Date of Award


Access Type

Dissertation - ERAU Login Required

Degree Name

Doctor of Philosophy in Mechanical Engineering


Mechanical Engineering

Committee Chair

Victor A. Huayamave, Ph.D.

First Committee Member

Charles F. Reinholtz, Ph.D.

Second Committee Member

Patrick Currier, Ph.D.

Third Committee Member

Eric J. Coyle, Ph.D.

Fourth Committee Member

Daryl Osbahr, M.D.


The use of knee orthosis, specifically on the tibiofemoral joint, has become the preferred treatment method for rehabilitation and injury prevention. Recent orthotic designs have proposed the use of springs to store energy during motion and provide assistance to the lower extremity. However, the biomechanical influence of orthotics at the knee joint has not been quantified. As such, this study aims to quantify the biomechanical response of the tibiofemoral joint complex to a non-linear spring-loaded knee joint orthosis (KJO). Joint angles, moments, and forces obtained from two dynamic trials were applied to a newly developed computational musculoskeletal model, and a static equilibrium problem was solved at each instant during the squat cycle, with and without a non-linear spring-loaded KJO, to find individual muscle forces of the lower extremity. The KJO was seen to increase the gluteus maximus muscle force while decreasing the soleus muscle force throughout the squat cycle. Due to the increased activation occurring in the gluteus maximus and the decrease in the rectus femoris during the brace-on descent, the knee joint axis moved in a less anterior direction then in the brace-off descent. As a result, the pelvis translated in a more posterior direction due to the tension supplied by the gluteus maximus and the ease of the soleus. Furthermore, hip and knee flexion were decreased in the upright position during the brace-on conditions. Results suggest that the KJO could be used as a performance tool to encourage a more balanced synergy that employs the posterior chain musculature versus a quadriceps dominant strategy while preventing hyperextension tendencies. In addition, the model created in this study paired with the inverse dynamics approach, could contribute to the current knowledge of biomechanical response estimations in clinical movement and force production analysis aiding physical therapist and orthopedic specialist in proscribing the most appropriate KJO to a specific patient.