Landing adaptations after ACL reconstruction

rehabilitated ACL reconstructed (ACLr) recreational athletes utilize adapted lower-extremity joint kinematics and kinetics during a high-demand functional task. Methods: The kinematic and kinetic performance of 11 healthy and 11 hamstring ACLr recreational athletes were compared during a 60-cm vertical drop landing. Results: At initial ground contact, the ACLr group demonstrated greater hip extension and ankle plantarflexion compared with the healthy group. The peak vertical ground-reaction force was not different between groups, but the ACLr group delayed the time to its occurrence. The knee extensors provided the major energy absorption function for both groups; however, the ACLr group performed 37 % more ankle plantarflexor work and 39 % less hip extensor work compared with the healthy group. Conclusions: The hamstring ACLr recreational athletes utilized an adapted landing strategy that employed the hip extensor muscles less and the ankle plantarflexor muscles more. The harvesting of the medial hamstring muscles for ACL reconstruction may contribute to the utilization of this protective landing strategy. Key Words: KNEE, KINEMATICS, KINETICS, SURGERY, PERFORMANCE, BIOMECHANICS Anterior cruciate ligament reconstruction with thecombined loops of the semitendinosus and gracilistendons is common in sports medicine (2). The selection of this graft over the central third of the patellar tendon is typically based on the morbidity associated with graft harvest. Graft site morbidity from the patellar tendon technique has been thought to be the primary mechanism attributed t

THE EFFECTS OF KNEE JOINT EFFUSION ON QUADRICEPS ELECTROMYOGRAPHY DURING JOGGING

To investigate and describe the influence of intra-articular effusion on knee joint kinematics and electromyographic (EMG) profiles during jogging. Thirteen individuals underwent a 20 cc 0.9% saline insufflation of the knee joint capsule and completed 8 jogging trials. Stance phase, sagittal plane knee joint kinematics and thigh muscular EMG profiles were compared pre- and post-insufflation utilizing a paired t-test (p = 0.05). Mild knee effusion caused a reduction in vastus medialis (p = 0.005) and lateralis (p = 0.006) EMG activity. The rectus femoris, biceps femoris and medial hamstring muscles did not exhibit changes due to this protocol. There were no changes in the sagittal plane knee joint kinematic pattern. Twenty cc effusion can cause quadriceps inhibition in the vastus medialis and the vastus lateralis in otherwise healthy individuals during jogging. This study provides baseline data for the effects of mild knee joint effusion on thigh musculature during jogging

Effects of Braiding on Tensile Properties of Four-Strand Human Hamstring Tendon Grafts

Background: Anterior cruciate ligament reconstruction is commonly performed with autogenous hamstring tendon grafts. Purpose: To ascertain the effects of braiding on ultimate tensile strength and stiffness of hamstring tendon graft. Study Design: Controlled laboratory study. Methods: Sixteen fresh-frozen semitendinosus and gracilis tendons were harvested from eight matched (right and left) human cadaveric specimens. Both sets of hamstring tendons from each matched pair were doubled, creating a four-strand graft. Grafts were then randomized so that one graft from each matched pair was braided and the other remained unbraided. The diameter of each graft construct was recorded. Grafts were tested to failure on a materials testing machine. Results: There were no significant differences in cross-sectional area before or after braiding. Fifteen of 16 tendons failed midsubstance; 1 failed at the lower clamp. Braiding reduced the initial tensile strength and stiffness of human hamstring tendon grafts in this study by 35.0% and 45.8%, respectively. Conclusions: Braiding may place the collagen fibers in a suboptimal orientation for loading that results in a weaker graft. We do not recommend the use of braiding if the strongest, stiffest initial graft is desired

Endurance Sports Medicine : A Clinical Guide

Endurance Sports Medicin