Pediatric Deformity Research Articles

Recent and Emerging Advances in Spinal Deformity.

Over the last several decades, significant advances have occurred in the assessment and management of spinal deformity. The primary focus of this narrative review is on recent advances in adult thoracic, thoracolumbar, and lumbar deformities, with additional discussions of advances in cervical deformity and pediatric deformity. A review of recent literature was conducted. Advances in adult thoracic, thoracolumbar, and lumbar deformities reviewed include the growing applications of stereoradiography, development of new radiographic measures and improved understanding of radiographic alignment objectives, increasingly sophisticated tools for radiographic analysis, strategies to reduce the occurrence of common complications, and advances in minimally invasive techniques. In addition, discussion is provided on the rapidly advancing applications of predictive analytics and outcomes assessments that are intended to improve the ability to predict risk and outcomes. Advances in the rapidly evolving field of cervical deformity focus on better understanding of how cervical alignment is impacted by thoracolumbar regional alignment and global alignment and how this can affect surgical planning. Discussion is also provided on initial progress toward development of a comprehensive cervical deformity classification system. Pediatric deformity assessment has been substantially improved with low radiation-based 3-D imaging, and promising clinical outcomes data are beginning to emerge on the use of growth-friendly implants. It is ultimately through the reviewed and other recent and ongoing advances that care for patients with spinal deformity will continue to evolve, enabling better informed treatment decisions, more meaningful patient counseling, reduced complications, and achievement of desired clinical outcomes.

Future Advances in Spine Surgery: The AOSpine North America Perspective.

This focus issue highlights state-of-the-art techniques, equipment, and practices in the modern era of spine surgery while providing a glimpse into the next generation of patient care. A broad range of topics are presented to cover the full spectrum of the field. Degenerative diseases are discussed in a series of 3 articles on (1) pathophysiology, management, and surgical approaches to degenerative cervical myelopathy; (2) novel approaches to degenerative thoracolumbar disease (eg, interspinous process spacers, minimally invasive/endoscopic approaches); and (3) animal models and emerging therapeutics in degenerative disk disease. Also included is a unique study aiming to establish the critically important cost-benefit relationship for spine procedures with perspectives on how value is defined and how to address variability.Primary and metastatic spine oncology are reviewed with a focus on upcoming targeted biologics, subspecialized radiotherapy (eg, proton-beam, carbon-ion, stereotactic radiosurgery), genetic profiling to stratify risk, and morbidity-reducing surgical approaches (eg, minimally invasive/endoscopic resections, percutaneous instrumentation). Trauma is discussed in 2 high-quality papers on controversies in spinal trauma and neuroprotective/neuroregenerative interventions for traumatic spinal cord injury. A stimulating article on cervical, thoracolumbar, and pediatric deformity highlights the rapid evolution of deformity surgery with a look at innovative tools (eg, high-fidelity 3-dimensional reconstructions, magnetically controlled growing rods) and their impact on quality of life. Additionally, a must-read article on surgical site infections discusses key risk factors and evidence-based preventative techniques to remain aware of. Finally, cutting-edge technologies, including computer-assisted navigation, shared-control robotics, neuromodulation, novel osteobiologics, and biomaterials, are covered in detail in a series of 3 fascinating papers on the next generation of the field.Each section intends to highlight the salient literature and afford insights from multiple key thought leaders in an effort to minimize bias and provide varied perspectives. Overall, we hope this issue provides high-quality, evidence-based data relevant to trainees and practicing surgeons while also stimulating excitement about the future of spine surgery.

Three-dimensional evaluation of heel raise test in pediatric planovalgus feet and normal feet

Planovalgus foot is a common pediatric deformity which may be associated with pain. To evaluate flexibility of the foot, the heel raise test is used. During this test the arch and hindfoot are assessed. Several studies have described planovalgus foot based on 3D gait and standing analysis. However, no studies have evaluated foot flexibility during heel raise using an objective 3D analysis. Therefore, the purpose of this study is to evaluate the flexibility of planovalgus feet during the heel raise test using an objective 3D assessment and to determine whether any hypotheses can be generated about potential differences between painful and painless flexible planovalgus feet and reference feet.Here, 3D foot analysis was conducted in 33 children (7 reference feet, 16 painless, and 10 painful flexible planovalgus feet) during the heel raise test. To identify the characteristics of planovalgus foot, the concept of 3D projection angles was used as introduced in the Heidelberg Foot Measurement Method (HFMM), with a modified marker set.All feet showed dynamic movements of the medial arch and hindfoot from valgus to varus position during heel raise. Reference feet had the smallest range of motion, perhaps due to joint stability and absence of foot deformity. Painful and painless flexible planovalgus feet demonstrated similar movements. No significant differences were found between the painful and painless groups. However, the kinematics of the pain group seemed to differ more from those of the reference group than did kinematics of the painless group.This assessment is a new, practical, and objective method to measure the flexibility of small children's feet.

Sacral-Alar-Iliac Fixation in Pediatric Deformity: Radiographic Outcomes and Complications

Study DesignRetrospective case series. ObjectivesTo assess the radiographic outcomes and complications of sacral-alar-iliac (SAI) fixation in children. Summary of Background DataPelvic fixation in children undergoing spinal deformity surgery can be challenging because of complex anatomy, compound biomechanical forces at the lumbosacral junction, and poor bone quality. MethodsRadiographic and clinical records of 80 consecutive patients aged 18 years or younger who underwent posterior spinal fusion surgery with SAI fixation by one pediatric orthopedic surgeon and who had a minimum 2 years of follow-up (mean follow-up: 3.5 years, range, 2–7 years) were retrospectively reviewed. Changes in coronal curve magnitude and pelvic obliquity were assessed using Student t tests. Significance was set at a p value less than .05 for all analyses. ResultsPelvic obliquity correction averaged 77%, from 26 ± 13 degrees before surgery to 6 ± 4 degrees at final follow-up (p < .001); 91% of the patients were corrected to a pelvic obliquity of less than 10 degrees. Coronal curve correction averaged 72%, from 78 ± 27 degrees before surgery to 22 ± 15 degrees at final follow-up (p < .001). No patient had vascular or neurologic complications or died perioperatively. Twenty patients (25%) had radiographic evidence of implant-related problems, of which there were nine screw fractures (all in the neck of screws with ≤8-mm outer diameter). Six patients had symptomatic complications associated with SAI fixation (three patients with pseudarthrosis at the lumbosacral junction, all of whom required revision surgery, two patients with implant prominence, and one patient with pain related to implant). Other complications included seven instances of wound dehiscence, three deep wound infections, and one superficial wound infection. ConclusionsSAI fixation provided a low-profile alternative to iliac screws for the correction of pelvic obliquity. The largest possible diameter screws are recommended, ideally >8 mm. Level of EvidenceLevel 4.

Proximal Junctional Kyphosis in Pediatric Deformity: Analysis of Management with a Surgical Technique Limiting Cervical Extension

Introduction Proximal junctional kyphosis (PJK) is a relatively frequent complication of spinal deformity surgery which can result in significant symptoms and potential neurological compromise. Reconstruction of PJK in the cervico-thoracic junction usually entails proximal extension of fixation to the cervical spine, with a compromise of function in this young population. Material and Methods We designed a retrospective review of clinical and radiological features in a consecutive series of patients treated for PJK of the upper thoracic spine. Objective: discuss the use of an anterior plus posterior reconstructive technique which aims to avoid proximal extension into the cervical spine for the management of PJK in the pediatric deformity population. Patients: Three patients with spinal deformity (neuromuscular scoliosis 2, Scheuermanns kyphosis 1) developing progressive PJK were operated with an anterior and posterior reconstruction. Clinical and radiographic follow-up is analyses with a minimum of 9 months. Results All patients were successfully managed with adequate control of the progressive deformity and proximal extension into the cervical spine was significantly limited with this anterior and posterior approach. Conclusions For this selected group of patients with upper thoracic PJK, an interior and posterior surgical reconstruction was successful in managing the condition with limited extension into the cervical spine, thus avoiding greater future functional compromise.

Can patients with magnetic growth rods safely undergo magnetic resonance imaging (MRI): a preliminary in vitro study

BACKGROUND CONTEXT: The management of early-onset paediatric deformity has been revolutionised by the development of adjustable growth rods. These rods elongate when an internal rare-earth magnet is triggered to rotate by an externally applied magnetic field. This patient group includes some who occasionally require further magnetic resonance imaging (MRI) of the neuroaxis, and given the magnetic properties of the rod, this is conventionally contraindicated once implanted.

Intra-operative implant waste in paediatric deformity surgery

Intra-operative implant waste in paediatric deformity surgery

Principles and Management of Pediatric Foot and Ankle Deformities and Malformation

Principles and Management of Pediatric Foot and Ankle Deformities and Malformation

What Is the Frequency of Intraoperative Alerts During Pediatric Spinal Deformity Surgery Using Current Neuromonitoring Methodology? A Retrospective Study of 218 Surgical Procedures

Introduction: There is variability in intraoperative neuromonitoring (IONM), anesthetic and surgical techniques for the treatment of pediatric spinal deformity. This study evaluates a series of patients treated at multiple centers utilizing transcranial motor and somatosensory evoked potentials (TcMEP and SSEP) and electromyography (EMG). The frequency of alerts and the intraoperative follow-up is reported.Methods: Standard patient demographics and IONM data were collected from a two-month cohort of pediatric spine deformity cases.Results: Data from 218 scoliosis patients were included from 46 facilities and 72 surgeons. Baseline upper and lower extremity TcMEP data were present in 96.7% and 93.9% patients respectively. Baseline upper and lower SSEPs were present in 99.5% and 95.4% respectively. Surgical TCMEP alerts occurred in 19 (8.7%) patients during deformity correction (n = 11), placement of instrumentation (n = 5), decompression (n = 2), and closing (n = 1) with concurrent SSEP alerts occurring in five patients. Nine had TCMEP recovery, eight showed partial recovery and two did not recover. Additional alerts occurred due to: positioning (n = 16), inhalational agent change (n = 4), global physiological change (n = 4) and technical reasons (n = 2).A total of 2164 pedicle screws were tested. Of 197 (9.1%) screws that tested from 6–9 mA, 171 (65.4%) were left unchanged, 10 (5.1%) removed, eight (4.1%) repositioned with improved threshold, and eight (4.1%) without improvement. Of 26 screws that tested ≤5 milliamperes (mA), 17 (65.4%) were left unchanged, five (19.2%) removed, two (7.7%) repositioned with improved threshold, and two (7.7%) without improvement.Conclusions: IONM provides data that causes re-evaluation in about 10% of pediatric spinal deformity cases.

Modified calcaneo-stop screw method for treatment of symptomatic pediatric flexible flatfoot deformity

Modified calcaneo-stop screw method for treatment of symptomatic pediatric flexible flatfoot deformity

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging.

Magnetically controlled growth rods (MCGRs) are a new technology for the management of early-onset pediatric deformity enabling guided spinal growth by controlling the curvature. These rods contain a rare earth magnet and are contraindicated for MRI. We have investigated the behavior MCGRs to determine whether MRI adversely affects rod properties and to determine the extent of image distortion. This is an in vitro experiment using two magnetic growth rods secured in a 1.5 T MRI. A gradient echo sequence MRI was performed to evaluate whether the rods elongated, contracted or rotated during scanning and a phantom model was used to evaluate the amount of artifact induced. The rod was not activated or subsequently impaired by the process of MRI. Image distortion of 28.9 cm along the long axis of the magnet and 20.1 cm perpendicular to this was seen with extension 10.6 cm cranial to the magnet housing. No negative effect was demonstrated on the magnetic rod elongation mechanism. This study has demonstrated that there are no detrimental effects of MRI on the MCGR and imaging of the head and neck phantom can still be interpreted. Further in vivo study is warranted.

Arthroscopic Treatments of Residual Pediatric Deformities

Advancements in hip arthroscopy and the recognition of the importance of early intervention in pediatric hip disorders have brought physicians a new surgical option for patients with residual hip deformity from pediatric diseases. Developmental dysplasia of the hip is the most common residual osseous morphology although there is a limited role of using hip arthroscopy. Slipped capital femoral epiphysis and Legg-Calve-Perthes lead to osseous morphologies that may be more amenable to arthroscopic intervention, although care must be taken to choose the appropriate patient.

At What Levels Are Freehand Pedicle Screws More Frequently Malpositioned in Children?

Study DesignRetrospective case series. BackgroundPrevious studies report that 5% to 17% of pedicle screws placed in children are malpositioned. Knowledge of the long-term effects of malpositioned screws is limited. We sought to further characterize risk factors for malpositioned pedicle screws in order to establish a more proactive role in limiting future complications. ObjectiveWe undertook this study to answer the following: 1) Is the rate of freehand pedicle screw malpositioning higher in children with spinal deformity, particularly at the apical concavity? 2) At what vertebral levels do freehand pedicle screws have the highest rates of malpositioning? 3) In which direction (medial or lateral) do freehand pedicle wall violations occur most often? MethodsIncidental postoperative computed tomographic (CT) exams were retrospectively reviewed in 85 pediatric patients (605 screws) treated with posterior spinal fusion using freehand pedicle screw technique. Of the screws imaged, 355 were in patients without deformity and 250 in patients with deformity. Breaches were categorized as mild (<2 mm), moderate (2–4 mm), or severe (>4 mm). ResultsScrews in pediatric deformity patients were more frequently malpositioned by 2 mm or more than were screws in patients without deformity (26% vs. 19%, p = .02). In patients with deformity, no higher rate of screw malposition was detected at the apical region. Overall, the highest rates of severe screw malposition were between T3 and T8. Pedicle breaches were more commonly in a medial direction compared with lateral (74% vs. 26%, p < .0001). However, severe breaches within the T3–T8 region were more often directed lateral than medial (92% vs. 8%, p ≤ .0001). ConclusionsThe clinical significance of asymptomatic pedicle screw breaches in children has not yet been determined. In this study, screws at the apical concavity were no more likely to be malpositioned than those at other sites. Efforts to reduce pedicle screw malposition would likely be most effective at the T3–T8 levels. Level of EvidenceLevel IV, Therapeutic Study. See the Guidelines for Authors for a complete description of the levels of evidence.

Canadian spine society 15th annual scientific conference.

Canadian spine society 15th annual scientific conference.

Treatment of Pediatric Scoliosis with Daytona Instrumentation Using the Cluster Technique

Introduction The authors show their experience with the use of Daytona instrumentation in the treatment of pediatric spine deformities. In the correction maneuvers it is important to build up clusters that are groups of pedicle screws joined together for stability in the derotation and provide greater force in the correction and also to prevent the hypokyphosis effect of all screw construct in the scoliosis correction. Materials and Methods Our department used the Daytona system in 81 patients with pediatric scoliosis since March 2011. The Daytona instrumentation is a novel instrumentation that uses pedicle screws with long tulips in their basic construction. The screws are uniplanar or polyaxial and the tulips are 30 mm long, which makes it much easier to put the rod in the construction without the need of a persuader and helps in the initial correction maneuver. The caps are specially designed to embrace the rod and prevent splaying of the screw during the tightening and untightening. The scoliosis correction maneuver that we used were rod derotation, derotation of the spine with groups of screws (cluster), “in situ” bending, compression and distraction, and segmental derotation. Using the clusters, there are less chances of screw pullout and splaying. Generous Ponte osteotomies are important for spine flexibility and better correction. We use Lenke's classification for the classification of scoliosis. We analyze the follow-up time, curve angles, flexibility, and the Cincinnati index. For patients with idiopathic scoliosis, we use the SRS 22r outcomes questionnaire. Results Retrospectively, we analyze 81 patients with scoliosis, 64 female and 17 male, with a mean age of 13.96 years (10–17 years). A total of 88% of the patients had idiopathic scoliosis. Others are neuromuscular and syndromic patients. Preoperatively, the mean angle was 78.09 degrees (38–120 degrees) and the mean flexibility index was 30.7%. Postoperatively, the mean angle was 23.6 degrees (5–62 degrees). Correction percentage was 68.1% and the Cincinnati index was 3.33%. The mean follow-up time was 16.9 months, at last follow-up the mean curve angle was 24.7 degrees, representing a loss to the postoperative period of 5% of loss of correction. The most frequent complications that we encounter were temporary loss of MEP and screw breakage. Comparing with the literature, the Daytona system is as effective as other systems in the market. Conclusion The Daytona instrumentation is a very good system for the treatment of adolescent idiopathic scoliosis; it is as effective as other systems with the added advantage of being much easier to place in the patient, and with the cluster technique we can save money with fewer screws and the derotation maneuver with clusters is a powerful correction technique.

Are MAGEC Rods a Contraindication to MRI: An In-Vitro Study Evaluating the Effect of MRI on Rod Growth, Temperature, and Image Interpretation

Introduction The management of early-onset pediatric deformity has been revolutionized by the development of adjustable growing rods. These rods contain a rare-earth magnet that rotates when triggered by an externally applied magnetic field resulting in rod elongation. This patient group includes those with underlying neuromuscular conditions who occasionally require further MRI of the neuraxis during development and, given the magnetic properties of the rod, they are conventionally contraindicated for this imaging modality once implanted. We have investigated the behavior of the MAGEC (Ellipse Technology) rod to determine whether MRI adversely affects the elongation properties of the rod or indeed directly causes any detrimental consequences, including rod elongation, shortening, heating, or significant artifact to outline implications for this patient group. Materials and Methods We designed an in-vitro experiment using two MAGEC rods secured in an MRI compatible restraint system to investigate MRI behavior of magnetic growing rods during scanning. We used a 1.5T Philips MRI and a restraint system designed to secure the rods within this environment. Repeated gradient echo multiscan sequence MRI of the neuraxis was performed to evaluate whether the rods elongated, contracted, or rotated during scanning, while we used MRI compatible heat-sensors attached to the outer housing of the rods to assess temperature changes. We also assessed the ability of the rods to lengthen after completion of the MRI and a phantom model to evaluate the amount of artifact induced by the rare-earth magnet. Results During repeated MRI of the neuraxis, the MAGEC rod mechanism was not triggered; however, the rods did rotate to bring the internal rare-earth magnet in line with the surrounding electromagnetic field, while only small forces were generated causing rod movement within the restraint system. The ability of the rods to lengthen after MRI was not enhanced or impaired and no significant heating effect on the external rod housing was demonstrated. The assessment of imaging with a phantom model did reveal a significant degree of artifact up to 30 cm because of the presence of the magnet within the electromagnetic field and, therefore, only MRI of the head and cervical spine could be interpreted with normal placement of MAGEC rods within the pediatric patient. Conclusion This study demonstrated that there are no detrimental effects of MRI on the MAGEC rod. In addition, while the degree of the artifact demonstrated prohibits imaging of the thoracolumbar spine, the MRI images of the head and cervical spine remain unimpaired. Finally, we did not demonstrate any significant force acting on the rod by the electromagnetic field that would cause implant dislodgement or loosening during MRI.

Patient-Reported Outcome Instruments in Pediatric Deformity Surgery: A Bibliometric Analysis

Study DesignBibliometric analysis. ObjectivesTo identify patient-reported outcomes instruments (PROIs) used in pediatric deformity surgery research over the past decade and their frequency and usage trends. Summary of Background DataThe emphasis on PROIs is increasing along with the demand for evidence-based medicine and cost-effectiveness research. Therefore, investigators and PROI consensus writers should be aware of the PROIs used in pediatric deformity and usage trends. MethodsFive top orthopedics journals were reviewed from 2004 to 2013 for clinical studies of surgical intervention in pediatric deformity that report PROIs. Publication year, level of evidence (LOE), and PROIs were reported for each article. Mean and range scores for the most frequently used PROIs were analyzed at 2-year follow-up. ResultsA total of 79 studies using PROIs were published in the pediatric deformity literature over the period studied. The researchers identified 21 named PROIs and 6 additional custom questionnaires. The Scoliosis Research Society (SRS)-22 was the most frequently used instrument (32.9%), followed by the SRS-24 (29.1%), Oswestry disability index (17.7%), visual analog scale (12.7%), SRS-30 (10.1%), and Short Form–36 (6.3%). Level of evidence III was most common (39.2%) and 1 LOE I study was identified. Mean preoperative and postoperative SRS instrument scores were 4.0 (95% confidence interval, 3.8–4.1) and 4.5 (95% confidence interval, 4.4–4.6), respectively, in SRS-22r equivalents. No studies met the criteria for mean and range calculation for the other top instruments. ConclusionsScoliosis Research Society instruments are used in 74.7% of pediatric deformity studies reporting PROIs. Therefore, there is a consensus that SRS instruments should be used in pediatric deformity outcome studies; yet, consistent use of the most up-to-date version, the SRS-22r, is still needed. General health questionnaires are currently underused in pediatric deformity research. Version reporting and use of the latest versions of PROIs need to be improved in future studies.

Magnetic growing rods in paediatric deformity patients: are they MRI compatible? An in-vitro study

RESULTS: Post-operative improvements were reported for each operation across each substratified outcome measure except general health. Lumbar foraminotomy patients reported the worst outcomes in every domain. CONCLUSIONS: Changes in PROMs vary depending not only on the pre-operative health status, but also on the type of operation carried out. This suggests some procedures may be more effective when considering QALYs, and may lead to limited resources being targeted at those procedures that have enhanced PROMs. CONFLICTS OF INTEREST: None. FUNDING SOURCES: None.

Causes and risk factors for 30-day unplanned readmissions after pediatric spinal deformity surgery.

Retrospective review of a prospective cohort. To determine the incidence, risk factors, and causes for 30-day unplanned readmission after pediatric spinal deformity surgery. The government has targeted 30-day readmissions as a quality of care measure. However, few studies have analyzed readmission in pediatric cohorts. A multicenter registry designed to collect pediatric surgical outcomes was queried for patients undergoing spinal deformity surgery in 2012. Patients were divided into groups of those with and without an unplanned readmission within 30 days postoperatively. Univariate and multivariate logistic regression analyses were used to compare the cohorts, and to identify variables associated with readmission. In total, 75 of 1890 pediatric patients undergoing spinal fusion for deformity had an unplanned 30-day readmission (3.96%). Readmissions were highest in the neuromuscular group (6.83%) and lowest in the idiopathic (2.66%) and infantile (1.31%) cohorts, (P < 0.01). The top reasons for readmission included wound complications (73.3%) and gastrointestinal disturbances (13.3%). In the univariate analysis, increasing surgical complexity, particularly fusions to the pelvis and isolated anterior spinal fusions, as well as increasing medical comorbidity burden were each associated with readmission (P < 0.05 for each). In the subsequent multivariate analysis, isolated anterior spinal fusions (odds ratio, 7.65; 95% confidence interval, 1.32-44.3) structural pulmonary abnormalities (odds ratio, 2.53; 95% confidence interval, 1.22-5.23) and an American Society of Anesthesiologists class of 3 or 4 (odds ratio, 2.18; 95% confidence interval, 1.07-4.47) were independently associated with readmission. The overall rate of 30-day unplanned readmissions after pediatric deformity surgery was low, but not insignificant. Surgeons should consider discharge optimization in the at-risk patient cohorts defined here, and should focus on wound complications and gastrointestinal disturbances to minimize readmissions. Quality reporting metrics should incorporate these risk factors to avoid unduly penalizing surgeons who take on complex cases. 3.

Preoperative halo-gravity traction for severe spinal deformities at an SRS-GOP site in West Africa: protocols, complications, and results.

Retrospective analysis of a prospectively collected single-center database. We describe a modified halo-gravity traction (HGT) protocol for patients with severe spinal deformities in West Africa, and assess the clinical and radiographic outcomes. Three-column osteotomies are frequently used in the correction of severe spinal deformities; however, these can be associated with high complication rates and significant risk for neurological injury. Preoperative traction is one modality used to obtain a partial correction prior to definitive fusion. Low numbers and variability of traction protocols, however, have limited previous reports of sustained HGT. All patients who underwent HGT in Ghana from April 2012 to August 2013 were reviewed. HGT was started at 20% body weight and increased by 10% per week until 50% body weight was reached by 4 weeks or thereafter as tolerated. Demographic variables, operative data, radiographic parameters, and health-related quality of life scores were collected. A deformity reduction index was calculated at each time point by summing the scoliosis and abnormal kyphosis for each patient and reported as a percentage of the preoperative deformity. Twenty-nine patients underwent HGT for an average 107 days prior to definitive posterior spinal fusion (24 patients) or placement of growing rods (5 patients). The major curve improved from an average 131° to 90° (31%) after HGT, and to an average 57° (56%) postoperatively. Pure kyphotic curves were rigid (flexibility 22% after traction), with a correction index of 3.88, which is similar to historical controls. Deformity correction with HGT plateaued at 63 days. Overall Scoliosis Research Society-22 questionnaire scores improved significantly pretraction versus postoperatively, but there was no change after traction versus before traction. There were 11 pin tract infections, with no neurological complications. HGT is a safe method to partially correct severe spinal deformities prior to a definitive procedure, and may reduce the need for higher risk 3-column osteotomies. Importantly, kyphosis secondary to infection with spontaneous apical ankylosis is relatively resistant to HGT. 4.