The effects of ankle joint position and gastrocnemius muscle contraction and relaxation on anterior tibial translation

Abstract

Historically, anterior tibial translation of the tibia on the femur has been assessed with clinical examinations tools both manual and mechanical that assure hamstring muscle relaxation in an effort to measure true movement. To date, no studies have reported similar outcomes with modified positions of the ankle joint or muscle contractile states of the gastrocnemius muscle. Given the biomechanical and anatomical attachments of the two-joint gastrocnemius muscle, it was hypothesized that altering the position and/or the muscle contractile state would minimize the amount of anterior tibial translation. A Quasi-experimental design with repeated measures.assessed the anterior tibial translation of thirty male and thirty female intercollegiate athletes in the United States between the ages of 18-23. Each subject was examined for anterior tibial translation in one of four ankle joint positions and the amount of anterior tibial translation in millimeters was recorded. Results found altered ankle joint positions and gastrocnemius muscle contractile states significantly decreased the amount of anterior tibial translation of the tibiofemoral joint at the α = 0.05 level when compared to the normal resting ankle position. These findings suggest testing for anterior tibial translation should occur with slight plantar flexion of the ankle in a relaxed gastrocnemius muscle state, in an effort to prevent against false negative assessments of movement. Furthermore, such findings may have implications on rehabilitation exercises designed to decrease anterior tibial translation shear forces.

Key words:

tibial translation, rehabilitation, biomechanical