In vivo Measurement of Knee Extensor Muscle Function in Mice


Knee extensor musculature is the most widely reported functional outcome in humans and the pathology or functional deficits are well documented in aging, orthopedic injury, disease and disuse. These measurements are closely related to functional capacity and future risk of injury and thus can be used to inform medical decisions for things like return to play following an ACL tear. However, unlike with humans, there are limited options available to non-invasively characterize quadriceps function in rodent models. In this study, authors looked to develop a repeatable, in-vivo assessment of knee extensor strength using a customized 1300A Whole Animal System. Development of this type of functional assessment can lead to useful endpoints in osteoarthritic research and orthopedic injuries of the knee. Successful customization of a commercially available system was achieved using a simple 3D printed bracket to reliably achieve knee extension measurements. Employment of this new technique resulted in consistent and repeatable measurements across multiple animals and lays the foundation for future in-vivo studies of the quadriceps to determine functional capacity and recovery with the ability to make longitudinal measurements in the same animal.