Atlantoaxial rotatory subluxation (AARS) represents a spectrum of instability involving the C1–C2 complex and accounts for a significant proportion of cervical spine rotation in children ^[1]. Approximately 50% of cervical rotation occurs at the atlantoaxial joint, predisposing it to instability when ligamentous or muscular support is compromised. Children are particularly vulnerable due to increased ligamentous laxity, horizontal orientation of the facet joints and underdeveloped cervical musculature ^[2,3] AARS commonly follows minor trauma or upper respiratory infection and presents with painful torticollis and the classic cock-robin posture. Acute cases are often reducible with rest, analgesia, traction, or immobilization. However, delayed presentation may result in adaptive facet changes and persistent muscular spasm, leading to irreducible deformity that necessitates surgical stabilization ^[4,5,6]. We present a case of chronic irreducible C1–C2 rotatory subluxation in a child successfully treated with posterior lateral mass fixation.

A 9-year-old female presented with painful abnormal head posture persisting for 6 weeks following a minor fall while playing. There was no history of fever, upper respiratory infection, congenital cervical anomaly, or inflammatory disorder.

Clinical findings

The head was tilted to the right with rotation of the chin to the left, consistent with cock-robin posture (Fig. 1). Cervical motion was markedly restricted and painful in all directions. Spasm and tenderness were present over the upper cervical region. Neurological examination was normal.

Figure 1: Clinical photograph demonstrating fixed torticollis with lateral flexion of the head to the right and rotation of the chin to the left (cock-robin posture). Facial features have been anonymized.

Radiological examination

Plain radiographs demonstrated asymmetry of the lateral masses. Computed tomography (CT) scan confirmed Fielding Type II C1–C2 rotatory subluxation with anterior displacement of C1 (Fig. 2 and 3). Magnetic resonance imaging (MRI) showed persistent malalignment without spinal cord compression (Fig. 4).

Figure 2: Pre-operative anteroposterior cervical spine radiograph demonstrating asymmetry of the C1 lateral masses relative to C2, suggestive of atlantoaxial rotatory subluxation.

Figure 3: Pre-operative computed tomography scan with three-dimensional reconstruction showing persistent rotation of the atlas (C1) relative to the axis (C2), consistent with Fielding Type II atlantoaxial rotatory subluxation.

Figure 4: Pre-operative magnetic resonance imaging of the cervical spine showing atlantoaxial malalignment without evidence of spinal cord compression.

Given the chronicity of 6 weeks and imaging findings, the deformity was considered irreducible.

Management

Initial conservative management included analgesics, cervical immobilization and activity restriction. No meaningful correction was achieved. Given the fixed deformity and failure to achieve reduction with conservative measures, the subluxation was considered clinically irreducible and surgical stabilization was planned.

Surgical technique

Under general anesthesia, posterior exposure of C1–C2 was performed with careful preservation of the vertebral artery and C2 nerve root. The Harms technique was preferred over transarticular screw fixation due to improved safety profile in pediatric anatomy and reduced vertebral artery risk. C1 lateral mass screws and C2 pedicle screws were inserted bilaterally under fluoroscopic guidance. Gentle intraoperative manipulation achieved restoration of alignment before rod fixation. Reduction was confirmed fluoroscopically before final tightening of the construct. Autologous bone graft was applied to promote fusion. Rigid fixation allowed stable correction of the deformity.

Outcome and follow-up

Immediate post-operative correction of head posture was achieved. Pain resolved significantly within days. Neurological function remained intact. Follow-up radiographs and CT imaging demonstrated maintained alignment and stable hardware position (Fig. 5).

Figure 5: Post-operative anteroposterior cervical spine radiograph demonstrating bilateral C1 lateral mass and C2 pedicle screw fixation with restoration of atlantoaxial alignment and stable hardware position.

At final follow-up, the patient resumed normal daily activities without recurrence.

AARS in children typically responds to early conservative treatment ^[1,2]. However, delayed presentation beyond several weeks increases the likelihood of persistent muscle contracture and facet remodeling, rendering reduction difficult or impossible ^[4,5,6]. Fielding Type II injuries involve unilateral facet subluxation with anterior displacement of C1, often requiring more aggressive management when chronic. CT imaging remains the gold standard for diagnosis and classification, while MRI is essential to assess ligamentous integrity and neural elements ^[1,2,7]. In irreducible cases, surgical stabilization is indicated to prevent progressive deformity, avoid neurological compromise and provide definitive correction. Posterior C1–C2 screw-rod fixation, as described by Goel and later modified by Harms, has largely replaced older wiring and transarticular techniques due to superior biomechanical stability, higher fusion rates, and improved safety profile ^[8,9,10]. Only limited literature describes chronic irreducible AARS requiring posterior C1–C2 fixation in the pediatric population. Shousha et al. ^[10] reported satisfactory long-term outcomes with posterior screw fixation in chronic cases. Our case further supports that rigid screw-rod stabilization provides reliable reduction and maintenance of alignment even after delayed presentation. In pediatric patients, careful screw trajectory planning is essential due to smaller anatomical dimensions and vertebral artery proximity. This case highlights that chronic painful torticollis following minor trauma should raise suspicion for atlantoaxial instability. Delay in diagnosis may convert a reducible condition into one requiring operative management.

Persistent painful torticollis in children warrants early advanced imaging to exclude atlantoaxial instability. Chronic irreducible rotatory subluxation requires surgical stabilization for definitive management. Posterior C1–C2 lateral mass fixation provides reliable correction, neurological safety, and excellent functional outcomes.

Early CT evaluation is essential in children with fixed torticollis. Chronic irreducible atlantoaxial instability is best managed with rigid posterior fixation to prevent long-term deformity and neurological compromise.