[Vertebral artery dissection due to a bone anomaly of the superior facet of C6: a rare cause of embolic stroke].

We report a rare case of repeated vertebral artery (VA) occlusion. The VA occlusion was due to a distal embolism originating from traumatic VA dissection resulting from mechanical compression due to excessive bone formation of the superior facet of C6. A 39-year-old male suffered from two embolic events in the right VA with a 4-month intervals. Three-dimensional computed tomography (3D-CT) revealed abnormal bone of the superior facet at the level of C6 and the verterbral artery compression. Angiography demonstrated the irregularity and the late clearance of the contrast material at the stenosis of VA, which was diagnosed as the dissection. Dynamic angiography showed right VA occlusion when rotating the patients head to the left and extending it backwards. External orthosis using a cervical collar for 1 month was undertaken, but the dissection remained, so coil embolization of the right VA was performed using an intravascular procedure. Because of the age of the patient, location, radiological features and clinical course, the authors considered the excessive bone formation was a bone anomaly rather than a cervical spondylotic change.

A novel method to evaluate vertebral remodeling by radiography following anterior cervical decompression and interbody fixation with cylindrical cages: a contrast-comparing method using "Scion image".

In an attempt to study bone remodeling by noninvasive methods, spinal bone radiodensity was assessed in five patients treated with anterior cervical decompression and fusion (ACDF) using cylindrical titanium cages. Plain radiographs were used to study specific areas of vertebral bone interposed in two-level cages with the two cephalad vertebrae for controls. Measurements were made immediately after surgery and 1, 3, 6, 12 and 18 months postoperatively. The data were analyzed quantitatively with a contrast-comparing method (CCM) using "Scion image". There were two cyclical changes in vertebral remodeling. First, in all patients there were gradual increases in bone density at the ventral part compared to the dorsal part of the vertebral body for up to 12 months; then the density decreased at 18 months. Second, a linear gradient in radiodensity from the ventral part to the dorsal part of the vertebral body observed immediately following spinal fusion gradually disappeared by 12 months; nonhomogeneous distributions of trabecular bone were appeared. Then, the linear gradient in density appeared again at 18 months. This investigation helps elucidate the radiographic evidence for the remodeling of vertebral bone in patients treated with ACDF.

Beta-tricalcium phosphate as a substitute for autograft in interbody fusion cages in the canine lumbar spine.

OBJECT: An interbody fusion cage has been introduced for cervical anterior interbody fusion. Autogenetic bone is packed into the cage to increase the rate of union between adjacent vertebral bodies. Thus, donor site-related complications can still occur. In this study a synthetic ceramic, beta-tricalcium phosphate (TCP), was examined as a substitute for autograft bone in a canine lumbar spine model. METHODS: In 12 dogs L-1 to L-4 vertebrae were exposed via a posterolateral approach, and discectomy and placement of interbody fusion cages were performed at two intervertebral disc spaces. One cage was filled with autograft (Group A) and the other with TCP (Group B). The lumbar spine was excised at 16 weeks postsurgery, and biomechanical, microradiographic, and histological examinations were performed. Both the microradiographic and histological examinations revealed that fusion occurred in five (41.7%) of 12 operations performed in Group A and in six (50%) of 12 operations performed in Group B. The mean percentage of trabecular bone area in the cages was 54.6% in Group A and 53.8% in Group B. There were no significant intergroup differences in functional unit stiffness. CONCLUSIONS: Good histological and biomechanical results were obtained for TCP-filled interbody fusion cages. The results were comparable with those obtained using autograft-filled cages, suggesting that there is no need to harvest iliac bone or to use allo- or xenografts to increase the interlocking strength between the cage and vertebral bone to achieve anterior cervical interbody fusion.

Beta-tricalcium phosphate combined with recombinant human bone morphogenetic protein-2: a substitute for autograft, used for packing interbody fusion cages in the canine lumbar spine.

Beta-tricalcium phosphate (beta-TCP) combined with recombinant human bone morphogenetic protein-2 (BMP-2) was examined as a substitute for autograft for packing into interbody fusion cages in the canine lumbar spine model. Discectomy and interbody cage fusion were performed at three disc spaces in eight dogs. Examination of microradiographs and histological sections of the lumbar spine at 16 weeks postsurgery revealed three fusions in the autograft cages (Group A), three in the beta-TCP cages (Group B), and five in the beta-TCP-BMP-2 cages (Group C). The mean percentage of trabecular bone area in the cages was 51.9% in Group A, 48.8% in Group B, and 65.6% in Group C. Mean percentage of trabecular bone formation and mechanical stiffness were highest in the cages filled with beta-TCP and BMP-2. Combination of BMP to beta-TCP may act as an osteoconductive and osteoinductive bone graft substitute in clinical spine surgery.