Femoral trochlear groove development after patellar subluxation and early reduction in growing rabbits.

PURPOSE: This animal study aimed to investigate whether early reduction in patellar subluxation could minimize femoral trochlear dysplasia in growing rabbits.

METHODS

Sixty rabbits were divided into four groups (N = 30 knees/group). The control group underwent no surgical procedures. The rabbits in the three experimental groups underwent surgical patellar subluxation. Those in the early-reduced group underwent reduction surgery 1 month after patellar subluxation. The late-reduced group underwent reduction surgery 2 months after patellar subluxation. The rabbits in the non-reduced group underwent no reduction surgery. CT scans were performed monthly to measure the sulcus angle and trochlear width and depth. Gross specimen examination and histological observation were performed to investigate anatomical configuration and changes in the trochlear groove cartilage.

RESULTS

CT scans demonstrated significant differences in the sulcus angle, trochlear width and trochlear depth by 6 months after subluxation surgery in the late-reduced and non-reduced groups. No obvious differences in these parameters were seen in the early-reduced group compared with the control group. Gross specimen examination and histological investigations showed degenerative changes in the femoral trochlear groove and cartilage by 6 months after subluxation surgery in the late-reduced and non-reduced groups. No degenerative changes were found in the early-reduced group, compared with the control group.

CONCLUSION

Our results indicate that patellar subluxation or dislocation early in an animal's development can lead to femoral trochlear dysplasia or flattening and that early relocation of the patella can prevent femoral trochlear dysplasia in growing rabbits.