In vivo evaluation of bioresorbable polylactide implants for cervical graft containment in an ovine spinal fusion model.
OBJECTIVE
An in vivo study was conducted in an ovine model to investigate the biomechanical changes after the animals underwent single-level anterior cervical discectomy followed by fusion in which autologous tricortical graft was used and implantation of cervical plates for which bioresorbable polymer screws and plates were used. The specific aims of the study were to evaluate whether implant failure or screw backout would occur over time and to measure the change in stiffness at the treated level at various postoperative time periods (3, 6, and 12 months).


METHODS
A total of 58 x-ray films were evaluated over the 12-month survival period. No screw breakage or displacement was observed in any animal during the temporal radiographic analysis. Radiographically confirmed fusion appeared to be complete at all time periods longer than 6 months. The biomechanical testing demonstrated dramatic reductions in range of motion at the fusion level in the animals allowed to survive for 6 and 12 months, indicating complete fusion after 6 months.


CONCLUSIONS
The bioresorbable polymer cervical graft containment system appears to provide a safe and effective alternative for cervical fusion, and warrants further clinical evaluation for its use in single-level anterior cervical discectomy and fusion without postoperative orthosis.
Cornwall
G Bryan
GB
MacroPore Biosurgery, Incorporated, San Diego, California, USA.
Ames
Christopher P
CP
Crawford
Neil R
NR
Chamberlain
Robert H
RH
Rubino
Anthony M
AM
Seim
Howard B
HB
Turner
A Simon
AS
D020341:Absorbable Implants; D000818:Animals; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D023421:Models, Animal; D011108:Polymers; D011859:Radiography; D016059:Range of Motion, Articular; D012756:Sheep; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D016474:Weight-Bearing
D011108:Polymers