Chronologic change in the growth plate after radiofrequency-induced thermal injury: MRI-histologic correlation.
ABSTRACT The purposes of this study were to assess chronologic changes in normal growth plate after radiofrequency-induced thermal injury and to evaluate the feasibility of MRI for revealing alteration of the growth plate.
Radiofrequency ablation was performed on the right proximal tibia of 13 8-week-old New Zealand White rabbits. An 18-gauge cooled-tip electrode with a 5-mm active tip was placed distal to the physis under fluoroscopic guidance. MRI, including T1- and T2-weighted images, gradient-recalled echo images, and contrast-enhanced T1-weighted images, was performed 2, 4, and 12 weeks after ablation. Rabbits were sacrificed 2 (n = 4), 4 (n = 4), and 12 weeks (n = 5) after ablation. The sequential changes in the ablated zone, the injured physis, and the nonablated portion of the physis were correlated between MRI features and histologic results.
Diameter of the nonenhancing lesion on MR images strongly correlated with the size of the region of coagulation necrosis at gross examination. The intraclass correlation coefficients were 0.98 and 0.94 for the long and short axes (p < 0.001). On gradient-recalled echo images, physial conspicuity was less in the injured physis than in the nonablated portion and less in the ablated than the control tibia. Physial conspicuity was graded for comparison with physial thickness at microscopic examination. The thickness of the physis was less in the ablated than in the control tibia 4 and 12 weeks after treatment (p < 0.05, paired Student t test). The cartilage column of the injured physis was delaminated 2 weeks after treatment, and a bone bridge through the injured physis was detected at 4 weeks.
Radiofrequency-induced thermal injury causes early closure of the physis. MRI can depict the extent of radiofrequency-induced thermal injury and alterations in the physis that lead to early closure.
- [Show abstract] [Hide abstract]
ABSTRACT: This longitudinal study documents cumulative and incremental growth in the New Zealand white rabbit from 2 to 34 weeks of age at biweekly intervals. Body weight, body length, femoral length, and tibial length have been assessed in 17 male and 12 female rabbits, with the data tabulated separately. A specially designed restrainer was used that allowed the sequential clinical measurements and femoral and tibial radiographs to be performed without the use of anesthesia. Skeletal growth was complete at 28 weeks, with the 34-week values thus representing mature adult lengths. The mean body weight at 2 weeks of age was 6% that at 34 weeks, and by 16 weeks, 72% of the weight at 34 weeks was achieved. Weight continued to increase in the adult. The mean body length at 2 weeks was 40% that at 34 weeks, and by 16 weeks, 91% of mature adult length was achieved. The mean femoral length at 2 weeks was 38% of the adult length, and at 16 weeks, it reached 95% of adult length. The mean tibial length at 2 weeks was 38% of the adult length, and 94% of the adult value was achieved by 16 weeks. The longitudinal data document the rate and extent of growth of the New Zealand white rabbit, and allow for more accurate timing and quantitation of physical and systemic interventions on the developing skeleton of the commonly investigated New Zealand white rabbit.Journal of Orthopaedic Research 02/1986; 4(2):221-31. · 2.88 Impact Factor
- Journal of Pediatric Orthopaedics 04/1984; 4(2):246-58. · 1.16 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Two patients are presented with significant problems of skeletal development and function consequent to electrical impulse propagation through the immature skeleton. Amputation stump revision in the first case allowed an opportunity to assess specific histologic and morphologic changes. Electrical damage completely destroyed portions of trabecular bone in the metaphyses and epiphyseal ossification centers. There were morphologic irregularities in the physis of the distal femur, while in the proximal tibia complete cessation of growth occurred through presumed electrical ablation of the physis. There was virtually no endosteal or periosteal callus, no intertrabecular inflammatory response, and no new bone formation well over a year following the original injury. The knee joint exhibited severe fibrous ankylosis. In the second case localized arrest of the posterolateral portion of the proximal tibial physis caused a valgus/recurvatum deformation, and probably slowed down distal growth sufficiently in the stump end to prevent irregular terminal overgrowth of the tibia, although it did occur in the fibula.Skeletal Radiology 02/1981; 6(3):187-92. · 1.74 Impact Factor