Assessment of hepatic inflammation after spinal cord injury using intravital microscopy.

OBJECTIVES: The liver has been shown to play a particularly important role in the initiation and progression of the early systemic inflammatory response (SIR) to spinal cord injury (SCI). The purpose of this study was to determine the time course of leucocyte recruitment to the liver, and to determine the effect of injury severity on the magnitude of leucocyte recruitment and hepatic injury. METHODS: Rats were randomly assigned to one of the following groups: uninjured, sham-injured (laminectomy and no cord injury), cord compressed or cord transected. At 30 min and 90 min after SCI rats had the left lobe of their livers externalised and visualised using intravital video microscopy. RESULTS: Thirty minutes after injury the total number of leucocytes per post-sinusoidal venule was significantly increased after cord transection compared to that in uninjured and sham-injured rats (P<0.05). Of these leucocytes, significantly more were adherent to venule walls (P<0.05). At 90 min the total number of leucocytes per post-sinusoidal venule and the number of adherent and rolling leucocytes was significantly increased after cord transection and cord compression (P<0.05). DISCUSSION: This is the first study to use intravital microscopy to visualise systemic inflammation in the liver following SCI. We have demonstrated immediate leucocyte recruitment to the liver within 30 min after injury and have shown that systemic inflammation increases with time after injury and with severity of injury.

Atlantoaxial instability treated with transarticular screw fixation.

We treated 11 patients with atlantoaxial instability using transarticular posterior screw fixation and lateral bone grafting. A posterior bone graft was added in eight patients. The results showed good reduction and a stable fixation. After 6 months ten patients had regained almost 70% of rotation and did not notice any significant limitation.

The USS pedicle hook system: a morphometric analysis of its safety in the thoracic spine. Universal Spine System.

The Universal Spine System (USS) pedicle hook design includes a fixation screw that passes obliquely in the anterocranial direction in the pedicle. The addition of the fixation screw was to address concerns with rotation of the hook and hook disengagement. This study was designed to evaluate the safety of the USS screw locked pedicle hook. Eleven cadaveric thoracic spines were instrumented posteriorly with USS pedicle hooks from T1 to T12. Spinal instrumentation was performed by a spinal surgeon experienced with the USS system. Spinal deformity was created prior to instrumentation, ranging from 0 to 55 degrees in the horizontal plane (rotation) and from 0 to 50 degrees in the frontal plane (scoliosis). Radiographs, computed tomography (CT), and segmental dissection were used for data acquisition. Morphometric CT analysis before instrumentation demonstrated that the transverse pedicular diameter was the smallest at T5 with a mean of 3.7 mm. The transverse pedicular angle (TPA) was found to always point toward the midline. The largest TPA was observed at T1 with a mean TPA of 28.4 degrees. The pedicle with the least angular deviation from the midline was T11 with a mean TPA of 7 degrees. Postinstrumentation CT analysis and segmental dissection revealed perforations of the pedicle cortex by the fixation screw in 15% of instrumented pedicles (26/172). There were 6 medial and 20 lateral perforations. Medial perforations occurred exclusively in the three most proximal spinal segments, whereas the lateral perforations occurred throughout the thoracic spine. The mean encroachment of the fixation screw was 1.67 mm medially and 1.95 mm laterally. This study demonstrates the variation in caliber and direction of the thoracic pedicles. Medial and lateral perforations of the pedicle can occur with the USS pedicle hook instrumented system.

The BWM spinal fixator system. A preliminary report of a 2-year prospective, international multicenter study in a range of indications requiring surgical intervention for bone grafting and pedicle screw fixation.

STUDY DESIGN: A prospective, international, multicenter study of 400 patients who received the BWM fixator system. OBJECTIVES: To assess the effectiveness and safety of the system in the management of various conditions requiring spinal fixation and bone grafting. SUMMARY OF BACKGROUND DATA: The BWM system was developed for the management of spinal instability of all etiologies occurring in the thoracic, thoracolumbar, and lumbosacral spine. METHODS: Patients with fracture, tumor, spondylolisthesis, spondylitis, failed back, or other degenerative conditions of the spine received the BWM instrumentation as described in the study literature and were regularly reviewed for 2 years. RESULTS: The results from the first 200 patients to complete the study showed an overall graft fusion rate of 94% (95% confidence interval: 91.3%-97.6%). There were marked improvements in measures of functional ability (P < 0.001, Wilcoxon test). Before surgery, less than half the patients were capable of outdoor activity. At 2 years, 80% were able to undertake outdoor activity. There were few perioperative difficulties reported. Postoperative complications associated with major surgery were seen in 18% patients. There were 23 (2.6%) pedicle screw failures, including two loosenings, and 13 (2.5%) spacer element failures, including three loosenings. CONCLUSIONS: Clinical failure was not necessarily a consequence of component failure. The BWM fixator provided excellent stabilization during the process of bone graft consolidation. The risks of complication or component failure were no higher than those associated with similar devices.

An anatomic, radiographic, and biomechanical assessment of extrapedicular screw fixation in the thoracic spine.

This study performed a thorough review of the pertinent thoracic spine anatomy to determine the appropriate landmarks for extrapedicular screw placement and indentified the anatomic structures at risk; assessed the safety and accuracy of the newly proposed screw insertion technique; determined the stability and strength of this new screw position through biomechanical testing; and analyzed the stability of this extrapedicular screw location with respect to bone mineral density of the vertebra.

Cauda equina syndrome: a complication of lumbar discectomy.

Six cases of acute postdiscectomy cauda equina syndrome (C.E.S.) following lumbar discectomy were reviewed retrospectively in a series of 2842 lumbar discectomies over a ten-year period. Five cases had coexisting bony spinal stenosis at the level of the disc protrusion. The bony spinal stenosis was not decompressed at the time of discectomy. Inadequate decompression played a role in the neurologic deterioration postoperation. The cause of the sixth case is unknown. Bowel and bladder recovery was good when the cauda equina decompressed early; sensory recovery was universally good, and motor recovery was poor if a severe deficit had developed before decompression. Careful review of the preoperative myelogram to rule out spinal stenosis and decompression of bony stenosis at discectomy are recommended for prevention of postoperative C.E.S. Urgent decompression of postoperative C.E.S. is advisable if compression of the cauda equina is confirmed radiographically.

A technique of posterior cervical fusion for instability of the cervical spine.

A technique of posterior cervical spine fusion (the "Dewar procedure") that allows immediate stabilization of the spine requiring only minimal external support is described. The procedure was performed in 16 patients with unstable fractures or fracture-dislocations of the cervical spine. All patients went on to develop solid fusion. Twelve patients incurred neurologic deficit due to their injury, and those with root involvement all recovered following fusion. Patients rendered quadriplegic as a result of their accident did not show any useful neurologic recovery but were able to start rehabilitation earlier and avoid the complications of nonoperative treatment. There were no significant complications related to surgery.

Orthopedic injuries of the lower limb and trunk in multiple system trauma.

There is a tendency in the patient who has suffered multiple injuries ot overlook the less obvious or less striking injury. The spine may be injured but the injury not recognized if the clues that are present on roentgenograms are ignored. There may be an increase in the interspinous distance with or without minor body compression in abdominal injuries due to seat-belts. Apparently minor fractures of transverse processes may indicate retroperitoneal injury severe enough to cause important urologic damage; when the 5th transverse process is fractured there may also be a fracture of the sacrum. Pelvic fractures may be accompanied by neurologic involvement. Fracture of the lower limb shaft does not eliminate the possibility of major disruption of knee ligaments. Swelling of the knee is the clue. An aggressive approach to the stabilization of fractures is advised, so that the treatment of other organs and reconstruction of blood vessels may more effectively be carried out. Compound fractures retain their high priority for early treatment, even in the presence of other important injuries.

Section II: General orthopaedics. Anterior cervical fusion for trauma.

Anterior bone grafts of 24 injured cervical spines were reviewed with respect to early postoperative instability and eventual malunion. Spinal redislocation or graft extrusion occurred in 21% representing failure to attain early stability. In 38%, the late complication of kyphotic malunion occurred, averaging 21%. The Yale instability criteria were fulfilled in 15 cases and mechanical complications developed in 87% of these. When posterior instability was present, the mechanical complication rate rose to 92%. Early stabilization of most neck injuries is not achieved by the anterior bone graft and its use as a means of "stabilization" is unsubstantiated by clinical experience.