MUSCLE TENDON TRANSF · BIOMECHANICAL AND NEUROMUSCULAR RESPONSE TO TENDON TRANSPOSITIONS IN RAT

Tendon transfer surgeries, performed in a wide variety of patients (e.g. cerebral palsy) are aimed at improving gait or upper extremity function. However, results of these surgical interventions are not fully predictable and do not always meet the expectations. Force transmission via connective tissues at the muscle belly surface (i.e. epimuscular myofascial force transmission), as recently discovered by Huijing and Maas, is expected to play a major role here. Previous research has focused predominantly on optimizing acute effects of transfer surgery, but knowledge about the adaptive processes taking place after surgery that co-determine success of the intervention, is lacking. Therefore, the objective of this project is to assess the biomechanical and neuromuscular response to tendon transpositions determining the long-term result of the surgery. In addition, the effects of adhesion barrier application are studied as a first step aimed to prevent scar tissue formation. The central hypothesis is that relocating the tendon as well as part of its muscle belly leads to adaptation of muscle and connective tissues, as well as to adjustments of muscle activity patterns. Following m. brachialis (BR) tendon transfer in rat, in vivo muscle function will be investigated (Aim 1); adaptation of intra- and extramuscular connective tissues will be quantified and effects of such adaptations on force transmission from the target muscle will be measured (Aim 2); effects of an adhesion barrier on the formation of connective tissue at the dissected muscle belly surface and on the functional outcome will be assessed (Aim 3),. This will be the first systematic study of tendon transfer addressing the postoperative adaptive processes over a wide range of organization levels. Knowledge obtained will ultimately lead to improved surgical practice in tendon transpositions and other surgical interventions, to recommendations for therapy after the transfer and to better clinical outcomes.