Thoracoscopic Vertebral Body Stapling for Treatment of Scoliosis in Young Children

Does vertebral body tethering cause disc and facet joint degeneration? A preliminary MRI study with minimum two years follow-up

BACKGROUND CONTEXT

Vertebral body tethering (VBT), a flexible compression-based growth modulation technique, was claimed to prevent disc degeneration due to its less rigid nature compared to other growth-friendly techniques. Yet, the consequences of VBT surgery on discs and facet joints have not been precisely acknowledged.

PURPOSE

The purpose of this study was to determine the changes in the intermediate and adjacent levels at least 2 years after surgery.

STUDY DESIGN/SETTING

Prospectively-followed consecutive patient cohort PATIENT SAMPLE: Adolescent idiopathic scoliosis patients who underwent thoracoscopic VBT between 2014 and 2017 were included.

OUTCOME MEASURES

Degeneration of the intervertebral discs using the Pfirrmann classification; Degeneration of facet joints using a scale of 0 to 3.

METHODS

Demographic, perioperative, clinical, radiographic data were collected. Skeletal maturity and height gain were assessed in every follow-up. Overcorrection, tether breakage, mechanical and pulmonary complications as well as readmission and reoperations were recorded. MRIs taken before surgery and at a minimum of 2 years follow-up were evaluated for degeneration at the intermediate and adjacent segment intervertebral discs and facet joints by a blinded senior radiologist and compared.

RESULTS

Twenty-five patients with a mean of 38.6±10.6 months (24-62) of follow-up were included. The mean age at surgery was 12.2 (10-14), and the median Sanders stage was 3 (1-7). A mean of 7.7±1.1 (6-11) levels were tethered. The mean preoperative main thoracic curve magnitude of 46°±7.7° was corrected to 23.3°±5.9° postoperatively, which was subsequently modulated to 12° ±11.5° during the follow-up. At the time of the MRI (mean 29±9.5 (24-62) months), the median Sanders stages was 7 (5-8). A total of 217 levels of discs and bilateral facet joints were evaluated in the preoperative and follow-up MRI images. Analyses of disc and facet scores revealed no significant differences between patients. Deterioration of previously degenerated discs was noted in one patient (from grade 2 to 3), while previously healthy lower adjacent facet joints were degenerated (grade 2) in another patient.

CONCLUSIONS

Intermediate discs and facet joints were preserved after growth modulation with VBT surgery at a mean of 29 months of follow-up. Studies in larger cohorts with longer follow-up are warranted to have more in-depth analyses of the effects of relative stabilization and altered biomechanical loads.

Continued vertebral body growth in patients with juvenile idiopathic scoliosis following vertebral body stapling

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To quantitatively measure the rate of growth of vertebral bodies in juvenile idiopathic scoliosis (JIS) treated with vertebral body stapling (VBS). VBS has been suggested to be a safe and effective method for modulating the growth of the young scoliotic spine, but few long-term studies have examined its efficacy.

METHODS

Seven patients with JIS 11 years of age or younger underwent VBS with a minimum 6-year follow-up. Vertebral body height on the unstapled and stapled aspects of the curve was measured from initial and final postoperative radiographs and converted into rate of growth per year. Known staple dimensions were used to standardize the measurements between radiographs. Interstaple distance was measured to demonstrate continued growth of the spine. Adjacent vertebral bodies without instrumentation served as an internal control of growth. Each vertebral body (n = 35) was analyzed as an individual experimental unit.

RESULTS

The average rate of growth was 0.86 mm/year (standard deviation [SD] 0.44, 95% confidence interval [CI] 0.71-1.0) per vertebral body on the stapled side and 0.83 mm/year (SD 0.46, 95% CI 0.67-0.98) per vertebral body on the unstapled side of the vertebral body. The adjacent vertebral body segments grew at a rate of 0.91 mm/year (SD 0.42, 95% CI 0.66-1.15) on the stapled side and 0.99 mm/year (SD 0.66, 95% CI 0.61-1.37) on the unstapled side, p < 0.01. The distance between staples increased significantly from 3.0 mm (SD 2.0, 95% CI 2.3-3.6) to 8.4 mm (SD 2.4, 95% CI 7.7-9.3).

CONCLUSIONS

Vertebral body growth in the presence of VBS occurred at a similar rate on the stapled and unstapled sides of the curve. The high standard deviation of instrumented segment growth further supports the conclusion that VBS is not a reliable method of growth modulation in the young scoliotic spine.

LEVEL OF EVIDENCE

IV.

Long-term Results of Spine Stapling for AIS to Skeletal Maturity and Beyond

BACKGROUND

We looked at long-term follow-up of spine stapling with Nitinol Staples. This was a cohort of all adolescent idiopathic scoliosis (AIS) patients with curves at high risk to progress based on curve magnitude, premenarchal status in all females, failure of brace treatment, and skeletal immaturity.

METHODS

This is a single surgeon retrospective review of consecutive AIS patients treated with Nitinol staples for progressive scoliosis. Fourteen patients, 16 curves from 2005 to 2008 were eligible. Minimum curve for stapling was 30 degrees. Standard preoperative, intraoperative, and postoperative data were collected. All patients were followed for a minimum of 36 months and to skeletal maturity. Three groups were: improved (group 1), correction of any amount; minimal progression (group 2), progression ≤10 degrees; and failure (group 3), ≥10 degrees of progression.

RESULTS

A total of 13 thoracic curves and 2 compensatory lumbar curves met the inclusion criteria (94%). Average follow-up was 61 months. The mean preoperative main thoracic curve was 35 degrees. All but 1 patients progressed at least 9 degrees in a brace prior to stapling. Females were all premenarchal, 10 patients were Risser 0 and 3 Risser 1. The average number of vertebrae stapled per curve was 6. Group 1 included 6 curves (40%). Group 2, 5 curves (33%). Group 3, 4 curves (27%). Three patients went on to uncomplicated fusion. Final curve measurement at the end of follow-up or before fusion (P=0.0037), curve progression (P≤0.001), and percentage of coronal correction on first postoperative standing radiograph (P=0.042) were the significant differences between groups 1+2 (successful) versus group 3 (failures). In total, 73% of this group either progressed ≤10 degrees or improved.

CONCLUSIONS

This is the first study that follows AIS patients treated with spine stapling to skeletal maturity. Staples likely changed natural history in some of our patients. Initial percentage of correction on first standing postoperative PA x-rays was the only predictor of success. Stapling was safe without any long-term complications.

LEVEL OF EVIDENCE

Level III-retrospective study.

Treatment of Idiopathic Scoliosis With Vertebral Body Stapling

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

Identify the effectiveness of vertebral body stapling (VBS) in children with idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

VBS has been proposed as an alternative to bracing moderate curves in patients with adolescent idiopathic scoliosis (AIS) although a clear picture of comparative efficacy and safety remains to be established.

METHODS

Ten skeletally immature patients with AIS and curves between 25° and 35° underwent anterior VBS by a single surgeon from 2008 to 2018. Indications included strong family history, high ScoliScore, curve progression despite bracing, or as an alternative for patients/families refusing bracing. Patients with thoracic kyphosis greater than 40°, curvature with a level above T4 or below L4, and double major curves were contraindicated. Patients with hybrid surgical plans or those who failed to reach skeletal maturity were excluded. Age, gender, levels stapled, pre- and postoperative radiographs, and incidence of secondary surgical intervention were evaluated. Outcomes were also compared with untreated and braced subjects from the BrAIST study.

RESULTS

Ten patients met the inclusion criteria. Average age at VBS was 11.8 (9.7-13.5) with an average major Cobb angle of 30.9° (26°-35°). Average duration of follow-up was 6.4 years. All patients demonstrated curve correction at their first postoperative visit. At final follow-up, 50% of patients experienced curve progression greater than 5°, whereas the remaining 50% either remained stable or corrected over time. The five patients whose curves progressed underwent VBS at a significantly younger age (10.8 vs. 12.8; p value .003). Four of these patients required additional surgical intervention for worsening scoliosis.

CONCLUSIONS

Although early outcomes after VBS appear to parallel the results of bracing, stapling does not affect the percentage of patients ultimately requiring PSIF. Initial curve correction degraded over time in younger patients with significant growth remaining, and high rates of progression in this group, even with bracing, merits investigation into more efficacious treatment strategies.

LEVEL OF EVIDENCE

Level III.

Vertebral Body Stapling for Moderate Juvenile and Early Adolescent Idiopathic Scoliosis: Cautions and Patient Selection Criteria

STUDY DESIGN

Single-surgeon retrospective case series.

OBJECTIVE

To validate and further describe clinical and radiographic outcomes of patients undergoing vertebral body stapling (VBS), with the goal of learning if VBS is a safe and effective alternative to bracing for treating moderate idiopathic scoliosis (IS) in the growing pediatric patient.

SUMMARY OF BACKGROUND DATA

VBS is a growth-modulation technique to control moderate idiopathic scoliosis (IS) while avoiding fusion. Existing studies state successful curve control rates equivalent to bracing, but the majority of reports have come from a single institution.

METHODS

All IS patients who underwent VBS by 1 surgeon were included. Indications were brace intolerance and a structural coronal curve of 25° to 40°. Proportional nitinol staples were used in all cases. Pre- and postoperative radiographs, pulmonary function testing, and physical exam measurements were serially recorded.

RESULTS

VBS was performed on 35 patients (28 females, 7 males) with mean age 10.5 years (range 7.0-14.6 years). Total of 31 patients (33 stapled curves) completed follow-up. Preoperative Risser grade was 0 in 31 patients, 1 in 1 patient, and 2 in 3 patients. Stapled curves were controlled with <10° of progression in 61% of cases. Curves <35° had a control rate of 75%, and patients <10 years had a 62% curve control rate. Eleven patients (31%) required subsequent fusions; two curves (6%) over-corrected. Preoperative supine flexibility > 30% was predictive of ultimate curve control. No neurologic complications were encountered; 5 patients (14%) developed small pneumothoraces.

CONCLUSION

This series contains the most patients and longest followup reported for VBS. Successful curve control was achieved less frequently than in previous reports, particularly in patients <10 years.

LEVEL OF EVIDENCE

4.

Vertebral body stapling in children younger than 10 years with idiopathic scoliosis with curve magnitude of 30° to 39°

STUDY DESIGN

Dual-center, retrospective study.

OBJECTIVE

To evaluate whether vertebral body stapling (VBS) influences curve progression between 30° and 39° in children younger than 10 years with idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Patients younger than 10 years with idiopathic scoliosis of more than 30° have a 100% risk of progression to spine fusion regardless of nonoperative treatment. VBS may represent an alternative fusionless treatment option for this group of high-risk patients.

METHODS

Patients younger than 10 years with idiopathic thoracic or lumbar scoliosis of 30° to 39° who were treated with VBS with a minimum of 24 months of follow-up were studied. Outcome variables were curve progression and magnitude, surgical complications, and a need for reoperation. Preoperative and postoperative curve magnitudes were compared using a paired Student t test. Postoperative curve magnitudes were compared with one another using a paired Student t test. A P value of less than 0.05 was defined as statistically significant.

RESULTS

Twelve patients were studied (female: n = 12; average age: 7.8 yr [range: 6.3-9.7 yr]). Thirteen curves were treated with VBS (thoracic: n = 9; lumbar: n = 4). The average follow-up was 3.4 years (range: 2.2-5.4 yr). The average preoperative curve magnitude was 33.4° (range: 30°-39°). The immediate postoperative curve magnitude (19.0°; range: 0°-29°) and curve magnitude at the most recent follow-up (23.0°; range: 10°-34°) were significantly less than the preoperative magnitude of 33.4°. Both thoracic curves (100%) and lumbar curves (100%) were treated successfully. Curve magnitudes did not change significantly postoperatively between the first erect radiographs and the most recent follow-up. Two patients had pneumothorax, and 1 patient had symptomatic pleural effusion. No patient required definitive fusion for curve progression.

CONCLUSION

VBS is effective in controlling curve progression in the high-risk group of children younger than 10 years with idiopathic scoliosis between 30° and 39° in whom bracing may be ineffective.