Forces transmitted in the knee joint during stair ascent and descent

Abstract

The normal function of the knee relies upon a complicated and delicate mechanical interaction between the force-bearing structures, including muscles, ligaments and articular surfaces. Injury or damage to any of these structures will lead to the degradation or loss of joint function. Stair locomotion is one of the most common forms of motion in daily living. The purposes of the study were to analyze forces transmitted by the force-bearing structures of the knee during normal stair ascent and descent and to evaluate their mechanical differences. Compared to stair descent, higher peak patellar tendon forces, peak flexor forces, posterior cruciate ligament (PCL) forces and contact forces were required during stair ascent. In contrast, the anterior cruciate ligament (ACL) trended to bear higher forces during stair descent. It is suggested that one should be cautious in the use of stair ascent and descent as a rehabilitation exercise for patients with injuries or diseases of the cruciate ligaments and articular surfaces. The results of the study will be helpful for the understanding of the normal mechanics of the knee during stair locomotion, contributing to the design and evaluation of rehabilitation programs for patients with knee problems such as ACL injury and osteoarthritis.