ANKLE PLANTARFLEXOR CONTRIBUTIONS TO KNEE JOINT LOADING AND ANTERIOR CRUCIATE LIAGAMENT FORCE DURING SINGLE-LEG LANDING

The purpose of this study was to identify the effects of height on ankle plantarflexor contributions to the knee joint loading and the anterior cruciate ligament (ACL) force during single leg landing. Eight healthy subjects performed landing from 30 and 60 cm heights. Subject-specific musculoskeletal models, based on single-leg landing, were developed in OpenSim using kinematics and kinetics data. Predicted muscle forces and knee joint reaction forces were input into another knee model to estimate ACL forces during landing. Large Soleus muscle forces (~5B.W.) were found to act on the tibia at the same time when peak ACL forces occurred. The Gastrocnemius muscles, which acted as an ACL antagonist peaked earlier than the Soleus with a lower magnitude (~3BW). The Gastrocnemius-Soleus complex acted to stabilize the knee joint during single leg landing