Identifying Factors Predictive of Atlantoaxial Fusion Failure in Pediatric Patients: Lessons Learned From a Retrospective Pediatric Craniocervical Society Study

Pediatric craniocervical fusion: predictors of surgical outcomes, risk of recurrence, and re-operation

PURPOSE

Craniocervical junction abnormalities include a wide variety of disorders and can be classified into congenital or acquired. This study aimed to review the surgical outcome of pediatric patients who underwent craniocervical and/or atlantoaxial fusion.

METHODS

This is a retrospective cohort study including all pediatric patients (≤ 18 years) who underwent craniocervical and/or atlantoaxial fusion between 2009 and 2019 at quaternary medical city.

RESULTS

A total of 25 patients met our criteria and were included in the study. The mean age was 9 years (range: 1-17 years). There was a slight female preponderance (N = 13; 52%). Most patients (N = 16; 64%) had non-trauamatic/chronic causes of craniocervical instability. Most patients presented with neck pain and/or stiffness (N = 14; 56%). Successful fusion of the craniocervical junction was achieved in most patients (N = 21; 84%). Intraoperative complications were encountered in 12% (N = 3) of the patients. Early postoperative complications were observed in five patients (20%). Five patients (20%) experienced long-term complications. Revision was needed in two patients (8%). Older age was significantly associated with higher fusion success rates (p = 0.003). The need for revision surgery rates was significantly higher among younger age group (3.75 ± 2, p = 0.01).

CONCLUSIONS

The study demonstrates the surgical outcome of craniocervical and/or atlantoaxial fusion in pediatric patients. Successful fusion of the craniocervical junction was achieved in most patients. Significant association was found between older age and successful fusion, and between younger age and need for revision surgery.

Feasibility of 3.5mm C2 pedicle screws in children: Part II, a computerized tomography analysis

BACKGROUND

There have been no studies with large sample sizes on growth of the pedicle of C2 in children. In the present study we measured the pedicle of C2 through computed tomography (CT) imaging in children aged less than 14 years and evaluated the suitability of the 3.5-mm screw for the pedicle in such children.

METHODS

The study was conducted on CT morphometric images of 420 children in our hospital between June 2018 and June 2020. The width (D1), length (D2), height (D3), inclination angle (α), and tail angle (β) of the C2 pedicle were measured. One-way analysis of variance and Student's t test were used for statistical analyses. The least-square method was used to analyze the curve fitting the trend of anatomical change in the pedicle. The largest degree of goodness of fit determined the best-fitting curve.

RESULTS

The size of the pedicle of C2 increased with age. The median ranges of D1, D2, D3, α, and β were 3.312-5.431 mm, 11.732-23.645 mm, 3.597-8.038 mm, 32.583°-36.640°, and 24.867°-31.567°, respectively. The curves fitting the trends of D1 and D3 were power functions, whereas D2 was fitted by a logarithmic curve. However, no curve fitted α or β.

CONCLUSION

A 3.5-mm screw can be placed in the pedicle of C2 in children aged more than one year. The growth and development trend of this pedicle can provide an anatomical reference for deciding on posterior cervical surgery and for selecting and designing pedicle screws for children.

Evaluation of 2011 AAP cervical spine screening guidelines for children with Down Syndrome

PURPOSE

Atlantoaxial instability (AAI) has a higher incidence rate among individuals with Down syndrome (DS) than the non-DS population. In 2011, the American Academy of Pediatrics (AAP) updated its AAI screening guidelines for children with DS from radiographic screening to radiographs only if there are clinical symptoms suggestive of cervical spine pathology. An assessment of whether this alteration has been associated with an increase in AAI-associated spinal cord injury has not been undertaken.

METHODS

We provide the first neurosurgical review of a large experience implementing the 2011 AAP guidelines. We reviewed the courses of patients with DS seen at the Sie Center for Down Syndrome at Children's Hospital Colorado who were evaluated for cervical spine disease and determined whether screening radiographic imaging could have led to earlier diagnosis or prevented development of neurological deficits. We also report an illustrative case of a 5-year-old female with Down syndrome who presented with instability after normal screening radiographs per the pre-2011 guidelines.

RESULTS

The clinical experience of the Sie Center demonstrates that even when limiting imaging to patients who show signs or symptoms of spine pathology, the vast majority of x-rays are negative. Our exemplary patient presented to the emergency department for neck pain without a history of significant trauma. She was diagnosed and treated for atlantoaxial subluxation associated with os odontoideum.

CONCLUSION

Routine radiographic screening may not be sufficiently predictive of DS individuals at risk to develop AAI. This experience supports the appositeness of the de-escalation of care asserted by the guidelines.

Use of recombinant human bone morphogenetic protein for revision cervical spine fusion in children with Down syndrome: a case series

OBJECTIVE

Patients with trisomy 21 (Down syndrome; DS) often have atlantoaxial instability (AAI), which, if severe, causes myelopathy and neurological deterioration. Children with DS and AAI who undergo cervical spine fusion have a high rate of nonunion requiring revision surgery. Recombinant human bone morphogenetic protein-2 (rhBMP-2) is a TGF-β growth factor that is used to induce bone formation in spine fusion. Although previous studies in the adult population have reported no reduction in pseudarthrosis rates with the use of rhBMP-2, there is a lack of literature in the pediatric DS population. This study describes the use of rhBMP-2 in children with DS and AAI during revision to treat nonunion.

METHODS

A retrospective review of a cervical spine fusion database (n = 175) was conducted. This database included all cervical spine fusions using modern instrumentation at the authors' institution from 2002 to 2019. Patients with DS who underwent a revision utilizing rhBMP-2 were included in the study. The number of prior fusions, use of rhBMP-2 in fusions, length of stay, halo use, and surgical data were collected. Postoperative complications and length of follow-up were also recorded.

RESULTS

Eight patients (75% female) met the inclusion criteria. The average age at revision with rhBMP-2 was 11 years (range 3-19 years). All patients were diagnosed with nonunion after an initial cervical fusion. All revisions were posterior fusions of C1-2 (n = 2) or occiput to cervical (n = 6). All revisions included implant revisions, iliac crest bone grafting, and rhBMP-2 use. One patient required irrigation and debridement of an rhBMP-induced seroma. Another patient required return to the operating room to repair a dural tear. There were no neurological, infectious, airway, or implant-related complications. Revision utilizing rhBMP-2 achieved fusion in 100% (n = 8) of patients. The average length of follow-up was 42.6 months. All patients demonstrated solid fusion mass on the last radiograph.

CONCLUSIONS

This is the first case series reporting the successful use of rhBMP-2 to facilitate cervical spine fusion in patients with DS after previous nonunion. In addition, few rhBMP-2-related postoperative complications occurred.