Functional Anatomy of the Craniolateral and Caudomedial Bundles of the Caudal Cruciate Ligament in Beagle Dogs.

OBJECTIVE  The aim of this study was to investigate functional anatomy of the craniolateral bundle (CrLB) and caudomedial bundle (CdMB) of caudal cruciate ligament in normal Beagles. MATERIALS AND METHODS  Twelve stifle joints of 12 Beagle cadavers that were euthanatized for reasons other than musculoskeletal disease were used. Anatomical characteristics of femoral and tibial attachment regions of the caudal cruciate ligament were described, and location and area of the footprints of the CrLB and CdMB were objectively determined. The CrLB was artificially divided into two equal fibre bundle units and the CdMB was artificially divided into four equal bundle units. Changes in the fibre arrangement were recorded during stifle range of motion, and the tension of each fibre bundle unit at various stifle joint angles was objectively measured. RESULTS  The CrLB was attached to the intercondylar fossa of the femur, and the CdMB was attached to the medial surface of the medial condyle of the femur. The centre of the CrLB attachment site was located craniomedial to that of the CdMB on the tibia. During stifle range of motion, each divided fibre bundle unit in the CrLB and CdMB was twisted externally. The tension of entire CdMB tended to be higher than that of entire CrLB at 180 to 135 degrees of the stifle angles. In full extension angle, the tension of entire CdMB was 1.55 times higher than that of entire CrLB. CLINICAL SIGNIFICANCE  This study contributes to understanding of the biomechanics and the function of the caudal cruciate ligament, which help to elucidate the pathophysiology of caudal cruciate ligament tear and to develop stifle joint stabilization surgery.