This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Knee osteoarthritis (OA) is the most common cause of functional disability, afflicting approximately 6% of U.S. adults over the age of 30. The medial compartment is most often affected. Knee pain and instability are common complaints affecting activities of daily living. Recently, knee bracing for unicompartment OA has gained popularity. Studies investigating their efficacy have reported significant pain relief although functional improvement remains inconclusive. It is unsubstantiated how the unloader brace produce this effect. The overall goal of this work is to ascertain the degree to which valgus unloader knee braces (neutral and 4 valgus correction) control mediolateral instability and whether medial muscle co-contraction indices are influenced during dynamic knee motion. We postulate that symptomatic pain relief, as reported in clinical trials, may be the result of diminished medial muscle co-contraction, the outcome from increased joint stability induced mechanically via the brace rather than ?medial compartment unloading.? Twenty five subjects (between 35 and 65 yrs) with genu varum, symptomatic medial compartment knee OA and prescribed a functional unloader brace will be recruited from a local orthopedic practice. Diagnosis will have been made by an orthopedic surgeon based on clinical history, a physical examination, and from radiographs. Simultaneous kinematic, kinetic and electromyographic measurements will be conducted on three separate 2 week intervals; (knee unbraced, with brace set in neutral, and with brace set at 4 valgus correction) for a duration of 6-8 weeks. Analysis will involve assessing knee movement patterns and how the muscles are activated in response to bracing and altered knee motion. This study is designed to characterize the mechanisms by which dynamic knee motion and joint stability is preserved. The information will provide valuable insights in how unloader knee braces affect movement and muscle activity patterns in those with medial knee OA and varus knee deformity, and the mechanism in which pain relief is mediated.
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