Bovine dowels for anterior cervical fusion: experience in 66 patients with a note on postoperative CT and MRI...

Anterior cervical discectomy and vertebral interbody fusion is a widely used technique in the treatment of radicular or cord compression. Instead of using autologous bone removed from the iliac crest, a heterologous bovine dowel was used for fusion. Sixty-six patients presenting with radicular pain or myelopathy were entered into the study retrospectively. Medial herniated, soft or calcified disc, osteophytes with and without herniated disc material, and bony stenosis at one or two levels were shown by CT or MRI studies. Postoperatively, 88% of the patients noted relief of pain and motor improvement. Most of the patients' sensory deficits and myelopathy improved within 6-12 months. No complications occurred and only one re-operation had to be performed at the same level. In the follow-up period between 1-4 years, no cases of instability after surgery were reported. Operating time and postoperative pain were reduced because bone harvest from the iliac crest was not necessary. In postoperatively performed CT and MRI, the bovine dowel was surrounded by a "halo"-like structure and the specific structure of the bovine implant was still present. No real bony fusion occurred, but clinical stability was equivalent to autologous bone fusion reported in the literature. However, there was no MRI evidence of "living bone tissue" within the bovine dowel. This finding is in contrast to the current belief that the bovine implant is replaced or infiltrated by bony growth.