Quantification of Finger Laxity in Skeletal Dysplasia

People with skeletal dysplasia often exhibit hyperlaxity of the joints. Accurate measurement of laxity in certain joints provides a simple noninvasive measure of function, therapeutic efficacy, and disease progression. A simple, reproducible device to measure joint laxity was developed. The device measures the angle and torque at the second metacarpophalangeal joint as it is passively extended. Sixty-one subjects (42 with skeletal dysplasia and 19 age-matched healthy controls) participated in an experiment to quantify laxity. Results show that laxity is significantly different in skeletal dysplasia compared with healthy controls and decreases with age. However, rate of decrease was significantly higher in healthy controls compared with the other groups.