Flexor Tendon Injury: Avascular or Vascularized Region Suture? Biomechanical and Histopathological Study in Rabbits.

The present study aims to analyze the mechanical and histopathological aspects of flexor tendon healing focusing on the suture placement site in a vascular or in an avascular region.  A total of 83 rabbits were submitted to a Kessler-type central suture in the vascularized tendon region (TN group) and in the avascular tendon region (FC group). The operated limb was immobilized for 3 weeks. The animals were sacrificed in the immediate postoperative period, and at 2, 3 and 6 weeks after the procedure. The mechanical properties studied were: maximum load, stress at maximum load, modulus of elasticity, energy at maximum load, and energy per area. The contralateral tendon was used as control. The histopathological study was descriptive.  The analysis of the mechanical properties showed similar behavior in both groups, with stabilization or discrete increased values between the immediate period and 3 weeks after the procedure, and marked increased values at 6 weeks. Histopathology demonstrated that the healing process was similar in the TN and FC groups.  Central suture placement in the vascularized or avascular fibrocartilaginous region results in no differences in the biomechanical and histopathological aspects of flexor tendon healing in rabbits.