Surgical management strategies for atlantoaxial instability/dislocation in down syndrome

To evaluate surgical strategies and clinical outcomes for atlantoaxial instability/dislocation (AAI/AAD) in Down syndrome (DS) patients.

A retrospective review was conducted on 12 DS patients with AAI/AAD treated between March 2018 and June 2024. Surgical plans were tailored based on reducibility: reducible cases underwent posterior atlantoaxial/occipitocervical fusion (n = 8), while irreducible cases received transoral anterior release combined with posterior fixation (n = 4). Outcomes were assessed through complications, radiographic parameters (anterior atlantodental interval, ADI), and neurological status (JOA score).

The cohort (5 males, 7 females) aged 5-28 years (mean 11.3 ± 6.4) completed 1-6 year follow-up. Clinical presentations included myelopathy (75.0%, 9/12) and neck pain (25.0%, 3/12). Radiographic anomalies included os odontoideum (66.7%, 8/12) and odontoid fracture (8.3%, 1/12). Postoperative ADI significantly decreased from 8.95 ± 3.19 mm to 3.40 ± 0.81 mm (P < 0.05), with JOA scores improving from 10.92 ± 4.40 to 15.50 ± 2.43 (P < 0.05). Complications occurred in 25.0% (3/12): one surgical site infection managed by debridement, one dural tear repaired intraoperatively, and one hardware displacement requiring revision. Median fusion time was 6 months (range 4.5-16). All patients demonstrated neurological improvement except one with residual lower limb weakness.

DS patients with AAI/AAD frequently present with os odontoideum and spinal cord compromise, necessitating surgical intervention. Reducible dislocations may be effectively managed with posterior fusion alone, whereas irreducible cases require combined anterior-posterior approaches. Early surgical intervention is recommended for DS patients exhibiting os odontoideum with AAI/AAD due to elevated risk of progressive myelopathy.