Treatment of neglected atlanto-axial rotatory displacement FRANSEN N, MOENS P, SCHELFAUT S Department of Orthopaedic Surgery, University Hospital Leuven, Belgium Disclosure: No conflict of interest

Background Atlanto-axial rotatory instability causes: Torticollis Neck pain Often misdiagnosed or delayed referral > irreducible displacement Standard treatment: 2 stage surgery Anterior, peroral reduction (odontoidectomy) Posterior fixation

Purpose Present an alternative treatment option for late-presenting , irreducible displacements Reduction with halo gravity traction during longer period Posterior fixation in 1 stage surgery Use of a structural autograft

Methods Retrospective analysis of single institution database from December 2014 till May 2016 Reviewed inpatient medical chart and imaging studies (pre-, post-reduction & postoperative CT) 3 reported cases Mean duration of symptoms: 4 months (3-9 months) Demographics Fielding grade Comorbidities Therapy Case 1 Female, 10y II Down & West syndr. C0-C2 fusion Case 2 Female, 9y III / C1-C2 fusion Case 3 Female, 5y I Grisel, Retardation

Reduction: Halo gravity Traction HALO 6-8 pins, with torque 4-8 lbs Starting weight 4-6 lbs + 1-2lbs every second day Maximum weight: ½ of total body weight (TBW) Lying, sitting, standing/walking, physiotherapy Daily pin tract care Regular neurological assesment (also cranial nerves) Weekly: X-ray cervical spine Results Reduction in all cases Mean duration: 23,6 days (20-26 days) Mean weight: 43,7% of TBW (40-48%) No permanent neurovascular impairement

PRE POST Structural deformity

Fixation: Posterior HARMS Fusion (2x C1-C2 fusion & 1x C0-C2 fusion) Delayed referral Structural deformities Permanent instability One solution: SURGICAL FIXATION

Use of structural allograft Tabula externa of pelvis To promote bony consolidation 4 months postoperative

Postoperative care Immobilisation 6-8 weeks Halo Jacket 6 weeks soft collar Follow-up 6 weeks, 3 months, 6 months, 1 year X-ray at each visit, CT at 3 months-visit Follow-up until skeletal maturity (1x/year)

Results Follow up: 6-23 months No pain Reduced head rotation, but good function (physiotherapy) Complete bony fusion at 3-4 months

Conclusion Delayed diagnosis or referral leads to irreducible atlanto-axial rotatory displacement with structural deformities. Structural deformities inhibit a succesfull conservative treatment. Closed reduction with halo gravity traction is a promising and safe alternative for open transoral reduction. The posterior instrumented fixation and use of the structural autograft result in an effective one stage surgical treatment.

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