Effect of Lumbar Core Strengthening on Pain, Disability, Proprioception, and Quadriceps Strength in Knee Osteoarthritis

Osteoarthritis (OA) is a highly prevalent degenerative joint disease that impacts quality of life and puts a burden on health care costs. Idiopathic knee OA is an age-related disease, with prevalence ranging from 19-28%. Aetiology of OA (whether systemic or mechanical) remains unclear.

Lumbar spine has been reported to be associated with knee joint because of the biomechanical interrelationship. Decreased lumbar lordosis (that may indicate weak back extensors) and range of motion (that may indicate weak core stabilizers) had significant correlations with an increased spinal inclination angle, which was an independent factor related to knee OA (by increasing knee flexion angle). Knee OA may radiate pain to the back that together lead to more limited hip motion causing overloaded knees. Convergence presents between nerve roots supplying mid-lumbar muscles and joints, and that supply femoral nerve and quadriceps. Progression of knee OA is associated with progression of lumbar spine osteoarthritis. Altered trunk kinematics may cause altered tibiofemoral kinematics.

Strengthening of trunk extensors may be very important for knee OA as fatiguing back extensors led to 1) increased quadriceps inhibition (QI) that may lead to poor attenuation of ground reaction forces and excessive forces on the knees, 2) altered standing postural control, 3) a forward-leaned posture that increases the external knee moments, 4) a reduction in trunk proprioception.

Core stabilization exercises combined with knee-focused exercise or combined with hip strengthening resulted in less pain and better function. Interestingly, these studies included only patellofemoral pain and OA patients. This program may benefit knee OA patients as well. Strength, neuromuscular training and lumbopelvic stabilization reduced muscle weakness (of quadriceps and hip abductors), pain, and disability in men with mild knee OA. However, specific role of lumbar core muscles on knee OA, their effect on wider population (including females) and their effect on higher severity knee OA are lacking.

Strengthening of trunk core muscles may help pelvic stability which found to be beneficial in improving the trunk and lower extremity movement control, hip muscles strength, gait speed and daily activities. However, this done in stroke patients, it is hypothesized to benefit knee OA patients as well. Assessment and treatment of the trunk musculature should be considered in the rehabilitation of patients who demonstrate abnormal lower-extremity kinematics as found in knee OA.