The efficacy of direct current stimulation for lumbar intertransverse process fusions in an animal model.

STUDY DESIGN: Posterolateral lumbar intertransverse process fusion using a rabbit model with autologous bone graft and direct current stimulation was compared with fusion achieved by using autologous bone graft alone. OBJECTIVES: To determine the efficacy of direct current electrical stimulation for the posterolateral lumbar intertransverse process fusion technique by using a 20-microA current and the more recently developed 60-microA current delivered by an implantable direct current stimulator. SUMMARY OF BACKGROUND DATA: Previous studies have demonstrated a positive effect of direct current electrical stimulation on posterior spinal fusion techniques. However, until recently, the environment of an intertransverse fusion was not well simulated. The current research examined the posterolateral lumbar intertransverse process fusion technique with direct current electrical stimulation using a rabbit model. This appears to parallel human fusion techniques more closely and allows for lower cost and technical ease. METHODS: In this study, 44 adult New Zealand white rabbits underwent an L5-L6 intertransverse process fusion. All the fusions used an autologous bone graft obtained from bilateral posterior iliac crests. A device was implanted in all the rabbits subcutaneously, and they were divided randomly into three groups: a sham or nonfunctioning group, a 20-microA low-current stimulator group, and a 60-microA higher-current stimulator group. Spinal fusion was evaluated radiographically, histologically, and manually as well as by biomechanical testing 5 weeks after surgery. RESULTS: Radiographic grades, manual palpation, biomechanical strength, and stiffness showed an increasing trend from sham or inactive stimulator groups to low-current and then to high-current stimulator groups. Histologic analysis revealed that the higher-current stimulator showed that, statistically, the healing response of the host tissue to the autograft had increased significantly, as compared with the sham. CONCLUSIONS: Direct current electrical stimulation is efficacious in improving both the healing rate and strength in this posterolateral lumbar fusion model. In addition, it appears that this effect is enhanced by increasing the stimulation current from 20 microA to 60 microA.

Vertebral artery pseudoaneurysm complicating posterior C1-2 transarticular screw fixation: case report.

BACKGROUND: Vertebral artery injury during posterior C1-2 transarticular screw fixation occurs in approximately 3% of patients and may remain asymptomatic or result in arteriovenous fistulae, occlusion, narrowing, or dissection of the vertebral artery, and lead to transient ischemic attacks, stroke, or death. CASE DESCRIPTION: This is the first report of a pseudoaneurysm resulting from damage to the vertebral artery during the procedure. This 31-year-old male underwent posterior C1-2 transarticular screw fixation for unstable os odontoideum. Injury to the left vertebral artery occurred while the hole for the left screw was being drilled. Temporary control of bleeding with local pressure was followed by immediate postoperative angiography that revealed a left vertebral artery pseudoaneurysm. Although the patient remained asymptomatic, therapeutic anticoagulation was instituted 6 hours postoperatively. Increasing size of the pseudoaneurysm was noted on routine follow-up angiography 4 weeks later. Endovascular occlusion of the pseudoaneurysm and left vertebral artery, with preservation of vertebrobasilar flow through the right vertebral artery, was accomplished without neurological consequence. CONCLUSIONS: Vertebral artery pseudoaneurysm complicating posterior C1-2 transarticular screw fixation may be effectively treated with endovascular approaches.

A randomized prospective study of posterolateral lumbar fusion. Outcomes with and without pedicle screw instrumentation.

STUDY DESIGN: A prospective evaluation of the clinical and radiographic outcomes of 71 patients who underwent lumbar fusion, with or without transpedicular instrumentation. The patients completed a questionnaire that determined pain relief, medication use, return to work, and overall satisfaction with surgery. OBJECTIVES: To explore the effect, if any, of instrumentation on the outcome of lumbar fusion surgery, according to reports of the patients, and whether there is a correlation between the radiographic determination of a solid fusion and the same patient-reported outcome. SUMMARY OF BACKGROUND DATA: The literature on this topic reports pseudarthrosis rates from 0% to 57% and good to excellent results from 56% to 95%. These studies provide no clear-cut recommendations concerning the effect of added lumbar instrumentation on patient-reported outcome in a prospective manner using concurrent control subjects. METHODS: The patients were randomized to groups with and without instrumentation after deciding to undergo a lumbar fusion and consenting to enter the study. Radiographs were obtained and questionnaires filled out at 6 weeks, 6 months, 1 year, and 2 years after surgery. RESULTS: There was no statistical difference in patient-reported outcome between the two groups. There was a slight nonsignificant trend toward increased radiographic fusion rate in the group with instrumentation that did not correlate with an increased patient-reported improvement rate. CONCLUSIONS: These results do not provide data that indicate a benefit in outcome from added instrumentation in elective lumbar fusions.

The use of intrathecal morphine for analgesia after posterolateral lumbar fusion: a prospective, double-blind, randomized study.

STUDY DESIGN: A prospective, randomized, double-blind, placebo-controlled study was undertaken to evaluate the efficacy and safety of intrathecal morphine for postoperative analgesia after posterolateral lumbar fusion. OBJECTIVES: To compare the early postoperative analgesia in patients who receive a single dose of intrathecal morphine intraoperatively with that of patients using a patient-controlled analgesia pump only. SUMMARY OF BACKGROUND INFORMATION: Although intrathecal morphine is used as an analgesic in a variety of medical and surgical conditions, very little has been published on its use after posterior lumbar spine surgery. Because the thecal sac is readily available during these procedures, the addition of a single injection of morphine before wound closure can be done with technical ease. If its efficacy and safety can be verified, then it could serve as a useful adjuvant to the postoperative analgesia regimen. METHODS: Sixty-eight consecutive patients undergoing posterolateral lumbar fusion were randomly assigned to two groups. The experimental group was injected intrathecally with morphine 30 minutes before wound closure, and the control group was similarly injected with a placebo of normal saline solution. All patients were connected to an on-demand patient-controlled analgesia pump to provide any additional necessary analgesia. Their use of the patient-controlled analgesia pump was tabulated by counting the number of demands and the actual amount of morphine delivered. Additionally, a visual analog scale was used to assess pain levels at pre-established regular intervals. RESULTS: The visual analog scale measurements were significantly lower for the intrathecal morphine group initially, but they surpassed those of the control group after 24 hours. Likewise, the number of patient-controlled analgesia pump demands and the amount of narcotic delivered initially were significantly lower in the experimental patients, but again reversed after the first postoperative day. The late rebound in pain and patient-controlled analgesia pump use did not reach statistical significance. There were no significant complications related to the analgesia. CONCLUSIONS: Intrathecal morphine can be safe and efficacious as an early postoperative analgesic after lumbar fusion when respiratory monitoring is used.

Traumatic spondylopelvic dissociation. A case report and literature review.

STUDY DESIGN: A case of traumatic spondylopelvic dissociation and a method of fixation are described. OBJECTIVES: The treatment of this rare injury pattern required differentiation from less severe lumbosacral fracture-dislocations or bilateral sacroiliac joint dislocations. SUMMARY OF BACKGROUND DATA: Several case reports have described less severe fracture patterns, but only a handful have illustrated true spondylopelvic dissociation in which there is complete displacement of the lumbar spine into the pelvis. METHODS: After initial stabilization at an outside hospital, the patient was transferred to the authors' institution for definitive care. After computed tomography imaging with three-dimensional multiplanar reconstruction, the fracture was stabilized with a pedicle screw construct attached to the pelvis by means of the Galveston technique. Bilateral iliosacral screws were used to increase stability. RESULTS: At a 2-year follow-up, the patient was pain-free and ambulating in an ankle-foot orthosis. He had a persistent deficit involving the right L5 and S1 nerve roots but was continent of stool. CONCLUSIONS: The unique fracture pattern described in this patient is presented to offer better insight into management of this complex injury and to delineate it from simpler patterns of injury to the lumbosacral junction.

Measurement of brachial plexus strain in arthroscopy of the shoulder.

The purpose of this study was to measure the strain on the brachial plexus that results from traction loads applied at various arm positions and to correlate this with visibility through the arthroscope. We mounted strain gauges to the upper trunk, lateral cord, median nerve, and radial nerve of five fresh human cadavers. Each cadaver was placed in a lateral decubitus position, with the head fixed in a neutral position, as for shoulder arthroscopy, and the strain on the plexus was measured as a function of arm position and traction load. A final cadaver was used to determine the accessibility and visibility in the arthroscope at each of the arm positions. At a given flexion angle, increasing abduction is associated with decreasing strain. At a given abduction angle, increasing flexion results in decreased strain. The minimum overall strain was noted at 90 degrees of flexion and 0 degree of abduction. Visibility at this position is limited. We conclude that the ideal arthroscopic position is a combination of two positions that would maximize visibility while minimizing strain to the nerves. These two positions are 45 degrees of forward flexion and 90 degrees of abduction in combination with 45 degrees of forward flexion and 0 degree of abduction.