. Quantitative sensory testing was conducted using mechanical (pressure) and thermal pain thresholds. Left/right judgement was assessed through a lower limb left/right judgement task on an online application. Generalised linear regressions were used to analyse differences between groups and explore associations between the demographic variables and the somatosensory measures.

15 participants with hip osteoarthritis and 15 controls were included. Mean (SD) age was 62.1 (11.2) years, median (IQR) BMI 26.2 (4.4) kg/m², and 21/30 (70%) were female. Pressure pain thresholds were lower in people with hip OA at both the hip (p = .049) and the ipsilateral elbow (p = .046). There were no differences detected between groups for thermal pain thresholds (p > .05). Left/right judgement accuracy was lower in controls compared to people with hip OA (p = .038). Associations between the somatosensory measures and demographic variables (sex, age, and BMI) varied across outcomes.

Increased mechanical, but not thermal, pain sensitivity was found in people with hip OA compared to controls. Demographic variables are associated with somatosensory measures and require consideration in any analyses using these measures.