Self-growing Instrumentation With Gliding Connectors for Collapsing Spine Deformities in Children: A Novel Technique

Safety and efficacy of growth-friendly instrumentation for early-onset scoliosis in patients with spinal muscular atrophy type 1 in the disease-modifying treatment era

Purpose

To evaluate the safety of growth-friendly instrumentation for early-onset scoliosis (EOS) in patients with spinal muscular atrophy (SMA) type 1 who received disease-modifying treatment (DMT) and analyze short-term efficacy.

Methods

Retrospective search was conducted between 2017 and 2023. Patients with genetically confirmed SMA type 1 who were surgically treated for spinal deformity and receiving DMTs (nusinersen, risdiplam, or onasemnogene abeparvovec) were included. SMA types 2 and 3 and patients who do not receive DMTs were excluded. Clinical and radiographic data were collected at preoperative, postoperative, and latest follow-up visits.

Results

Twenty-eight patients (mean follow-up: 16 months (range 2-41)) were included. The mean age at surgery was 60 months (range 29-96). Fifteen were treated with dual magnetically controlled growing rods (MCGR), four with unilateral MCGR and a contralateral guided growth system, three with Vertical Expandable Prosthetic Titanium Rib (VEPTR®) implants, five with self-distracting systems, and one with traditional dual growing rods. The mean amount of correction was 57% (44°± 17) for scoliosis and 83% (13°± 11) for pelvic obliquity. The mean T1-12 height gain during surgery was 31 mm (±16 mm), while the mean T1 S1 height gain was 51 mm (±24 mm), and instrumented growth was observed during follow-up. Five patients (18%) developed six serious adverse events: three surgical site infections, two anchor failures, and one rod fracture, and all required unplanned reoperations. No neurologic complication, difficulty during nusinersen injections, or respiratory decline was recorded.

Conclusion

We report that spinal deformity in this population can be safely treated with growth-friendly instrumentation, with similar complication rates when compared with SMA type 2.

Mid-term results of a modified self-growing rod technique for the treatment of early-onset scoliosis

AIMS

To report the mid-term results of a modified self-growing rod (SGR) technique for the treatment of idiopathic and neuromuscular early-onset scoliosis (EOS).

METHODS

We carried out a retrospective analysis of 16 consecutive patients with EOS treated with an SGR construct at a single hospital between September 2008 and December 2014. General demographics and deformity variables (i.e. major Cobb angle, T1 to T12 length, T1 to S1 length, pelvic obliquity, shoulder obliquity, and C7 plumb line) were recorded preoperatively, and postoperatively at yearly follow-up. Complications and revision procedures were also recorded. Only patients with a minimum follow-up of five years after surgery were included.

RESULTS

A total of 16 patients were included. Six patients had an idiopathic EOS while ten patients had a neuromuscular or syndromic EOS (seven spinal muscular atrophy (SMA) and three with cerebral palsy or a syndrome). Their mean ages at surgery were 7.1 years (SD 2.2) and 13.3 years (SD 2.6) respectively at final follow-up. The mean preoperative Cobb angle of the major curve was 66.1° (SD 8.5°) and had improved to 25.5° (SD 9.9°) at final follow-up. The T1 to S1 length increased from 289.7 mm (SD 24.9) before surgery to 330.6 mm (SD 30.4) immediately after surgery. The mean T1 to S1 and T1 to T12 growth after surgery were 64.1 mm (SD 19.9) and 47.4 mm (SD 18.8), respectively, thus accounting for a mean T1 to S1 and T1 to T12 spinal growth after surgery of 10.5 mm/year (SD 3.7) and 7.8 mm/year (SD 3.3), respectively. A total of six patients (five idiopathic EOS, one cerebral palsy EOS) had broken rods during their growth spurt but were uneventfully revised with a fusion procedure. No other complications were noted.

CONCLUSION

Our data show that SGR is a safe and effective technique for the treatment of EOS in nonambulatory hypotonic patients with a neuromuscular condition. Significant spinal growth can be expected after surgery and is comparable to other published techniques for EOS. While satisfactory correction of the deformity can be achieved and maintained with this technique, a high rate of rod breakage was seen in patients with an idiopathic or cerebral palsy EOS. Cite this article: Bone Joint J 2020;102-B(11):1560-1566.

Early Results of a Management Algorithm for Collapsing Spine Deformity in Young Children (Below 10-Year Old) With Spinal Muscular Atrophy Type II

BACKGROUND

Progressive C-shaped scoliosis with marked pelvic obliquity is common to spinal muscular atrophy (SMA). Reducing the number of procedures with effective deformity control is critical to minimize the risk of pulmonary complications. This study reports the preliminary results of magnetically controlled growing rods (MCGR) in SMA-related collapsing spine deformity.

METHODS

Inclusion criteria for this retrospective review were: (1) SMA type 2 patients, (2) early onset scoliosis (below 10 y), (3) collapsing spine deformity with pelvic obliquity, (4) growth-friendly scoliosis treatment with MCGR, (5) in between 2014 and 2017. Extracted data included demographic and clinical information, radiologic parameters, surgical details, and final status of the patients.

RESULTS

A total of 11 patients (7 boys, 4 girls) were included. The average age at index surgery was 8.2 (6 to 10) years. Dual MCGR was implanted in 8 patients. In 3 patients, because of curve rigidity and inability of apex to be brought into the stable zone, apical fusion with gliding connectors (convexity) and a single MCGR (concavity) was preferred. Instrumentation included the pelvis in 9 and stopped at the lumbar spine (L3) in 2 patients at the index procedure. Average preoperative deformity of 81.8 degrees (66 to 115) decreased to 29 degrees (11 to 57) postoperatively and was 26 degrees at average 35 months (16 to 59). Pelvic obliquity of 20.9 degrees (11 to 30) decreased to 4.9 degrees (2 to 8) after index surgery and was 6.5 degrees (2 to 16) at the last follow-up. T1-S1 height of 329 mm (280 to 376) after index surgery increased to 356 mm (312 to 390) after 9.2 (4 to 20) outpatient lengthening. No neurologic, infectious, or implant-related complication was recorded. Distal adding-on deformity occurred in 2 patients without initial pelvic fixation.One patient deceased secondary to pneumonia at 16 months after surgery.

CONCLUSIONS

Short-term results indicate that MCGR may be a good option in SMA-associated collapsing spine deformity to reduce the burden of repetitive lengthening procedures. The authors recommend apical deformity control in the convex side in case of curve rigidity. In addition, including the pelvis in the instrumentation at index surgery is critical to prevent distal adding-on.

LEVEL OF EVIDENCE

Level IV-retrospective case series.