Patients with knee osteoarthritis (OA) have been shown to have somatosensory deficits of the lower extremity. This study was designed to assess the association of these deficits with dynamic joint loading and their relationship to the structural and symptomatic severity of knee OA.
Subjects with symptomatic knee OA underwent evaluation of the vibratory perception threshold (VPT) using a biothesiometer at 5 sites at the lower extremity. Dynamic joint loading was assessed through gait analyses. Knee pain was evaluated using a visual analog scale score for pain based on the Western Ontario and McMaster Universities OA Index. Radiographic severity of knee OA was assessed using the Kellgren/Lawrence (K/L) grading scale on radiographs obtained with the knee in a standing position.
Dynamic knee joint loading was directly associated with the VPT at the metatarsophalangeal (MTP) joint (Spearman's rho=0.384, P=0.033), indicating that the worse the vibratory sense, the higher the knee load during gait. The K/L severity grade was directly associated with the VPT at the MTP joint and lateral femoral condyle, after adjustment for age, sex, body mass index, and knee pain. After adjustment for confounders, there were no significant associations observed between the VPT and pain at any of the sites tested.
These findings demonstrate an association between greater somatosensory deficits and higher dynamic loads in OA. They also demonstrate structural consequences associated with somatosensory deficits in OA, since the extent of sensory loss directly correlated with the radiographic severity of knee OA. However, there was no relationship observed between vibratory sense and symptomatic knee OA pain.