A new ankle laxity tester and its use in the measurement of the effectiveness of taping.

Damage to the lateral ligaments of the ankle, namely the anterior talofibular (ATFL) and the calcaneofibular (CFL) ligaments, is a frequently reported sports injury. The anterior drawer test is generally used to evaluate whether the ATFL has been torn, while the talar tilt test is used to determine if the CFL has been injured. Although these two manual tests are often utilized for quick diagnosis, they have been criticized because of their subjective nature and their inability to produce quantitative and reproducible results. A prototype ankle tester was manufactured that could measure the input force and torque, as well as the linear and angular deprivations for the anterior drawer test and the talar tilt test, respectively. This device was used to take readings on 10 human volunteers of a mean age of 21.6 years. This device was X-ray compatible, adjustable for varying patient sizes, relatively small, portable, and easy to operate. Testing was performed to determine how the stiffness of the ankle would respond to taping, and the effect of walking on the taped ankle. The overall mean anterior drawer was 5.93 mm and the mean talar tilt was 51.6 degrees for bare ankles using a force of 111 N (25 lbs) for the drawer and a torque of 16 N m for the tilt. Taping provided an average increase in stiffness of 11.3%, demonstrating that it did provide increased stability. However, statistically significant (P<0.05) decreases in the stiffness subsequent to taping were observed between the initially taped ankles and after 20 min of walking, when it was shown that talar tilt had increased. The prototype ankle tester produced repeatable measurements, and results show that the increase in stiffness due to taping did decrease after a short period of time.