Graft Dislocation Research Articles

Surgical outcome of single segment ventral fusion with plate osteosynthesis in therapy refractory chronic cervico-brachialgia

In anterior cervical stabilization, collapses of the grafted bone with resulting localized kyphosis and graft dislocation has been reported. It was the aim of this clinical trial to evaluate the benefit of additional plating while taking specific implant-related complications into account. The results of single level anterior cervical spinal fusion were evaluated. In 44 patients suffering from chronic cervical radicular pain with degenerative changes, arthrodesis with iliac-crest bone and plate fixation was performed. Apart from clinical parameters, the pre- and postoperative segmental kyphosis and cervical lordosis were evaluated. The total cervical alignment increased from 15.4 degrees to 18.5 degrees while the alignment of the fused segment increased from 2.6 degrees to 7.7 degrees. Postoperative decrease of correction did not occur. Bony fusion was confirmed in 95% after 12 months and 100% aller 36 months. Our results show that patients had more relief from radicular pain (80%) than from unspecific neck pain (66%). In single level anterior cervical fusion, additional plating successfully prevents dislocation of the bone graft and postoperative kyphosis. The clinical results and pseudarthrosis rate do not differ from studies without plating. Long. term follow-up studies are necessary to show the benefit of the reduced postoperative kyphosis.

Meniscal regeneration or meniscal transplantation?

Owing to the initial necrosis to which any freely transplanted biological graft is subjected, meniscus transplantation is based on similar principles to meniscal regeneration. Both methods rely on repopulation of extrinsic cells of the graft. In the former procedure a biological matrix (meniscus, tendon, fatpad) is used as graft (scaffold), whereas in meniscal regeneration commercially available resorbable or non-resorbable scaffolds are implanted. However, the cellular (re)population and (re)vitalization process is deleterious rather than beneficial for the function of the graft as the remodelling of the tissue leads to shrinkage and narrowing of the implant. In addition, improper fixation and subsequent elongation of the anterior and posterior bony attachments leads to peripheral graft dislocation, loss of the load distribution function, and subsequently to cartilage degeneration. Hence, meniscus transplantation or regeneration faces two major problems: 1) remodelling of graft to inferior tissue properties after allograft transplantation, or lacking establishment of normal tissue properties after use of biological matrixes other than the meniscus (fatpad, tendon), or commercially available matrixes; 2) improper fixation with elongation of the anterior and posterior attachments. Furthermore, use of allografts incorporates the risk for disease transmission. Today we are unable to control these problems, and therefore the concept of meniscal replacement does not work yet. Further research is necessary to control remodelling and improve fixation to make this procedure a successful one in the future.

Polyethylene terephthalate and polyurethane coatings for endovascular stents: preliminary results in canine experimental arteriovenous fistulas.

To evaluate polyethylene terephthalate and polyurethane as coatings of vascular endoprostheses in the treatment of experimental arteriovenous fistulas (AVFs). Nineteen bilateral carotid artery-to-external jugular vein AVFs were created in 10 adult dogs. Fourteen polyethylene terephthalate-coated and five polyurethane-coated self-expandable nitinol stents were placed with a transfemoral approach. Angiography was performed immediately after placement, after 1 and 3 weeks, and at months 3, 6, 9, and 12. All grafts were examined histopathologically. The AVF was successfully occluded with all but one of the polyethylene terephthalate-coated stents. Graft patency was seen with 12 polyethylene terephthalate-coated stents, while acute vessel occlusion was evident with two polyethylene terephthalate-coated stents following percutaneous transluminal angioplasty immediately after implantation. In the group with polyurethane-coated stents, three graft dislocations and two delayed vessel occlusions were observed. In both groups, histologic examination disclosed a mild foreign body reaction with a few macro-phages. No inflammatory reactions were seen. An unorganized fibrin layer was found adjacent to the polyurethane coating. Polyethylene terephthalate-coated nitinol stents showed good biocompatibility and a high rate of occlusion of experimental AVFs. The mechanical properties of the polyethylene terephthalate coating were similar to those of the nitinol stents, which facilitated handling. Polyurethane-coated stents showed frequent dislocation.

Silicone gel sheet dressings for prevention of post-minigraft cobblestoning in vitiligo.

Punch grafting was performed in 15 patients using punches varying in size from 2 to 3 mm in diameter. Silicone gel sheets were used as a post-operative dressing. Removal of the dressings after 7 days revealed no lifting of grafts in 13 patients. A minimally raised surface seen in two patients flattened after 6 to 8 weeks of continuous use of the dressing. At two months of follow-up, no cobblestoning or any other untoward effect was evident. Firm pressure provided by silicone gel sheets probably prevents cobblestoning by counteracting forces which tend to lift the grafts. Additionally, the sheets act as a brace preventing graft dislocation, provide a sterile atmosphere underneath the grafts, facilitate periodic observation due to their transparency, and are easily removed at the time of follow-up.

Histomorphological examination of endoluminal stent grafting in the descending aorta in a sheep model.

Experiments were designed to examine the wound healing characteristics at the aorta-endograft interface. Thoracic aneurysms were induced in sheep and excluded by endovascular placement of a selfexpanding stent graft (Corvita Endovascular Graft). After a follow-up of 1, 4, or 12 weeks sheep were sacrificed and the corresponding segments of the aorta were subjected to histological examinations. Histomorphological evaluation of all groups underlined sufficient exclusion of lesions of the aortic wall by endovascular grafting. There was no evidence of proximal or distal leakage, graft dislocation or migration. The results appeared to be evidence that the endoluminal stent graft may be incorporated by the host aortic tissue.

The value of fibular intersomatic fusion in the treatment of recent cervical spinal cord injuries.

A Series of six patients with recent cervical spine fracture and spinal cord injury treated by corpectomy and fibular strut graft is presented. Three patients had a complete sensorimotor tetraplegia and the other three had an incomplete sensory but complete motor lesion. All patients had fractures of one or two adjacent vertebrae with concomitant displacement which was corrected by skull traction prior to surgery. Gas myelography in three patients revealed herniated disc material in two instances. Corpectomy and fusion were carried out on the 12th, 13th, 29th, 32nd, 33rd, and the 58th post-traumatic day. There was no immediate mortality or major complication associated with the procedure. One late death in an elderly patient 6 months post-operatively is felt to be unrelated to the procedure. In this series gas myelography was carried out at a later date following the injury. The goal of the operation was therefore not primarily to decompress the cord but to stabilise the fractured spine in order to allow earlier mobilisation than traditional treatment in traction. Average time out of bed was 9 days post-operatively and 36 days post-injury. Solid fusion sufficient to allow discontinuation of all neck support was achieved in 3 months in all patients. There were no episodes of graft displacement or dislocation and in only one patient was there a moderate increase in angulation at the fracture site. In the patient who died 6 months postoperatively gross and histologic examinations showed incorporation and union at the ends of the graft and bridging of the injured area by new bone. The authors feel the above procedure in selected patients—six out of 62 patients admitted with cervical spine and spinal cord injury within 4 weeks of trauma during the past 39 months—is an important adjunct to the treatment and rehabilitation at their spine fracture and spinal cord injury.