pISSN 1598-298X / eISSN 2384-0749 J Vet Clin 34(2) : 115-118 (2017)
http://dx.doi.org/10.17555/jvc.2017.04.34.2.115
115
Pin and Bone Cement Fixation of Fifth-Sixth Lumbar Vertebral Fracture-Luxation in a Korean Goral (Nemorhaedus caudatus)
Seong-jae Choi, Jong-taek Kim, Yeon-su Oh and Byung-Jae Kang1
College of Veterinary Medicine and Institute of Veterinary Science, Kangwon National University, Chuncheon 24341, Korea (Received: February 16, 2017 / Accepted: April 10, 2017)
Abstract : A Korean goral (immature, female) was presented with paraplegia following motor vehicle trauma. The patient was diagnosed with an L5-6 vertebral fracture-luxation based on digital radiographs. Surgical reduction and stabilization of the fracture-luxation were performed via a dorsal approach to the lumbar spine. It was confirmed in surgery that the patient had L5-7 spinous process fractures, L6 bilateral articular process fractures, and an L5-6 luxation.
Free fragments were removed and the luxation was reduced. During reduction, caudodorsal dislocation of the L5 caudal vertebral end plate was discovered and the displaced end plate was removed. The L5-6 vertebral luxation was stabilized using pins and bone cement. However, the presence of an intact spinal cord was not confirmed. Two weeks postoperatively the patient became dyspneic and arrested. A necropsy was performed, which revealed that the surgical stabilization was intact. Pulmonary edema was identified and the immediate cause of death was determined to be systemic inflammatory response syndrome.
Key words : Vertebra, Fracture, Luxation, Goral, Nemorhaedus caudatus.
Introduction
Korean gorals (Nemorhaedus caudatus raddeanus) are widespread across the Korean peninsula and are found pri- marily in the mountainous areas (8). Fracture-luxations are common in wild animals following motor vehicle trauma (15). In small animal medicine, spinal surgery is seldom rec- ommended if deep pain perception (DPP) has been absent for more than 48 hours (17). In DPP negative cases, many sur- geons recommend medical management or euthanasia due to a poor prognosis for return to function. Although the Korean goral in this report had no DPP, we performed surgery in an effort to improve her level of comfort because the Korean goral is designated a natural monument species (No. 217) by the Cultural Heritage Administration of Korea and is also classified as endangered wildlife grade I by the Ministry of Environment of Korea (10). There are many proposed tech- niques for stabilization of vertebral fracture-luxations. Dor- sal stabilization of spinal fractures using pins and PMMA is a well-described and commonly used technique in the tho- racic and lumbar spine (3,16,19). In this report, we used six pins combined with polymethylmethacrylate (PMMA) for stabilization.
Case
A paraplegic Korean goral (immature, female) weighing 18 kg was rescued and brought to the Kangwon Wildlife Rescue Center at Kangwon National University. Cause of the
fracture-luxation was reported to be motor vehicle trauma.
Physical and orthopedic examinations revealed pain and crepi- tus in the lumbar spine and neurologic deficits in the hind limbs. Radiographs of the lumbar spine showed an L5-6 ver- tebral fracture-luxation (Fig 1). Surgical reduction and stabi- lization was performed via a dorsal approach to the lumbar spine. It was confirmed during surgery that the patient had L5-7 spinous process fractures, L6 bilateral articular process fractures, and an L5-6 fracture-luxation. Free bone fragments were removed and the luxation was reduced using a combi- nation of a periosteal elevator and hemostatic forceps. The instruments were placed carefully in the interarcuate space to lever L5 caudodorsally into its appropriate anatomic loca- tion. During reduction, caudodorsal dislocation of the L5 caudal vertebral end plate was discovered and the displaced end plate was removed (Fig 2). Reduction was temporarily maintained by placing 1.4 mm Kirschner wires across the articular processes of the L5-6 joint. Before inserting Stein- mann pins, a Kirschner wire was used to probe the cancel-
1Corresponding author.
E-mail: bjkang@kangwon.ac.kr
Fig 1. Lateral (A) and ventrodorsal (B) radiographs demonstrat- ing L5-6 fracture-luxation.
116 Seong-jae Choi, Jong-taek Kim, Yeon-su Oh and Byung-Jae Kang
lous bone of the pedicle to ensure that the pins would not compromise the cortex of the medial pedicle. Definitive sta- bilization was achieved using 1.2 or 2.5 mm positive profile
end-threaded Steinmann pins across each vertebral body at L5-6. The size of the individual pins was left to the sur- geon’s discretion. All pinholes were predrilled with an appro- Fig 2. Intraoperative view of caudodorsal dislocation of L5 caudal vertebral end plate. The white arrow is pointing to the vertebral end plate.
Fig 3. Intraoperative view of pins and bone cement engaging L5 and L6, used to stabilize an L5-6 luxation.
Fig 4. Immediate postoperative lateral (A) and ventrodorsal (B) radiographs.
Pin and Bone Cement Fixation of Fifth-Sixth Lumbar Vertebral Fracture-Luxation in a Korean Goral (Nemorhaedus caudatus) 117
priate sized drill bit. A depth gauge was used to measure the depth of the hole. This same distance then was measured along the threaded portion of the pin to determine the proper depth of insertion. All pins were cut and the exposed portions were bent to achieve maximum overlap of the pins. PMMA (Depuy, CMW 1) mixed with 1 g of sterile powdered cefazo- lin sodium was applied dorsally to bond the pins (Fig 3).
Curing PMMA was cooled with sterile saline (0.9% NaCl) solution. Epaxial fascia, subcutaneous tissue, and skin were closed routinely. The patient was administered cefazolin sodium (22 mg/kg) and Tramadol (4 mg/kg) intravenously at the induction of anesthesia and every 12 hours until recov- ered. Ventrodorsal and lateral radiographs were obtained immediately after surgery to assess reduction of the fracture- luxation and pin placement (Fig 4).
Postoperative management included injectable antibiotics and analgesics. Recovery took place at the Kangwon Wild- life Rescue Center. Two weeks postoperatively, the patient suddenly became dyspneic and arrested. A postmortem exam- ination was referred to the pathology laboratory. A necropsy was performed which revealed that the surgical stabilization was intact. Grossly, serous atrophy was observed around the heart; pulmonary congestion and pleural effusion were also noted. The effusion was characterized as a brown, turbid exu- date and was found together with fibrinous pleuritis. A simi- lar appearing effusion was discovered in the abdominal cavity; fibrinous serositis and intestinal congestion were observed as well. The immediate cause of death was deter- mined to be systemic inflammatory response syndrome.
Discussion
We described reduction and stabilization of an L5-6 verte- bral fracture-luxation in a Korean goral using pins and bone cement. Various techniques have been described for the treat- ment of vertebral fractures in veterinary orthopedics. Of these, pin and bone cement fixation has commonly been used for vertebral fracture-luxation in dogs and cats.
Fractures and dislocations of the thoracic and lumbar spine in dogs can present as back pain alone or can be combined with neurological deficits ranging from mild ataxia to para- plegia. This may be accompanied by urinary dysfunction and loss of DPP (6). Vertebral fractures and dislocations are one of the major causes of neurologic damage in dogs and gener- ally arise from motor vehicle trauma (6). When the fracture- luxation was reduced in this case, it was not confirmed that the spinal cord was intact. In many cases, it is possible to correct vertebral malalignment, thereby relieving spinal cord compression and improving neurologic function. However, when there is significant vertebral dislocation accompanied by transection of the spinal cord, there is no hope for a func- tional recovery (18). The prognosis for a functional recovery is determined mainly by the severity of the injury to the spinal cord (9). A poor clinical outcome is associated with severe neurological deficits, especially loss of DPP for a prolonged period of time (4,13). Severe axis deviation is frequently associated with a worse outcome in dogs and ultimately leads to euthanasia (1).
Research in humans has advocated vertebrectomy. In one
report, three human patients presented to the hospital with acute thoracic fracture-luxations and paraplegia. Surgery in- volved removal of all free bone fragments to obtain good fracture reduction and contact between the vertebral end plates. Direct contact between two healthy end plates resulted in excellent arthrodesis (12). In this case, solid fixation with screws and bone cement provided immediate stability, elimi- nating pain and may allow the use of a wheelchair after recovery. In the future, it appears that vertebrectomy might be indicated in cases with more severe vertebral fracture or luxation compared with the one in this report.
Several factors should be considered when managing frac- tures in wild animals. Some wildlife clinicians advise against surgical fixation of fractures in the Korean goral because of the prolonged recovery and lengthy captivity required (11).
However, despite a poor prognosis, surgery was recom- mended in the case presented here with the goal of relieving the goral’s pain, not of returning spinal cord function.
Vertebral fracture-luxations are most commonly seen in wild animals as a result of motor vehicle trauma (2,5,14).
Surgical reconstruction of the vertebrae would not be indi- cated in other wild animals with absent DPP, however, the Korean goral is an endangered species of wild goat. Although traumatic injuries in the Korean goral have rarely been stud- ied, wildlife-vehicle collisions have been identified as the major cause of these injuries (7). Even though this report is limited to a single case and ultimately the patient died, this report demonstrated the successful stabilization of a lumbar fracture-luxation in a Korean goral, and showed a valuable clinical trial in that attempt to correct the traffic accident fracture of an endangered animal.
Acknowledgement
This study was supported by Basic Science Research Pro- gram through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2015R1C1A1A01051759).
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