Design and Evaluation of a Patellar Tendon-Bearing Brace with Off-Loading Mechanism on Tibia

The current study aimed to design a patellar-tendon-bearing (PTB) brace capable of measuring and quantifying weight offloading on the tibia. The PTB brace was designed with off-loading mechanism on the tibia with features, including ankle joint, vertical sliding adaptor, vertical sliding piece, and upper connector of load cells to PTB brace. Also, the present study investigated the effect of brace on 20 healthy individuals under 8 different off-loading conditions, based on measuring the vertical distance between the calf shells and foot plate through a sliding adapter at 0.5, 1, 1.5, 2, 2.5, 3, and 3.5 cm. The Pedar device and load cells embedded in PTB brace were used to determine the extent of offloading and assess the reliability and validity of brace. Increasing the vertical distance between the calf shells and the footplate can lead to a greater amount of offloading. Accordingly, off-loading ranged from a minimum of 16.5% at 0 cm position to a maximum of 60.48% at 3.5 cm position of sliding adapter. Percentage values of tibia off-loading in 8 conditions were not significantly different in Padar devices and PTB brace. Therefore, PTB brace load cells, as a valid method, can measure off-loading levels. When fabricating a PTB brace, a monitoring system with load cells is essential to measure the amount of tibial offloading, leading to readjustment if limb slides down inside the brace. Additionally, a component is needed to correctly position limb in off-loading condition. In the current study, sliding adapter of brace can provide that capability.