Are All Unloader Braces Created Equal? Recommendations for Evidence-Based Implementation of Unloader Braces for Patients with Unicompartmental Knee OA

Abstract

Unicompartmental knee osteoarthritis (UKOA) is a complex issue that is estimated to affect roughly 28% of patients with knee OA, and can result in severe cartilage degeneration, meniscus deficiency, and concomitant varus or valgus malalignment. This malalignment results in abnormally high joint reaction forces in the affected compartment, which can elicit pain, cause dysfunction, and exacerbate joint degradation. For more than two decades, the use of knee unloader braces has been advocated as a cost-effective option for symptomatic management of UKOA.During bipedal ambulation with a normal lower extremity mechanical axis, ground reaction forces create a knee adduction moment (KAM) such that the medial compartment of the knee experiences approximately 60% of joint loading and the lateral compartment experiences approximately 40% of joint loading. UKOA disrupts the mechanical axis, altering KAM and joint loading and causing pain, dysfunction, and disease progression. In theory, knee unloader braces were designed to mitigate the symptoms of UKOA by normalizing KAM via shifts in the lever arms about the knee. However, studies vary, and suggest that push-mechanism knee unloaders do not consistently provide significant biomechanical benefits for medial or lateral UKOA. Current evidence suggests that pull-mechanism unloaders may be more effective, though contrasting data have also been reported, such that further validation is necessary. The purpose of our study was to synthesize current best evidence for use of knee unloader braces for management of UKOA to suggest evidence-based best practices as well as gaps in knowledge to target for future studies. Unloader bracing for patients with UKOA appears to be a cost-effective treatment option for patients with medial UKOA who have insurance coverage. Pull-mechanism unloader bracing should be considered in conjunction with other nonoperative management therapies for those who are willing to adhere to consistent brace use for weight-bearing activities.