Comparison of Fusion Rates Based on Graft Material Following Occipitocervical and Atlantoaxial Arthrodesis in Adults and Children

Abstract

Administrative data regarding patients who underwent instrumented occipitocervical or atlantoaxial arthrodesis do not demonstrate differences in fusion rates based on the graft material selected. When compared to many contemporary primary datasets, fusion failure was more frequent; however, several recent studies have shown higher failure rates than previously reported. This may be influenced by broad patient selection and fusion failure criteria that were selected in order to maximize the generalizability of the findings.

The modified occipital condyle screw: A quantitative anatomic study investigating the feasibility of a novel instrumented fixation technique for craniocervical fusion

“…Craniocervical fusion is often indicated due to instability in the setting of acute trauma, but may also less commonly be related to pathologic fractures or destabilization from infection, neoplasm, inflammatory disease such as rheumatoid arthritis, or congenital malformations. [ 12 30 ] Overall fusion rate in occipitocervical arthrodesis with either occipital bone or condyle fixation nears 100%;[ 16 31 ] however, pseudarthrosis in the pediatric population was as high as 15%–18% with deep wound infection and skeletal dysplasias as notable risk factors. [ 16 20 32 ] Skeletal dysplasia involves a group of inherited disorders of the bone, which are frequently associated with craniocervical junction abnormities, such as odontoid dysplasia, basilar impression, basilar invagination, or atlantooccipital or atlantoaxial instability.…”

“…[ 12 30 ] Overall fusion rate in occipitocervical arthrodesis with either occipital bone or condyle fixation nears 100%;[ 16 31 ] however, pseudarthrosis in the pediatric population was as high as 15%–18% with deep wound infection and skeletal dysplasias as notable risk factors. [ 16 20 32 ] Skeletal dysplasia involves a group of inherited disorders of the bone, which are frequently associated with craniocervical junction abnormities, such as odontoid dysplasia, basilar impression, basilar invagination, or atlantooccipital or atlantoaxial instability. [ 33 ] These disorders include achondroplasia, Morquio´s syndrome, osteogenesis imperfecta, and others, predisposing to hardware failure and surgical fixation complications.…”

“…[ 1 13 ] In such cases, occipital condyle screw fixation, rather than occipital bone fusion, has emerged as an alternative approach or salvage technique. [ 14 15 ] While fusion rates for both occipital bone and occipital condyle fixation have been reportedly high in pediatric and adult patients,[ 15 16 17 18 19 ] a subset of patients with skeletal dysplasia and other congenital anomalies of the craniocervical junction are at particular risk for pseudarthrosis and implant failure. [ 20 21 ]…”

Trabecular volumetric bone mineral density of the occipital bone at preferred screw placement sites measured by quantitative computed tomography

“…Fusion rates for this type of fixation were reported to range from 74% to 100% with the use of bone graft. 15,[17][18][19][20][21] Several studies investigated the morphology of the occipital bone and concluded that its maximum thickness was at the external occipital protuberance (EOP), [22][23][24][25][26][27][28] which is a bony landmark easily recognizable on the outer surface and on imaging. Heywood et al 29 suggested the optimal occipital screw length to be 8 mm, which is why safe zones for screw placement were defined based on bone thickness > 8 mm.…”

“…Furthermore, the greatest stability was achieved with a combination of an occipital plate‐subaxial rod system and C2 pedicle screws. Fusion rates for this type of fixation were reported to range from 74% to 100% with the use of bone graft 15,17–21 . Several studies investigated the morphology of the occipital bone and concluded that its maximum thickness was at the external occipital protuberance (EOP), 22–28 which is a bony landmark easily recognizable on the outer surface and on imaging.…”