BACKGROUND: Unloading knee braces often are used after tibiofemoral articular cartilage repair. However, the experimental basis for their use in patients with normal tibiofemoral alignment such as those undergoing cartilage repair is lacking. QUESTIONS/PURPOSES: The purpose of this study was to investigate the effect of varus and valgus adjustments to one commercially available unloader knee brace on tibiofemoral joint loading and knee muscle activation in populations with normal knee alignment. METHODS: The gait of 20 healthy participants (mean age 28.3 years; body mass index 22.9 kg/m(2)) was analyzed with varus and valgus knee brace conditions and without a brace. Spatiotemporal variables were calculated as were knee adduction moments and muscle activation during stance. A directed cocontraction ratio was also calculated to investigate the relative change in the activation of muscles with medial (versus lateral) moment arms about the knee. Group differences were investigated using analysis of variance. The numbers available would have provided 85% power to detect a 0.05 increase or decrease in the knee adduction moment (Nm/kg*m) in the braced condition compared with the no brace condition. RESULTS: With the numbers available, there were no differences between the braced and nonbraced conditions in kinetic or muscle activity parameters. Both varus (directed cocontraction ratio 0.29, SD 0.21, effect size 0.95, p = 0.315) and valgus (directed cocontraction ratio 0.28, SD 0.24, effect size 0.93, p = 0.315) bracing conditions increased the relative activation of muscles with lateral moment arms compared with no brace (directed cocontraction ratio 0.49, SD 0.21). CONCLUSIONS: Results revealed inconsistencies in knee kinetics and muscle activation strategies after varus and valgus bracing conditions. Although in this pilot study the results were not statistically significant, the magnitudes of the observed effect sizes were moderate to large and represent suitable pilot data for future work. Varus bracing increased knee adduction moments as expected; however, they produced a more laterally directed muscular activation profile. Valgus bracing produced a more laterally directed muscular activation profile; however, it increased knee adduction moments. CLINICAL RELEVANCE: When evaluating changes in knee kinetics and muscle activation together, this study demonstrated conflicting outcomes and questions the efficacy for the use of unloader bracing for people with normally aligned knees such as those after articular cartilage repair.
RCT Entities:
BACKGROUND: Unloading knee braces often are used after tibiofemoral articular cartilage repair. However, the experimental basis for their use in patients with normal tibiofemoral alignment such as those undergoing cartilage repair is lacking. QUESTIONS/PURPOSES: The purpose of this study was to investigate the effect of varus and valgus adjustments to one commercially available unloader knee brace on tibiofemoral joint loading and knee muscle activation in populations with normal knee alignment. METHODS: The gait of 20 healthy participants (mean age 28.3 years; body mass index 22.9 kg/m(2)) was analyzed with varus and valgus knee brace conditions and without a brace. Spatiotemporal variables were calculated as were knee adduction moments and muscle activation during stance. A directed cocontraction ratio was also calculated to investigate the relative change in the activation of muscles with medial (versus lateral) moment arms about the knee. Group differences were investigated using analysis of variance. The numbers available would have provided 85% power to detect a 0.05 increase or decrease in the knee adduction moment (Nm/kg*m) in the braced condition compared with the no brace condition. RESULTS: With the numbers available, there were no differences between the braced and nonbraced conditions in kinetic or muscle activity parameters. Both varus (directed cocontraction ratio 0.29, SD 0.21, effect size 0.95, p = 0.315) and valgus (directed cocontraction ratio 0.28, SD 0.24, effect size 0.93, p = 0.315) bracing conditions increased the relative activation of muscles with lateral moment arms compared with no brace (directed cocontraction ratio 0.49, SD 0.21). CONCLUSIONS: Results revealed inconsistencies in knee kinetics and muscle activation strategies after varus and valgus bracing conditions. Although in this pilot study the results were not statistically significant, the magnitudes of the observed effect sizes were moderate to large and represent suitable pilot data for future work. Varus bracing increased knee adduction moments as expected; however, they produced a more laterally directed muscular activation profile. Valgus bracing produced a more laterally directed muscular activation profile; however, it increased knee adduction moments. CLINICAL RELEVANCE: When evaluating changes in knee kinetics and muscle activation together, this study demonstrated conflicting outcomes and questions the efficacy for the use of unloader bracing for people with normally aligned knees such as those after articular cartilage repair.
Authors: Robert D A Gaasbeek; Brenda E Groen; Brieke Hampsink; Ronald J van Heerwaarden; Jacques Duysens Journal: Gait Posture Date: 2006-09-07 Impact factor: 2.840
Authors: Karen Hambly; Vladimir Bobic; Barbara Wondrasch; Dieter Van Assche; Stefan Marlovits Journal: Am J Sports Med Date: 2006-01-25 Impact factor: 6.202
Authors: Philipp Niemeyer; Jan M Pestka; Peter C Kreuz; Christoph Erggelet; Hagen Schmal; Norbert P Suedkamp; Matthias Steinwachs Journal: Am J Sports Med Date: 2008-09-18 Impact factor: 6.202
Authors: Louis Draganich; Bruce Reider; Todd Rimington; Gary Piotrowski; Krishna Mallik; Scott Nasson Journal: J Bone Joint Surg Am Date: 2006-12 Impact factor: 5.284
Authors: Jay R Ebert; William B Robertson; David G Lloyd; M H Zheng; David J Wood; Timothy Ackland Journal: Cartilage Date: 2010-07 Impact factor: 4.634
Authors: Lianzhi Chen; Jessica Jun Yi Zheng; Guangyi Li; Jun Yuan; Jay R Ebert; Hengyuan Li; John Papadimitriou; Qingwen Wang; David Wood; Christopher W Jones; Minghao Zheng Journal: J Orthop Translat Date: 2020-05-15 Impact factor: 5.191