Original Research

Efficacy of Unloader Bracing in Reducing Symptoms of Knee Osteoarthritis

Am J Orthop. 2016 July;45(5):306-311

Braces designed to unload the more diseased compartment of the knee have been used to provide symptomatic relief from osteoarthritis (OA). Research on the efficacy of these braces is needed.

Thirty-one patients with knee OA were randomized to receive an unloader brace (n = 16) or not to receive a brace (control group, n = 15). Knee Injury and Osteoarthritis Outcomes Score (KOOS) and visual analog scale (VAS) scores were used to evaluate outcomes.

KOOS results showed that the brace group had significantly less pain (P < .001), fewer arthritis symptoms (P = .007), and better ability to engage in activities of daily living (P = .008). There was no difference in function in sport and recreation (P = .402) or in knee-related quality of life (P = .718). VAS results showed that the brace group had significantly less pain throughout the day (P = .021) and had improved activity levels (P = .035). There was no difference in ability to sleep (P = .117) or in use of nonsteroidal anti-inflammatory drugs (P = .138).

Our study results showed that use of an unloader brace for medial compartment knee OA led to significant improvements in pain, arthritis symptoms, and ability to engage in activities.

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References

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Knee osteoarthritis (OA) is a progressive, degenerative joint disease characterized by pain and dysfunction. OA is a leading cause of disability in middle-aged and older adults,¹ affecting an estimated 27 million Americans.² With the continued aging of the baby boomer population and rising obesity rates, the incidence of OA is estimated to increase by 40% by 2025.³ The clinical and economic burdens of OA on our society—medical costs and workdays lost—are significant and will continue to be a problem for years to come.⁴

Total knee arthroplasty (TKA) is an option for severe end-stage OA. Most patients with mild to moderate OA follow nonsurgical strategies in an attempt to avoid invasive procedures. As there is no established cure, initial treatment of knee OA is geared toward alleviating pain and improving function. A multimodal approach is typically used and recommended.^5,6 Nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and narcotic analgesics are commonly prescribed. NSAIDs can be effective⁷ but have well-known cardiovascular, renal, and gastrointestinal risks. If possible, narcotic analgesics should be avoided because of the risk of addiction and the problems associated with dependence. Intra-articular injections of corticosteroids or hyaluronic acid (viscosupplementation) are often recommended to reduce pain associated with arthritis. Braces designed to “off-load” the more diseased medial or lateral compartment of the knee have also been used in an effort to provide symptomatic relief. These low-risk, noninvasive unloader braces have increasingly been advanced as a conservative treatment modality for knee OA,^6,8-10despite modest evidence and lack of appropriately powered randomized controlled trials.¹¹ As more research on the efficacy of these braces is needed, we conducted a study to determine whether an unloader brace is an acceptable and valid treatment modality for knee OA.

Patients and Methods

This was a prospective, randomized, controlled trial of patients with symptomatic, predominantly unicompartmental OA involving the medial compartment of the knee. The study protocol was approved by the Institutional Review Board at Baptist Hospital in Pensacola, Florida. Patients were excluded if they had a rheumatologic disorder other than OA; a history of knee surgery other than a routine arthroscopic procedure; any soft-tissue, neurologic, or vascular compromise preventing long-term brace use; or obesity preventing effective or comfortable brace use. It is generally felt that unloader bracing may not be effective for patients with severe contractures or significant knee deformity; therefore, those lacking more than 10° of extension or 20° of flexion, or those who had a varus deformity of more than 8° of varus, were not offered enrollment.

Ideal sizes for the proposed study groups were determined through power analysis using standard deviations from prior similar investigations. The target was 30 patients per group.

Patients gave informed consent to the work. A computer-generated randomization schedule was used to randomize patients either to receive a medial unloader brace (Fusion OA; Breg, Inc) or not to receive a brace. Patients in these brace and control groups were allowed to continue their standard conservative OA treatment modalities, including NSAID use, home exercises, and joint supplement use. Patients were restricted from receiving any injection therapy or narcotic pain medication in an effort to isolate the effects of bracing on relief of pain and other symptoms.

All patients were examined by an orthopedic surgeon or fellowship-trained primary care sports medicine specialist. Age, sex, height, and weight data were recorded. Body mass index was calculated. Anteroposterior, lateral, flexion weight-bearing, and long-leg standing radiographs were obtained. Two orthopedic surgeons blindly graded OA¹² and calculated knee varus angles.¹³ Values were averaged, and intraobserver reliability and interobserver reliability were calculated.

Prospective subjective outcomes were evaluated with the Knee Injury and Osteoarthritis Outcome Score (KOOS), administered on study entry and at 4, 8, 16, and 24 weeks during the study. The KOOS has 5 subscales: Pain, Symptoms, Function in Daily Living, Function in Sport and Recreation, and Knee-Related Quality of Life. Each subscale is scored separately. Items are rated 0 (extreme problems) to 100 (no problems). Patients were also asked to complete a weekly diary, which included visual analog scale (VAS) ratings of pain, NSAID use, sleep, and activity level. VAS items were rated 1 (extreme problems) to 100 (no problems). For brace-group patients, hours of brace use per day were recorded. Patients were required to use the brace for a minimum of 4 hours per day.

KOOS and VAS data were analyzed with repeated-measures analysis of variance. Significance level was set at P < .05.