Effectiveness of Bilateral Single-Hinged Knee Bracing in Osteoarthritis: A Finite Element Study.

Effectiveness of knee braces remains to be identified. Therefore, the purpose of this study was to investigate the effectiveness of bilateral single-hinged knee bracing in knee osteoarthritis (OA) using finite element (FE) method. A three-dimensional FE model consisted of main model (knee-brace structure) and submodel (strap-muscle system) was developed. The submodel was used to convert the elastic strap-muscle interaction into an equivalent stiffness value required by the main model. Adding 100 N · mm/rad torsion spring to the brace with 5 kPa strap pressure lowered maximum von Mises stress in the knee OA components at a flexion angle greater than or equal to 90°. Separately, employing 10% brace pre-tension to the brace with 5 kPa strap pressure started to reduce stresses at a flexion angle of 70°. The configuration involving a combination of 10% brace pre-tension and 300 N · mm/rad torsion spring with 30 kPa strap tightness produced stress reduction over the entire range from 0° to 100° flexion angle. The basic bilateral single-hinged knee brace has shown to reduce stresses in the knee OA at high flexion angles only. Compared to the torsion spring, the brace pre-tension has shown to provide more significant benefits (i.e. stress reduction at lower flexion angles). The most sophisticated effects were achieved when the torsion spring was used in combination with the brace pre-tension. These two features can be potentially used for the development of an active knee brace if they can be modulated at different flexion angles or during the gait cycle.