To examine the relation of pain sensitization to altered motor activity in knee OA as assessed by hamstrings muscle co-contraction during maximal effort knee extension.
Medial, lateral, and overall hamstring co-contraction was assessed in the Multicenter Osteoarthritis (MOST) Study cohort using electromyography during isokinetic knee extension at 60°/second. Mechanical temporal summation of pain (TS) was assessed at the right wrist and pressure pain thresholds (PPT) were assessed at the patellae; PPTs were categorized into sex-specific tertiles. Muscle co-contraction was categorized into age- and sex-specific tertiles. We evaluated the relation of measures of sensitization to muscle co-contraction using a generalized logistic regression model.
1633 participants were included: mean age and BMI was 67.3 ± 7.7 years and 30.3 ± 5.6 kg/m
Greater pain sensitization, as assessed by presence of TS at the wrist and low patellar PPT, was associated with greater overall and medial hamstring co-contraction during knee extension. This provides support to the possibility that peripheral and/or central nervous system alterations may not only affect pain sensitivity, but also motor function.