Assessment of functional knee bracing: an in vivo three-dimensional kinematic analysis of the anterior cruciate deficient knee

Objective. To describe three-dimensional tibial and femoral movements in vi vo and examine the effect of a brace on knee kinematics during moderate to intense activity. Design. Skeletal kinematics of anterior cruciate ligament deficient knees w as measured with and without braces during moderate to intense activity. Background. Invasive markers implanted into the tibia and femur are the mos t accurate means to directly measure skeletal motion and may provide a more sensitive measure of the differences between brace conditions. Methods. Steinmann traction pins were implanted into the femur and tibia of four subjects having a partial or complete anterior cruciate ligament rupt ure. Non-braced and braced conditions were randomly assigned and subjects j umped for maximal horizontal distance to sufficiently stress the anterior c ruciate ligament. Results. Intra-subject peak vertical force and posterior shear force were g enerally consistent between conditions. Intra-subject kinematics was repeat able but linear displacements between brace conditions were small Differenc es in angular and linear skeletal motion were observed across subjects. Bra cing the anterior cruciate ligament deficient knee resulted in only minor k inematic changes in tibiofemoral joint motion. Conclusion. In this study, no consistent reductions in anterior tibial tran slations were observed as a function of the knee brace tested. Relevance Investigations have reported that knee braces fail when high load s are encountered or when load is applied in an unpredictable manner. Quest ions remain regarding tibiofemoral joint motion, in particular linear displ acements. The pin technique is a means for direct skeletal measurement and may provide a more sensitive measure of the differences between brace condi tions. (C) 2001 Elsevier Science Ltd. All rights reserved.