BOVINE DOWELS FOR ANTERIOR CERVICAL FUSION - EXPERIENCE IN 66 PATIENTS WITH A NOTE ON POSTOPERATIVE CT AND MRI APPEARANCE

Anterior cervical discectomy and vertebral interbody fusion is a widel y used technique in the treatment of radicular or cord compression. In stead of using autologous bone removed from the iliac crest. a heterol ogous bovine dowel was used for fusion. Sixty-six patients presenting with radicular pain or myelopathy were entered into the study retrospe ctively. Medial herniated, soft or calcified disc, osteophytes with an d without herniated disc material, and bony stenosis at one or two lev els were shown by CT or MRI studies. Postoperatively, 88% of the patie nts noted relief of pain and motor improvement. Most of the patients' sensory deficits and myelopathy improved within 6-12 months. No compli cations 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 ins tability after surgery were reported. Operating time and postoperative pain were reduced because bone harvest from the iliac crest was not n ecessary. In postoperatively performed CT and MRI, the bovine dowel wa s surrounded by a ''halo''-like structure and the specific structure o f the bovine implant was still present. No real bony fusion occurred, but clinical stability was equivalent to autologous bone fusion report ed in the literature. However, there was no MRI evidence of ''living b one tissue'' within the bovine dowel. This finding is in contrast to t he current belief that the bovine implant is replaced or infiltrated b y bony growth.