The torsional alignment changed significantly of hindlimb in growing rabbits after patellar dislocation

Abstract

Background Torsional malalignment has been considered as a risk factor for patellar dislocation. But the influence of patellar dislocation for torsional alignment development remains unknown. The present study aims to investigate whether the torsion alteration of the hindlimb occur after patellar dislocation in growing rabbits. Methods In the present study, 30 one-month old rabbits were included. The experimental group consists of 30 left knees of rabbits and were underwent patellar lateral dislocation. And the control group consists of 30 right knees and no surgical procedure was performed. The Computed Tomography (CT) scan was performed on each knee when the surgery was finished and at the time the rabbits were skeletal mature (5 months post-surgery). The angles of femoral version and tibial torsion were measured using a three-dimensional method and analyzed between the experimental group and control group. Results The femoral version and tibia torsion in the experimental and control group immediately after surgery were not significantly different. However, 5 months after surgery, the femoral version angle of the experimental group (-5.50±6.13°) was significantly different with that of the experimental group (-10.90±4.74°)( P < 0.05). But the tibia torsion angle in the experimental group (7.17±7.25°) and control group (4.47±6.34°) were not significantly different ( P = 0.144). Conclusion From this study, patellar dislocation can lead to alteration of femoral version in growing rabbits. This may indicate the early treatment for patellar dislocation in children is particularly important to avoid torsional malalignment in the future. These findings may develop pathology and etiology of patellar dislocation.