BIOMECHANICAL AND HISTOLOGIC PROPERTIES OF THE CANINE PATELLAR TENDONAFTER REMOVAL OF ITS MEDIAL 3RD

Three groups of dogs were used for this study. All dogs had the medial third of the patellar tendon removed from one knee, while the contral ateral knee was used as a control. The time zero group was immediately sacrificed; the other two groups were sacrificed at 3 and 6 months. O nce the tissues were harvested, the patellar tendon was isolated and b iomechanical and histologic analyses were conducted. Three and 6 month s after surgery, there was a large amount of visible scar tissue in th e tendon. The cross-sectional area of the tendons was 275% and 288% of controls at 3 and 6 months, respectively. The tensile modulus of the tendon was statistically less than controls at both 3 and 6 months. Th e energy to failure and stiffness of the operated tendons were not sta tistically different than controls at 3 or 6 months after surgery. The results of this study directly contrast with those of an earlier stud y on the removal of the central third of the patellar tendon. While a number of factors could explain differences observed between removal o f a central or medial third, this study confirms the short-term damagi ng effects of surgical removal of a portion of the patellar tendon to reconstruct a torn anterior cruciate ligament.