Development of the femoral trochlear groove in rabbits with patellar malposition

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The geometry of the trochlear groove is considered to be an important determinant in the pathogenesis of the patellofemoral joint disorders. However, the effect of patellar position during the development of the femoral trochlear groove is unclear. This animal study aimed to investigate the relationship between the position of the patella and development of the femoral trochlear groove in growing rabbits. Thirty-two knees from 16 rabbits were included in this study and were divided into two groups. First group consisted of the left knees and was used as a control group with no surgical interventions. The second group involved the right knees on which patellar tendon Z-plasty lengthening was performed to cause patellar malposition (patella alta) before 1month of age. Computed tomographic (CT) evaluations of both knees were obtained when the animals were 1month age before the surgical intervention and also at 6months after the surgical intervention. Angle and depth measurements were acquired from the proximal, middle, and distal reference points along the femoral trochlear groove. After the CT scan acquisition at 6months following the surgical procedures, rabbits were killed and additional measurements of the trochlear groove angles were performed manually. The mean middle and distal trochlear groove angles for the experiment group with patella alta were significantly higher compared to that of control group (p<0.017). The increase in mean trochlear depth for the animals in the control group was found to be significantly higher compared to experiment group at the distal zone (p<0.017). Distal femoral groove with an inadequately positioned patella becomes more flattened and this may be a predisposing factor for patellar instability. Controlled laboratory study, Level II.