1. 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

2. 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

3. 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):
Bracing is ineffective

4. 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?

5. 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 ＋

6. 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

7. 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

8. 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.

9. 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.

10. 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

11. 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

12. 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