By Jon G. Divine, MD, and Timothy E. Hewett, PhD
Osteoarthritis (OA) typically results in the development of hyaline cartilage destruction and repetitive mechanical friction involving one or more of the three knee joint compartments. The development of knee OA is a long-term overuse condition, which is often initiated by a single event and/or mechanical wear and tear associated with activities resulting in articular (hyaline) cartilage injury.1 Medial compartment involvement can spiral downhill rapidly as a result of dysfunctional mechanical forces combining to narrow the compartment. Nonsurgical management should be optimized prior to joint replacement surgery. Usually initiated by the primary care physician, current nonsurgical options include either individually, or some combination of, glucosamine, hyaluronic acid injections, exercises, weight loss, and unloading brace wear. Effectiveness of each method and combinations of methods are under investigation. Valgus bracing for osteoarthritis of the knee appears to be one such modality that can be used effectively to "buy time" before the patient is required to undergo joint replacement surgery. The application of a valgus "unloading" knee brace is the only OA management strategy that can potentially offer a redistribution of dysfunctional mechanical forces immediately upon application. There is most definitely a role for valgus bracing in rehabilitative management of the symptomatic osteoarthritis patient. Developed in the mid '90s as an offshoot of functional braces, unloading braces are becoming more frequently used by those individuals with OA at the knee. The unloader brace has proven to be most popular and readily accepted by patients. With a brace that employs a three-point pressure system, the force from the knee is transferred to the thigh and tibia, away from the symptom-provoking joint compartments. UNLOADING BRACES AND OA There are studies that demonstrate increased activity as a result of brace wear. In one of the first studies evaluating the effectiveness of unloading braces on OA symptoms, Hewett et al evaluated a brace designed to decrease loads on the medial tibiofemoral compartment in OA patients with chronic pain and arthrosis to determine if pain symptoms decreased and function improved, and if dynamic gait characteristics were altered during walking.2 Nine subjects underwent a dynamic gait analysis and were compared with a control group of 11 normal subjects matched for age and walking speed. Following 9 weeks of brace wear, statistically significant improvements were found for all pain parameters, and these improvements continued at the 1-year evaluation. Before brace wear, patients had a walking tolerance of 51 minutes prior to the onset of pain symptoms. No differences were found in the dynamic gait parameters measured with and without the brace.2 One of the earliest studies to look at potential changes in mechanical variables in OA patients wearing an unloading brace, Lindenfeld et al specifically looked at changes in the adduction moment. Scores from an analog pain scale decreased 48% with brace wear, and function with activities of daily living increased 79%. Mean adduction moment without the brace measured 4.0 +/- 0.8% body weight times height versus 3.6 +/- 0.8% body weight times height when wearing the brace (10% decrease). The mean adduction moment for control subjects was 3.5 +/- 0.6% body weight times height. Nine of 11 patients had a decrease in the adduction moment with the brace, five of 11 patients had a reduction higher than 10%, and decreases in this moment were as high as 32.3 In one of the very few prospective, parallel-groups, randomized clinical trials, patients with OA who also had a varus deformity were evaluated with regard to their ability to improve their disease-specific quality of life and functional status. The patients were stratified according to age (< 50 years or >50 years), deformity (mechanical axis in <5° of varus or >5° of varus), and the status of the anterior cruciate ligament (torn or intact). The patients were randomly assigned to one of three treatment groups: medical treatment only (control group), medical treatment and use of a neoprene sleeve, or medical treatment and use of an unloader brace. There was a significant difference between the unloader-brace group and the neoprene-sleeve group with regard to pain after both a 6-minute walking test and the 30-second stair-climbing test.4 In an interesting early study looking at actual condylar separation while wearing the unloading brace, 12/15 (80%) reported relief of pain and demonstrated condylar separation of the degenerative compartment. The three patients who did not demonstrate condylar separation were obese, which made accurate brace fitting difficult.5
