Instrumented anterior lumbar interbody fusion with equine bone protein extract

Study Design. Randomized and self-controlled study with anterior lumbar interbody fusion in a porcine model. Objective. To determine the osteoinductive potential of an equine bone protein extract in anterior interbody spinal fusion. Summary of Background Data. Interbody spinal fusion with bone graft transplantation is a common spine procedure. Complications related to bone graft harvesting are still a major concern. Equine demineralized bone matrix has been reported to be osteoinductive. However, the application of equine bone protein extract in spine fusion has not been documented. In this experiment, we evaluated equine bone protein extract in a porcine spinal fusion model. Methods. Due to their size and availability, we chose 12 normal Danish landrace pigs, each weighing 50 kg, as our experimental animals. Lumbar spine interbody fusion of L3/4, L4/5 using titanium alloy cages and pedicle screws instrumentation was performed on each pig. Cages packed with either autograft or equine bone protein extract (COLLOSS (R) E; OSSACUR AG, Oberstenfeld, Germany) were randomly assigned to the 2 levels anteriorly. The pigs were followed for 3 months. After sacrifice, radiograph, microcomputed tomography, and histomorphometry were used to evaluate the spine segments. Results. All pigs went through the observation without major complications. Radiograph examination after 12 weeks revealed no implant breakage, loosening, or spinal deformity. Microcomputed tomography scanning showed that cages with COLLOSS (R) E had the same fusion rate (11/12) as those with autograft. Three-dimensional evaluation from microcomputed tomography found a significant difference only in trabecular thickness; trabeculae from COLLOSS (R) E-filled cages were much thinner (P = 0.04). Histologic evaluations demonstrated longitudinally formed bone trabeculae in both autograft and COLLOSS (R) E-filled cages. Bone volume calculation from histomorphometry correlates well with that from microcomputed tomography results (R = 0.5; P = 0.01). Conclusion. In this porcine model, COLLOSS (R) E is as effective as autograft for anterior spinal fusion.