Chronic Ankle Instability Leads to Lower Extremity Kinematic Changes During Landing Tasks: A Systematic Review.

Ankle and knee injuries are two of the most common injuries. It has been shown that ankle sprains can lead to chronic ankle instability thereby affecting the function of the ankle. Since the lower extremity is a kinetic chain anything that affects the ankle is thought to affect the knee and hip as well. Changes in lower extremity function associated with chronic ankle instability may predispose patients for non-contact ACL injuries. The purpose of this study was to provide a systematic review of the research done on chronic ankle instability (CAI) and lower extremity kinematics during landing tasks. SportsDiscus, PubMed, and CINAHL were used to search "ankle instability" and "landing kinematics." Included articles must have evaluated patients with chronic ankle instability and have identified kinematic changes at the knee to be included in the review. A total of 338 subjects participated in the six studies identified. The principal findings in these studies were that CAI subjects had decreased knee flexion compared to the control group. Hip flexion was the same between CAI and control groups and dorsiflexion range of motion had mixed results. Patients with chronic ankle instability demonstrate decreased knee flexion. Decreased knee flexion has shown to be a key risk factor in non-contact knee injuries. In the future, more research needs to be done comparing chronic ankle instability to non-contact knee injury rates.