Mathew, Smitha

Background: The purpose of this study was to report on 2-year results of vertebral body tethering (VBT), performed under a Food and Drug Administration protocol, to obtain insight into outcomes and complications. Methods: Forty prospectively enrolled patients with adolescent idiopathic scoliosis (AIS) who had a Sanders score of ≤4 or a Risser score of ≤2 underwent VBT for curves between 40° and 70°. Surgical, radiographic, and patient-reported outcomes were reviewed at a minimum 2-year follow-up. Results: Mean age at surgery was 13 (range, 10 to 16) years. The 40 patients were 90% female; 95% White, 2.5% other, and 2.5% unreported; and 92.5% non-Hispanic, 5% Hispanic, and 2.5% unreported. A mean of 8 (range, 5 to 12) levels were instrumented. Most patients were at Sanders 4 (65%) and Risser 0 (63%). Mean length of stay was 3 ± 1 days, estimated blood loss was 236 ± 158 (range, 25 to 740) mL, and operative time was 4.4 ± 1.4 hours. Mean correction of the major curve was 44% (range, 22% to 95%) on the 3-month standing radiograph, 49% at 1 year, and 46% (range, −10% to 93%) at 2 years. The mean major Cobb angle improved from 51° ± 8° (range, 40° to 70°) preoperatively to 27° ± 11° (range, 3° to 56°) at 2 years. Success at 2 years, defined by a Cobb angle of <35° and no reoperation, was seen in 30 patients (75%) and was associated with a mean Cobb angle of <35° on the first postoperative standing radiograph (p < 0.001). Twelve patients (30%) demonstrated improvement in the curve with growth. By 2 years, 2 (5%) of the patients underwent repeat surgery (1 release for overcorrection, 1 lumbar VBT for lumbar curve progression after thoracic VBT). The Scoliosis Research Society (SRS) satisfaction score improved 2 years following surgery (p < 0.001), but other SRS domains only remained stable over time. Beyond 2 years, 1 additional lumbar tether was required after thoracic VBT, 1 implant was removed, and 3 fusions were performed, for a 10% fusion rate and overall 20% reoperation rate at a mean of 3.8 ± 1.1 years of follow-up. The rate of cord breakage in the study population was 20%. Conclusions: In skeletally immature patients treated in the U.S. under a prospective Investigational Device Exemption, there was a 75% rate of successful outcomes at 2 years. Most correction was obtained at the time of surgery, and inadequate intraoperative curve correction was associated with a higher Cobb angle on the first postoperative standing radiograph and failure by 2 years. Level of Evidence: Therapeutic Level II . See Instructions for Authors for a complete description of levels of evidence.

Background: Interest in vertebral body tethering (VBT) as an alternative to posterior spinal fusion for adolescent idiopathic scoliosis (AIS) continues to grow. The purpose of this study was to prospectively assess intervertebral disk health on magnetic resonance imaging (MRI) at 1 year following VBT in AIS patients. Methods: AIS patients were enrolled in a prospective surgeon-sponsored Food and Drug Administration (FDA) Investigational Device Exemption (IDE) Study and underwent MRI at 1-year following VBT. All spanned disks and the untethered disks immediately adjacent to the upper instrumented vertebra and lowest instrumented vertebra levels were evaluated according to Pfirrmann grading criteria. Associations between patient factors and preoperative and postoperative disk health and patient-reported outcomes were evaluated. Results: Twenty-two patients were enrolled with a postoperative MRI (25 curves, 188 disks), and 7 patients (7 curves) had both preoperative and postoperative MRIs (67 disks). The mean age was 12.7 years. Most were Risser 0 (65%) and either Sanders Skeletal Maturity Score 3 (35%) or 4 (53%). In the 7 patients with preoperative and postoperative MRI, the mean Pfirrmann grade of the disks spanned by the tether was 1.88 preoperatively and 2.31 postoperatively (P=0.0075). No statistically significant differences in preoperative versus postoperative Pfirrmann grade were identified in the disks adjacent to the upper or lower instrumented vertebrae. No association was found between patient-reported outcomes and Pfirrmann grade. Conclusion: At 1 year postoperatively, increased degenerative changes in disks spanned by the tether was identifiable on MRI without evidence of adjacent segment disk disease. These changes were not associated with patient-reported outcomes. Level of Evidence: Level III.

Background: Previous studies report elevated serum titanium (Ti) levels in children with spinal implants. To provide additional data on this topic, we sought to assess serum ion levels at multiple timepoints in pediatric patients with growing spine devices, spinal fusion instrumentation, and extremity implants placed for fracture treatment. We hypothesized that serum Ti, cobalt (Co), and chromium (Cr) levels would be elevated in pediatric patients with growing spine devices compared with patients with extremity implants. Methods: Pediatric patients undergoing any primary spine implant placement, those with spine implant revision or removal surgery and patients with other appendicular implant removal had serum Ti, Co, and Cr ion levels drawn at the time of surgery. Fifty-one patients (12 growing spine devices, 13 fusions, and 26 extremity implants) had one set of labs, 31 of whom had labs drawn both preoperatively and postoperatively. Biopsies obtained from tissue specimens at the time of implant revision were analyzed histologically for the presence of metal debris and macrophage activity. Results: Patients with growing spine implants had elevated serum Ti (3.3 vs. 1.9 ng/mL, P=0.01) and Cr levels (1.2 vs. 0.27 ng/mL, P=0.01) in comparison to patients with fusion rods or extremity implants. With respect to patients with extremity implants, patients with growing spine devices had elevated serum Ti (3.3 vs. 0.98 ng/mL, P=0.013), Co (0.63 vs. 0.26 ng/mL, P=0.017), and Cr levels (1.18 vs. 0.26 ng/mL, P=0.005). On matched pairs analysis, patients who had labs drawn before and after spine implantation had significant increase in serum Ti levels (0.57 vs. 3.3 ng/mL, P=0.02). Histology of tissue biopsies adjacent to growing spine implants showed presence of metal debris and increased macrophage activity compared with patients with extremity implants. Conclusion: Serum Ti, Co, and Cr levels are elevated in children with spinal implants compared with those with extremity implants, particularly in those with growing spine devices. However, the clinical significance of these findings remains to be determined. Level of Evidence: Level II—prospective comparative study.

Background: Anterior vertebral body tethering is an alternative to fusion surgery for the treatment of adolescent idiopathic scoliosis (AIS) that is purported to preserve spinal motion. There is limited information regarding the measurable motion that is maintained over the instrumented levels following thoracic anterior vertebral body tethering surgery in humans. The purpose of the present study was to assess radiographic spinal motion 1 year after anterior vertebral body tethering. Methods: As part of a prospective U.S. Food and Drug Administration investigational device exemption study, 32 patients were treated with thoracic anterior vertebral body tethering. At 1 year postoperatively, patients were evaluated with standing flexion-extension and side-bending radiographs in a microdose biplanar slot scanning imaging system. The angle subtended by the screws at the upper instrumented vertebra (UIV) and lower instrumented vertebra (LIV) was measured on left and right-bending radiographs to evaluate the coronal arc of motion and was compared with preoperative values over the same levels. At 1 year postoperatively, the sagittal Cobb angle was measured over the instrumented levels on flexion and extension radiographs. Results: Side-bending radiographs revealed that the mean angle subtended by the screws changed from 15° ± 8° on left-bending radiographs to 8° ± 6° on right-bending radiographs. The mean coronal arc of motion on bending was 7° ± 6°, with 20 (62.5%) of 32 patients having a coronal arc of motion of >5°. The mean preoperative coronal arc of motion over the instrumented segments was 30° ± 9°. On flexion-extension lateral radiographs made at 1 year postoperatively, the mean kyphotic angle over the instrumented segments was 33° ± 13° in flexion and 11° ± 14° in extension, for a mean postoperative arc of motion of 21° ± 12° between flexion and extension radiographs. Conclusions: At 1 year following thoracic anterior vertebral body tethering for the treatment of AIS, the thoracic spine showed a measurable range of coronal and sagittal plane motion over the instrumented levels without evidence of complete autofusion. Motion in the coronal plane decreased by 77% following anterior vertebral body tethering. These findings provide proof of concept that sagittal spinal motion is preserved after thoracic anterior vertebral body tethering, although the functional importance remains to be determined. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Purpose Tarsal coalitions are congenital fusions of two or more tarsal bones and can lead to foot pain and stiffness. Few studies examine the long-term reoperation rates following paediatric tarsal coalition surgery. Methods A population-based database, linking medical records at all medical centres to capture the entire medical history of the full population of a Midwest county, was used to identify tarsal coalitions in children between 1966 and 2018. Records were reviewed for clinical data, surgical records and followed up to identify any subsequent surgical interventions. Results A total of 58 patients (85 coalitions) were identified; 46 calcaneonavicular (CN) coalitions, 30 talocalcaneal (TC) coalitions and nine other coalitions (seven talonavicular, one naviculocuboid, one naviculocuneiform). In all, 46 coalitions were treated surgically (43 coalition resections, three arthrodeses) and 39 were treated nonoperatively. Patients treated surgically were less likely to report ongoing symptoms at final follow-up compared with patients managed nonoperatively (33% versus 67%; p = 0.0017). With a median 14.4 years (interquartile range 9.3 to 19.7) follow-up, there was an overall re-operation rate of 8.7% (4/46). Differences in reoperation rates by initial surgery (resection versus arthrodesis; p = 0.2936), coalition type (CN versus TC versus Other; p = 0.6487) or composition (osseous versus fibrocartilaginous; p = 0.29) did not reach statistical significance. Conclusion This is the first population-based study demonstrating the durability of surgical management of tarsal coalitions in a paediatric population. At final follow-up, patients treated surgically are less likely to report persistent symptoms compared with patients managed nonoperatively. Long-term reoperation rates appear to be low (8.7%). Level of evidence III

Background: Tarsal coalitions are an important reason for foot pain in children. Early estimates placed the prevalence at up to 2%, while more recent data suggest that it is as high as 11% to 13%. To our knowledge, there have been no population-based studies to determine the true incidence of symptomatic tarsal coalitions in a pediatric population. Methods: A population-based database was used to identify all new diagnoses of symptomatic tarsal coalitions in children 18 years old or younger between 1966 and 2018. Patient records were reviewed for clinical data, and comparisons were made between the types and characteristics of the coalitions identified to determine differences in the affected populations. The annual age-specific, sex-specific, and type-specific incidence rates were estimated. Results: During the study period, 58 patients with a total of 79 symptomatic tarsal coalitions were identified (annual incidence = 3.5 per 100,000 children). There were 43 calcaneonavicular (CN) coalitions (annual incidence = 1.9 per 100,000 children), 27 talocalcaneal (TC) coalitions (annual incidence = 1.2 per 100,000 children), as well as 9 other coalitions (7 talonavicular, 1 naviculocuboid, and 1 naviculocuneiform) (annual incidence = 0.4 per 100,000 children). The overall incidence peaked between the ages of 10 and 14 years for both boys and girls (8.1 per 100,000 and 7.4 per 100,000 children, respectively). Statistical differences were identified between the types of tarsal coalitions. TC coalitions present at an older age relative to CN and other coalitions (mean,13.9, 12.7, and 11.4 years, respectively; p = 0.02). While CN and TC coalitions were similar in composition (23% and 30%, respectively, were osseous as opposed to fibrocartilaginous), other coalitions were more likely to be osseous (78%) (p = 0.0035). Other coalitions were also less likely to require surgery than CN and TC coalitions (11%, 74%, and 56%, respectively; p = 0.0015). Conclusions: This population-based study demonstrates differences in the clinical presentation of tarsal coalitions and provides an estimate of the true incidence of symptomatic tarsal coalitions in a pediatric population.