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.
"MRI can be used to evaluate and map physeal closure, which can be caused by lack of physeal activity or bone bridges (Sydner et al. 2001, Friend and Widmann 2008). The physis is well seen on most MRI sequences and has signal characteristics that are similar to those of articular cartilage (Moon et al. 2012). Based on T1-value calculations, we found reduction in the water content of the physis immediately after the procedure . "
[Show abstract][Hide abstract] ABSTRACT: Background and purpose
Current techniques for epiphysiodesis involve opening of cortical windows; use of staples, screws, and tension devices; and fusion with curettes or drills. Complications may have serious consequences. There is a need for a more reliable, precise, and less traumatic procedure that overcomes the known complications from existing techniques. We analyzed a new epiphysiodesis technique using radio-frequency ablation (RFA) in a porcine model.
Six 35-kg and two 25-kg immature pigs were used. 1 hind leg of each animal was randomly selected and the proximal tibia growth plate was ablated laterally and medially. The contralateral leg was used as a control. MR images were obtained immediately after the ablation and 12 weeks later for 6 animals, and 24 weeks later for the other 2 animals. CT was done for the 2 animals that were followed for 24 weeks for proof of bone bridges.
Both tibias were equal in length initially. At the 12-week follow-up, there was an average leg length discrepancy of 3.9 mm (95% CI: 3.0–4.8), and at 24 weeks the difference was 8.4 mm and 7.5 mm. No damage to the adjacent tissue was found. Bone bridges and physeal closure were found after 24 weeks. The pigs showed no discomfort after the intervention.
We found RFA to be feasible for epiphysiodesis in a pig model. The method is minimally invasive and recovery may be quick compared to conventional methods. We recommend that the method should be tested in larger-scale safety studies before clinical application.
[Show abstract][Hide abstract] ABSTRACT: Arthroscopic shoulder surgery is emerging for a variety of indications in pediatric and adolescent patients with several potential advantages over surgical procedures traditionally performed with open surgery. Arthroscopic procedures can be less invasive, with more rapid recovery, improved cosmesis, and improved visualization. Arthroscopic Bankart repair plays an important role in the management of adolescents with traumatic shoulder instability, while throwing athletes may be treated by arthroscopic surgery to address injuries affecting the rotator cuff and posterosuperior labrum. Avulsion injuries of the greater or lesser tuberosity are rare in this population, but when they occur they may also be treated arthroscopically with similar techniques as performed with arthroscopic rotator cuff repair. Septic shoulder is another condition which may be treated arthroscopically with improved visualization of the glenohumeral joint and decreased surgical dissection. Special considerations with regard to patient positioning, portal placement, and surgical techniques are important when performing shoulder arthroscopy in pediatric patients as these may differ from similar procedures for adults.
The Pediatric Upper Extremity, 01/2015: pages 1709-1732; , ISBN: 978-1-4614-8513-1
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