Double major curvature treated with vertebral body tethering of both curves: how do outcomes compare to posterior spinal fusion?

PURPOSE

Vertebral body tethering (VBT) is a non-fusion alternative to posterior spinal fusion (PSF). There have been few reports on VBT of two curvatures. We aim to compare the radiographic outcomes between VBT and PSF in patients with double curvatures in which both curves were instrumented.

METHODS

29 AIS patients matched by Lenke, age (± 2 years), triradiate cartilage closure status, major Cobb angle (± 8°), and T5-T12 kyphosis (± 10°). Variables were compared using Wilcoxon rank-sum tests, Student's t tests, and chi-Square. Clinical success was defined as major curve < 35°.

RESULTS

Group baseline demographics were similar. Major thoracic (T) curve types had significantly better major (VBT 51.5 ± 7.9° to 31.6 ± 12.0° [40%] vs. PSF 54.3 ± 7.4° to 17.4 ± 6.5° [68%]; p = 0.0002) and secondary curve correction in the PSF group. 71% of major T VBT patients were clinically successful versus 100% of PSF. Major thoracolumbar (TL) curve types experienced comparable major (VBT 52.3 ± 7.0° to 18.3 ± 11.4° (65%) vs. PSF 53.0 ± 5.2° to 23.8 ± 10.9° (56%); p = 0.2397) and secondary curve correction. 92% of major TL VBT patients were clinically successful versus 75% in the PSF group. There was no difference in T5-12 kyphosis or lumbar lordosis between groups for any curve type. There were 4 patients (13.8%) with major complications in the VBT group compared to 0 (0%) in the PSF.

CONCLUSION

Patients with double major AIS who underwent VBT with major T curve types had less correction than PSF; however, those with major TL curves experienced similar radiographic outcomes regardless of procedure. Complications were greater for VBT.

Anterior vertebral body tethering shows clinically comparable shoulder balance outcomes to posterior spinal fusion

PURPOSE

Posterior spinal fusion (PSF) is the current gold standard in surgical treatment for adolescent idiopathic scoliosis. Vertebral body tethering (VBT) is a fusionless alternative. Shoulder balance is an important metric for outcomes and patient satisfaction. Here we compare shoulder balance outcomes between PSF and VBT.

METHODS

In this retrospective review, the pre-operative and post-operative absolute radiographic shoulder height (|RSH|) of 45 PSF patients were compared to 46 VBT patients. Mean values were compared and then collapsed into discrete groups (|RSH| GROUP) and compared. Patients were propensity score matched. Regression models based on pretest-posttest designs were used to compare procedure type on post-operative outcomes.

RESULTS

Pre-operatively there were no differences in |RSH| between PSF and VBT, however, at latest post-operative follow-up PSF maintained a larger |RSH| imbalance compared to VBT (0.91 cm vs 0.63 cm, p = 0.021). In an ANCOVA regression, PSF was associated with a larger |RSH| imbalance compared to VBT, F(1, 88) = 5.76, p = 0.019. An ordinal logistic regression found that the odds ratio of being in a worse |RSH| GROUP for PSF vs VBT is 2.788 (95% CI = 1.099 to 7.075), a statistically significant effect χ2(1) = 4.658, p = 0.031. Results were similar in subgroup analyses of Lenke 1 and Lenke 2 patients, though to less statistical significance.

CONCLUSION

While PSF was found to be associated with worse |RSH| outcomes, the actual numbers (2-3 mm) are unlikely to be clinically meaningful. Thus, in this analysis, VBT can be said to show comparable shoulder balance outcomes to PSF.

Bilateral vertebral body tethering: identifying key factors associated with successful outcomes

PURPOSE

The treatment of operative double major pediatric spinal deformities (e.g., Lenke 3 or 6) with bilateral vertebral body tethering (VBT) can be significantly more challenging when compared to other deformity patterns (e.g., Lenke 1) or treatment with a posterior spinal fusion. We aimed to identify preoperative and perioperative characteristics that were associated with successful postoperative outcomes in patients treated with both a thoracic and thoracolumbar (e.g., bilateral) tether.

METHODS

We retrospectively assessed radiographic and clinical data from patients enrolled in a large multi-center study who had a minimum postoperative follow-up of two years. Standard radiographic parameters were extracted from standing spine and left hand-wrist radiographs at various timepoints. We classified patients based on their preoperative deformity pattern (Primary Thoracic [TP] vs. Primary Thoracolumbar [TLP]) and assessed: (1) deformity balance, (2) tilt of the transitional vertebra, and (3) postoperative success.

RESULTS

We analyzed data from thirty-six patients (TP: 19 and TLP: 17). We observed no relationship between deformity balance at first erect and postoperative success (p = 0.354). Patients with a horizontal transitional vertebra at first erect were significantly (p = 0.001) more likely to exhibit a successful outcome when compared to those who exhibited a tilted transitional vertebra (83% vs. 62%). Patients who had TLP were also more likely to exhibit a successful outcome when compared to patients who exhibited TP (76% vs. 50%).

CONCLUSION

These data indicate that double major deformities can be successfully treated with VBT, particularly for those who exhibit TLP.

Reducing Uncertainty in Anterior Vertebral Body Tethering: Predicting Postoperative Curvature With Fulcrum Bending Radiographs

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

Mid-term Anterior Vertebral Body Tethering (AVBT) results demonstrate an acceptable degree of clinical success, yet the revision rate remains notably higher than fusion. Fulcrum-bending radiographs have previously been shown to more reliably predict radiological outcomes in Adolescent Idiopathic Scoliosis (AIS) as compared to supine-lateral bending radiographs. This study aims to discern how Fulcrum Flexibility Rate (FFR) correlates with Correction Rate (CR) and establish whether this can reliably predict residual deformity following AVBT surgery.

METHODS

A review of 38 consecutive AIS patients undergoing thoracic AVBT between 2015 - 2020 was performed. Preoperative (standing and fulcrum-bending) and postoperative (first-erect) radiographs were evaluated for curve magnitude using the Cobb-method. The FFR, CR and Fulcrum Bending Correction Index (FBCI) were calculated. Patients were also percentile-ranked according to their FFR and dichotomized into flexible and rigid cohorts for comparison. Student t-test, Pearson correlation and linear stepwise regression was applied.

RESULTS

AVBT resulted in a significant improvement in the major Cobb angle (Preoperative: 50.9±7.5° vs Postoperative: 19.9±9.4°; P < .0001) with a mean FBCI of 98.0%. Bivariate correlation revealed a moderate relationship between fulcrum-bending and first-erect Cobb angle (r = .5306, P = .0006). Linear regression demonstrated a predictive relationship between fulcrum-bending and first-erect Cobb using the equation 'Postoperative Cobb = 7.5 + .65(Fulcrum-bending Cobb).'

CONCLUSION

This is the first study to demonstrate the ability of fulcrum-bending radiographs to predict early radiographic outcomes following AVBT, 'timepoint-zero' for the growth modulation process.

Anterior Vertebral Body Tethering for Scoliosis Patients With and Without Skeletal Growth Remaining: A Retrospective Review With Minimum 2-Year Follow-Up

BACKGROUND

Anterior vertebral body tethering (AVBT) has been approved for skeletally immature (IM) adolescent idiopathic scoliosis patients, but the role of AVBT in patients with minimal remaining skeletal growth is controversial. The purpose of this study was to compare minimum 2-year (YR2) outcomes in skeletally IM patients vs those with minimal remaining skeletal growth.

METHODS

Patients with single thoracic AVBT were grouped by their preoperative (PR) skeletal maturity: IM (n = 16, Risser 0-2) vs mature (M, n = 19, Risser 3-5). Outcomes were assessed at PR, first erect (FE), and YR2. Median (range) was compared with nonparametric tests (P < 0.05).

RESULTS

The PR age was 12.5 (9-16) vs 15 (12-18) years with major Cobb 51° (36°-69°) and 49° (40°-69°) for IM and M, respectively. At FE, there was no difference in correction; however, at YR2, the IM group yielded a lower residual curve (15° [-16° to 38°] vs 29° [12°-42°], P = 0.008). Thoracolumbar/lumbar curves were corrected without group differences. Clinically successful correction (<35°) (15 [94%] vs 15 [79%]) and suspected cord breakages (2 [13%] vs 2 [12%]) were similar at YR2. Two overcorrections occurred, both in IM patients. Scoliosis Research Society-22 outcomes at final follow-up were similar between groups. No revision reoperations or conversions to spinal fusion were needed.

CONCLUSIONS

Skeletally IM patients benefit from greater growth-modulated curve correction than M patients, however, at the increased risk of overcorrection. M patients maintained clinically significant correction at latest follow-up. Longer-term follow-up is required to determine durability of outcomes for patients undergoing AVBT who have minimal remaining growth at the time of index surgery.

CLINICAL RELEVANCE

This study is relevant to spine surgeons, spine physiotherapists, and patients with idiopathic scoliosis. It offers evidence of clinical correction of scoliosis in mature patients.

LEVEL OF EVIDENCE: 3

Vertebral Body Tethering in 49 Adolescent Patients after Peak Height Velocity for the Treatment of Idiopathic Scoliosis: 2-5 Year Follow-Up

Vertebral Body Tethering (VBT) is a non-fusion surgical treatment for Adolescent Idiopathic Scoliosis (AIS) that elicits correction via growth modulation in skeletally immature patients. VBT after peak height velocity is controversial and is the subject of this study. A retrospective review of Risser 3−5 AIS patients treated with VBT, and min. 2-year FU was performed. Pre to post-op changes in clinical outcomes were compared using Student’s t-test or the Mann-Whitney test. A total of 49 patients met criteria, age 15.0 ± 1.9 years, FU 32.5 ± 9.1 months. For thoracic (T) major curvatures, T curvature improved from 51.1 ± 6.9° to 27.2° ± 8.1° (p < 0.01) and TL from 37.2° ± 10.7° to 19.2° ± 6.8° (p < 0.01). For thoracolumbar (TL) major curvatures, T improved from 37.2° ± 10.7° to 18.8° ± 9.4° (p < 0.01) and TL from 49.0° ± 6.4° to 20.1° ± 8.5° (p < 0.01). Major curve inclinometer measurements and SRS-22 domains, except activity, improved significantly (p ≤ 0.05). At the latest FU, one (2%) patient required fusion of the T curve and revision of the TL tether due to curve progression in the previously uninstrumented T curve and tether breakage (TB) in the TL. Twenty (41%) patients experienced TB. VBT in AIS patients with limited remaining skeletal growth resulted in satisfactory clinical outcomes at the latest FU.

Vertebral Body Tethering: Rationale, Results, and Revision

Vertebral body tethering is a nonfusion technique for the surgical correction of adolescent idiopathic scoliosis. For skeletally immature patients for whom vertebral body tethering is indicated, it is an alternative option to the gold standard posterior spinal fusion (PSF) and may at least partially preserve motion in instrumented segments of the spine. Benefits of the procedure include the possibility of avoiding the long-term sequelae of PSF such as adjacent segment disease and proximal junctional kyphosis. Recent retrospective case series of vertebral body tethering have shown promising results with correction rates up to 70% but greater variability in outcomes compared with PSF. The complication profile of the procedure also appears to differ from PSF with tether breakage and overcorrection as primary concerns in addition to approach-related complications. Although early outcomes have been promising, additional studies to optimize surgical timing, long-term outcomes, and the possible role of tethering in the more skeletally mature patient are required.

What are parents willing to accept? A prospective study of risk tolerance in AIS surgery

INTRODUCTION

Surgical treatment of Adolescent Idiopathic Scoliosis (AIS) involves healthy individuals with spinal deformity. Parents are responsible for surgical consent on behalf of their children, a burden which causes trepidation and concern. Therefore, explanation of operative risk is a critical component of informed consent and parent decision-making. We set out to quantify parental risk aversion (RA).

METHODS

RA questionnaires were administered preoperatively to parents of 58 AIS patients undergoing spinal fusion (SF). RA is the likelihood of a parent to consent to their child's SF (1- least likely, 10- most) with increasing allotments of data about potential complications at each stage (S1-complication named, S2-explained, S3-incidence given, S4-all information). A statistically significant mean difference in answers for each stage was assessed using paired sample t test or Wilcoxon rank t test. Normality was assessed by performing Shapiro-Wilk test.

RESULTS

AIS patients (age 14.2 years, 85% female, major curve 61°) were included. Mean scores for each of the stages were 4.4 ± 3.1, 4.9 ± 3.1, 6.5 ± 3.0, 6.6 ± 3.0, respectively. Highest and lowest RA were reported for death and infection, respectively. The greatest increase in likelihood to proceed with surgery was seen after education on malposition of implants and on death, 2.6 and 2.5, respectively (p < 0.001). The lowest increase in likelihood to proceed with surgery was seen after education on infection, 1.5 (p < 0.001). For all complications, there was an increase in parent willingness to proceed after providing descriptions and occurrence rate with a mean increase from S1 to S4 of 2.1 (95% CI 1.4-2.4), p < 0.001.

CONCLUSION

As more detailed information was made available regarding potential complications with SF for AIS, parental RA toward surgery decreased and their willingness to proceed with surgery for their child improved.

The patient generated index and decision regret in adolescent idiopathic scoliosis

HYPOTHESIS

AIS patients and their parents will have distinct perspectives regarding the impact of AIS on patients' lives.

INTRODUCTION

Current outcome assessment tools for AIS do not fully assess patient-specific disease impact and fail to distinguish between patient and parent perspectives. Patient Generated Index (PGI) has been used in other disease states to assess individual experiences. This study assesses PGI in operative AIS patients and their parents.

DESIGN

Level 1, prospective multi-center study.

METHODS

44 AIS patient and parent pairs completed the PGI questionnaire comprised of three stages (S1, S2, S3) and decision regret (DR). S1 asks for five areas of the patient's life most affected by AIS and a 6th encompassing all other areas of their lives affected, S2 focuses on the magnitude of effect, S3 identifies desire to improve affected areas and DR if the surgery did not improve the specific area. S1 free responses were organized into 14 domains. Descriptive statistics were reported for stage scores; free-response format of PGI and DR limited ability for paired sample t test analysis.

RESULTS

Mean age at surgery was 14.3 years, 84% female, and mean major curve magnitude was 61°. The three most common patient-reported concerns prior to surgery were (in descending order): sports, general function, and general fitness. However, the three most common parent-reported concerns were (in descending order): general function, sports, and appearance. Patients reported self-esteem and parents reported physical appearance as the most affected domain (S2). Patients reported pain and self-esteem and parents reported sleep and self-esteem as main operative aspirations (S3). Decision regret was the highest for uncertainty of future health in patients and sleep in parents.

CONCLUSION

AIS patients and their parents reported different concerns and DR regarding surgical treatment. PGI provides insight into patient and parent views toward the disease as well as treatment aspirations.