SON REVERSIBLES LOS FENÓMENOS DEGENERATIVOS DEL CUÁDRICEPS AL REPARAR DIFERIDAMENTE UNA LESIÓN DEL TENDÓN PATELAR

Purpose:  Evaluate the regression of degenerative changes in the quadricipital muscle after a delayed extensor mechanism repair. The hypothesis is that a delayed repair favors the regression of degenerative changes related to the precocity of the repair.  Material and Methods:  Experimental study in 15 BKS male mice: a complete section of both patellar tendons was made. Animals were randomly divided into 3 study groups (5 mice per group), according to the week after the lesions at which the right quadriceps were repaired: 1 (Group 1), 2 (Group 3), and 4 (Group 3). Left quadriceps remained unrepaired and was used as the corresponding control for each group. All animals were sacrificed 4 weeks after the repair. A blind pathologist analyzed macroscopic and histologic evaluations. Statistical analysis included tests for paired and independent samples (p=0.05). Results: - Macroscopy: there were three repair failures, two in group 2 and one in group 3. Quadricipital length in group 1 was the only significant difference (p = 0.04222) observed between the intervened muscles and their corresponding control. No statistical differences were present between the intervention groups, neither when compared to their corresponding controls for the other macroscopic parameters.  - Histology: No statistical differences were present between the intervention groups, neither when compared to their corresponding controls for the other macroscopic parameters. Conclusion:  A delayed repair of a complete knee extensor mechanism injury in this experimental model did not demonstrate the regression of the degenerative muscle changes. The precocity of the repaired correlated with fewer repair failures and a greater quadricipital length. Clinical Relevance:  The present experimental study enhances the importance of an early repair for complete knee extensor mechanism injury.  Key Words: Extensor Mechanism, Quadriceps, Muscular Degeneration, Tendon Repair, Knee