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146 Section III: Spinal Procedures

A

B C

Figure 15.8 Placement of transarticular screws for ventral atlantoaxial fixation. (A) A House curette (asterisk) is placed in the alar notch for directing the
angle of the screw placement from the midline. (B) Screw placements. (C) Once screws have been placed, the articular cartilage is removed and cancellous
bone graft is placed in the ventral articular space.

All the ventral techniques recognize the need for long‐term bony Surgical Complications
arthrodesis. A pneumatic drill or a #11 scalpel blade and small bone Ventral fixation has a higher rate of success but may predispose the
curette are used to remove the articular surfaces of C1 and C2. animal to a higher risk of surgical complications. Those reported
Cancellous bone autografts are used to promote osteogenesis, include iatrogenic neurological trauma, focal tracheal necrosis or
osteoinduction and osteoconduction [24]. Autographs or allo- perforation, aspiration pneumonia, implant failure, breakage, laryn-
graphs can be used. geal paralysis secondary to recurrent laryngeal neuropraxia, and
While odontectomy is described with the ventral approach, the Horner’s syndrome secondary to trauma of the vagosympathetic
procedure is considered difficult and necessitates more extensive trunk [34]. Dorsal complications are associated with similar cervi-
C1 and C2 body osteotomies. The technique may be required in cal myelopathic effects, implant failure/malalignment, and greater
cases of severely dorsally angulated dens. However, rigid stabiliza- pain morbidity due to muscle dissection [20]. The potential for
tion is often adequate as it prevents further mechanical trauma to many of these complications can be eliminated using the modified
the adjacent spinal cord [33]. right paramedian approach described by Shores and Tepper [24].