SECONDARY GAIT CHANGES IN SUBJECTS WITH RECURRENT ANKLE SPRAIN -SUBTALAR AND KNEE JOINT MOMENTS DURING STANCE-

Abstract

This study assessed how the frontal plane moment and angle at the subtalar joint was associated with the knee joint varus moment during stance in persons with an unstable lateral ankle. METHODS Forty two female athletes (20 persons with an unstable lateral ankle: 21.4±2.4 yrs, 1.58±0.06 m, 50.6±5.4 kg and 22 healthy controls: 22.5 ±3.3 yrs, 1.61±0.05 m, 53.4±7.4 kg) participated in this experiment. Subjects were recruited by the investigator with the assistance of intramural athletic trainers. The inclusion criteria for persons with an unstable lateral ankle were: a history of at least two lateral ankle sprains to the same ankle during the past 2 years, a history of ankle pain or swelling during injury, and apprehension during either anterior drawer or talar tilt tests. Three-dimensional gait analyses were conducted with a motion analysis system (VICON) operating at 60 Hz with 12 infrared cameras and 8 force platforms (KISTLER) operating at 60 Hz. Subjects were asked to walk barefoot at a self-selected walking cadence (115.1±5.3 steps/min for persons with an unstable lateral ankle, 114.7±8.4 steps/min for healthy controls, P=0.861), indicated by a metronome. Moments were derived using a three-dimensional inverse dynamics model of the lower extremity [3]. The average moments at the subtalar and knee joints were equivalent to the division of the area under the moment-time curve and its time of application, respectively. Evaluations of the average angles and ground reaction forces were performed using the same methods as for those applied for the average moments [3]. Unpaired Student’s t-test was used to determine the statistical significance between the persons with an unstable lateral ankle and the healthy controls. In addition, simple regression analysis with Pearson coefficients was used to determine correlation between the subtalar joint valgus moment and the knee joint varus moment during stance. Table 1. Stance phase average values between healthy controls and persons with