Adapting Isokinetic Dynamometry for Individuals with Transtibial Amputations

Abstract

Transtibial amputations impact one’s ability to perform activities of daily living. Continuous load bearing on the intact limb during ambulation and standing can lead to strength asymmetries in the lower limbs. Objective assessment of strength asymmetries in lower extremity muscles is critical as transtibial amputees are prone to several secondary conditions
stemming from these musculoskeletal imbalances. Isokinetic dynamometry has been used to safely evaluate muscle asymmetries, but testing is usually performed using the participant’s
own prosthesis which can vary in available range of motion and suspension method. Furthermore, this methodology excludes those who are not prosthesis users. The purpose of this research was to design, build and test a transtibial adapter for dynamometry that can be used on the residual limb with or without a prosthesis for objective assessment of leg strength. Clinical feedback was sought from one transtibial amputee regarding the usability and comfort of the adapter while performing an isokinetic knee extension/flexion task. The participant was capable of completing the knee contractions without any reported pain or discomfort, suggesting that our prototype may be an option to adapt dynamometry for this population. Further research with the prototype with a larger sample and more contraction conditions is needed to further assess whether the design presented is a viable option to adapt dynamometry for transtibial amputees.