Radiofrequency application to the growth plate in the rabbit: a new potential approach to epiphysiodesis

Radiofrequency energy is being used more and more frequently in orthopaedics, mainly in the treatment of bone tumors. We postulated that radiofrequency ablation may produce growth plate lesions similar to those observed in the bone and conducted this study to see whether radiofrequency may be used as a technique for producing epiphysiodesis.

We randomized 60 8-week-old female New Zealand white rabbits into 3 groups. Group A was destined for a total epiphysiodesis at 60 degrees C, group B was destined for a total epiphysiodesis at 90 degrees C, and group C for a lateral hemiepiphysiodesis at 90 degrees C. Radiofrequency energy was delivered in 1 minute in all 3 groups. Using fluoroscopic imaging, radiofrequency was applied percutaneously to the left proximal tibial physis whereas the right growth plate received a sham procedure. A bicortical pin was used to evaluate the longitudinal growth rate at every monthly radiologic control, beginning 8 weeks after the procedure. Comparisons between the right and left side and between groups A and B were achieved using a paired t test. A histopathologic study was conducted in parallel to the radiographic study.

In a radiograph at the 8-week point, pin migration was 4.74 mm on the left side compared with 9.72 mm on the right (P<0.0001), in group A. In group B, pin migration on the left was 1.37 mm compared with 5.49 mm on the right (P<0.0001). In group C, mean angular deviation was 11.6 degrees on the left compared with 1.9 degrees on the right (P=0.0001). These differences were maintained until the end of growth. Pathology specimens revealed cellular anarchy, loss of columnar stratification, and height of the physis on the left side, which occurred earlier and were more pronounced in group B than in group A. In group C, these changes involved only the lateral half of the left physis whereas its medial counterpart remained normal. There was no evidence of articular cartilage damage.

This experimental study shows that radiofrequency can efficiently and rapidly achieve epiphysiodesis. It is one of many methods that can be used for this purpose. The development of new electrodes suitable for use on human growth plates and the elaboration of specific utilization protocols may lead to its use in children. Its simplicity and precision may lead to a quick and efficient growth arrest with little pain and postoperative disability in addition to reduced costs.

Radiofrequency has proved to be effective in producing growth arrest in rabbits with no complications. Technical improvements and adaptations may allow its use for pediatric limb inequalities or angular deformities in the near future.