Jackson, Taylor J.

Posterior spinal fusion has long been established as an effective treatment for the surgical management of spine deformity. However, interest in nonfusion options continues to grow. Vertebral body tethering is a nonfusion alternative that allows for the preservation of growth and flexibility of the spine. The purpose of this investigation is to provide a practical and relevant review of the literature on the current evidence-based indications for vertebral body tethering. Early results and short-term outcomes show promise for the first generation of this technology. At this time, patients should expect less predictable deformity correction and higher revision rates. Long-term studies are necessary to establish the durability of early results. In addition, further studies should aim to refine preoperative evaluation and patient selection as well as defining the benefits of motion preservation and its long-term effects on spine health to ensure optimal patient outcomes.

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.

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

Study Design: Retrospective Study. Objective: To compare methods of assessing pre-operative bone density to predict risk for osteoporosis related complications (ORC), defined as proximal junctional kyphosis, pseudarthrosis, accelerated adjacent segment disease, reoperation, compression fracture, and instrument failure following spine fusions. Methods: Chart review of primary posterior thoracolumbar or lumbar fusion patients during a 7 year period. Inclusion criteria: preoperative dual-energy x-ray absorptiometry (DXA) test within 1 year and lumbar CT scan within 6 months prior to surgery with minimum of 1 year follow-up. Exclusion criteria: <18 years at time of index procedure, infection, trauma, malignancy, skeletal dysplasia, neuromuscular disorders, or anterior-posterior procedures. Results: 140 patients were included. The average age was 67.9 years, 83 (59.3%) were female, and 45 (32%) had an ORC. There were no significant differences in patient characteristics between those with and without an ORC. Multilevel fusions were associated with ORCs (46.7% vs 26.3%, p = 0.02). Patients with ORCs had lower DXA t-scores (-1.62 vs -1.10, p = 0.003) and average Hounsfield units (HU) (112.1 vs 148.1, p ≤ 0.001). Multivariable binary logistic regression analysis showed lower average HU (Adj. OR 0.00 595% CI 0.0001-0.1713, p = 0.001) was an independent predictor of an ORC. The odds of an ORC increased by 1.7-fold for every 25 point decrease in average HU. Conclusions: The gold standard for assessing bone mineral density has been DXA t-scores, but the best predictor of ORC remains unclear. While both lower t-scores and average HU were associated with ORC, only HU was an independent predictor of ORC.

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.

OBJECTIVE The goal of this study was to compare different recognized definitions of osteoporosis in patients with degenerative lumbar spine pathology undergoing elective spinal fusion surgery to determine which patient population should be considered for preoperative optimization. METHODS A retrospective review of patients in whom lumbar spine surgery was planned at 2 academic medical centers was performed, and the rate of osteoporosis was compared based on different recognized definitions. Assessments were made based on dual-energy x-ray absorptiometry (DXA), CT Hounsfield units (HU), trabecular bone score (TBS), and fracture risk assessment tool (FRAX). The rate of osteoporosis was compared based on different definitions: 1) the WHO definition (T-score ≤ −2.5) at total hip or spine; 2) CT HU of < 110; 3) National Bone Health Alliance (NBHA) guidelines; and 4) “expanded spine” criteria, which includes patients meeting NBHA criteria and/or HU < 110, and/or “degraded” TBS in the setting of an osteopenic T-score. Inclusion criteria were adult patients with a DXA scan of the total hip and/or spine performed within 1 year and a lumbar spine CT scan within 6 months of the physician visit. RESULTS Two hundred forty-four patients were included. The mean age was 68.3 years, with 70.5% female, 96.7% Caucasian, and the mean BMI was 28.8. Fracture history was reported in 53.8% of patients. The proportion of patients identified with osteoporosis on DXA, HUs, NBHA guidelines, and the authors’ proposed “expanded spine” criteria was 25.4%, 36.5%, 75%, and 81.9%, respectively. Of the patients not identified with osteoporosis on DXA, 31.3% had osteoporosis based on HU, 55.1% had osteoporosis with NBHA, and 70.4% had osteoporosis with expanded spine criteria (p < 0.05), with poor correlations among the different assessment tools. CONCLUSIONS Limitations in the use of DXA T-scores alone to diagnose osteoporosis in patients with lumbar spondylosis has prompted interest in additional methods of evaluating bone health in the spine, such as CT HU, TBS, and FRAX, to inform guidelines that aim to reduce fracture risk. However, no current osteoporosis assessment was developed with a focus on improving outcomes in spinal surgery. Therefore, the authors propose an expanded spine definition for osteoporosis to identify a more comprehensive cohort of patients with potential poor bone health who could be considered for preoperative optimization, although further study is needed to validate these results in terms of clinical outcomes.

Background: Limb salvage of the proximal tibia can be difficult due to the growth potential of and functional demands of the pediatric patients. Multiple reconstruction techniques exist, however, the ideal form of reconstruction is yet to be elucidated. The purpose of the current study is to evaluate outcomes in patients with an intercalary resection of the proximal tibia reconstructed with an allograft with or without a free vascularized fibula flap (FVF). Methods: Seventeen pediatric patients (9 males, 8 females) underwent lower extremity limb salvage with the use of intercalary cadaveric allograft at a mean age of 12±4 years. The most common diagnoses were osteosarcoma (n=6) and Ewing sarcoma (n=6). Patients were reconstructed with an allograft alone (n=6) or supplemented with an FVF (n=11). Results: All surviving patients had at least 2 years of clinical follow-up, with the mean follow-up of 12±7 years. The mean time to union of the allograft was 11±4 months, with 6 patients requiring additional bone grafting. There was no difference in the need for an additional bone graft (odds ratio=1.14, P=1.0) between patients with an FVF and those without. Four patients underwent an amputation, all with an allograft alone, due to disease recurrence (n=2) and due to infection (n=2). As such, there was a higher 10-year overall limb-salvage rate when the allograft was combined with an FVF compared with an allograft alone (100% vs. 33%, P=0.001). At last follow-up, the mean Mankin and Musculoskeletal Tumor Society rating was 86%, with a higher mean score in patients reconstructed with an FVF (94% vs. 70%, P=0.002). Conclusion: Use of an intercalary allograft supplemented with an FVF to reconstruct the proximal tibia provides a durable means of reconstruction with an excellent functional outcome following oncologic proximal tibia resection in a pediatric population. Level of Evidence: Level III—therapeutic level.