Tibial plateau angle in four common canine breeds with cranial cruciate ligament rupture, and its relationship to meniscal tears.

OBJECTIVES: To compare tibial plateau angle (TPA) among Labrador Retrievers, Rottweilers, Boxers, and German Shepherd Dogs that had undergone tibial plateau leveling osteotomies (TPLO) for cranial cruciate ligament disease, and to determine if higher TPAs are associated with increased risk for concurrent meniscal injury.
METHODS: This was a retrospective study including 275 client-owned dogs of one of the four aforementioned breeds that received TPLO radiographs between 1999 and 2005 prior to undergoing the TPLO procedure. The TPA measured by the original surgeon was compared among four breeds and analyzed with respect to presence or absence of meniscal injury diagnosed via arthroscopy or arthrotomy at the time of surgery.
RESULTS: Labrador Retrievers, Rottweilers, Boxers, and German Shepherd Dogs had mean TPAs of 25.9 degrees , 26.2 degrees , 25.9 degrees , and 28.2 degrees , respectively. The TPA of German Shepherd Dogs was significantly higher than that of the other breeds of dogs examined. TPA higher than the mean for dogs in this study did not significantly increase the risk for concurrent meniscal injury. CLINICAL SIGNIFICANCE: German Shepherd Dogs with cranial cruciate ligament disease had a significantly higher TPA compared to the other breeds examined. Higher TPA did not increase the likelihood of meniscal tears in this study. However, several variables that were not assessed, including the degree of cranial cruciate ligament integrity at the time of surgery and the time between original CrCL deficiency and surgical assessment, could have affected this analysis.