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STUDY DESIGN: Compare the effectiveness of two different techniques for the management of osteoid osteoma of the spine. OBJECTIVE: To describe the technique, feasibility, and indications of two different minimally invasive surgical methods for the treatment of osteoid osteoma of the spine. SUMMARY OF THE BACKGROUND DATA: Current treatment of osteoid osteoma of the spine is usually conventional surgical excision. The successful treatment of osteoid osteoma of the appendicular skeleton by percutaneous radiofrequency probe ablation is known; however, there have been only a few cases reported utilizing this method to treat osteoid osteoma of the spine. The high success rate of percutaneous transpedicle vertebral biopsy and diskectomy led us to believe this technique can also be applicable for the treatment of osteoid osteoma of the spine. METHODS: Two patients with symptomatic osteoid osteoma of the spine underwent two different surgical managements with local anesthesia. In one patient, the osteoid osteoma was localized in the apex of the right L4 superior articular process joint. Under computed tomography guidance he underwent radiofrequency coagulation with the use of a radiofrequency generator at 90 degrees for 240 seconds. The lesion in the second patient was located in the right pedicle of the T9 vertebra close to the exiting nerve root and was cored out by means of a special percutaneous instrument designed for percutaneous biopsy under fluoroscopic guidance. RESULTS: Both patients experienced immediate relief of pain, resumed their regular activities, and also remained free of symptoms after the 2.5- and 3-year follow-up. CONCLUSION: Minimally invasive surgery can successfully be applied in the treatment of osteoid osteoma of the lumbar spine. When the nidus is not adjacent to the neural elements radiofrequency thermal ablation can be an effective and safe treatment of osteoid osteoma in the spine. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective, consecutive patient series., Objective: To quantify the risks and the complications associated with screw fixation devices of the cervical spine., Summary of Background Data: The usefulness of lateral mass internal fixation has been well documented in the clinical setting. However, there is a paucity of studies examining the complications associated with these devices in a degenerative clinical setting., Methods: From 1999 to 2007, 225 consecutive patients underwent posterior cervical fixation using a screw-plate and polyaxial screw-rod implant systems. There were 105 women and 120 men (age range: 45 to 84 y; mean, 68 y). In all patients, the surgical indication was cervical spondylosis with myelopathy. Mean follow-up interval was 18 months (range: 12 to 72 mo). Screw position was evaluated by computed tomography scanning postoperatively in all patients. Clinical and radiographic outcome was assessed at each visit after surgery., Results: Intraoperative complications include fracture of lateral mass in 27 screws placement and nerve irritation in 3 bicortical screws. Early complications include hematoma formation in 2 cases and C5 root palsy in 5 cases after spinal canal decompression. Late complications include pseudarthrosis in 6 cases and screw pull-out in 3 cases. There were no cases of spinal cord or vertebral artery injury, infections, deaths, or adjacent segment disease. All patients had radiographic union, and no patient developed mechanical implant failure requiring removal of instrumentation. Reoperation was required in 14 (6.2%) cases because of nerve injury, hematoma formation, pseudarthrosis, and screw pull-out., Conclusions: Our clinical findings indicate that lateral mass fixation can be used safely with minimal complications and low rate of morbidity for cervical myelopathy treatment.

Study Design: A biomechanical study using human cadaveric cervical spines was conducted., Objective: To determine whether the cervical stability achieved with lateral mass fixation using unicortical screw purchase is comparable with that obtained with lateral mass fixation using bicortical screw purchase., Summary of Background Data: Cervical lateral mass fixation has traditionally required bicortical screw fixation, which is associated with potential injury to the vertebral vessels and cervical nerve roots. Unicortical fixation eliminates these possible complications. Limited stability studies suggest that unicortical fixation in the lateral masses provides stability comparable with that of bicortical fixation. However, no comprehensive biomechanical study has compared the cervical stability between bicortical and unicortical lateral mass fixations., Methods: A total of 11 human cadaveric cervical spinal sections between C3 and C5 were tested in flexion-extension, torsion, and lateral bending modes, both with and without laminectomy, on an MTS machine. The lateral masses were plated and tested with bicortical screws in all 11 specimens. Long (14 mm) unicortical screws were used in 8, and short (10 mm) screws were used in 6 of the 11 specimens. Displacement then was determined in millimeters (of flexion-extension and lateral bending) and degrees (of torsion) for each value of applied torque (0.45, 0.9, 1.35, 1.8 Nm). Two-way analysis of variance using unequal data sets then was applied., Results: Analysis demonstrates that bicortical constructs were, on the average, stiffer than unicortical constructs in most bending modes. No significant differences were found, however, between bicortical constructs and long unicortical constructs without laminectomy. In the presence of a destabilizing laminectomy, a difference was found in the lateral bending mode. More differences were found between bicortical and short unicortical constructs both with and without laminectomy., Conclusions: Cervical lateral mass fixation with "long" (up to but not through the anterior lateral mass cortex) unicortical Magerl screws may provide an acceptable and safe alternative to bicortical screw fixation.

Study Design: This report describes two cases of acute spondylodiscitis, caused by, complicating two different conditions: microdiscectomy for herniated nucleus pulposus and decompressing laminotomy for spinal stenosis., Objective: To describe a rare and life-threatening spinal infection and discuss its successful management., Summary of Background Data: To our knowledge, no published reports in the English language have described this potentially devastating infection as a complication of elective noninstrumented discectomy or decompressive laminotomy., Methods: Two cases of a very early onset of acute spondylodiscitis, caused by, after minimally invasive lumbar spine surgeries are presented. The elapsed time between these two complications was 1 week. The clinical presentation was characteristically stormy in both cases. On postoperative day 2, the patients developed high fever with intense chills and concomitant acute low back pain rapidly increasing in severity. The overall clinical appearance was alarming. The patients were carefully investigated immediately and scrutinized for possible origin of the infection. Treatment consisted of prompt intravenous antibiotics and surgical debridement., Results: The history and clinical manifestations of postoperative spondylodiscitis were corroborated with magnetic resonance imaging findings and bacteriologic and hematologic laboratory examination. Blood cultures revealed as the responsible pathogenic microorganism. The source of the pathogens was contaminated normal saline used for surgical lavage. Both patients were able to completely resume their previous occupations after aggressive surgical debridement/irrigation and 3 months of antibiotic treatment., Conclusions: may become a potential pathogen, causing severe spinal infection after elective surgery. For prompt diagnosis and effective treatment of this life-threatening infection, one should maintain high index of suspicion and should not procrastinate in initiating treatment, which should consist of appropriate intravenous antibiotics and surgical debridement.

Study Design: Retrospective., Objectives: To determine the incidence, clinical presentation, diagnostic laboratory values, imaging characteristics, and optimal treatment of hematogenous pyogenic facet joint infections., Summary of Background Data: There are 27 documented cases of hematogenous pyogenic facet joint infections. Data regarding incidence, clinical presentation, diagnosis, and treatment response are incomplete because of the paucity of reported cases., Methods: This is a retrospective study of all cases of hematogenous pyogenic facet joint infection treated at one institution. Data from previous publications were combined with the present series to identify pertinent clinical characteristics and response to treatment., Results: A total of six cases (4%) of hematogenous pyogenic facet joint infection were identified of 140 cases of hematogenous pyogenic spinal infection at our institution. Combining all reported cases reveals the following: The average patient age is 55 years. Ninety-seven percent of cases occur in the lumbar spine. Epidural abscess formation complicates 25% of the cases of which 38% develop severe neurologic deficit. Erythrocyte sedimentation rate and C-reactive protein are elevated in all cases. Staphylococcus aureus is the most common infecting organism. Magnetic resonance imaging is accurate in identifying the septic joint and associated abscess formation. Percutaneous drainage of the involved joint has a higher rate of success (85%) than treatment with antibiotics alone (71%), but the difference is not significant (P = 0.37)., Conclusions: Hematogenous pyogenic facet joint infection is a rare but underdiagnosed clinical entity. Facet joint infections may be complicated by abscess formation in the epidural space or in the paraspinal muscles. Uncomplicated cases treated with percutaneous drainage and antibiotics may fare better than those treated with antibiotics alone. Cases complicated by an epidural abscess and severe neurologic deficit should undergo immediate decompressive laminectomy.

Study Design: In adult female sheep, histologic and biomechanical criteria were used to determine whether the osteoconductive performance of plaster of paris would promote the incorporation of the tubular titanium mesh implants used for interbody vertebral fusions., Objectives: To compare the osteogenicity of plaster of paris with that of autogenous iliac crest bone and bone marrow 6 months after they were loaded into tubular titanium mesh cages and implanted as L3-L5 bridges after L4 corpectomies., Summary of Background Data: One of the aims of surgery for vertebral pathology is to stabilize the spine by interbody fusions. The morbidity associated with the use of iliac crest autograft bone for fusion grafts prompted trials using plaster of paris as an osteoconductive substrate., Methods: The total volume of bone that invested the L3-L5 mesh cages after 6 months was quantitated by computed tomography scans. All specimens subsequently were cut into fusion mass segments for biomechanical testing in flexion, extension, compression, and torsion, and then embedded in plastic for sectioning and histomorphometry to determine the trabecular bone volume within the titanium mesh., Results: In each experimental model, implants of plaster of paris were the osteoconductive equal of autogenous iliac crest bone/marrow preparations. The volumes of bone formed around and within the titanium mesh were identical, and the tissues were biomechanically indistinguishable. A partial mechanism was determined by modifying the system for midshaft femoral defects., Conclusions: In the sheep, a tubular titanium mesh packed with plaster of paris forms an osteoconductive conduit to achieve a biomechanically stable interbody lumbar vertebral fusion.

The objective of this research was to determine the efficacy and safety of an experimental instrumentation device designed for transpedicular spinal fixation by evaluating fusion rates and clinical pain and function scores; to determine complication rates associated with the device; and to compare the obtained data with that previously published in the literature. Four hundred forty-two consecutive patients were enrolled in this 4-year, Food and Drug Administration-monitored investigational device exemption trial to undergo surgery for implantation of the device. Eighteen surgeons at 11 nationwide medical centers performed the operations and subsequent evaluations. The study population was derived from three diagnostic categories: degenerative disc disease, multioperated back, and vertebral fracture. The data source consisted of radiographs, clinical examination, and structured forms and questionnaires. Patients were evaluated preoperatively, intraoperatively, and postoperatively at 3, 6, 12, and 24 months. By the 24-month postoperative interval, attrition had reduced the study population to 342 patients, among whom bony fusion was obtained in 91.5%. Pain scores demonstrated a statistically significant improvement in clinical outcome. Intraoperative complications occurred in 21.9% of patients. Of the 442 study patients, 2.9% experienced device-related complications. Moreover, a total of 2,304 screws and bolts were implanted in this patient population. Of these, 0.39% were reported to have fractured. Among the 342 study patients observed during 24 months, the breakage rate of device components (bolt or screw) was 2.63%. These data compare favorably to existing reports of spinal arthrodesis effected with other types of instrumentation and without device implantation. In a 4-year trial, the experimental transpedicular fixation instrumentation produced successful spinal fusion in the majority of our study population, with acceptable complication rates.

Torsional injuries may be a precursor to intervertebral disc degeneration, but published rabbit models indicate a latent time of 6 months. We describe a rabbit model in which instability and disc degeneration appear within 3 months. Sixty-five male New Zealand rabbits underwent presurgical irradiation to inhibit heterotopic bone formation. Control animals then underwent either a soft-tissue release or facetectomy and capsulotomy, whereas experimental animals received surgery and an acute 30 degrees torsional lumbar injury. Capsulotomy, as well as facetectomy without torsion, failed to effect disc degeneration. However, the rabbits that received torsion exhibited clear indications of degenerative disc changes (thinning, increased PLA2 levels, and decreased nucleus pulposus volume) within 60-90 days. The observations associate disc degeneration with a destabilizing acute torsional injury.

The mechanism mediating the chronic pain associated with lumbar disc degeneration may involve neurotransmitters elaborated by dorsal root ganglion (DRG). This hypothesis has been tested in an applicable rabbit model of disc degeneration. Twenty control male rabbits underwent a soft-tissue release; 20 experimental rabbits sustained a facetectomy and capsulotomy and received an acute torsional lumbar injury. The levels of calcitonin gene-related peptide, vasoactive intestinal peptide, and substance P were measured in the DRG, spinal cord, and disc at 10, 30, 60, and 90 days postoperatively. Torsional injury was associated with a statistically significant increase in most DRG and spinal cord neurotransmitter values after 60-90 days. These points in time marked the periods of maximum biomechanical instability and disc narrowing. Such data support concepts about the association between chronic lumbar spinal instability, disc degeneration, and pain.

Thirty single-pedicle and triangulated pedicle screws were subjected to pull-out tests until complete dislodgment was achieved. Peak load, displacement curves, angle of triangulation, and equivalent mineral density were recorded. Dual pedicle screw triangulation produced a 154.4% increase in peak pull-out strength compared with that of the single pedicle screw. Salvage triangulation (replacing failed screws with a triangulation construct) produced a 127.4% increase in peak strength over that of the single screw. Positive correlation was found between individual screw peak strength, bone mineral density, and displacement at peak load. Primary and salvage triangulation produced higher resistance to pull-out than a single pedicle screw, which reflects the potential, beneficial effect of using this technique. Triangulation, therefore, can be used as primary (prophylactic) technique to enhance pedicular screw pull-out during forceful vertebral manipulation.

Study Design: Two prospective groups of patients received intraoperative autologous transfusion during reconstructive spine surgery. Before intraoperative autologous transfusion, one group underwent normovolemic hemodilution and apheresis of blood components in the operating room while being prepared for surgery. The allogeneic blood products needed for transfusion by each group were studied and compared with those of a retrospective group of patients receiving conventional transfusion therapy., Objectives: To determine if a combination of intraoperative autologous transfusion and hemodilution and apheresis decreases reliance on allogeneic blood products and increases autologous transfusions., Summary of Background Data: Transfusion rates of allogeneic red blood cells, which were unchanged by intraoperative autologous transfusion alone, were lowered when treatment included transfusion of these cells and preoperative autologous deposit. However, donor exposures from transfusions of allogeneic platelets and fresh frozen plasma have not been addressed., Method: Preoperative hemodilution and apheresis of autologous red blood cells, fresh plasma, and platelets, performed during induction of anesthesia for spine surgery was followed by intraoperative autologous transfusion using the same supplies. Intra- and postoperative transfusion of blood products to each group were evaluated and compared; allogeneic transfusions were given to a retrospective cohort of patients who received conventional transfusion therapy., Results: Hemodilution and apheresis followed by intraoperative autologous transfusion reduced exposures to individual blood donor products resulting in fewer transfusions and in transfusion of significantly fewer blood products. Intraoperative autologous transfusion alone decreased the number of red blood cells transfused, but required the same donor exposures for fresh frozen plasma and platelet support as the cohort of patients who received conventional transfusion therapy., Conclusions: A combination of hemodilution and apheresis and intraoperative autologous transfusion significantly decreased transfusion of allogeneic blood products and reliance on preoperative autologous deposit. Autologous transfusion of all blood products was significantly increased.