Fig. 5

A 41-year old male patient diagnosed C4/5 disc herniation underwent anterior C4/5 discectomy and DCI arthroplasty. Transaxial CT of preoperative (a) and final follow-up (b) showed HO formation at the index level during follow-up. Sagittal CT at the final follow-up (c) illustrated the formation of an ossified bridge, which would restrict ROM of FSU. Also, the osteophyte narrowed the nerve root canal, causing pain and numbness of left arm. Symptom relieved after conservative treatment