How to rectify the convex coronal imbalance in patients with unstable dystrophic scoliosis secondary to type I neurofibromatosis: experience from a case series

A novel classification of congenital cervicothoracic scoliosis: identification of coronal subtypes and their prognostic significance

OBJECTIVE

To propose a novel classification system for stratifying coronal curve patterns in congenital cervicothoracic scoliosis with hemivertebrae (CTS-HV).

METHODS

Type A: regional cervicothoracic deformity only disturbing the balance of head-neck-shoulder complex; Type B: cervicothoracic deformity with significant trunk tilt to the convex side; Type C: cervicothoracic deformity with a significant compensatory thoracic curve. The reliability and reproducibility were assessed via the Kappa test. The differences among different subtypes in deformity parameters and bony structures were compared to identify the causative factors predisposing to different subtypes.

RESULTS

98 patients were classified into Type A (47 cases), Type B (31 cases), and Type C (20 cases). The Kappa test showed excellent reliability (Kappa value = 0.847) and reproducibility (Kappa value = 0.881). The proportions of Klippel-Feil syndrome in Types B (71.0%) and C (85.0%) were significantly higher than in Type A (46.8%; all P < 0.05). Type A (66.0%) and Type B (71.0%) predominantly had their hemivertebra (HV) at T3 or T4, while Type C (75%) mostly had HV at T1 or T2. Type B exhibited the most severe trunk tilt, head shift, neck tilt, head tilt, and coronal balance distance (all P < 0.05). Type C had the lowest T1 tilt and first rib angle despite the greatest cervicothoracic Cobb angle (all P < 0.05).

CONCLUSIONS

This novel reliable classification allows a better understanding of structural diversity and different coronal compensatory mechanisms for the natural progression of CTS-HV. It can contribute to determining the individualized treatment strategy and standardizing academic communication for this rare clinical entity.

Postoperative Coronal Imbalance in Lenke 5C Adolescent Idiopathic Scoliosis: Evolution, Risk Factors, and Clinical Implications

OBJECTIVE

To explore the changes in coronal imbalance (CIB) in Lenke 5C adolescent idiopathic scoliosis (AIS) after posterior selective fusion surgery and determine their implications for surgical decision-making.

METHODS

One hundred twenty patients were categorized according to the preoperative coronal pattern (type A, coronal balance distance [CBD]<20 mm; type B, CBD≥20 mm and coronal C7 plumbline [C7PL] shifted to the concave side of the curve; type C, CBD≥20 mm and C7PL shifted to the convex side of the curve). CIB group (CIB+) was defined as having a CBD≥20 mm at the 2-year follow-up.

RESULTS

Compared to type A patients, the prevalence of postoperative CIB was higher in type C patients both immediately postoperative (22% vs. 38%, p<0.05) and at the final follow-up (5% vs. 29%, p<0.05), whereas type A patients showed a greater improvement in CBD (9 of 12 vs. 6 of 24, p<0.05) at the final follow-up. The majority of patients in all groups had recovered to type A at the final follow-up (96 of 120). The proximal Cobb-1 strategy reduced the incidence of postoperative CIB (1 of 38) at the 2-year follow-up, especially in preoperative type C patients. Multivariate logistic regression analysis revealed that type C and overcorrection of the thoracolumbar curve were risk factors for CIB at the 2-year follow-up (p=0.007 and p=0.026, respectively).

CONCLUSION

Patients with type C CIB in AIS exhibited unsatisfactory restoration, with 29% of them exhibiting CIB at the final follow-up. The selective fusion strategy of proximal Cobb-1 may reduce the risk of postoperative CIB especially when the preoperative coronal pattern is type C.

Clinical features and surgical treatments of scoliosis in neurofibromatosis type 1: a systemic review and meta-analysis

BACKGROUND

Neurofibromatosis type 1 (NF 1) is an autosomal-dominant tumor predisposition genetic disease affecting approximately 1 in 3000 live births. The condition could present various manifestations ranging from skin abnormalities to neurological tumors. The musculoskeletal system could also be frequently affected, and scoliosis is the most common orthopedic manifestation. Characterized by the early-onset and rapid progression tendency, NF 1-related dystrophic scoliosis presented discrepancies from idiopathic scoliosis in terms of natural history, clinical features, and management outcomes and thus required special attention. In the current study, the authors conducted a systemic review to outline the body of evidence of the natural history, clinical characteristics, surgical outcomes, and surgical complications of NF 1-induced scoliosis, aiming to provide an elucidative insight into this condition.

METHOD

Systemic review and meta-analysis were conducted according to the latest Preferred Reporting Items for Systematic Reviews Meta-Analyses (PRISMA) guidelines. The search was performed in Medline, Embase, and Web of Science Core Collection up to December 27, 2022, using related keywords. Clinical features such as frequencies, segmental involvement, and hereditary information were summarized and described qualitatively. Meta-analysis was conducted using R software and the 'meta' package to yield an overall outcome of efficacy and safety of surgical management, precisely, spinal fusion procedure and growing rods procedure. Corrective rate of Cobb angle, sagittal kyphosis angle, and T1-S1 length post-operative and at the last follow-up was used to evaluate the efficacy, and the occurrence of surgery-related complications was used to evaluate the safety.

RESULT

A total of 37 articles involving 1023 patients were included. Approximately 26.6% of the NF 1 patients would present with scoliosis. Patients tend to develop scoliosis at an earlier age. The thoracic part turned out to be the most affected segment. No obvious correlation between scoliosis and genotype or hereditary type was observed. Both spinal fusion and growing rod surgery have shown acceptable treatment outcomes, with spinal fusion demonstrating better performance in terms of effectiveness and safety. The growing rods technique seemed to allow a better lengthening of the spine. The mainstay post-operative complications were implant-related complications but could be managed with limited revision surgery. Severe neurological deficits were rarely reported.

CONCLUSION

Scoliosis, especially the subtype characterized by dystrophic bony changes, is a significant orthopedic manifestation of NF1. It has an early onset, a tendency to persistently and rapidly progress, and is challenging to deal with. The current review outlines the available evidence from the perspective of natural history, clinical features, and the treatment efficacy and safety of the mainstay surgical options. Patients with NF1 scoliosis will benefit from a better understanding of the disease and evidence based treatment strategies.

Sectional Correction Technique in Dystrophic Scoliosis Secondary to Neurofibromatosis Type 1: A Comparison with Traditional 2-Rod Correction Technique

OBJECTIVE

The purpose of this study was to compare the traditional 2-rod correction technique with the sectional correction technique in terms of radiographic results and clinical outcomes for patients with dystrophic scoliosis caused by neurofibromatosis type 1 (NF1).

METHODS

From May 2015 to April 2018, 53 patients with dystrophic scoliosis caused by NF1 underwent 1-stage posterior corrective surgery. Patients were separated into 2 groups based on technique: the sectional correction technique (SC group) and the traditional 2-rod technique (TT group). Before surgery and at the final follow-up, the demographic information, radiographic parameters, and clinical outcomes were compared between the groups using independent-sample t tests.

RESULTS

The SC group consisted of 24 patients, while the TT group consisted of 29 patients. Patients in the SC group showed a higher coronal balance distance after the operation (8.3 ± 8.2 mm vs. 16.2 ± 8.8 mm, P = 0.002) and at the final follow-up (9.5 ± 9.3 mm vs. 19.3 ± 10.1 mm, P < 0.0001). At the last follow-up, the loss of correction in the SC group was 2.2 ± 0.9 and 2.1 ± 0.7 in the coronal and sagittal planes, respectively, and these values were significantly lower than those in the TT group (5.3 ± 1.6 in the coronal plane and 4.5 ± 1.9 in the sagittal plane, both P < 0.05). The SC group had better improvement based on appearance and satisfaction score at the final follow-up.

CONCLUSIONS

The sectional correction technique using a concave domino connector can restore coronal imbalance and reduce the risk of implant failure.