Do-not-miss-injury: conservative treatment of traumatic ligamentous atlantoaxial instability with unilateral rupture of the alar ligament and minor facet joint dissociation C1/C2.

Traumatic atlantoaxial instability resulting from an isolated ligament injury is exceptionally rare in adults. Isolated alar ligament ruptures have only been reported sporadically in the literature. These injuries are often misdiagnosed or overlooked, which can lead to delayed recognition and serious consequences for the patient's health and quality of life.We report the case of a previously healthy male professional ice hockey player who sustained a unilateral rupture of the left alar ligament accompanied by minor atlantoaxial facet joint dissociation following a high-speed collision during a tournament. The injury was managed conservatively with 12 weeks of rigid cervical spine immobilisation, multimodal analgesia and follow-up radiographic assessment 12 weeks after the injury.The patient made a full recovery and returned to competitive sports 5 months after the injury with no residual symptoms or functional limitations.