Injuries to the superficial digital flexor tendon (SDFT) are extremely common amongst racehorses, very difficult to treat, often career limiting and a major welfare concern. Injury is not surprising considering the extreme mechanical demands on the SDFT, and we have previously carried out in-vitro tests and discovered why some SDFTs are fatigue resistant whilst others easily injure.

We have established that sections of the SDFT must slide relative to each other for effective function, enabled by a low stiffness matrix. However, as the matrix stiffens (such as with age) it limits sliding, increasing injury risk.

We now wish to develop methods to investigate SDFT sliding in-vivo, developing a clinical diagnostic tool for assessing SDFT health and injury. Our team have developed methods to characterise sliding between sections of the human Achilles tendon, and aim to transfer this expertise to investigating SDFT sliding. We will use cadaveric legs to validate our measures, also allowing us to relate in-vivo sliding to our wealth of knowledge of healthy tendon mechanics in-vitro.

We will pilot our methods as a diagnostic tool with both healthy horses and those with SDFT injury. A pilot longitudinal study of injured SDFTs, investigating how sliding alters during healing, will build the platform for a future larger study of SDFT healing, assessing our novel diagnostic tool for monitoring healing, to see if it can determine when a safe reintroduction to training can be considered.