Faculty Bibliography

BACKGROUND CONTEXT: The technical difficulties associated with the development of an intervertebral disc prosthesis include endurance demands on the device, lack of consensus concerning the biomechanical principles governing the articulation of the spinal joint and the performance of materials available for implantation. PURPOSE: Although biologically based disc prostheses and augmentations may be the endpoint of spinal disc replacements, these devices and associated technologies will still require decades of work in order to achieve fruition. The more immediate solution will require a durable, biocompatible device capable of restoring range of motion. The evaluation of such a device must include failure testing of critical components as well as a series of fatigue experiments under overloaded conditions. STUDY DESIGN/SETTING: Recent literature citing adjacent level degeneration associated with segmental mobilization and a lack of correlation between successful fusion and clinical success has prompted the need for a dynamic intervertebral disc prosthesis. METHODS: Combined with a better understanding of the biomechanics and the prospect of an increasing percentage of more elderly patients, the future of spinal fusion for pain and instability may need to be reexamined. The authors propose a novel metal-on-metal design for an intervertebral device that features a fixed center of rotation, a mechanical torsional limit, a unique feature to allow for the location of the device in a patient-specific manner, and means by which the device may be implanted directly anterior or anterolaterally. RESULTS: Physiological ranges of motion are retained by the prosthesis. In addition, initial and long-term fixations are achieved through spines and bone ingrowth coating. The device comprises a retained ball and socket positioned between two baseplates. The ball and socket joint permits articulation through the appropriate physiological range of motion and center of rotation as the baseplates provide a stable platform for implantation. CONCLUSIONS: An intervertebral disc prosthesis has been designed and has demonstrated mechanical performance beyond what is required physiologically under preliminary testing

OBJECTIVE: To compare the characteristics, presentation, and surgical outcome of patients with microdiscectomies at L1-L2 and L2-L3 with those we treated at L3-L4. We further sought to compare these results with those reported in the literature for discectomies at the L4-L5 and L5-S1 levels. METHODS: We reviewed the clinical data collected from 69 patients who had 72 L1-L2, L2-L3, and L3-L4 microdiscectomies performed from 1989 to 1999 at the New York University Medical Center. Patients who had surgery at L1-L2 or L2-L3 were grouped and compared with those treated at the L3-L4 level. Patients' charts were retrospectively reviewed at a mean of 12.9 months after surgery for presenting signs and symptoms, patient characteristics, and surgical outcome. Long-term follow-up via telephone interview was obtained at an average of 81.3 months after surgery. RESULTS: In the L1-L2 + L2-L3 group, 58% of the patients had previous lumbar disc surgery, compared with only 10% of those in the L3-L4 group, and 20% in the L1-L2 + L2-L3 group required a fusion during the procedure compared with only 10% in the L3-L4 group. These differences are both statistically significant. The short-term chart review demonstrates that only 58% and 53% of patients in the L1-L2 + L2-L3 group were improved with regard to radicular and back pain, respectively, whereas those in the L3-L4 group reported 94 and 87% rates of improvement in the same categories, both highly statistically significant findings. The long-term follow-up confirmed a highly statistically significantly worse outcome in the L1-L2 + L2-L3 group, with only 33% of patients reporting an improvement in their economic or functional status, compared with an 88% rate of improvement in the L3-L4 group. The outcome of our patients with L3-L4 herniations was similar to that reported in the literature for herniations at L4-L5 and L5-S1. CONCLUSION: Herniated discs at the L1-L2 or L2-L3 level are different entities from those at lower levels of the lumbar spine. The surgical outcome in terms of postoperative back and radicular pain is worse for herniated discs at L1-L2 and L2-L3 compared with those treated at L3-L4. Our patients with L1-L2 or L2-L3 surgically treated herniated discs were more likely to have had previous lumbar surgery and required a fusion more often than their counterparts with L3-L4 herniated discs

OBJECTIVE: A combination of analgesics with different mechanisms of action may improve postoperative pain control and reduce the incidence of side effects. This study was designed to assess the efficacy of preoperative administration of rofecoxib (Vioxx; Merck & Co., Inc., Somerset, NJ) in reducing pain and opioid requirements after single-level lumbar microdiscectomy. METHODS: A randomized, double-blind, placebo-controlled clinical trial was performed on 61 consenting patients who were considered American Society of Anesthesiologists Class I or II and who were scheduled for elective single-level lumbar microdiscectomy. Patients received either two doses of rofecoxib 50 mg or a placebo preoperatively. The outcome measures included morphine use in the postanesthesia care unit (PACU), discharge times, and side effect profile. Data were analyzed by use of independent sample t tests for continuous variables or chi(2) tests for categorical variables. A P value of <0.05 was considered significant. RESULTS: The two groups were comparable with respect to patient characteristics, intraoperative opioid and hypnotic consumption, and duration of surgery. Patients in the rofecoxib group required significantly less morphine postoperatively. Significantly more patients in the placebo group reported pain scores greater than 7 at admission to the PACU. Time to first request for analgesia was shorter in the placebo group, but the difference did not reach statistical significance. There were no significant differences between groups in the incidence of nausea, time to discharge from the PACU, or hospital stay. CONCLUSION: Preoperative rofecoxib is effective in reducing postoperative narcotic consumption in patients undergoing lumbar laminectomy. The use of rofecoxib does not shorten PACU length of stay or hospital discharge time. These outcome measures depend on multiple administrative factors

BACKGROUND CONTEXT: Lumbar nerve root blocks and epidural steroid injections are frequently employed in the management of degenerative conditions of the lumbar spine, but relatively few papers have been published that address the complications associated with these interventions. Serious complications include epidural abscess, arachnoiditis, epidural hematoma, cerebrospinal fluid fistula and hypersensitivity reaction to injectate. Although transient paraparesis has been described after inadvertent intrathecal injection, an immediate and lasting deficit has not been previously described as sequelae of a nerve root block. PURPOSE: We present three cases in which either persisting paraplegia or paraparesis occurred immediately after administration of a lumbar nerve root block and propose a mechanism for this devastating but previously unreported complication. STUDY DESIGN/SETTING: Case reports of three patients. PATIENT SAMPLE: Three patients, two women and one man ranging in age from 42 to 64 years, underwent three procedures performed at three different facilities, in the hands of two different injectionists. In each instance, penetration of the dura was not thought to have occurred. In two procedures the needles were placed transforamenally, one at L3-4 on the left and one at L3-4 on the right, and in the third the needle tip was placed immediately lateral to the S1 nerve root. OUTCOME MEASURES: Patient follow-up data from medical office records. METHODS: In each case, needle placement was verified with injection of a contrast media in conjunction with either computerized tomography or biplanar fluoroscopy. No backbleeding or cerebrospinal fluid was encountered upon aspiration in any of the procedures. Magnetic resonance imaging (MRI) was performed within 48 hours of injury in all patients. RESULTS: In each patient, paraplegia suddenly ensued after instillation of the steroid solution and, in each instance, postprocedure MRI revealed increased signal in the low thoracic spinal cord on T2-weighted imaging consistent with edema. The sudden onset of neurological deficit and the imaging changes noted in the spinal cord point to a vascular explanation for these injuries. We postulate that in these patients the spinal needle either penetrated or caused injury to an abnormally low dominant radiculomedullary artery, a recognized anatomical variant. This vessel, also known as the artery of Adamkiewicz, in 85% of individuals arises between T9 and L2, usually from the left, but in a minority of people may arise from the lower lumbar spine and rarely even from as low as S1. The artery of Adamkiewicz travels with the nerve root through the neural foramen and irrigates the anterior spinal artery. Injury of it or injection of particulate matter into it, as what may happen with the commonly used epidural steroid injectates, may result in infarction of the lower thoracic spinal cord, producing the clinical and imaging findings seen in these three patients. CONCLUSIONS: We present the cases of three patients who had lasting paraplegia or paraparesis after the performance of a nerve root block. We propose that the mechanism for this rare but devastating complication is the concurrence of two uncommon circumstances, the presence of an unusually low origin of the artery of Adamkiewicz and an undetected intraarterial penetration of the procedure needle

Degenerative lumbar spinal stenosis is a problem of increasing importance as the population ages and functional expectations remain high. It usually develops secondary to spondylosis. Classic symptoms of lumbar stenosis are back pain, radiating leg pain, and sciatica exacerbated by walking. This neurogenic claudication usually can be distinguished from other conditions that produce leg pain during the history and physical examination. Plain radiographs suffice for persons with mild to moderate stenosis; more severe symptoms or neurologic involvement calls for other imaging. Management begins conservatively with anti-inflammatory agents and local modalities. Epidural corticosteroids are being used increasingly despite controversy. Surgery may be indicated for patients in whom nonoperative treatment is unrewarding and is safe even for very elderly persons. (33 ref 1 bib) <19>

STUDY DESIGN: This is a report of three cases of epidural abscess occurring after use of intraoperative epidural methylprednisolone in 31 patients who had undergone lumbar microdiscectomy. The possible role of epidural steroids in the cause of these abscesses is discussed, and a review the literature concerning its value is provided. OBJECTIVE: To evaluate experiences with the efficacy and safety of perioperative methylprednisolone. SUMMARY OF BACKGROUND DATA: No previous study has described a high infection rate with the use of epidural methylprednisolone. The literature supporting epidural steroids is equivocal, and reports supporting their perioperative use are scant. METHODS: In an 8-month period, 31 patients received 1 mL (40 mg) epidural methylprednisolone at the conclusion of microdiscectomy. Therapy was discontinued after an increased postoperative deep infection rate was noted. Results in these patients were compared with those in more than 400 others who did not receive intraoperative steroids during a 7-year period. RESULTS: In the steroid group, three epidural abscesses were encountered. There were no deep infections in the nonsteroid group. CONCLUSION: The use of perioperative epidural methylprednisolone in the currently reported cases was associated with three incidences of infection. A prospective study is needed to examine its use.

Spinal infections encompass a broad spectrum of pathology. Any element of the spine, the vertebrae, disks, surrounding soft tissues, potential spaces, or the cord itself may be involved solely, or more commonly, in combination. Staphylococcus aureus is the organism most frequently found, with Gram negative bacteria often cited in association with infections of the urinary tract and in intravenous drug abusers. Early diagnosis and treatment are essential for optimal outcomes. In some cases, the only necessary treatment consists of parenteral antibiotics and immobilization. However, certain instances require operative intervention. The goals of treatment for any infection of the spine are: early diagnosis with identification of the offending organism, preservation of neurological function or cessation of progressive neurologic deficit, and complete eradication of the infection with a pain-free, stable spine.

OBJECTIVE: We review the results of treatment of a series of patients with spinal osteomyelitis, to formulate a systematic and comprehensive approach to the management of this disease in light of recent technical and conceptual advances in imaging, spinal biomechanics, and internal fixation. METHODS: We retrospectively reviewed the records for 57 consecutive patients with pyogenic spinal osteomyelitis who were treated between June 1987 and June 1995. Pain and weakness were the most common presenting symptoms. The mean duration of symptoms at the time of diagnosis was 10.6 weeks. Surgical indications included the presence or development of motor deficits with epidural compression and/or localized kyphotic deformities or the failure of medical therapy. RESULTS: Thirty-three patients underwent surgery as their initial treatment. Six additional patients experienced medical therapy failure and received subsequent surgical treatment. Seventeen patients were treated using an anterior approach only, 13 were treated using a posterior approach only, and 9 were treated using a combined anterior and posterior approach. After a minimal follow-up period of 24 months, 93% of the surgically treated patients showed neurological improvement or were neurologically intact, with a mean 16-degree decrease in localized kyphotic deformities and with solid bony fusion and resolution of pain for all patients. CONCLUSION: Early surgical decompression results in rapid improvement of neurological deficits, decreases in kyphotic deformities, and stabilization with bony fusion. The presence of active infection does not preclude the use of internal fixation. Nonsurgical management is indicated for patients with minimal or no neurological deficits and the absence of significant localized kyphotic deformities. However, 25% of patients who were initially treated nonsurgically experienced medical therapy failure and underwent surgical treatment