gms | German Medical Science

Objective: Recently, we showed a significant deteriorating effect of soft tissue trauma injury in rabbit tibia and muscle in an acute limb shortening-distraction model. The aim of our study was to examine the influence of the human cysteine rich protein 61 (CYR61, CCN1) as a mediator in angiogenesis on muscle strentgh recovery.

Methods: The study was performed with 22 skeletally mature male New Zealand White rabbits (NZW) with an average weight of 3.8 kg (drop-out rate of 9%). The NZW rabbits were divided into two equal groups. In both groups an acute compartment syndrome was generated by 90 min. ischemia and 30 min. of muscle contusion with 100 kPa (=10N/ 1cm2) and the limb was shortened by resection of a 10 mm bone segment simulating the fracture site debridement. The contralateral leg functioned as the non operated control. In the test group a collagen matrix coated with 2 5µg CYR61 was locally applied circumferent the fracture. In both groups an external fixator was applied and the limb was shortened through resection of a 10 mm segmental bone block. Distraction commenced 10 days postsurgery at a rate of 0.5 mm every 12 h using an external fixation device (Orthofix^®). Compartment pressure was measured until 48h postoperatively, arterial blood pressure was documented continuously. Bilateral pressure measurements confirmed the onset of acute compartment syndrome (defined as pressure greater than 30 mmHg) on the traumatized side in both groups. Muscle strength was monitored bilaterally prae-trauma and every 5th days until 30 days posttrauma.

Results and conclusions: After trauma there was an increase of compartment pressure from 7.5±1.4 to 33.9±3 mmHG and a reduction to 11.26±43 mmHg post-operatively. The arterial blood pressure was uniform with MAP of 81.4 mmHG. In all animals osseous consolidation occured. Muscle strength showed a continuous regeneration after a sharp decrease postoperatively until 30 days posttrauma. The average muscle strengh recovery of the test group was 86.41±10.29% of the contralateral side and 58±28% in the control (p=0.05). Histomorphometric analysis of the tibialis anterior muscle demonstrated a significant difference in fibrous degeneration in the control of 14.9% compared to 6.3% in the test group (p<0.05) Acute soft tissue trauma influences callus formation, fracture healing, muscle strength and regeneration. In our study we could demonstrate that locally applied CYR61 influences the muscle regeneration not only histomorphometrically. Besides, application of CYR61 reduced scar tissue formation and showed an increase of muscle strength regneration compared to the control group.