Association among neuromuscular and anatomic measures for patients with knee osteoarthritis

Birmingham TB, Kramer JF, Kirkley A, Inglis JT, Spaulding SJ, Vandervoot AA. Association among neuromuscular and anatomic measures for patients with knee osteoarthritis. Arch Phys Med Rehabil 2001;82:1115-8. Objective: To investigate neuromuscular and anatomic factors involved in varus gonarthrosis by identifying measures associated with degenerative changes. Design: Descriptive study. Individual measures that explained substantial portions 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 assessment laboratory. Patients: Volunteer sample of 20 subjects (age range, 59 ± 9yr) with no history of neurologic disease. Intervention: Not applicable. Main Outcome Measures: We assessed degenerative changes, varus alignment, standing balance, and knee proprioception. Weight-bearing radiographs were used to assess the extent of degenerative changes and the degree of varus alignment. Single-limb standing balance control was assessed through tests performed on a force platform. Knee proprioception was assessed with an isokinetic dynamometer, using a joint angle replication test. Results: Forward-stepwise multiple linear regression indicated that the extent of degenerative changes could be best predicted from a linear combination of the independent variables, varus alignment, and standing balance (R =.80, F2,17 = 14.81, p =.0002). Sixty-four percent of the variability in ratings of degenerative changes was explained by alignment and standing balance measures (37% by varus alignment, 27% by standing balance). Alignment and balance measures were poorly correlated (r =.12, p =.63), further suggesting that they provided different information about gonarthrosis. Conclusions: Although varus alignment is widely accepted as a clinically important factor in gonarthrosis, and is the focus of many treatment efforts, our results suggest that objective measures of standing balance are also important. As a result, the potential impact of rehabilitation to improve the control of standing balance should be further evaluated in this patient population. © 2001 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation