Development and evaluation of a surrogate ankle for use with a rotational traction measurement apparatus

Biofidelic devices are used in the automobile industry to assess injury risk during a vehicular accident. Similar biofidelic devices may have broad applicability in the field of sports injury prevention and could be used to enhance player safety. Ankle sprains constitute one of the most common sports injuries. Past studies have suggested that high rotational traction at the shoe—surface interface may increase the likelihood of lower-extremity injury. Researchers have assessed this risk by measuring the peak torque during an applied rotation. On the other hand, ankle sprains may be dependent upon the amount of strain developed in the ankle ligaments during rotation of the foot—ankle complex and not the magnitude of torque. The current study quantifies the torsional stiffness of the human foot—ankle complex based on cadaver experiments. The development of a surrogate foot—ankle complex is then detailed and compared with the human response. Finally, the results of a rotational traction study on a couple of football shoe—surface interfaces are presented using the surrogate ankle. The testing resulted in a new outcome variable, namely the peak twist of the ankle, that may allow assessment of the risk of injury to the ankle due to excessive rotational traction at the shoe—surface interface.