Stabilization of a vertebral fracture by a monolateral external fixator placed percutaneously with fluoroscopy guidance in a rabbit (Oryctolagus cuniculus)

Abstract

CASE DESCRIPTION A 2-year-old intact male Mini Lop rabbit (Oryctolagus cuniculus) exhibited acute paraplegia and was suspected of having a traumatic spinal injury after leaping from the owner’s arms. CLINICAL FINDINGS In the physical examination, the patient was conscious and responsive and presented a loss of hind-limb motor function. The results of the neurologic examination indicated a T3-L3 spinal cord lesion. Vertebral column radiography and CT showed a fracture of the dorsal arch in the right caudal part of vertebra L1 and a fracture of the caudal end plate of vertebra L1 without displacement. TREATMENT AND OUTCOME The vertebral fracture was stabilized by a monolateral external fixator placed percutaneously with fluoroscopy guidance. The rabbit was discharged 48 hours after surgery. Three days later, the rabbit was able to walk with mild paraparesis, and 2 weeks after surgery, the rabbit showed full recovery of neurologic function. The follow-up performed 6 weeks after surgery showed normal gait, good alignment and complete consolidation of the fracture. The external fixator was then removed. The follow-up examination and radiographic findings showed complete recovery at 2 and 6 months after surgery. CLINICAL RELEVANCE The most common cause of traumatic posterior paralysis in rabbits is vertebral fracture. This article describes the possibility and successful outcome of stabilizing a vertebral fracture in a rabbit with an external fixator using a minimally invasive fluoroscopic technique. This technique, described to the authors’ knowledge for the first time in a rabbit, allows a fracture to be stabilized accurately without any incisions while minimizing complications and postoperative pain.

Computed Tomographic Evaluation of Safe Corridors for Pin Placement in Rabbit Thoracolumbar Vertebrae and Sacrum

“…6 In both cases, pin position remained static at 6 to 7 weeks as the rabbits demonstrated neurologic improvement. 5,6 Biomechanical studies in rabbit models comparing number of pins and unilateral versus bilateral constructs are necessary. The vertebral structures of rabbits are smaller compared to that of dogs and cats, which introduce their own set of challenges.…”

“…15 In the two case reports in which smooth pins and PMMA were used for spinal stabilization in rabbits, one was applied bilaterally (4 pins), 5 while one was applied unilaterally (5 pins). 6 In both cases, pin position remained static at 6 to 7 weeks as the rabbits demonstrated neurologic improvement. 5,6 Biomechanical studies in rabbit models comparing number of pins and unilateral versus bilateral constructs are necessary.…”

“…The use of intraoperative fluoroscopy for pin placement in rabbits has been proven to be successful and resulted in good outcome in one rabbit with nondisplaced vertebral fracture. 6 To engage maximal bone purchase, pins were targeted in the cranial and caudal end cortical bone where they contain the majority of the bone stock as the middle section tapers into a sliver of triangular protuberance. The small length of the ECS limited placement of multiple pins.…”

“…4 At this time, published information involving spinal stabilization in rabbits is limited to two case reports. 5,6 A 2.2 kg miniature lop with T12-L1 dorsal lamina synovial cyst was treated with a dorsal laminectomy and bilateral articular facet removal followed by stabilization with pins and polymethylmethacrylate (PMMA). This resulted in mildly improved clinical signs (weakly ambulatory paraparesis) 7 weeks after surgery compared to before surgery (nonambulatory paraparesis).…”

“…5 In the second case, a 2kg paraplegic miniature lop with positive nociception and a nondisplaced transverse L1 endplate fracture and was successfully treated with pins and epoxy resin external fixator under fluoroscopic guidance, resulting in normal neurologic function three months postoperatively. 6 Pin placements in rabbit vertebrae are feasible despite their small size; however, there are no guidelines for anatomic determination of safe corridors for pin insertion for spinal stabilization. Potential complications include inadequate engagement of the vertebrae and penetration into vital structures (spinal cord, aorta, colon).…”