Background: Ankle bracing has not been studied for its effects of knee joint kinematics and kinetics in the adolescent female athlete. Hypothesis: A) A statistically significant mean increase of knee joint valgus and extensor moments and valgus angles would be found in the braced group during the drop vertical jump and the single log hop tests and B) A statistically significant mean decrease in knee joint varus and extensor moments and valgus angles will be found between pre- and post-test acclimation periods in the braced condition. Study Design: Randomized Controlled Trial. Methods: Fifteen adolescent female athletes performed Drop Vertical Jump (DVJ) and Single Leg Hop (SLH) tests without ankle bracing and with a lace-up style ankle brace. Subjects wore braces over a 1 week period and retested. Results: During the DVJ, bracing increased knee extensor moments during the first 50 ms of landing but had no affect on knee frontal plane moments. Bracing increased vertical ground reaction force (vGRF) within the first 50ms of landing, and peak vGRF with less time to achieve peak vGRF. During the SLH, bracing increased knee flexion at IC and decreased knee frontal plane displacement into valgus. Ankle bracing increased vGRF within the first 50ms of landing and decreased stance time. Conclusions: Ankle bracing increased vGRF and knee extensor moments during the first 50ms of landing. Clinical Relevance: The adolscent female athlete may be at risk for knee injury during the initial landing phse when wearing a lace-up style ankle brace.
