Outcomes of instrumented fusion in the pediatric cervical spine

Allograft Bone Use in Pediatric Subaxial Cervical Spine Fusions

BACKGROUND

The use of freeze-dried allograft as a bone graft substitute for pediatric spine surgery is safe and efficacious in the thoracic and lumbar spines. Allograft bone use in segmental instrumented fusions in the subaxial cervical spine has not been well reported in the literature. We sought to describe our experience with allograft bone in this patient cohort, and to compare union rates to patients treated with autograft.

METHODS

Medical records were queried over a 10-year time period (2004 to 2014). Inclusion criteria were all pediatric patients (18 y old and below) who underwent subaxial cervical spine fusion with minimum follow-up of 24 months. Variables queried included demographics, type of graft material used, diagnosis, approach (anterior, posterior, combined), levels instrumented, placement of postoperative halo, surgical-related complications, and achievement of fusion.

RESULTS

A total of 26 patients qualified for inclusion (18 allograft, 8 autograft). No differences existed between the 2 groups regarding age, sex, or number of fused levels. In the allograft cohort, average age at initial surgery was 13.3 years (range, 5 to 18 y). The most common reasons for surgery included trauma (6), tumor (3), and syndrome-associated kyphosis (3). The average number of instrumented levels was 4 (range, 2 to 13). Four patients (22%) developed a postoperative surgical complication. There were 2 asymptomatic pseudarthroses not requiring revision. At a minimum of 24-month follow-up (average, 45 mo; range, 24 to 121 mo), the allograft group demonstrated a fusion rate of 88%, which was comparable with a fusion rate of 87% in the autograft group.

CONCLUSIONS

The use of allograft bone for pediatric subaxial instrumented cervical spine fusions is safe in a variety of conditions, with the same rate of fusion as autograft. Rates of complications are acceptable. To avoid donor-site morbidity from autogenous graft harvest, we recommend considering allograft bone in subaxial cervical spine fusions with modern segmental instrumentation.

LEVEL OF EVIDENCE

Level IV-case series; therapeutic.

Screw fixation for atlantoaxial dislocation related to Down syndrome in children younger than 5 years

The aim of this study was to present cases of upper cervical fixation in Down syndrome patients younger than 5 years. In two cases, C1 lateral mass screws were installed. However, owing to the irreducible atlantoaxial dislocation, the screw backed out and fractured. Therefore, O-C2 fusion was performed. Furthermore, C2 bilateral lamina screws were added to the C2 pedicle screw for reinforcement. C1-C2 fusion is an option for Down syndrome patients younger than 5 years with atlantoaxial dislocation, when the dislocation is reducible. If the dislocation is irreducible, or the implant cannot be firmly secured, the fixation range should be expanded to O-C2 or below.

Traumatic atlanto-occipital dislocation in children-a case-based update on clinical characteristics, management and outcome

BACKGROUND

Atlanto-occipital dislocation (AOD) is a rare but severe sequela of high energy trauma. Children are at increased risk, due to their immature spine and biomechanical characteristics.

LITERATURE REVIEW

The prevailing mechanism of injury is motor vehicle collision as passenger. AOD commonly presents with cardiorespiratory arrest, spinal cord injury or cranial nerve deficits. Concomitant injuries, such as traumatic brain injury, are frequently encountered. Diagnosis is made on CT and MRI imaging. Posterior internal fixation is the recommended treatment. Thirty-four percent of patients die, 41 % survive with deficits and 25 % have a complete neurological recovery. Initial symptoms, GCS score and degree of spinal cord injury appear to be predictors of outcome.

ILLUSTRATIVE CASE

We report the case of a 9-year-old boy, who presented in extremis with cardiac arrest after a motor vehicle collision. Upon successful resuscitation, diagnostic imaging showed AOD and a Chiari I malformation. An occiput-C2 posterior instrumented fusion was performed. The patient subsequently received intensive rehabilitation and recovered to independent ambulation, with a persistent, asymptomatic Chiari I malformation.

CONCLUSION

This case highlights the potential for positive outcome in paediatric AOD, despite the presence of strong predictors of poor or fatal outcome at presentation.

Patient-reported outcomes of occipitocervical and atlantoaxial fusions in children

OBJECTIVE There is limited literature on patient-reported outcomes (PROs) and health-related quality of life (HRQOL) outcomes in pediatric patients undergoing surgery for craniovertebral junction pathology. The aim of the present study was to assess surgical and quality of life outcomes in children who had undergone occipitocervical or atlantoaxial fusion. METHODS The authors retrospectively reviewed the demographics, procedural data, and outcomes of 77 consecutive pediatric patients who underwent posterior occipitocervical or atlantoaxial fusion between 2008 and 2015 at Texas Children's Hospital. Outcome measures (collected at last follow-up) included mortality, neurological improvement, complications, Scoliosis Research Society Outcomes Measure-22 (SRS-22) score, SF-36 score, Neck Disability Index (NDI), and Pediatric Quality of Life Inventory (PedsQL). Multivariate linear regression analysis was performed to identify factors affecting PROs and HRQOL scores at follow-up. RESULTS The average age in this series was 10.6 ± 4.5 years. The median follow-up was 13.9 months (range 0.5-121.5 months). Sixty-three patients (81.8%) were treated with occipitocervical fusion, and 14 patients (18.1%) were treated with atlantoaxial fusion. The American Spinal Injury Association (ASIA) grade at discharge was unchanged in 73 patients (94.8%). The average PRO metrics at the time of last follow-up were as follows: SRS-22 score, 4.2 ± 0.8; NDI, 3.0 ± 2.6; the parent's PedsQL (ParentPedsQL) score, 69.6 ± 22.7, and child's PedsQL score, 75.5 ± 18.7. Multivariate linear regression analysis revealed that older age at surgery was significantly associated with lower SRS-22 scores at follow-up (B = -0.06, p = 0.03), and the presence of comorbidities was associated with poorer ParentPedsQL scores at follow-up (B = -19.68, p = 0.03). CONCLUSIONS This study indicates that occipitocervical and atlantoaxial fusions in children preserve neurological function and are associated with acceptable PROs and ParentPedsQL scores, considering the serious nature and potential for morbidity in this patient population. However, longer follow-up and disease-specific scales are necessary to fully elucidate the impact of occipitocervical and atlantoaxial fusions on children.

Classification and Management of Pediatric Subaxial Cervical Spine Injuries

Appropriate management of subaxial spine injury in children requires an appreciation for the differences in anatomy, biomechanics, injury patterns, and treatment options compared with adult patients. Increased flexibility, weak neck muscles, and cranial disproportion predispose younger children to upper cervical injuries and spinal cord injury without radiographic abnormality. A majority of subaxial cervical spine injuries can be treated nonoperatively. Surgical instrumentation options for children have significantly increased in recent years. Future studies of outcomes for children with subaxial cervical spine injury should focus on injury classification and standardized outcome measures to ensure continued improvement in quality of care for this patient population.

Occipitocervical Fixation

BACKGROUND

Occipitocervical junction instability can lead to serious neurological injury or death. Open surgical fixation is often necessary to provide definitive stabilization. However, long-term results are limited to small case series.

OBJECTIVE

To review the causes of occipitocervical instability, discuss the indications for surgical intervention, and evaluate long-term surgical outcomes after occipitocervical fixation.

METHODS

The charts of all patients undergoing posterior surgical fixation of the occipitocervical junction by the senior author were retrospectively reviewed. A total of 120 consecutive patients were identified for analysis. Patient demographic characteristics, occipitocervical junction pathology, surgical indications, and clinical and radiographic outcomes are reported.

RESULTS

The study population consisted of 64 male and 56 female patients with a mean age of 39.9 years (range, 7 months to 88 years). Trauma was the most common cause of instability, occurring in 56 patients (47%). Ninety patients (75%) were treated with screw/rod constructs; wiring was used in 30 patients (25%). The median number of fixated segments was 5 (O-C4). Structural bone grafts were implanted in all patients (100%). Preoperative neurological deficits were present in 83 patients (69%); 91% of those patients improved with surgery. Mean follow-up was 35.1 ± 27.4 months (range, 0-123 months). Two patients died, and 10 were lost to follow-up before the end of the 6-month follow-up period. Fusion was confirmed in 107 patients (89.1%). The overall complication rate was 10%, including 3 patients with vertebral artery injuries and 2 patients who required revision surgery.

CONCLUSION

Occipitocervical fixation is a durable treatment option with acceptable morbidity for patients with occipitocervical instability.

Pediatric occipitocervical fixation: radiographic criteria, surgical technique, and clinical outcomes based on experience of a single surgeon

OBJECTIVE If left untreated, occipitocervical (OC) instability may lead to serious neurological injury or death. Open internal fixation is often necessary to protect the neurovascular elements. This study reviews the etiologies for pediatric OC instability, analyzes the radiographic criteria for surgical intervention, discusses surgical fixation techniques, and evaluates long-term postoperative outcomes based on a single surgeon's experience. METHODS The charts of all patients < 18 years old who underwent internal OC fixation conducted by the senior author were retrospectively reviewed. Forty consecutive patients were identified for analysis. Patient demographic data, OC junction pathology, radiological diagnostic tools, surgical indications, and outcomes are reported. RESULTS The study population consisted of 20 boys and 20 girls, with a mean age of 7.3 years. Trauma (45% [n = 18]) was the most common cause of instability, followed by congenital etiologies (37.5% [n = 15]). The condyle-C1 interval had a diagnostic sensitivity of 100% for atlantooccipital dislocation. The median number of fixated segments was 5 (occiput-C4). Structural bone grafts were used in all patients. Postsurgical neurological improvement was seen in 88.2% (15/17) of patients with chronic myelopathy and in 25% (1/4) of patients with acute myelopathy. Preoperatively, 42.5% (17/40) of patients were neurologically intact and remained unchanged at last follow-up, 42.5% (17/40) had neurological improvement, 12.5% (5/40) remained unchanged, and 2.5% (1/40) deteriorated. All patients had successful fusion at 1-year follow-up. The complication rate was 7.5% (3/40), including 1 case of vertebral artery injury. CONCLUSIONS Occipitocervical fixation is safe in children and provides immediate immobilization, with excellent survival and arthrodesis rates. Of the radiographic tools evaluated, the condyle-C1 interval was the most predictive of atlantooccipital dislocation.

Bone morphogenetic protein in pediatric spine fusion surgery

BACKGROUND

There is a paucity of literature describing the use of bone graft substitutes to achieve fusion in the pediatric spine. Outcomes and complications involving the off-label use of bone morphogenetic protein 2 (BMP-2) in the pediatric spine are not clearly defined. The purpose of this study is to review the existing literature with respect to reported outcomes and complications involving the use of low-dose BMP-2 in pediatric patients.

METHODS

A Medline and PubMed literature search was conducted using the words bone morphogenetic protein, BMP, rh-BMP-2, bone graft substitutes, and pediatric spine.

RESULTS

To date, there are few published reports on this topic. Complications and appropriate BMP-2 dosage application in the pediatric spine remain unknown.

CONCLUSIONS

This report describes the potential for BMP-2 to achieve successful arthrodesis of the spine in pediatric patients. Usage should be judicious as complications and long-term outcomes of pediatric BMP-2 usage remain undefined in the existing literature.

Morphometric analysis of the developing pediatric cervical spine

OBJECTIVE Our understanding of pediatric cervical spine development remains incomplete. The purpose of this analysis was to quantitatively define cervical spine growth in a population of children with normal CT scans. METHODS A total of 1458 children older than 1 year and younger than 18 years of age who had undergone a cervical spine CT scan at the authors' institution were identified. Subjects were separated by sex and age (in years) into 34 groups. Following this assignment, subjects within each group were randomly selected for inclusion until a target of 15 subjects in each group had been measured. Linear measurements were performed on the midsagittal image of the cervical spine. Twenty-three unique measurements were obtained for each subject. RESULTS Data showed that normal vertical growth of the pediatric cervical spine continues up to 18 years of age in boys and 14 years of age in girls. Approximately 75% of the vertical growth occurs throughout the subaxial spine and 25% occurs across the craniovertebral region. The C-2 body is the largest single-segment contributor to vertical growth, but the subaxial vertebral bodies and disc spaces also contribute. Overall vertical growth of the cervical spine throughout childhood is dependent on individual vertebral body growth as well as vertical growth of the disc spaces. The majority of spinal canal diameter growth occurs by 4 years of age. CONCLUSIONS The authors' morphometric analyses establish parameters for normal pediatric cervical spine growth up to 18 years of age. These data should be considered when evaluating children for potential surgical intervention and provide a basis of comparison for studies investigating the effects of cervical spine instrumentation and fusion on subsequent growth.

Cervical Spine Instrumentation in Children

Instrumentation of the cervical spine enhances stability and improves arthrodesis rates in children undergoing surgery for deformity or instability. Various morphologic and clinical studies have been conducted in children, confirming the feasibility of anterior or posterior instrumentation of the cervical spine with modern implants. Knowledge of the relevant spine anatomy and preoperative imaging studies can aid the clinician in understanding the pitfalls of instrumentation for each patient. Preoperative planning, intraoperative positioning, and adherence to strict surgical techniques are required given the small size of children. Instrumentation options include anterior plating, occipital plating, and a variety of posterior screw techniques. Complications related to screw malposition include injury to the vertebral artery, neurologic injury, and instrumentation failure.

Congenital subaxial cervical subluxation presenting as a bilateral Erb's palsy: surgical management, rehabilitation, and outcome

INTRODUCTION

Subaxial spine injuries during infancy are uncommon.

CASE REPORT

We present the case of an infant referred to our brachial plexus clinic with proximal weakness of both arms noted immediately following a complicated breech delivery. Nerve conduction studies were consistent with bilateral proximal upper plexus injury; however, radiological evaluation revealed a C4-C5 subluxation and MRI features of bilateral C5 root avulsions. He was immobilized in a cervical-body orthosis and underwent open reduction and posterior C4-C5-C6 fixation at 10 weeks age using luque rods, sublaminar wires, and rib graft. The spine was immobilized in a custom molded cervicothoracic brace for a total of 3 months, and a home exercise program prescribed. Follow-up radiographic evaluation showed good posterior bony fusion by 2 months but persistent bilateral proximal upper limb weakness with reduced compound motor action potential (CMAP) amplitudes of the axillary and musculocutaneous nerves. Bilateral supraclavicular exploration and C5 root neurotization using the ipsilateral C7 nerve roots were performed at 7 months of age. Voluntary biceps activity followed by voluntary external rotation with gravity eliminated was noted within the next 2-3 months. He progressed to develop near normal motor control of bilateral upper limbs within 1 year.

CONCLUSIONS

We wish to report this rare entity and our favorable outcome using a strategy of early spinal stabilization and neurotization repair to restore function following proximal nerve root injury.

Management of subaxial cervical instability in very young or small-for-age children using a static single-screw anterior cervical plate: indications, results, and long-term follow-up

OBJECTIVE Subaxial cervical instability in very young or small-for-age children is uncommon and typically arises from trauma or skeletal dysplasia. Various operative techniques have been used to achieve stabilization in pediatric patients with evidence of instability, including anterior, posterior, and combined approaches. In this study, the authors report their results with subaxial cervical instability in this patient population treated using a static single-screw anterior cervical plate (ACP) system and allograft fusion. METHODS In a retrospective chart review, the authors identified all patients 6 years of age or younger who underwent an anterior cervical fusion procedure using a static single-screw ACP system either as a stand-alone construct or as part of an anterior-posterior stabilization procedure. Reasons for fusion included trauma, tumor, and congenital anomalies. RESULTS Five patients 6 years of age or younger underwent anterior cervical fusion using a static single-screw system during the 19-year study period. Follow-up ranged from 12 to 51 months (mean 26.8 months). Two patients underwent repeat surgery, one 7 days after and the other 21 months after their initial procedure. At last follow-up, a mean vertical growth of 22.8% was seen across the fused segments, with no evidence of kyphotic or lordotic abnormalities. CONCLUSIONS In very young or small-for-age children, the use of a static single-screw ACP system appears to be a safe and effective option to manage subaxial cervical instability. Bony fusion and continued longitudinal growth occur within the fused segments, with no evidence of long-term cervical malalignment.

The Use of Bone Morphogenetic Protein in Pediatric Cervical Spine Fusion Surgery: Case Reports and Review of the Literature

Study Design Case report. Objective There is a paucity of literature describing the use of bone graft substitutes to achieve fusion in the pediatric cervical spine. The outcomes and complications involving the off-label use of bone morphogenetic protein (BMP)-2 in the pediatric cervical spine are not clearly defined. The purpose of this article is to report successful fusion without complications in two pediatric patients who had instrumented occipitocervical fusion using low-dose BMP-2. Methods A retrospective review of the medical records was performed, and the patients were followed for 5 years. Two patients under 10 years of age with upper cervical instability were treated with occipitocervical instrumented fusion using rigid occipitocervical fixation techniques along with conventionally available low-dose BMP-2. A Medline and PubMed literature search was conducted using the terms "bone morphogenetic protein," "BMP," "rh-BMP2," "bone graft substitutes," and "pediatric cervical spine." Results Solid occipitocervical fusion was achieved in both pediatric patients. There were no reported perioperative or follow-up complications. At 5-year follow-up, radiographs in both patients showed successful occipital cervical fusion without evidence of instrumentation failure or changes in the occipitocervical alignment. To date, there are few published reports on this topic. Complications and the appropriate dosage application in the pediatric posterior cervical spine remain unknown. Conclusions We describe two pediatric patients with upper cervical instability who achieved successful occipital cervical fusion without complication using off-label BMP-2. This report underscores the potential for BMP-2 to achieve successful arthrodesis of the posterior occipitocervical junction in pediatric patients. Use should be judicious as complications and long-term outcomes of pediatric BMP-2 use remain undefined in the existing literature.

Long-term growth and alignment after occipitocervical and atlantoaxial fusion with rigid internal fixation in young children

OBJECT The long-term consequences of atlantoaxial (AA) and occipitocervical (OC) fusion and instrumentation in young children are unknown. Anecdotal reports have raised concerns regarding altered growth and alignment of the cervical spine after surgical intervention. The purpose of this study was to determine the long-term effects of these surgeries on the growth and alignment of the maturing spine. METHODS A multiinstitutional retrospective chart review was conducted for patients less than or equal to 6 years of age who underwent OC or AA fusion with rigid instrumentation at 9 participating centers. All patients had at least 3 years of clinical and radiographic follow-up data and radiographically confirmed fusion. Preoperative, immediate postoperative, and most recent follow-up radiographs and/or CT scans were evaluated to assess changes in spinal growth and alignment. RESULTS Forty children (9 who underwent AA fusion and 31 who underwent OC fusion) were included in the study (mean follow-up duration 56 months). The mean vertical growth over the fused levels in the AA fusion patients represented 30% of the growth of the cervical spine (range 10%-50%). Three different vertical growth patterns of the fusion construct developed among the 31 OC fusion patients during the follow-up period: 1) 16 patients had substantial growth (13%-46% of the total growth of the cervical spine); 2) 9 patients had no meaningful growth; and 3) 6 patients, most of whom presented with a distracted atlantooccipital dislocation, had a decrease in the height of the fused levels (range 7-23 mm). Regarding spinal alignment, 85% (34/40) of the patients had good alignment at follow-up, with straight or mildly lordotic cervical curvatures. In 1 AA fusion patient (11%) and 5 OC fusion patients (16%), we observed new hyperlordosis (range 43°-62°). There were no cases of new kyphosis or swan-neck deformity, evidence of subaxial instability, or unintended subaxial fusion. No preoperative predictors of these growth patterns or alignment were evident. CONCLUSIONS These results demonstrate that most young children undergoing AA and OC fusion with rigid internal fixation continue to have good cervical alignment and continued growth within the fused levels during a prolonged follow-up period. However, some variability in vertical growth and alignment exists, highlighting the need to continue close long-term follow-up.

Computed tomography parameters for atlantooccipital dislocation in adult patients: the occipital condyle-C1 interval

OBJECT

Atlantooccipital dislocation (AOD) in adults cannot be diagnosed with adequate specificity and sensitivity using only CT or plain radiography, and the spine literature offers no guidelines. In children, the most sensitive and specific radiographic measurement for the diagnosis of AOD is the CT-based occipital condyle-C1 interval (CCI). The goal of the current study was to identify the normal CCI in healthy adults and compare it with the CCI in adults with AOD to establish a highly sensitive and specific cutoff value for the neuroimaging diagnosis of AOD.

METHODS

A total of 81 patients, 59 without AOD and 22 with AOD, were included in this study. Measurements obtained from thin-slice CT scans of the craniovertebral joint to assess atlantooccipital dislocation included the CCI, condylar sum, the Wholey and Harris intervals, Powers and Sun ratios, Wackenheim line, and Lee X-lines.

RESULTS

The group of patients without AOD included 30 men (50.8%) and 29 women (49.2%) with a mean age of 42.4 ± 16 years (range 19-87 years). The group of patients with AOD included 10 men (45.5%) and 12 women (54.5%) with a mean age of 38.2 ± 9.7 years (range 20-56 years). Interrater reliabilities within a 95% CI were all greater than 0.98 for CCI measurements. A total of 1296 measurements of the CCI were made in 81 patients. The mean CCI for non-AOD patients was 0.89 ± 0.12 mm, the single largest CCI measurement was 1.4 mm, and the largest mean for either right or left CCI was 1.2 mm. The mean condylar sum was 1.8 ± 0.2 mm, and the largest condylar sum value was 2.2 mm. Linear regression with age predicted an increase in CCI of 0.001 mm/year (p < 0.05). The mean CCI in AOD patients was 3.35 ± 0.18 mm (range 1.5 mm-6.4 mm). The shortest single CCI measurements in the AOD patients were 1.1 mm and 1.2 mm. The mean condylar sum for all 22 AOD patients was 6.7 ± 2.7 mm and the shortest condylar sums were 3.0 mm. Cutoff values for AOD were set at 1.5 mm for the CCI and 3.0 mm for the condylar sum, both with a sensitivity of 1 and false-negative rate of 0. Sensitivity for the Powers, Wholey, Harris, Sun, Wackenheim, and Lee criteria were determined to be 0.55, 0.46, 0.27, 0.23, 0.41, and 0.41, respectively.

CONCLUSIONS

The CCI is shorter in adult patients as opposed to the pediatric population. The revised CCI (1.5 mm) and condylar sum (3.0 mm) cutoff values have the highest sensitivity and specificity for the diagnosis of AOD in the adult population.

A Computed Tomographic Morphometric Study of the Pediatric Occipital Bone Thickness: Implications for Pediatric Occipitocervical Fusion

STUDY DESIGN

This study is a computed tomographic-based morphometric analysis of the pediatric occipital bones as related to pediatric occipitocervical fusion.

OBJECTIVE

To quantify reference data concerning the thicknesses of the immature occipital bones to guide the pediatric occipitocervical fusion.

SUMMARY OF BACKGROUND DATA

To the best of our knowledge, no published study has provided insight into the thicknesses of pediatric occiputs with different age groups.

METHODS

80 pediatric patients were divided into 4 age groups, and their occiputs were studied on Philips Brilliance 256 iCT scan.

RESULTS

The mean thickness ± standard deviations of the pediatric occipital bones with different age groups is shown. The median and the paramedian regions are always thicker than the more lateral regions at each age group and the thickest point in the occiputs is mostly at the external occipital protuberance. The mean thickness of occiputs showed an obvious significant difference between each 2 age groups and no significant difference between male and female in different age groups except the group 4.

CONCLUSION

Our investigation provides insight into the anatomy of occiputs in pediatric population and preoperative CT evaluation must be required to further decrease the risk of occipitocervical fusion.

The efficacy of routine use of recombinant human bone morphogenetic protein-2 in occipitocervical and atlantoaxial fusions of the pediatric spine: a minimum of 12 months' follow-up with computed tomography

OBJECT The purpose of this study focusing on fusion rate was to determine the efficacy of recombinant human bone morphogenetic protein-2 (rhBMP-2) use in posterior instrumented fusions of the craniocervical junction in the pediatric population. The authors previously reported the short-term (mean follow-up 11 months) safety and efficacy of rhBMP-2 use in the pediatric age group. The present study reports on their long-term results (minimum of 12 months' follow-up) and focuses on efficacy. METHODS The authors performed a retrospective review of 83 consecutive pediatric patients who had undergone posterior occipitocervical or atlantoaxial spine fusion at Texas Children's Hospital or Riley Children's Hospital during the period from October 2007 to October 2012. Forty-nine patients were excluded from further analysis because of death, loss to follow-up, or lack of CT evaluation of fusion at 12 or more months after surgery. Fusion was determined by postoperative CT scan at a minimum of 12 months after surgery. The fusion was graded and classified by a board-certified fellowship-trained pediatric neuroradiologist. Other factors, such as patient age, diagnosis, number of vertebral levels fused, use of allograft or autograft, dosage of bone morphogenetic protein (BMP), and use of postoperative orthosis, were recorded. RESULTS Thirty-four patients had a CT scan at least 12 months after surgery. The average age of the patients at surgery was 8 years, 1 month (range 10 months-17 years). The mean follow-up was 27.7 months (range 12-81 months). There were 37 fusion procedures in 34 patients. Solid fusion (CT Grade 4 or 4-) was achieved in 89.2% of attempts (33 of 37), while incomplete fusion or failure of fusion was seen in 10.8%. Based on logistic regression analysis, there was no significant association between solid fusion and age, sex, BMP dose, type of graft material, use of postoperative orthosis, or number of levels fused. Three of 34 patients (8.8%) required revision surgery. CONCLUSIONS Despite the large number of adult studies reporting positive effects of BMP on bone fusion, our long-term outcomes using rhBMP-2 in the pediatric population suggest that rates of fusion failure are higher than observed in contemporary adult and pediatric reports of occipitocervical and atlantoaxial spine fusions.

Unilateral fixation for treatment of occipitocervical instability in children with congenital vertebral anomalies of the craniocervical junction

OBJECT Patients with occipitocervical (OC) instability from congenital vertebral anomalies (CVAs) of the craniocervical junction (CCJ) often have bony abnormalities that make instrumentation placement difficult. Within this patient population, some bilateral instrumentation constructs either fail or are not feasible, and a unilateral construct must be used. The authors describe the surgical management and outcomes of this disorder in patients in whom unilateral fixation constructs were used to treat OC instability. METHODS From a database of OC fusion procedures, the authors identified patients who underwent unilateral fixation for the management of OC instability. Patient characteristics, surgical details, and radiographic outcomes were reviewed. In each patient, CT scans were performed at least 4 months after surgery to evaluate for fusion. RESULTS Eight patients with CVAs of the CCJ underwent unilateral fixation for the treatment of OC instability. For 4 patients, the procedure occurred after a bilateral OC construct failed or infection forced hardware removal. For the remainder, it was the primary procedure. Two patients required reoperation for hardware revision and 1 developed nonunion requiring revision of the bone graft. Ultimately, 7 patients demonstrated osseous fusion on CT scans and 1 had a stable fibrous union. CONCLUSIONS These findings demonstrate that a unilateral OC fixation is effective for the treatment of OC instability in children with CVAs of the CCJ in whom bilateral screw placement fails or is not feasible.

Anatomic feasibility of posterior cervical pedicle screw placement in children: computerized tomographic analysis of children under 10 years old

OBJECTIVE

To evaluate the anatomical feasibility of 3.5 mm screw into the cervical spine in the pediatric population and to establish useful guidelines for their placement.

METHODS

A total of 37 cervical spine computerized tomography scans (24 boys and 13 girls) were included in this study. All patients were younger than 10 years of age at the time of evaluation for the period of 2007-2011.

RESULTS

For the C1 screw placement, entry point height (EPH) was the most restrictive factor (47.3% patients were larger than 3.5 mm). All C2 lamina had a height larger than 3.5 mm and 68.8% (51/74) of C2 lamina had a width thicker than 3.5 mm. For C2 pedicle width, 55.4% (41/74) of cases were larger than 3.5 mm, while 58.1% (43/74) of pedicle heights were larger than 3.5 mm. For pedicle width of subaxial spine, 75.7% (C3), 73% (C4), 82.4% (C5), 89.2% (C6), and 98.1% (C7, 1/54) were greater than 3.5 mm. Mean lamina width of subaxial cervical spine was 3.1 (C3), 2.7 (C4), 2.9 (C5), 3.8 (C6), and 4.0 mm (C7), respectively. Only 34.6% (127/370) of subaxial (C3-7) lamina thickness were greater than 3.5 mm. Mean length of lateral mass for the lateral mass screw placement was 9.28 (C3), 9.08 (C4), 8.81 (C5), 8.98 (C6), and 10.38 mm (C7).

CONCLUSION

C1 lateral mass fixation could be limited by the morphometrics of lateral mass height. C2 trans-lamina approach is preferable to C2 pedicle screw fixation. In subaxial spines, pedicle screw placement was preferable to trans-lamina screw placement, except at C7.

Avoiding early complications and reoperation during occipitocervical fusion in pediatric patients

OBJECT

Surgical arthrodesis for pediatric occipitocervical (OC) instability has a high rate of success in a wide variety of challenging circumstances; however, identifying potential risk factors can help to target variables that should be the focus of improvement. The aim of this paper was to examine risk factors predictive of failure in a population of patients who underwent instrumented OC arthrodesis using a uniform surgical philosophy.

METHODS

The authors conducted a retrospective cohort study of pediatric patients who underwent OC fusion from 2001 to 2013 at a single institution to determine risk factors for surgical failure, defined as reoperation for revision of the arthrodesis or instrumentation. The primary study outcome was either radiographic confirmation of successful OC fusion or surgical failure requiring revision of the arthrodesis or instrumentation. The secondary outcome was the underlying cause of failure (hardware failure, graft failure, or infection). Univariate analysis was performed to assess the association between outcome and patient demographics, cause of OC instability, type of OC instrumentation, bone graft material, biological adjuncts, and complications.

RESULTS

Of the 127 procedures included, 20 (15.7%) involved some form of surgical failure and required revision surgery. Univariate analysis revealed that patients with deep wound infections requiring debridement were more likely to require surgical revision of the hardware or graft (p = 0.002). Subgroup analysis revealed that patients with skeletal dysplasia or congenital spinal anomalies were more likely to develop hardware failure than patients with other causes of OC instability (p = 0.020). Surgical failure was not associated with the method of C-2 fixation, type of rigid OC instrumentation, bone graft material, use of bone morphogenetic protein or biological adjuncts, cause of instability, sex, age, or having previous OC fusion operations.

CONCLUSIONS

Pediatric patients in the present cohort with postoperative wound infections requiring surgical debridement had higher surgical failure rates after OC fusion. Those with skeletal dysplasia and congenital spinal anomalies were more likely to require reoperation for hardware failure. Better understanding of the mode of surgical failure may enable surgeons to develop strategies to decrease the need for reoperation in pediatric patients with OC instability.

Fixation with C-2 laminar screws in occipitocervical or C1-2 constructs in children 5 years of age or younger: a series of 18 patients

OBJECT.: There are rare indications for upper cervical spine fusion in young children. Compared with nonrigid constructs, rigid instrumentation with screw fixation increases the fusion rate and reduces the need for halo fixation. Instrumentation may be technically challenging in younger children. A number of screw placement techniques have been described. Use of C-2 translaminar screws has been shown to be anatomically feasible, even in the youngest of children. However, there are few data detailing the clinical outcome. In this study, the authors describe the clinical and radiographic follow-up of 18 children 5 years of age or younger who had at least one C-2 translaminar screw as part of an occipitocervical or C1-2 fusion construct.

METHODS

A retrospective review of all children treated with instrumented occipitocervical or C1-2 fusion between July 1, 2007, and June 30, 2013, at Riley Children's Hospital and Texas Children's Hospital was performed. All children 5 years of age or younger with incorporation of at least one C-2 translaminar screw were identified.

RESULTS

Eighteen children were studied (7 boys and 11 girls). The mean age at surgery was 38.1 months (range 10-68 months). Indications for surgery included traumatic instability (6), os odontoideum (3), destructive processes (2), and congenital instability (7). A total of 24 C-2 translaminar screws were placed; 23 (95.8%) of 24 were satisfactorily placed (completely contained within the cortical walls). There was one medial cortex breach without neurological impingement. There were no complications with screw placement. Three patients required wound revisions. Two patients died as a result of their original condition (trauma, malignant tumor). The mean follow-up duration for the surviving patients was 17.5 months (range 3-60 months). Eleven (91.7%) of the 12 patients followed for 6 months or longer showed radiographic stability or completed fusion.

CONCLUSIONS

Use of C-2 translaminar screws provides an effective anchor for internal fixation of the upper cervical spine. In this study of children 5 years of age or younger, the authors found a high rate of radiographic fusion with a low rate of complications.

Traumatic atlanto-occipital dislocation in children

Although once considered an invariably fatal injury, improvements in diagnosis and management have made atlanto-occipital dislocation (AOD) a survivable injury. MRI is the preferred imaging modality; occasionally, flexion/extension/distraction fluoroscopy may be required to determine craniovertebral stability. Early surgical stabilization is recommended for all children with AOD. Early occipitocervical fusion using screws in combination with a rod or plate, or sublaminar wires with a contoured rod, coupled with autograft bone, provide immediate stabilization and a high fusion rate. Halo immobilization and traction are contraindicated in the management of AOD in children because of the risk of displacement of the injured occipitocervical joint. Postoperative hydrocephalus is frequent and should be suspected when neurologic decline occurs after fixation. Nearly half of children who survive AOD will have residual neurologic deficits.

Spondylolysis of C-2 in children 3 years of age or younger: clinical presentation, radiographic findings, management, and outcomes with a minimum 12-month follow-up

OBJECT

Cervical spondylolysis is a rare condition that results from a pars interarticularis defect. The C-6 level is the most frequently involved site in the cervical spine. Its clinical presentations range from incidental radiographic findings to neck pain and, rarely, neurological deficits. Although 150 patients with subaxial cervical spondylolysis have been reported, a mere 24 adult and pediatric patients with C-2 spondylolysis have been described. The long-term outcomes of very young children with bilateral C-2 spondylolysis are of great interest, yet only a few longitudinal studies exist.

METHODS

The authors retrospectively reviewed 5 cases of bilateral C-2 spondylolysis at Texas Children's Hospital and Riley Children's Hospital; these were combined with 5 other cases in the literature, yielding a total of 10 patients. Data regarding the patients' age, sex, C2-3 angulation and displacement, associated spine anomalies, neurological deficits, treatment, and most recent follow-up were recorded.

RESULTS

The patients' ages ranged from 3 to 36 months (mean 12.9 months). There were 6 boys and 4 girls. The C2-3 angulation, displacement, and width of pars defect were measured when available. The mean C2-3 angulation was 9.5° (range 1-34°), the mean C2-3 displacement was 4.78 mm (range 1.1-10.8 mm), and the mean width of the pars defect was 4.16 mm (range 0.9-7 mm). One patient developed myelopathy and spinal cord injury. All 10 of the patients were treated initially with conservative therapy: 3 with close observation alone, 1 with a rigid cervical collar, 4 with a Minerva jacket, 1 with a sternal-occipital-mandibular immobilizer, and 1 with a halo vest. Three patients ultimately underwent surgery for internal fixation due to progressive instability or development of neurological symptoms. All patients were neurologically intact at the last follow-up (mean 44.3 months, range 14-120 months).

CONCLUSIONS

Based on the literature and the authors' own experience, they conclude that most very young children with C-2 spondylolysis remain neurologically intact and maintain stability in long-term follow-up despite the bony defect. This defect is often an asymptomatic incidental finding and may be managed conservatively. More aggressive therapy including surgery is indicated for those patients with a neurological deficit from spinal cord compromise secondary to stenosis and local C-2 kyphosis, progressive deformity, or worsening C2-3 instability.

Occipital condyle to cervical spine fixation in the pediatric population

Fixation at the craniovertebral junction (CVJ) is necessary in a variety of pediatric clinical scenarios. Traditionally an occipital bone to cervical fusion is preformed, which requires a large amount of hardware to be placed on the occiput of a child. If a patient has previously undergone a posterior fossa decompression or requires a decompression at the time of the fusion procedure, it can be difficult to anchor a plate to the occipital bone. The authors propose a technique that can be used when faced with this difficult challenge by using the occipital condyle as a point of fixation for the construct. Adult cadaveric and a limited number of case studies have been published using occipital condyle (C-0) fixation. This work was adapted for the pediatric population. Between 2009 and 2012, 4 children underwent occipital condyle to axial or subaxial spine fixation. One patient had previously undergone posterior fossa surgery for tumor resection, and 1 required decompression at the time of operation. Two patients underwent preoperative deformity reduction using traction. One child had a Chiari malformation Type I. Each procedure was performed using polyaxial screw-rod constructs with intraoperative neuronavigation supplemented by a custom navigational drill guide. Smooth-shanked 3.5-mm polyaxial screws, ranging in length from 26 to 32 mm, were placed into the occipital condyles. All patients successfully underwent occipital condyle to cervical spine fixation. In 3 patients the construct extended from C-0 to C-2, and in 1 from C-0 to T-2. Patients with preoperative halo stabilization were placed in a cervical collar postoperatively. There were no new postoperative neurological deficits or vascular injuries. Each patient underwent postoperative CT, demonstrating excellent screw placement and evidence of solid fusion. Occipital condyle fixation is an effective option in pediatric patients requiring occipitocervical fusion for treatment of deformity and/or instability at the CVJ. The use of intraoperative neuronavigation allows for safe placement of screws into C-0, especially when faced with a challenging patient in whom fixation to the occipital bone is not possible or is less than ideal.

A review of the neurological and neurosurgical implications of Down syndrome in children

Down syndrome is the most commonly encountered chromosomal translation and has been associated with significant congenital abnormalities in various organ systems. Along with classic facial findings, it may involve the gastroenterologic, cardiac, ophthalmologic, endocrine, immunologic, orthopedic, or neurologic systems. With respect to the neurological system, a higher incidence of moyamoya, seizure disorders, strokes, and spinal ligamentous laxity has been described in these children. We have summarized the current available literature with respect to children who have Down syndrome and the varying neurological pathologic entities associated to help health care providers better understand these patients.