In vitro evaluation of an implantable force transducer (IFT) in a patellar tendon model.

A new implantable transducer has been developed for in situ evaluation of ligament and tendon forces. Unlike previous devices, this sensor is placed within the specimen, minimizing measurement errors due to impingement on surrounding soft tissues and bone. In this study, we present the sensor design details as well as test results from initial in vitro trials in the goat patellar tendon model. Device performance and influence of the device on the specimen were evaluated under several loading conditions. In all cases, device output had a strong correlation with induced tissue load. Significant variations in device performance were only noted at high tissue deformation rates. More extensive investigations will be conducted to assess how changes in transducer design might alter performance characteristics.