Spontaneous Anterior Arch Fracture of the Atlas Following C1 Laminectomy in a Patient With Osteopetrosis: A Case With Five Years of Follow-Up.

Osteopetrosis is a rare group of genetic disorders characterized by excessive bone density due to impaired osteoclast function and can lead to various complications, including fractures and immune dysfunction. We describe the case of a 63-year-old man with osteopetrosis who presented with cervical discomfort and was diagnosed with an anterior arch fracture of the atlas, a rare spontaneous fracture following C1 laminectomy. Initially, no neurological abnormalities were observed, and imaging confirmed the continuity of the transverse ligament. Thus, the decision was made to follow the natural course in the absence of instability. Conservative treatment with a cervical collar was initiated, and the fracture gap began to fill by three years postoperatively, though nonunion persisted at five years. The patient remained asymptomatic and did not require further surgical intervention. This case highlights that stress concentrated on the anterior arch of the atlas due to the unique bone quality in osteopetrosis, and the subsequent natural course of the fracture did not require additional surgical treatment. Careful follow-up is essential to monitor for any pathological changes.