Detection of early changes after growth plate injury using MRI.

Abstract

To elucidate the association between growth plate injury size and the beginning of physeal growth disturbance by MRI. Thirty-two 5-week-old male Japanese white rabbits were used. Injuries were made to the right tibial proximal growth plate central region with a 3.0-mm and a 1.2-mm drill. The left tibia was used as a control. MRI (7.04 Tesla [T], gradient echo: repetition time [TR], 71.68 ms; echo time [TE], 3.60 ms; proton-density weighted imaging: TR, 2000 ms; TE, 12 ms) of the growth plates was performed at 1, 4, 8, 10, and 12 weeks postinjury. Tibia length, histology, radiography, and microcomputed tomography (µCT) were studied. MRI showed that at 10 and 12 weeks postinjury in the 3.0-mm group, the medial and lateral growth plates in the noninjured regions were significantly reduced compared with the controls (P < 0.05). At 12 weeks postinjury in the 1.2-mm group, medial and lateral growth plates in the noninjured regions were significantly reduced (P < 0.05). Tibia length and histological growth plate height of injured side in both groups were significantly shorter than controls at 12 weeks postinjury (P < 0.05). Comparison with the controls showed no significant difference at any of the time periods in either the 3.0- or 1.2-mm group according to the radiographic studies (P > 0.05). Bony bridges developed in all the subjects of the 3.0-mm group and in five of eight subjects of the 1.2-mm group, as shown by µCT images. This study suggested that growth plate injury size was associated with the timing of the beginning of physeal growth disturbance.