Search Results

Abstract

Objective—To determine the outcome of dogs and cats in which a tension band technique was used to stabilize traumatic fractures and luxations of the thoracolumbar vertebrae.

Design—Retrospective study.

Animals—38 client-owned animals (22 dogs and 16 cats) weighing between 1.4 and 45 kg (3 and 99 lb).

Procedure—Medical records of cats and dogs that underwent tension band stabilization of thoracolumbar fractures and luxations at the University of Zurich between 1993 and 2002 were reviewed. The stabilization technique was a modification of a spinal stapling technique with a figure 8 hemicerclage wire placed in a tension band fashion across the lesion. Neurologic status, lesion location and type, and concomitant traumatic injuries were assessed from the medical records and preoperative radiographs. Clinical outcome and complications were determined through follow-up examinations or telephone conversations with the owners.

Results—Complete or satisfactory neurologic recovery was achieved in 30 (79%) patients. Seven patients were euthanatized (6 owing to poor neurologic recovery and 1 owing to implant failure), and 1 dog was managed at home despite paraplegia. Clinically, only 4 patients (11%) had evidence of implant or fixation failure; all were dogs weighing > 16 kg (35 lb).

Conclusions and Clinical Relevance—Results suggest that the tension band technique may be appropriate for stabilization of fractures and luxations of the thoracolumbar vertebrae in cats and small- or medium- sized dogs. In larger dogs, fixation strength may be insufficient to stabilize certain fracture types and ancillary external or internal fixation methods may be needed. (J Am Vet Med Assoc 2004;225:78–83)

Abstract

Objective—To determine whether different suture configurations could improve the biomechanical performance of 3 suture materials used with bone anchors.

Samples—3 suture materials (60-lb test nylon leader line, size 2 polyblend polyethylene composite suture, and 150-lb test ultrahigh–molecular weight spun polyethylene).

Procedures—Each suture material was looped through the eyelet of a metallic bone anchor and constructs were evaluated by use of an acute uniaxial load. Three configurations were tested for each suture material: single stranded (SS), double stranded (DS), and single stranded plus plastic insert (SSP). Force at failure, extension at failure, force at 3 mm of extension, stiffness, and site of failure of the suture were recorded for each test.

Results—For all sutures, the DS configuration was the stiffest and yielded significantly higher forces at failure and forces at 3 mm of extension. The SS configuration had the lowest forces at failure. The SSP configuration yielded greater forces at failure for all suture materials, compared with the SS configuration, with a comparable stiffness. All sutures failed at the eyelet in the SS and DS configurations. In the SSP configuration, 60-lb test nylon leader line and 150-lb test ultrahigh-molecular weight spun polyethylene failed at the eyelet less frequently than did the polyblend composite suture.

Conclusions and Clinical Relevance—Among the tested constructs, a DS suture configuration used in combination with the metallic bone anchor gave the best biomechanical results for all suture materials. Considering that the SSP configuration yielded greater forces at failure, compared with the SS configuration, covering metallic edges in bone anchors with softer materials might protect sutures and result in increased forces at failure.

Abstract

Objective—To investigate a technique for repair of sacroiliac luxation with positional screw insertion from the ventral surface of the sacral wing via a ventral abdominal approach.

Sample Population—Hemipelvis specimens from cadavers of 5 small- to large-breed dogs and 9 European shorthair cats.

Procedures—An optimal entry point and a safe drill corridor for implant placement were determined (4 hemipelvis specimens). Anatomic landmarks were identified, and the surgical technique for a ventral abdominal approach was described. Single positional screw placement was performed across the sacroiliac joint in 23 hemipelvis specimens. Screws were aimed at 25°(n = 2), 35° (2), and 45° (19) angles to the vertical axis in a transverse plane (α angles) and at a 90° angle to the longitudinal axis in a dorsal plane (β angle). Implant placement was assessed by radiographic evaluation of the cadavers and of the hemipelvis specimens devoid of soft tissue.

Results—By use of α angles of 35° and 45°, 20 of 21 implants were placed adequately; screws crossed the sacroiliac joint and penetrated the wing of the ilium without damaging adjacent nerves. The measured median α angle was 38°, and the median β angle was 88°. One complication was recorded.

Conclusions and Clinical Relevance—Cortical positional screw placement from the ventral aspect of the sacral wing by use of a ventral abdominal approach could be an alternative to conventional techniques. This novel technique may be useful for repair of bilateral sacroiliac luxation, treatment of concomitant soft tissue injuries of the caudal portion of the abdominal cavity or abdominal wall, and repair of pelvic floor fractures in a single approach.

Abstract

Objective—To investigate sacroiliac luxation repair with positional screw insertion from the ventral surface of the sacral wing via a ventral abdominal approach in cats.

Animals—18 European shorthair cats.

Procedures—All cats underwent clinical examination including orthopedic and neurologic examination and assessment of lameness and pain before and immediately after surgery and 6 and 16 weeks after surgery. All sacroiliac luxations were stabilized with a single positional 2.4-mm cortical titanium self-tapping screw. The pelvic floor was also repaired in selected cats. Screw entry points and angles determined in a prior study of cadavers were used. Radiographs were taken before surgery and during follow-up evaluations to assess postoperative sacroiliac luxation reduction, implant placement, and repair stability.

Results—All implants were placed correctly. Iatrogenic sciatic nerve injuries occurred in 2 cats. Median time to ambulation was 1.5 days for cats with sacroiliac luxation as the sole injury. Radiographic outcome of sacroiliac luxation repair was excellent in 15 of 17 repairs, good in 1 of 17 repairs, and poor in 1 of 17 repairs. Clinical outcome was excellent in 11 of 15 cats and good in 4 of 15 cats.

Conclusions and Clinical Relevance—Insertion of a positional screw across the sacroiliac joint via a ventral abdominal approached can be an alternative to conventional techniques of sacroiliac luxation repair in cats. This novel technique allowed repair of bilateral sacroiliac luxation, repair of pelvic floor fractures, and treatment of soft tissue injuries of the abdominal cavity or abdominal organs with a single approach.

Abstract

Objective—To determine angles of insertion for laminar vertebral fixation of L1 and L2 by use of a locking plate in dogs and to confirm screw placement by use of computed tomography (CT).

Sample—Vertebral specimens harvested from 8 canine cadavers.

Procedures—The point of insertion and minimum and maximum insertion angles for laminar and facet screws for laminar vertebral stabilization were determined by use of CT. A precontoured locking plate was then placed by use of 1 locking screw in the lamina of each lumbar vertebra and 1 nonlocking screw in the facet joint. The position and angle of the screws were examined by use of CT, and penetration into the vertebral canal was recorded.

Results—Mean ± SD insertion angles for L1 and L2 were 18 ± 4° and 21 ± 5° toward the vertebral canal and 11 ± 4.4° and 10 ± 3° in a dorsal direction, respectively. Insertion angles for the facet joint were between 24 ± 4° ventrally and 12 ± 2° dorsally. Insertion of the screw did not penetrate the vertebral canal for 23 of 24 (96%) screws. For 23 of 24 inserted screws, the previously determined angle was maintained and purchase of bone and cortices was satisfactory.

Conclusions and Clinical Relevance—Placement of laminar and facet screws in canine vertebrae was possible and can be performed safely if angles of insertion determined pre-operatively via CT are maintained.