Technique for C-1, C-2, and C-3 fixation in cases of odontoid fracture

Spinal fracture or luxation

Spinal trauma is a common cause of spinal cord dysfunction in dogs and cats. When the spine is injured by exogenous injury, the impact often results in vertebral fracture or luxation. As each injury is unique, treatment guidelines have to be individualized to the animal. This article reviews the clinical management including surgical and nonsurgical treatments for animals with vertebral fracture/luxation.

A clinical comparison of one- and two-screw odontoid fixation

OBJECT

The optimal treatment of Type II odontoid fractures is controversial. Various therapies have been used, including nonrigid immobilization, halo orthosis, posterior atlantoaxial arthrodesis, and odontoid screw fixation. Of these, odontoid screw fixation is the only treatment modality that provides immediate stabilization and preserves normal motion at C1-2. It has been suggested in cadaveric biomechanical studies that there is no advantage to using more than one screw for anterior odontoid fixation. The authors compared the clinical safety and efficacy of one- and two-screw anterior odontoid fixation.

METHODS

The authors retrospectively reviewed the medical records and radiographs of 42 consecutive patients who had undergone fixation for treatment of odontoid fractures at a single institution between 1989 and 1995. The group treated with a single screw consisted of 20 patients (11 males and nine females) with an average age of 54 years. The union rate in this group, as determined by postoperative dynamic radiographs, was 81%. The group treated with two screws consisted of 22 patients (13 men and nine women) with an average age of 64 years, whose union rate was 85%.

CONCLUSIONS

Anterior odontoid screw fixation is a safe and efficacious treatment for odontoid fractures. In the authors' experience there was no significant difference in the successful union rates achieved with either the one- or two-screw fixation techniques (81% and 85%, respectively; chi(2) = 0.09, p = 0.76).

Surgical management of atlantoaxial nonunions

Sixteen patients referred for atlantoaxial fixation failures were treated surgically with revision procedures during the past decade. Of these 16 patients, atlantoaxial instability occurred because of rheumatoid arthritis in five, as odontoideum in seven, transverse ligament disruption in two, and odontoid fracture nonunion in two. The 16 individuals (10 men, six women; mean age 43.7 years; age range 20-77 years) had undergone a total of 20 C1-2 internal fixation procedures that failed. Surgical strategies for definitive revision of the nonunions in these 16 subjects included 10 rigid internal fixations with transarticular screws, three revised C1-2 fixations with autogenous bone struts and wire or cables, and three extended fixations with occipitocervical instrumentation. Autogenous grafts were used in all revisions. A postoperative halo brace was used in five individuals with osteoporotic bone; all patients wore a restrictive postoperative cervical orthosis. Postoperatively, 15 patients (94%) had a stable construct (mean follow up 35 months; range 12-79 months), which included 13 osseous unions and two stable fibrous unions. One patient had nonunion; he fractured his anterior C1-2 transarticular screws 2 years postoperatively. He had occipital radicular pain without myelopathy but refused further surgery. Atlantoaxial pseudarthroses were effectively treated by addressing the pathological, biomechanical, and technical reasons for failed fusion. Successful fusion after reoperation was improved by using autologous bone grafts, adequately controlling atlantoaxial motion (with rigid transarticular screws internally or externally with a halo vest), compressing the bone grafts between the arches of C-1 and C-2 with wire cables, meticulously preparing the fusion bed, and by optimizing the pharmacological and clinical parameters to promote bone healing.

The acrylic-wire option in cervical spine fixation. A retrospective study

This retrospective study was undertaken to assess the stability of the cervical spine after fixation with acrylic wire implants. Of the 44 patients with various pathological conditions of the cervical spine selected for this treatment in the course of 20 years, 36 were considered suitable for long-term follow-up evaluation. In 30 cases (83%) the stability of the spine was rated good. It is concluded that the acrylic-wire combination is a valuable surgical option in certain conditions i.e. old age, short life expectancy, poor general health, mental disease, in which long confinement in bed or in orthopaedic appliances is poorly tolerated.

Surgical stabilization of cervical spinal fractures using methyl methacrylate. Technical considerations and long-term results in 52 patients

This study analyzes the long-term outcome of 52 consecutively treated patients with acute cervical spinal fracture/dislocation who underwent posterior surgical stabilization using methyl methacrylate in the absence of bone grafting. The patients ranged in age from 15 to 93 years. In 40 patients the injury was located in the lower cervical spine; for these a previously described surgical format was employed. In 12 patients the fracture involved C-1 or C-2, and the modification used for these injuries is presented. The postoperative period of evaluation ranged from 6 months to 12 years. There was one case of infection, which eventually required removal of the acrylic, but there were no instances of new neurological injury or of operative mortality. Failure of stabilization occurred in two previously reported patients treated early in the series. Comparison of the patient outcome in this study with that of certain other reports suggests that at least four technical factors are important for the success of methyl methacrylate stabilization: 1) the acrylic inlay must be provided with an anchor to bone; 2) the anchor must be of a type that does not easily erode through bone; 3) the inclusion of wire must be done in a manner that allows each strand to be completely encased in the acrylic; and 4) the cross-sectional area of the inlay is critical.

The interspinous method of posterior atlantoaxial arthrodesis

Thirty-six patients underwent C1-2 posterior wiring and fusion procedures over a 5-year period for unstable C-2 fractures (eight cases), unstable atlas-axis combination fractures (six cases), rheumatoid C1-2 instability (14 cases), os odontoideum (four cases), traumatic C1-2 ligamentous instability (three cases), or instability secondary to a C-2 tumor (one case). In each case, the atlantoaxial arthrodesis utilized sublaminar wire at C-1 and incorporated an iliac-crest strut-graft positioned between the posterior arches of C-1 and C-2, held in place by securing wire around the base of the spinous process of the axis. Follow-up examination was performed in all patients after a mean postoperative duration of 33.7 months. The technical aspects and clinical merits of this fusion procedure, which led to a 97% union rate (one nonunion) and minimal morbidity and mortality rates, are presented.

Posterior cervical reconstruction with methyl methacrylate cement and wire: a clinical review

The charts and radiographs of 20 patients who were treated for traumatic cervical instability by the Department of Neurosurgery at the University of Virginia by means of posterior reconstruction with methyl methacrylate cement and fixation wires were reviewed by the Department of Orthopaedic Surgery. Based primarily on radiographic criteria, it was found that posterior reconstruction failed to rigidly immobilize the underlying unstable motion segments in 11 patients. Four of these patients required additional surgery to correct postoperative instability. Based on this experience, cement and wire reconstructions are now recommended only when: 1) they can be limited to one cervical level; 2) No. 18 fixation wire is used; 3) wiring is performed from a facet on one side to the adjacent spinous processes; and 4) autogenous bone graft is added to the posterior elements on the side of the midline opposite the cement and wire.

Posterior acrylic surgical fixation of odontoid fractures

Fourteen cases of odontoid fractures had, as primary treatment, a posterior surgical fixation (C1 + C2 + C3 and occiput in some cases) by means of acrylate and stainless steel wires, without waiting for the unpredictable final results of external systems of stabilization. The youngest patient was 20 years old, the oldest 84 years old. No immediate or late neurological complications occurred (follow-up: one year to ten years). All the patients were mobilized early without external fixation. Union of the dens took place in eleven cases, and good stabilization in the remainder. Thirteen patients recovered, one improved. Posterior acrylic fixation is the treatment of choice in cases of odontoid fracture, particularly in elderly patients in whom a solid union rarely is obtained.

New steel device for occipitocervical fixation. Technical note

A new steel device for occipitocervical fixation is described. The system is easily and quickly applied, and affords a stronger and more secure means of attachment of the steel wires than using the occipital bone alone.