Results of Conservative and Surgical Management in Children with Idiopathic and Nonidiopathic Os Odontoideum.

OBJECTIVE: The outcomes of conservative and operative treatment of os odontoideum in children remain unclear. Our objective was to study the outcomes of conservative and surgical treatment of idiopathic os odontoideum in children and compare these outcomes in age- and treatment-matched nonidiopathic children with os odontoideum. METHODS: A retrospective multicenter review identified 102 children with os odontoideum, of whom 44 were idiopathic with minimum 2-year follow-up. Ten patients were treated conservatively, and 34 underwent spinal arthrodesis. Both groups were matched with nonidiopathic patients by age and type of treatment. Cervical arthrodesis was recommended for patients with increased atlantoaxial distance or reduced space available for the cord in flexion-extension radiographs. RESULTS: All 20 children undergoing conservative treatment remained asymptomatic during follow-up, but 1 nonidiopathic patient developed cervical instability. The idiopathic group had significantly less severe radiographic cervical instability and less neurologic complications than the nonidiopathic group (P < 0.05 for all comparisons). Thirty-three (97%) patients in the idiopathic group and 32 (94%) patients in the nonidiopathic group (94%) had spinal fusion at final follow-up (P = 0.55). The risk of complications (15% vs. 41%; odds ratio 0.234, 95% confidence interval 0.072-0.757, P = 0.015) and nonunion (6% vs. 24%; odds ratio 0.203, 95% confidence interval 0.040-0.99, P = 0.040) were significantly lower in the idiopathic than in the nonidiopathic group. Idiopathic children undergoing rigid fixation achieved spinal fusion. CONCLUSIONS: Idiopathic patients with stable atlantoaxial joint at presentation remained asymptomatic and intact during conservative treatment. Idiopathic children with os odontoideum undergoing spinal arthrodesis had significantly fewer complications and nonunion than nonidiopathic children. LEVEL OF EVIDENCE: III.

Os Odontoideum in Children: Treatment Outcomes and Neurological Risk Factors.

BACKGROUND: Treatment outcomes and risk factors for neurological deficits in pediatric patients with an os odontoideum are unclear. METHODS: We reviewed the data for 102 children with os odontoideum who were managed at 11 centers between 2000 and 2016 and had a minimum duration of follow-up of 2 years. Thirty-one children had nonoperative treatment, and 71 underwent instrumented posterior cervical spinal arthrodesis for the treatment of C1-C2 instability. Nonoperative treatment consisted of observation (n = 29) or immobilization with a cervical collar (n = 1) or halo body jacket (n = 1). Surgical treatment consisted of atlantoaxial (n = 50) or occipitocervical (n = 21) arthrodesis. One patient also underwent transoral odontoidectomy. RESULTS: Thirty children (29%) presented with neurological deficits, 28 of whom had radiographic atlantoaxial instability (atlantoaxial distance >5 mm) or limited space (≤13 mm) available for the spinal cord (risk ratio, 7.8 [95% confidence interval, 2.0 to 31] compared with children with no radiographic risk factors). The 27 children without neurological deficits or atlantoaxial instability at presentation underwent nonoperative treatment and remained asymptomatic. Of the initial nonoperative cohort, one child developed atlantoaxial instability, and another had a persistent neurological deficit; both children underwent spinal arthrodesis during the study period. One child with cervical instability declined surgery and remained asymptomatic. Spinal fusion occurred in 68 patients in the surgical group by the end of the study period (mean, 3.7 years; range, 2.0 to 11.8 years). Surgical complications occurred in 21 children, including nonunion in 12, new neurological deficits in 4, cerebrospinal fluid leak in 2, symptomatic instrumentation requiring removal 2, and vertebral artery injury in 1. Nine children underwent revision surgery. In the surgical group, Japanese Orthopaedic Association neurological function scores improved significantly from preoperatively to the latest follow-up for the upper extremities (p = 0.026) and lower extremities (p = 0.007). CONCLUSIONS: The risk of developing a neurological deficit was strongly associated with atlantoaxial instability and limited space available for the spinal cord in children with os odontoideum. Nonoperative treatment was safe for asymptomatic patients without atlantoaxial instability. Spinal arthrodesis resolved the neurological deficits of children with symptomatic os odontoideum. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.