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Veterinary Forum July 2009 (Vol 26, No 7)

Surgical Update — L7 Vertebral Fracture

by Aaron Wehrenberg, DVM

    Editor's Note: This case report demonstrates the success that is possible when treating patients with spinal fractures, especially fractures low in the lumbar area. Because damage often involves nerve roots rather than the spinal cord, the injury responds well to treatment. In some cases involving minor deficits, cage rest may be appropriate. When surgery is appropriate, reduction and realignment of the vertebral segments are important; laminectomy is not always necessary. — Don R. Waldron, DVM, DACVS, Column Editor

    Henley, a 3-year-old, neutered shih tzu, presented to the emergency service at VCA Northwood in Indianapolis for paralysis of the pelvic limbs. A good Samaritan who had found Henley brought the dog to the Humane Society for Hamilton County (Figure 1), and the organization's veterinarian had subsequently referred the animal.

    Referral radiographs showed that Henley had sustained an L7 vertebral body fracture with the sacrum luxated ventrally and cranially (Figure 2). Neurologic examination showed normal reflexes to the pelvic limbs, with a lower motor neuron (LMN) bladder and absent perineal reflex. The forelimbs and cranial nerves were within normal limits. Motor activity was absent in the tail, and the dog had conscious proprioceptive deficits of both pelvic limbs, with no motor activity in either limb. The dog was classified as a nonambulatory paraplegic with deep pain intact bilaterally. Surgery was elected.

    The results of thoracic radiography, electrocardiography, and blood work were within normal limits. Abdominal radiography suggested an intact bladder, and ultrasonography of the abdomen found no free fluid.

    Pain medication consisted of constant-rate infusion (CRI) morphine. Intravenous fluid therapy and strict rest for 2 days were elected to allow signs of shock to subside before surgery.

    At surgery a dorsal approach to the lumbosacral junction was elected. Reduction of the fracture and lumbosacral junction was achieved by aligning the lumbosacral articular facets, which were secured by placing two 2.7-mm screws across the facets into the sacrum and ilium. Before screw placement, the articular cartilage was removed from both joints. Dorsal laminectomy of the L7 vertebrae was performed to accommodate cauda equina swelling. Before relocation, the spinal cord and cauda equina had deviated approximately 60° ventrally, and some of the cauda equina nerve roots were injured (severe contusions).

    Postoperative radiography revealed good fracture alignment and screw placement (Figure 3). A fentanyl patch was placed, and CRI morphine was continued during recovery in the ICU.

    Approximately 12 hours after surgery, the patient was able to walk around its cage, and 2 days after surgery, the patient had regained the ability to urinate and defecate normally. The perineal reflex was normal.

    At the 2-week follow-up for staple removal, the dog had fully recovered, showed no neurologic deficits, and had no urinary or fecal issues. The dog was strictly confined for an additional 6 weeks, at which time the neurologic examination found no abnormalities. Henley has since been adopted.


    Lesions of the lumbosacral spinal area typically lead to pelvic limb deficits.1 Urinary and/or fecal incontinence is a result of injury to the pelvic and pudendal nerves, and typically the patient demonstrates a lower motor neuron bladder.1 The presence of urinary or fecal incontinence may be permanent or may resolve slowly.

    Different surgical procedures for the management of caudal lumbar fractures have been described. For this case, dorsal laminectomy and fusion through the articular processes of L7 and S1 were elected. Extending screw placement into the body of the sacrum and the adjacent ilium offered the best option for recovery. As with fusion of any joint, removal of the articular cartilage from the facet joints is required to form a solid union.1 Bone removed from the dorsal laminectomy — primarily from the dorsal spinous process of L7 — was saved to be used as a bone graft at the sites of fusion.2 A dorsal laminectomy was performed both for the bone grafting procedure and to allow better visualization of the cauda equina.

    Screw placement is critical for ensuring proper alignment and preventing impingement on any nerves of the cauda equina. After the dorsal laminectomy, the L7 and S1 facets are aligned by fracture reduction. (Fracture reduction and realignment often can be difficult; an assistant can help with traction of the tail outside the operative field.) The screw holes are then drilled through the facets from the dorsomedial aspect of the L7 facet into the sacrum in a ventrolateral orientation.2 The ideal angle for placement of the two screws is approximately 30° to 45° from the sagittal plane.2 Because of the severity of the luxation and difficulty in proper alignment in this case, both screws were placed in a lag fashion to pull the sacrum dorsally, thereby achieving better anatomic alignment. Before the screws were completely tightened, the previously harvested bone graft was placed where the articular cartilage had been removed from each facet junction.

    As with any spinal cord injury, pain management is critical before and after surgery. Treatment for other underlying conditions also is necessary before surgery. Patients that present with severe injuries to the spinal cord and surrounding vertebrae typically have undergone extensive trauma, and it is essential that shock and other confounding problems (e.g., pneumothorax, urinary system compromise, diaphragmatic hernia, ventricular tachycardia) be treated before surgical fixation is attempted. In addition, proper handling of the patient is critical to prevent further damage to the spinal cord and its branching nerves.

    1. Nicholas JH, Wheeler SJ. Small Animal Spinal Disorders: Diagnosis and Surgery, ed 2. Toronto, Canada: Elsevier; 2005:183-209.

    2. Slatter D. Textbook of Small Animal Surgery, ed 3. Philadelphia: Saunders; 2003:1238-1243.

    References »

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