Xingye Li, Jianxiong Shen, M.D. 2017/10/30 Growing Rod Treatment of Dystrophic Scoliosis in Neurofibromatosis Type 1 Xingye Li, Jianxiong Shen, M.D. Dept of Orthopedic Surgery, Peking Union Medical College Hospital Beijing, China

Background Neurofibromatosis-1 (NF1) Dystrophic scoliosis in NF1: A systemic disease featured by compromised cell growth in neural tissues, affecting approximately 1:2500 to 1:3500 individuals worldwide Dystrophic scoliosis in NF1: Sharp-angulated, short segment dystrophic scoliosis that is characterized by: severe wedging and rotation of the apical vertebral bodies scalloping of the vertebral bodies

Tendency of deterioration Natural history: Tendency of deterioration 2017/10/30 Example radiographs showing natural history of scoliosis A: 28°at age 8 yrs B: 101°at 15 yrs C: 130°at 21 yrs Saito N, Ebara S, Ohotsuka K, Kumeta H, Takaoka K. Natural history of scoliosis in spastic cerebral palsy. The Lancet. 1998;351(9117):1687-92. Bracing is ineffective

Treatment Question： Complications Non-Fusion Approach: 2017/10/30 Recommendation: Early Fusion >40°, aged 10-12yrs: PSF aged <10-12yrs: PSF or ASF >50°, or combined with kyphosis: ASF+PSF Complications Inadequate spinal growth Chest movement problem Impaired lung development Crankshaft phenomenon … Question： Non-Fusion Approach: The outcome of dual growing-rod surgeries for NF1 patients with dystrophic EOS?

Method: Case Series Inclusion criteria: ＋ Dystrophic scoliosis: sharp-angulated short segmented severe wedging & rotation scalloping Characteristic changes of NF1: café-au-lait macules neurofibromas brain tumors iris hamartomas etc. Surgical history: Dual growing-rod implantation At least 1 lengthening procedure Complete following-up records ＋

Method: Radiology Exam AP & Lateral X-ray of: Pre-op Post-op of the initial instrumentation Pre/post-op of each lengthening procedure Measurements: Coronal Cobb angle Length of T1-T12 Kyphosis of thoracic spine T1-T12

Results Basic info 2010. 1- 2015.1 10 patients enrolled 7 female, 3 male Age of onset: 5.7 years Age of instrumentation: 7.8 years No complications noted Follow-up: 6 – 67 months, median 30 mths Lengthening procedures: 1-6, average 3.5 procedures Interval between procedures: 6-12 mths Improvement of Cobb angle and the length of T1-T12 Pre-op Post-op p value Last follow-up Coronal Cobb angle (°) 74.7±23.3 31.9±10.4 <0.001 31.1±13.2 0.8197 Length of T1-T12 (cm) 19.86±2.50 22.24±2.33 24.12±2.40 * Paired t-test

Results Increase in the length of T1-T12 2017/10/30 Average: 19.9cm Preoperatively, the average T1-T12 length of patients was 19.86cm. The initial dual growing-rod instrumentation surgery lengthened T1-T12 to 22.24cm in average. Lengthening procedures achieved averaged 1.88cm growth (average 0.67cm per procedure) in thoracic spine and reached 24.12cm after the last follow-up. At the same time, patients gained in average 2.3cm of growth in body height per 6 months after the implantation of growing rods.

Results Decrease in coronal Cobb angle 2017/10/30 Average: 74.7 ° 57.3% correction rate Average: 31.1 ° 58.4% correction rate The average degree of coronal Cobb angle at baseline was 74.7°. After the dual growing-rod implantation, the average Cobb angle was reduced to 31.9° (average 57.3% correction rate). The improvement of the coronal Cobb angle was significant. Despite unfused, no significant progress in the degree of curves was observed. After the latest lengthening procedure, the average degree of coronal Cobb angle remained at 31.1°, i.e. 58.4% correction rate. In the sagittal plane, the average thoracic Cobb angle was 35.9° preoperatively and 26.3° postoperatively. 3 patients had hyperkyphosis (kyphosis>=50°) of thoracic vertebra, with averaged preoperative kyphosis at 59.3°. The kyphosis in all 3 patients were corrected to averaged 31.7° and remained stable in the follow-up period.

Example: 6/F 6 lengthening procedures, 63 months follow-up 2017/10/30 Pre-OP Cobb: 134° Kyphosis: 69° T1-T12: 13.9cm Body height: 100cm Post initial instrumentation Cobb: 51° Kyphosis: 30° T1-T12: 19.1cm Body height: 106cm

6 lengthening procedures, 63 months follow-up Example: 6/F 6 lengthening procedures, 63 months follow-up 2017/10/30 3rd Lengthening (28 months) Cobb: 39° Kyphosis: 26° T1-T12: 20.9cm Body height: 125cm 6th Lengthening (63 months) Cobb: 41° Kyphosis: 29° T1-T12: 22.3cm Body height: 137cm

2017/10/30 Conclusions Growing rod implantation and lengthening procedures in the treatment of dystrophic scoliosis of NF1 patients could: Achieve satisfactory correction rate Correct kyphosis Avoid further progression of the curves Preserve the growth potential of spine