The Influence of Functional Knee Bracing on the Anterior Cruciate Ligament Strain Biomechanics in Weightbearing and Nonweightbearing Knees

Abstract

Functional knee braces are commonly prescribed after anterior cruciate ligament injury or reconstruction; however, their ability to protect the ligament, or graft, remains unclear. Our objective was to evaluate the anterior cruciate ligament strain response in braced and unbraced knees during weightbearing and nonweightbearing in combination with three externally applied loads: 1) anterior-posterior shear forces, 2) internal-external torques, and 3) varus-valgus moments. The Legend brace was tested. All external loads were applied to the tibia with the knee flexed to 20 degrees. Reproducible data were obtained from 11 subjects. For anterior shear loads up to 130 N, the brace significantly reduced strain values compared with the unbraced knee during nonweightbearing and weightbearing conditions. For internal torques of the tibia (up to 9 N x m), strain in the braced knee was significantly less than in the unbraced knee when the knee was nonweightbearing only. The brace did not reduce strain values when the knee was subjected to external torques (9 N x m) or varus-valgus moments (10 N x m) in weightbearing and nonweightbearing knees. These data indicate that a functional knee brace can protect the anterior cruciate ligament during anterior-posterior shear loading in the nonweightbearing and weightbearing knee and during internal torques in the nonweightbearing knee.

Do Knee Braces Prevent Ski Knee Injuries?

“…They can also reduce strain on the ACL for internal torques applied to the tibia up to 9 Nm in a non-weight-bearing condition when compared to an unbraced knee, but did not reduce strain values on the ACL when the knee was subjected to external torques (9 Nm) or varus-valgus moments (10 Nm) in weight-bearing and non-weight-bearing conditions (6,7). This protection can be put in perspective when compared to forces everyday activities exert on the ACL.…”

Quadriceps Function After Exercise in Patients with Anterior Cruciate Ligament–Reconstructed Knees Wearing Knee Braces

“…Our findings are consistent with those of previous researchers [15][16][17] who demonstrated a decrease in quadriceps muscle function and activation after aerobic exercise. Although numerous authors have looked at the effects of knee braces [18][19][20][21][22][23][24][25][26][27][28][29] and neoprene sleeves 10,30 on neuromuscular performance during dynamic activities, very few have compared these effects during a bout of aerobic exercise. Previous studies of knee bracing and neuromuscular function have indicated that knee braces 21,22,24,[26][27][28] decreased quadriceps muscle function and that neoprene sleeves 10,30 improved knee joint proprioception.…”

Anterior Cruciate Ligament Bracing: Evidence in Providing Stability and Preventing Injury or Graft Re-Rupture

“…[6][7][8][9] Human and surrogate models have been used to confirm the effects of bracing. Using arthroscopy, Beynnon et al, 7 implanted transducers into the ACL of patients to measure strain.…”

“…This article focuses upon prophylactic braces, which are used to limit valgus stress injuries, and functional braces, which are used to prevent anterior translation of the tibia and to limit stress on anterior cruciate ligament-deficient and reconstructed knees. [5][6][7][8][9] The use, mechanism of action, clinical efficacy, and recommendation for prescription of prophylactic and functional braces are discussed as they apply to the prevention of ligamentous knee injuries in different patient populations. The Physician and Sportsmedicine Downloaded from informahealthcare.com by Fudan University on 05/16/15 For personal use only.…”