Association among neuromuscular and anatomic measures for patients with knee osteoarthritis

Objective: To investigate neuromuscular and anatomic factors involved in va rus gonarthrosis by identifying measures associated with degenerative chang es. Design: Descriptive study. Individual measures that explained substantial p ortions of the variability in ratings of knee joint-degenerative changes in patients with knee medial compartment osteoarthritis. Setting: Outpatient orthopedic clinic and biomechanics and muscular assessm ent laboratory. Patients: Volunteer sample of 20 subjects (age range, 59 +/- 9 yr) with no history of neurologic disease. Interventions: Not applicable. Main Outcome Measures: We assessed degenerative changes, varus alignment, s tanding balance, and knee proprioception. Weight-bearing radiographs were u sed to assess the extent of degenerative changes and the degree of varus al ignment. Single-limb standing balance control was assessed through tests pe rformed on a force platform. Knee proprioception was assessed with an isoki netic dynamometer, using a joint angle replication test. Results: Forward-stepwise multiple linear regression indicated that the ext ent of degenerative changes could be best predicted from a linear combinati on of the independent variables, varus alignment, and standing balance (R = .80, F-2,F-17 = 14.81, p =.0002). Sixty-four percent of the variability in ratings of degenerative changes was explained by alignment and standing bal ance measures (37% by varus alignment, 27% by standing balance). Alignment and balance measures were poorly correlated (r =.12, p =.63), further sugge sting that they provided different information about gonarthrosis. Conclusions: Although varus alignment is widely accepted as a clinically im portant factor in gonarthrosis, and is the focus of many treatment efforts, our results suggest that objective measures of standing balance are also i mportant. As a result, the potential impact of rehabilitation to improve th e control of standing balance should be further evaluated in this patient p opulation.