Methods: Radiograms of the 11 study subjects (six men and five women), aged 22–90 years who visited the outpatients’ clinic for various neck complaints without trauma history were examined. C4–5 synostosis was an incidental finding in all the subjects. Results: All the fused bodies were inwaisted and had anterior caudal breaking but no interior corporal flaring. Adjacent segment disease was not found in eight patients aged <40 years. Disk degeneration was found at C3–4 and C5–6 in three patients each and at C6–7 in two patients. Disk degeneration was limited to the adjacent segments. Conclusions Degenerative disk changes are associated with the natural aging process, and the corporal morphology of the fused vertebral becomes inwaisted similar to that in the single vertebrae.

Methods: Radiograms of the 11 study subjects (six men and five women), aged 22–90 years who visited the outpatients’ clinic for various neck complaints without trauma history were examined. C4–5 synostosis was an incidental finding in all the subjects. Results: All the fused bodies were inwaisted and had anterior caudal breaking but no interior corporal flaring. Adjacent segment disease was not found in eight patients aged <40 years. Disk degeneration was found at C3–4 and C5–6 in three patients each and at C6–7 in two patients. Disk degeneration was limited to the adjacent segments. Conclusions Degenerative disk changes are associated with the natural aging process, and the corporal morphology of the fused vertebral becomes inwaisted similar to that in the single vertebrae.