The Journal of Bone and Joint Surgery 81:111-114 (1999)
© 1999 The Journal of Bone and Joint Surgery, Inc.
Fracture-Dislocation of the Lumbar Spine After Arthrodesis with Instrumentation for Idiopathic Scoliosis. A Case Report*
JEROEN G. NEYT, M.D. and
STUART L. WEINSTEIN, M.D., IOWA CITY, IOWA
Investigation performed at the University of lowa Hospitals and Clinics, Iowa City
 |
Introduction
|
|---|
|
Case Report
|
|---|
An otherwise healthy boy was referred to the University of Iowa Hospitals and Clinics at the age of fourteen years and eight months for the evaluation of idiopathic scoliosis. There was no family history of scoliosis or neuromuscular disorders. Radiographs of the spine demonstrated an upper left thoracic curve of 34 degrees, a lower right thoracic curve of 43 degrees, and a lumbar curve of 18 degrees. The Risser sign was 0. An operation was recommended because of the high probability of progression of the curves. By the time that the operation was performed, at the age of fifteen years and three months, the lower thoracic curve had progressed from 43 to 52 degrees. A posterior spinal arthrodesis was performed with use of autologous bone from the iliac crest and Cotrel-Dubousset instrumentation from the second thoracic to the first lumbar vertebra. The operation and the postoperative course were uncomplicated. At the time of the two-year follow-up examination, the patient was asymptomatic and was functioning at a normal level. Radiographs made at that time revealed good coronal and sagittal alignment of the spine. A solid fusion was present with no loss of correction, and the hardware was intact.
Three years after the index operation, the boy was injured when the automobile that he was driving rolled over; he was wearing a seat belt at the time of the accident. He had a temporary loss of consciousness at the site of the accident. On arrival of the emergency services personnel, he complained of pain in the face, the neck, both shoulders, and the lower back. He was transported to a local hospital on a backboard, and his head and neck were immobilized with a hard collar and a supportive device. He was hemodynamically stable and had a score of 14 points on the Glasgow coma scale4. He was noted to have lacerations of the upper lip, bilateral periorbital ecchymosis, and abrasions of the right axilla, both shoulders, and the left knee. The cranial nerves were intact. The neurovascular, chest, and abdominal examinations revealed normal findings. Radiographs of the cervical spine demonstrated a fracture of the first cervical vertebra. A computed tomographic scan of the head was normal.
The patient was airlifted to our institution. The administration of steroids (1977 milligrams of methylprednisolone in 100 milliliters of normal saline solution at a dosage of thirty milligrams per kilogram of body weight over the course of one hour) was initiated at the time of liftoff. On arrival at the hospital, the patient was awake and alert. The motor strength of the flexors of the right hip was diminished to grade 4 of 5, and the sensation in the right first and second lumbar dermatomes was slightly decreased. The motor strength of the lower extremities was otherwise normal. On admission, the patient was managed with the infusion of methylprednisolone (362 milligrams per hour) and the intravenous administration of cimetidine (300 milligrams twice a day). Radiographs of the spine revealed a fracture-dislocation of the second on the third lumbar vertebra (Figs. 1 and 2). A computed tomographic scan revealed a compression fracture of the second lumbar vertebral body with associated fractures of the pedicles and the transverse processes. The laminar ring of the second lumbar vertebra appeared to be fractured in two places, and the spinous process was displaced. The second lumbar vertebral body was noted to be displaced posteriorly and to the right with respect to the third lumbar vertebral body. The diameter of the spinal canal was reduced by 25 percent at the site of the dislocation.
View larger version (86K):
[in this window]
[in a new window]
|
FIG1: Fig. 1 Anteroposterior radiograph of the lumbar spine, made with the patient in the supine position. Note that the caudad extent of the previous arthrodesis and instrumentation was to the level of the first lumbar vertebra. A rotatory fracture-dislocation of the second on the third lumbar vertebra is evidenced by lateral displacement of the body of the second lumbar vertebra on the third lumbar vertebra and by malalignment of the pedicles and the spinous processes between the first lumbar vertebra and the lumbar segments caudad to it. There is also a widened gap between the spinous processes of the first and second lumbar vertebrae, which indicates a disruption of the posterior ligaments.
|
|
View larger version (78K):
[in this window]
[in a new window]
|
FIG2: Fig. 2 Cross-table lateral radiograph, made in the operating room with the patient on a spinal frame, showing the posterior displacement of the second on the third lumbar vertebra. The spinal instrumentation is firmly affixed to the posterior elements of the first lumbar vertebra. The posterior aspect of the body of the second lumbar vertebra is displaced into the spinal canal. There is evidence of compression of the anterior portion of the body of the second lumbar vertebra, and a small avulsion fragment is seen anterior to that structure.
|
|
Computed tomographic scans through the first cervical vertebra revealed fractures through the anterior and posterior arches on the left as well as a small amount of posterolateral displacement of the left lateral mass. A computed tomographic scan of the maxillofacial area showed a right tripod fracture and a fracture of the right nasal bone. The fracture of the zygomatic arch extended into the lateral aspect of the right glenoid. The fracture of the cervical spine was treated with a hard collar.
The lumbar spinal fracture was determined to be unstable, and operative treatment was recommended. At the time of the operation, on the ninth day of hospitalization, neurological findings were unchanged after intubation with the patient awake. Radiographs of the cervical and lumbar spine that were made after the patient had been turned prone did not reveal any change in the alignment of the spine. A posterior midline incision was made from the tenth thoracic to the fourth lumbar vertebra, with great care being taken to avoid exposure or injury of the facet joints of the fourth and fifth lumbar vertebrae. The posterior elements of the spine were exposed from the caudad cross-link of the in situ implant to the fourth lumbar vertebra. The fusion of the upper lumbar spine was judged to be intact, and the fusion mass did not extend beyond the laminae of the first lumbar vertebra. The fracture had occurred immediately adjacent to the fusion mass. The right facet joint between the first and second lumbar vertebrae was noted to be completely disrupted. The fracture extended across the pars interarticularis of the second lumbar vertebra to the ligamentum flavum. Two hooks were placed under the inferior aspect of the laminae of the fourth lumbar vertebra, and two additional hooks were placed over the superior aspect of the laminae of the third lumbar vertebra. The caudad cross-link of the in situ implant was removed, and bone was removed from around both of the rods so that a new cross-link could be placed on the right side. No additional cross-connector could be placed on the left side because of the proximity of the rod to the posterior elements of the spine. A twenty-centimeter-long rod was contoured to the appropriate lordosis and was passed into the hooks that had been placed at the third and fourth lumbar levels on the left side of the spine. Compression was then applied between these hooks in order to stabilize the rod to the caudad portion of the spine. The actual reduction of the fracture-dislocation was accomplished under direct vision by cantilevering the caudad portion of the spine with use of the newly inserted rod and by manually compressing the previously fused cephalad segment. This maneuver generated forces of distraction and translation at the site of the fracture-dislocation, which, in combination with the ligamentotaxis effect produced by the intact anterior longitudinal ligament, allowed reduction of the fracture-dislocation. The newly inserted rod was then cross-linked to the in situ rod. A second rod was similarly attached on the right side of the spine. Radiographs made during the operation demonstrated reduction of the fracture-dislocation and restoration of alignment. Bone from the iliac crest was inserted in the lateral gutters from the twelfth thoracic to the fourth lumbar vertebra after decortication.
On the first postoperative day, the patient was found to be neurologically intact, with grade-5 motor strength for all muscle groups as well as normal sensation. The patient was discharged on the sixth postoperative day and was instructed to wear a hard collar and a thoracolumbar orthosis for three and four months, respectively. Eighteen months later, the site of the arthrodesis between the second and fourth lumbar vertebrae had healed. The patient had no pain and reported that he regularly performed strenuous manual labor as part of his job with a packing company. Radiographs demonstrated good coronal and sagittal alignment (Figs. 3 and 4).
View larger version (64K):
[in this window]
[in a new window]
|
FIG3: Fig. 3 Posteroanterior radiograph made with the patient standing, eighteen months after extension of the instrumentation and arthrodesis to the fourth lumbar vertebra.
|
|
View larger version (56K):
[in this window]
[in a new window]
|
FIG4: Fig. 4 Lateral radiograph made with the patient standing, eighteen months after extension of the instrumentation and arthrodesis to the fourth lumbar vertebra.
|
|
|
Discussion
|
|---|
We are aware of few reports in the literature that focus on fractures or dislocations at the site of, or adjacent to, fused segments of the spine. Drennan and King described a traumatic dislocation of the sixth on the seventh cervical vertebra in a patient who was involved in a motor-vehicle collision two years after a successful arthrodesis of the spine from the first thoracic to the first lumbar vertebra1. At the time of the operation, a disruption of the intraspinous and supraspinous ligaments at the caudad two cervical levels and of the ligamentum flavum between the sixth and seventh cervical vertebrae was found. The authors concluded that the vulnerability of the cervicothoracic junction to injury was increased in patients who had an arthrodesis of the cephalad thoracic segments. King and Bradford reported on a fracture-dislocation of the eleventh on the twelfth thoracic vertebra in a patient who was involved in a motor-vehicle collision two years and four months after a successful arthrodesis with Harrington instrumentation from the third thoracic to the second lumbar vertebra2. Because of the angulation of the rods in situ, closed reduction was judged to be impossible. The authors concluded that the presence of the instrumentation and a solid fusion mass had saved the patient from neurological damage.
The mechanical properties of the spine and the constraints of its environment determine its response to load5. In the erect posture, 80 to 90 percent of the axial compressive force is absorbed by the anterior column of the normal spine and the remaining 10 to 20 percent is distributed to the posterior joints and muscles3. The pattern of load-sharing changes considerably when an arthrodesis is performed in the thoracolumbar region because the articulation of the stiff and mobile segments, which normally is located at the junction of the twelfth thoracic and first lumbar vertebrae, is shifted caudally—in the case of our patient, to the junction of the first and second lumbar vertebrae. The fracture pattern was determined to be unstable because of the involvement of all three columns of the spine5. Reduction of the traumatic displacement of the second lumbar vertebral body and realignment in both the coronal and the sagittal plane restored the diameter of the spinal canal. Given the presence of posterior instrumentation in situ, a posterior approach to the fracture site was selected. The application of a cantilevering rod that was contoured in lordosis and anchored to the third and fourth lumbar vertebrae allowed reduction of the fracture-dislocation and, thus, decompression of the spinal canal. The use of pedicle screws may have spared one or two mobile segments but may not have generated the lever arm required to reduce the fracture-dislocation.
The operative treatment of idiopathic scoliosis is directed toward restoration of spinal alignment and maintenance of the alignment by means of arthrodesis. Extension of the arthrodesis construct to the fourth lumbar vertebra leaves only the level of the fourth and fifth lumbar vertebrae and the level of the fifth lumbar and first sacral vertebrae as mobile segments. The presence of a long lever arm extending from the first thoracic to the fourth lumbar vertebra may increase the risk of late degeneration caudad to the fused segments. However, the clinical outcome in our patient should not differ from that in patients with idiopathic adolescent scoliosis who have had primary arthrodesis to the level of the fourth lumbar vertebra.
|
Footnotes
|
|---|
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
Department of Orthopaedic Surgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa 52242.
|
References
|
|---|
-
Drennan, J. C., and and King, E. W.: Cervical dislocation following fusion of the upper thoracic spine for scoliosis. A case report. J. Bone and Joint Surg., 60-A: 1003-1005, Oct. 1978.[Free Full Text]
-
King, H. A., and and Bradford, D. S.: Fracture-dislocation of the spine after spine fusion and Harrington instrumentation for idiopathic scoliosis. A case report. J. Bone and Joint Surg., 62-A: 1374-1376, Dec. 1980.[Free Full Text]
-
Lowery, G. L., and Harms, J.: Principles of load-sharing. In The Textbook of Spinal Surgery, edited by K. H. Bridwell and R. L. DeWald. Ed. 2, pp. 155-166. Philadelphia, Lippincott-Raven, 1996.
-
Teasdale, G., and and Jennett, B.: Assessment of coma and impaired consciousness. A practical scale. Lancet, 2: 81-84, 1974.[Medline]
-
White, A. A. III and Panjabi, M. M.: Physical properties and functional biomechanics of the spine. In Clinical Biomechanics of the Spine, pp. 1-56. Philadelphia, J. B. Lippincott, 1978.
 CiteULike  Connotea  Del.icio.us  Facebook  Technorati  Twitter What's this?
|
Top
Introduction
Case Report