Scott C E Brandon1, Marcus J Brown2, Allison L Clouthier2, Aaron Campbell3, Jim D Richards4, Kevin J Deluzio2. 1. Department of Mechanical and Materials Engineering, Queen's University, McLaughlin Hall, Kingston, Ontario K7L 3N6, Canada; Human Mobility Research Centre, Kingston General Hospital, Angada 2, Kingston, Ontario K7L 2V7, Canada; School of Engineering, University of Guelph, Guelph, Ontario N1G 2W1, Canada. Electronic address: scott.brandon@uoguelph.ca. 2. Department of Mechanical and Materials Engineering, Queen's University, McLaughlin Hall, Kingston, Ontario K7L 3N6, Canada; Human Mobility Research Centre, Kingston General Hospital, Angada 2, Kingston, Ontario K7L 2V7, Canada. 3. Human Mobility Research Centre, Kingston General Hospital, Angada 2, Kingston, Ontario K7L 2V7, Canada; Department of Surgery, Kingston General Hospital, Kingston, Ontario K7L 2V7, Canada. 4. Allied Health Research Unit, University of Central Lancashire, Preston PR1 2HE, UK.
Abstract
BACKGROUND: Braces for medial knee osteoarthritis can reduce medial joint loads through a combination of three mechanisms: application of an external brace abduction moment, alteration of gait dynamics, and reduced activation of antagonistic muscles. Although the effect of knee bracing has been reported independently for each of these parameters, no previous study has quantified their relative contributions to reducing medial knee loads. METHODS: In this study, we used a detailed musculoskeletal model to investigate immediate changes in medial and lateral loads caused by two different knee braces: OA Assist and OA Adjuster 3 (DJO Global). Seventeen osteoarthritis subjects and eighteen healthy controls performed overground gait trials in unbraced and braced conditions. RESULTS: Across all subjects, bracing reduced medial loads by 0.1 to 0.3 times bodyweight (BW), or roughly 10%, and increased lateral loads by 0.03 to 0.2 BW. Changes in gait kinematics due to bracing were subtle, and had little effect on medial and lateral joint loads. The knee adduction moment was unaltered unless the brace moment was included in its computation. Only one muscle, biceps femoris, showed a significant change in EMG with bracing, but this did not contribute to altered peak medial contact loads. CONCLUSIONS: Knee braces reduced medial tibiofemoral loads primarily by applying a direct, and substantial, abduction moment to each subject's knee. To further enhance brace effectiveness, future brace designs should seek to enhance the magnitude of this unloader moment, and possibly exploit additional kinematic or neuromuscular gait modifications.
BACKGROUND: Braces for medial knee osteoarthritis can reduce medial joint loads through a combination of three mechanisms: application of an external brace abduction moment, alteration of gait dynamics, and reduced activation of antagonistic muscles. Although the effect of knee bracing has been reported independently for each of these parameters, no previous study has quantified their relative contributions to reducing medial knee loads. METHODS: In this study, we used a detailed musculoskeletal model to investigate immediate changes in medial and lateral loads caused by two different knee braces: OA Assist and OA Adjuster 3 (DJO Global). Seventeen osteoarthritis subjects and eighteen healthy controls performed overground gait trials in unbraced and braced conditions. RESULTS: Across all subjects, bracing reduced medial loads by 0.1 to 0.3 times bodyweight (BW), or roughly 10%, and increased lateral loads by 0.03 to 0.2 BW. Changes in gait kinematics due to bracing were subtle, and had little effect on medial and lateral joint loads. The knee adduction moment was unaltered unless the brace moment was included in its computation. Only one muscle, biceps femoris, showed a significant change in EMG with bracing, but this did not contribute to altered peak medial contact loads. CONCLUSIONS: Knee braces reduced medial tibiofemoral loads primarily by applying a direct, and substantial, abduction moment to each subject's knee. To further enhance brace effectiveness, future brace designs should seek to enhance the magnitude of this unloader moment, and possibly exploit additional kinematic or neuromuscular gait modifications.
Authors: Luiz Fernando Approbato Selistre; Glaucia Helena Gonçalves; Fernando Augusto Vasilceac; Paula Regina Mendes da Silva Serrão; Theresa Helissa Nakagawa; Marina Petrella; Richard Keith Jones; Stela Márcia Mattiello Journal: Braz J Phys Ther Date: 2020-02-26 Impact factor: 3.377