Biomechanical Analysis on Different Methods of Growing Rod Fixation for Early Onset Scoliosis / 医用生物力学

Objective To study the effects of selecting different fixing segments on biomechanical characteristics of the spine during the treatment of early onset scoliosis（EOS） by growing rod technique. Methods By using finite element method, four spine models (C6-S1 segments) fixed by growing rod were established: preoperative model, T1-L4 fixed model, T2-L4 fixed model, T3-L4 fixed model. Then 7 N·m torque load and 1 rad angular displacement load were applied on superior surface of C6 segment to analyze biomechanical characteristics for adjacent structure of the fixed vertebral body. Results The whole spinal range of motion (ROM) decreased significantly after operation. When the T2-L4 segment was fixed, the spine activity was mostly restricted, the compensatory activity of adjacent vertebrae increased significantly, and the intervertebral disc stress increased significantly. Conclusions When T2 segment is selected as the upper instrumented segment, the risk of proximal junctional kyphosis and spinal degeneration is the highest, which should be avoided in clinical surgery.

Comparison of the Effects of Magnetically Controlled Growing Rod and Tradiotinal Growing Rod Techniques on the Sagittal Plane in the Treatment of Early-Onset Scoliosis

OBJECTIVE: Comparing the effects of magnetically controlled growing rod (MCGR) and traditional growing rod (TGR) techniques on the sagittal plane in the treatment of early-onset scoliosis (EOS).METHODS: Twelve patients were operated using dual MCGR technique in one center, while 15 patients were operated using dual TGR technique for EOS in another center. Patients’ demographic characteristics, complications and radiological measurements such as cobb angle, thoracic kyphosis, lumbar lordosis, T1–S1 range (mm), proximal junctional angle, distal junctional angle, sagittal balance, coronal balance, pelvic incidence, sacral slope and pelvic tilt were assessed and compared in preoperative, postoperative and last follow-up period.RESULTS: Age and sex distributions were similar in both groups. The mean number of lengthening in the MCGR group was 12 (8–15) and 4.8 (3–7) in the TGR group. Two techniques were shown to be effective in controlling the curvature and in the increase of T1–S1 distance. In TGR group, four patients had rod fractures, six patients had screw pull-out and four patients had an infection, whereas three patients had screw pull-out and one patient had infection complications in the MCGR group.CONCLUSION: There was no significant difference between the two groups in terms of cobb angle, coronal and sagittal balance and sagittal pelvic parameters. MCGR can cause hypokyphosis and proximal junctional kyphosis in a minimum 2-year follow-up period. The implant-related complications were less in the MCGR group. However, larger case groups and longer follow-up periods are required for the better understanding of the superiority of one method on other in terms of complications.

Comparison of hybrid and traditional growing rod techniques in the treatment of early-onset congenital scoliosis / 中华外科杂志

Objective@#To compare the surgical outcomes between hybrid and traditional growing rod (GR) techniques in the treatment of early-onset congenital scoliosis (C-EOS).@*Methods@#A review was conducted of C-EOS patients who had undergone hybrid GR treatment at Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School. Another group of patients who had undergone traditional GR were well matched to the hybrid GR group at a 1∶1 ratio in terms of main Cobb angle, age at initial surgery, and lengthening numbers. There were 5 boys and 8 girls with an age of (5.6±2.8) years in the hybrid GR group, and 6 boys and 8 girls with an age of (6.1±3.0) years in the traditional GR group, respectively. All patients had minimum 2-year follow-up and over 2 lengthening procedures. Radiographic data were compared with paired t tests in either group between each visit, and with independent t tests between the two groups.@*Results@#On average, the hybrid group had a follow-up of (42.2±13.4) months (range:27-81 months), and had (4.0±1.8) lengthening procedures with a lengthening interval of (10.5±1.0) months; and the traditional GR group had a follow-up of (45.4±15.2) months (range: 24-76 months), and experienced (4.2±1.9) lengthenings with an interval of (10.8±1.1) months. After the index surgery, the major Cobb angle, C7 translation, apical vertebral translation, and thoracic kyphosis (TK) had remarkable improvement in both groups. Notably, the hybrid GR group had significantly higher correction rates of major Cobb angle (t=2.348, P=0.027) and TK (t=3.768, P<0.001) than the traditional GR group. At the latest follow-up, the hybrid GR group had remarkably smaller Cobb angle of the major curve than the traditional GR group (t=2.790, P=0.010). At the same time, the hybrid GR group had higher T1-S1 height gain than the traditional GR group (t=2.846, P=0.008) after the index surgery. Whereas, non-significant difference was noted between two groups with regards to the T1-S1 growth rate during follow-up (t=0.516, P=0.610). Ten complications occurred during the follow-up period, including 2 in the hybrid GR group and 8 in the traditional GR group. The incidence of rod breakage and PJK in the traditional group was 3 and 4 times as high as that of the hybrid GR group, respectively.@*Conclusions@#The hybrid growing rod can not only help to improve the correction of spinal deformity but also decrease postoperative complications during follow-up. Moreover, apical short fusion shows no significant influence on spinal growth.

Comparison of the Effects of Magnetically Controlled Growing Rod and Tradiotinal Growing Rod Techniques on the Sagittal Plane in the Treatment of Early-Onset Scoliosis

OBJECTIVE: Comparing the effects of magnetically controlled growing rod (MCGR) and traditional growing rod (TGR) techniques on the sagittal plane in the treatment of early-onset scoliosis (EOS). METHODS: Twelve patients were operated using dual MCGR technique in one center, while 15 patients were operated using dual TGR technique for EOS in another center. Patients’ demographic characteristics, complications and radiological measurements such as cobb angle, thoracic kyphosis, lumbar lordosis, T1–S1 range (mm), proximal junctional angle, distal junctional angle, sagittal balance, coronal balance, pelvic incidence, sacral slope and pelvic tilt were assessed and compared in preoperative, postoperative and last follow-up period. RESULTS: Age and sex distributions were similar in both groups. The mean number of lengthening in the MCGR group was 12 (8–15) and 4.8 (3–7) in the TGR group. Two techniques were shown to be effective in controlling the curvature and in the increase of T1–S1 distance. In TGR group, four patients had rod fractures, six patients had screw pull-out and four patients had an infection, whereas three patients had screw pull-out and one patient had infection complications in the MCGR group. CONCLUSION: There was no significant difference between the two groups in terms of cobb angle, coronal and sagittal balance and sagittal pelvic parameters. MCGR can cause hypokyphosis and proximal junctional kyphosis in a minimum 2-year follow-up period. The implant-related complications were less in the MCGR group. However, larger case groups and longer follow-up periods are required for the better understanding of the superiority of one method on other in terms of complications.

Results of Magnetically Controlled Growing Rods for Early Onset Scoliosis / 대한정형외과학회잡지

PURPOSE: To evaluate the first results of surgical treatment using newly developed magnetically controlled growing rods (MCGR) for early onset scoliosis (EOS). MATERIALS AND METHODS: From January 2013 to January 2017, 5 patients, who underwent surgical treatment with MCGR for EOS and were followed for more than one year, were analyzed retrospectively. The demographic and radiology data, including age at surgery, diagnosis, number of lengthening, Cobb angle, T1–S1 length, T1–T12 length, and complications, were analyzed. RESULTS: The mean age of the patients was 6.0±2.7 years old. The subjects were 3 males and 2 females: 2 with neuromuscular scoliosis, 1 with syndromic scoliosis, 1 with idiopathic scoliosis, and 1 with congenital scoliosis. The mean number of lengthening was 9.8±2.9 times and the follow-up was 21.6±5.7 months. The Cobb angle improved from 82.0°±28.5° to 48.3°±28.8° at the last follow-up. The T1–S1 length increased from 283.1±72.7 mm to 342.6±86.3 mm at the last follow-up. The T1–T12 length increased from 163.1±50.5 mm to 202.3±65.5 mm at the last follow-up. One screw loosening complication was encountered and there were no neurological complications. CONCLUSION: The treatment using MCGR for EOS is effective and useful.

Juvenile Idiopathic Scoliosis / 대한정형외과학회잡지

Juvenile idiopathic scoliosis includes scoliosis diagnosed from three to ten years old according to the chronological age. Spine growth in juveniles does not occur at a rapid rate spinal deformity does not show rapid progress. However, because of the intimate relationship between chest wall growth and the spine, decrease of chest wall capacity due to scoliosis could lead to development of cardiovascular and pulmonary complication, especially in early age. In scoliosis in early age, other causes of the deformity including neurological problems should be evaluated. If the scoliosis angle is more than 25 degrees, it could progress very easily, thus aggressive treatment is needed. A new growing-sparing surgical technique (growing rod and growth modulation) is introduced for improvement of spine and chest growth, and for prevention of crankshaft phenomenon.

Research progress of growing rod surgery for early-onset scoliosis / 国际外科学杂志

Early-onset scoliosis (EOS) orthopedic treatment is a worldwide problem in recent years.With the growing rod technique clinical application and development of innovative,it has opened up a new way of orthotics for scoliosis.This paper reviews the development process of growing rods in treatment of early onset scoliosis.

Comparison of Mechanical Property of Conventional Rods versus Growing Rods for Pediatric Early Onset Scoliosis

STUDY DESIGN: This is a mechanical study. OBJECTIVES: We wanted to investigate the mechanical properties of newly developed dual growing rods for obtaining approval for their clinical application. SUMMARY OF LITERATURE REVIEW: The current expandable spinal implant system appears effective for controlling progressive early onset scoliosis, and it allows for spinal growth and improving lung development. MATERIALS AND METHODS: We investigate the yield load and ultimate load during compression, tension and torsion of the growing rods and the conventional rods assembly using UHMWPE blocks, and the diameter of the rods was 6.0 mm and they expanded 5cm long. We also performed a fatigue test with growing rods, and the diameter of which was 6.0 mm and it expanded 2.5cm long. The guideline for the American Society for Testing Materials was followed during the entire mechanical test. With the growing rods and conventional rods, we tested for each mechanical property7 times with the new rods and blocks. RESULTS: The yield load of the growing rods and conventional rods were 845.2+/-18.2 (N) and 812.9+/-29.9 (N), respectively, and the ultimate load of the growing rods and conventional rods were 961.9+/-31.1 (N) and 914.9+/-25.6 (N), respectively, when compression force was applied. The yield load and ultimate load of the growing rods were statistically higher than those of the conventional rods (p0.05). The yield loads of the growing rods and conventional rods were 11.56+/-0.59 (Nm) and 12.46+/-0.71 (Nm), respectively, the ultimate loads of the growing rods and conventional rods were 16.97+/-0.94 (Nm) and 17.42+/-2.66 (Nm) during the torsion, respectively. The yield load and ultimate load of the growing rods were statistically lower than that of the conventional rods (p<0.05). CONCLUSIONS: The newly developed growing rods have a higher yield load and ultimate load under compression, a similar ultimate load under tension and a lower yield load and ultimate load under torsion. The differences of the yield load and ultimate load under torsion were minimal, and so the growing rods and conventional rods have similar mechanical properties.

Halo pelvic distraction and elastic growing rods fixation for treatment of scoliosis during growing period / 中国矫形外科杂志

[Objective]To introduce the operative method and clinical experience of 200 cases with halo pelvic distraction and elastic growing rods fixation for treatment of scoliosis during growing period and comparison with pedicle screw systems. [Method]According to the principle of Harrington hook-rod system,inferior extremity was one hook hanged on the total lamina of lumbar vertebrae and superior extremity were two hooks hanged on the inferior articular process of thoracic vertebrae,rod I and rod II were connected by joint,between the end of rod I and joint set the spring cover for automatic extension followed spine growth.For the longer growing period children,the small incision could be performed between the hook and rod for fractional distraction to help the spine longitudinal grown until skeletal development and maturation.[Result]The average rate of correction of 200 cases with Scoliosis were 70.32% after 2~15 years follow-up survey,the height of the patients were increased by 5~22 cm and the preserved range of spinal motion was better than pedicle screw systems in long term follow up.Incidence of hook displacement was 2% and rod breaking was 3%.Reasons of hook displacement and rod breaking was related to unfitting installation and methods of internal fixation,incidence of hook displacement and rod breaking were decreased significantly post reform.[Conclusion]Halo pelvic distraction and elastic growing rods fixation for treatment of scoliosis during growing period which is a kind of biological method,does not affect the longitudinal growth of spine and prevent the complication of crankshaft phenomenon caused by pedicle screw systems.