Osteogenic Protein Versus Autologous Interbody Arthrodesis in the Sheep Thoracic Spine

Abstract

Interbody spinal fusions showing biomechanical and histomorphometric equivalency to autologous fusions have been achieved with rhOP-1. The functional unit stability and histologic osteointegration evidenced by the BAK/rhOP-1 complex shows this interbody arthrodesis technique to be a viable alternative toconventional autologous iliac crest, thereby obviating the need for an iliac crest donor site and associated patient morbidity.

Orthopaedic applications of osteogenic protein-1 (BMP-7)

“…Computed tomography (CT) and microradiography showed fusion for the destabilization alone group in one of six, BAK-cage alone in two of six, autograft alone in four of eight, BAK-cage plus autograft in five of eight and BAK-cage plus OP-1/collagen carrier in six of eight. This was confirmed histologically [15]. Taken together these studies suggested that OP-1 provided a viable alternative for iliac crest autograft in animal models; thereby obviating the need for a graft donor site and associated patient morbidity.…”

“…The bone density of the OP-1 induced fusions exceeded the bone density of fusions in the autograft group by an average of 40% indicating that the use of OP-1 can increase the reliability of dorsal vertebral interbody fusion, the degree of bone density in the area of the fusion, and can also lead to greater bone formation at earlier stages as compared with autograft in sheep [28]. Cunningham et al [15] compared the efficacy of OP-1 with that of autograft for interbody arthrodesis by application of BAK-cages in the thoracic spine. For this he performed a multilevel thoracic decompression on three non-contiguous levels by thoracoscopic approach in 12 sheep.…”

Comparison of plain radiographs with CT scan to evaluate interbody fusion following the use of titanium interbody cages and transpedicular instrumentation

“…Cunningham et al [8], in their study of rhOP-1 using BAK cages in sheep thoracic spine, found a 100% correlation between CT and histological microradiographs in the BAK-autograft group. They were able to demonstrate at 4 months in all specimens classified as fused, definitive evidence of contiguous well-organized bony trabeculation through the BAK cages spanning the fusion site from the adjacent vertebral bodies.…”

“…-CT scan: This was defined as the presence of bridging bony trabeculation through the cage from endplate to endplate without evidence of lucency along either margin as suggested by Cunningham et al [8] and visualized on the sagittal and coronal MPR scans. This was also very well demonstrated by Kuslich et al [18] in one of their patients who had a CT scan.…”

CT-based classification of long spinal allograft fusion

“…CT imaging also correlates well with histology and micro-radiography, implying that high quality computerized tomography can be as accurate as open surgical exploration in the assessment of fusion status [9]. Cunningham et al [7] in their study of rhBMP-1 using BAK cages in sheep, found a 100% correlation between CT imaging and histological microradiographs in the BAKautograft group. They were able to demonstrate in all specimens classified as fused at 4 months definitive evidence of contiguous well-organized bony trabeculation through the BAK cages spanning the fusion site from the adjacent vertebral bodies.…”