Percutaneous Pedicle Screw Stabilization: Surgical Technique, Fracture Reduction, and Review of Current Spine Trauma Applications.

Percutaneous pedicle screw fixation has evolved as a useful tool in the management of spinal trauma. As a minimally invasive approach, it provides the stability of open instrumentation while limiting blood loss, avoiding excessive muscle/soft-tissue insult, and improving postoperative pain and mobilization. Muscle-dilating techniques also preserve greater paraspinal muscle volume and strength compared with open midline approaches. In patients with spinal trauma, the use of percutaneous instrumentation and indirect reduction can theoretically preserve the fracture hematoma and its osteogenic inflammatory factors. The evolution of spinal instrumentation and the refinement of indirect reduction techniques has improved the capacity for correction of traumatic deformity. Although perioperative and short-term results have been well described, few long-term outcomes data exist.

Lemierre Disease: A Case With Multilevel Epidural Abscess and Aggressive Neurological Weakness: Case Report and Literature Review.

BACKGROUND: Lemierre disease is a rare postanginal sepsis caused by the anaerobe Fusobacterium necrophorum. It is associated with a pharyngitis that progresses quickly to thrombophlebitis of the internal jugular vein and metastatic abscesses to pulmonary, soft tissue, articular, and organ systems. It is rarely associated with spinal epidural abscesses. Because of the increasing antibiotic resistance, its incidence is on the rise. METHODS: A single-patient case report of an adolescent male who initially presented to our institution for bacteremia and febrile episodes. Over a 1-week course, he developed severe back pain and progressive lower extremity weakness. Advanced imaging revealed an epidural abscess spanning T2-L3 level with extension into the psoas and the paraspinal musculature. Acute management consisted of broad-spectrum intravenous (IV) antibiotics and hemilaminectomy decompression from T2 to L3. The patient completed a 6-week course of IV antibiotics and was followed for a 1-year time period with close clinical follow-up. RESULTS: Blood cultures identified the infecting organism as F. necrophorum. The combination of IV antibiotics and acute hemilaminectomy decompression resulted in successful clearance of the infecting organism with normalization of inflammatory markers and cultures. The patient noted immediate and sustained neurological improvement, with return of full motor and sensory function. At the 1-year timepoint, the patient was able to return to sports and no sagittal/coronal imbalance was noted on radiographs. CONCLUSIONS: An aggressive case of Lemierre disease with extensive epidural abscess formation and neurological weakness was successfully managed with the combination of IV antibiotics and extensive hemilaminectomies for decompression. The patient exhibited no long-term sequela as a result of either the epidural abscess or of its treatment. LEVEL OF EVIDENCE: Level V.

Effect of body mass index on early outcomes of minimally invasive degenerative lumbar surgery.

This retrospective study examined the early outcomes of healthy weight and severely obese subjects who underwent minimally invasive (MI) fusion and decompression surgery for degenerative lumbar disease at one to two spinal levels. A single surgeon (D.A.) operated on all subjects. Subjects were categorized based on body mass index [normal (18.5-24.9 kg/m(2)) or severely obese (over 35 kg/m(2))]. Surgical data included blood loss, hospital length of stay, narcotic use, discharge disposition, and postoperative infection. Data were compared using Levene's test for equality of variances, t test for equality of means, Pearson chi-square test, and Cramer's V correlation test (α ≤ .05 for all). SPSS software was utilized for all tests. Significant differences between the groups included blood loss, hospital length of stay, and early narcotic use. In the early postoperative setting, healthy weight subjects went home sooner and lost less blood, but needed more narcotic prescriptions filled than their obese counterparts. The use of MI spinal surgery in the severely obese population provides manageable issues for the patient and no significant complications when compared with the healthy weight population, indicating that it is a good alternative for obese patients.

Comparative reliability of 3 thoracolumbar fracture classification systems.

STUDY DESIGN: Prospective study of 3 spine surgeons, 3 spine fellows, 3 nonspine orthopedists, and 12 orthopedic residents classifying 97 thoracolumbar fractures using the Denis, Association for Osteosynthesis (AO), and Thoracolumbar Injury Severity Score (TLISS) systems and reclassifying them 3 months later. OBJECTIVE: To compare the reliability of the Denis, AO, and TLISS classification systems and evaluate the skills necessary for their use. SUMMARY OF BACKGROUND DATA: The Denis and AO systems are the traditional methods of classification of thoracolumbar fractures. The purpose of this study was to evaluate a novel classification system, the TLISS and compare its reliability among observers as compared with the Denis and AO classifications. METHOD: Ninety-seven sequential fractures from 1 surgeon's practice at a level 1 trauma center were collected. Twenty-one orthopedic physicians from two area level 1 trauma centers then completed the evaluation of the all fractures. Evaluator experience included staff, spine fellows, and residents. The interobserver and intraobserver reliability were determined. RESULT: In the TLISS, subgroups of evaluators, showed variation in reliability as expected with the highest reliability occurring in the senior resident group and attending spine surgeon group. The lowest reliabilities were in the nonspine attending orthopedists and junior residents. In each group, the neurologic status was consistently the category with the highest interobserver and intraobserver reliability. In the Denis and AO classifications, the highest reliabilities were again in the senior residents and spine attendings. The lowest were again in the nonspine attendings and junior residents. CONCLUSIONS: As a management tool, the TLISS seems to be an acceptably reliable system when compared with the Denis and AO systems. There is a base level of knowledge and familiarity necessary for the application of the system at reliable levels.

An in vitro biomechanical investigation: variable positioning of leopard carbon fiber interbody cages.

STUDY DESIGN: This study is a biomechanical analysis of intervertebral cage placement, using a biomechanical model that has the appropriate matching geometry of the lumbar spine at the level of L4-L5 based upon prior morphometric studies. OBJECTIVE: The goal of this in vitro biomechanical analysis of interbody cages is to determine the effect of interbody cage position on the mechanics of posterior spinal instrumentation. This biomechanical analysis can potentially be used to guide surgical technique for placement of interbody cage devices. SUMMARY OF BACKGROUND DATA: Lumbar interbody spinal fusion cages are increasingly being used to promote spinal fusion and improve sagittal alignment in patients with degenerative disk disease. The transforaminal approach for placement of these cages has become popular, although the actual position of the cage that will provide optimal mechanical support in the intervertebral space is not known. MATERIALS AND METHODS: Leopard carbon fiber interbody cages (DepuySpine, Raynham, MA) were placed in a spinal fusion model simulating the L4-L5 disk space in one of 3 positions-anterior, middle, or anterolateral. We tested 5 constructs in each of the 3 positions, applying cyclic axial loads of 500 N at a rate of 4 Hz for 100,000 cycles. Strain on the posterior instrumentation and displacement of the cages was measured at periodic intervals. Load to failure of each construct was tested after 100,000 cycles were complete. RESULTS: Statistical analysis of biomechanical indicators show more strain in the anterolateral position as compared with the anterior position (P=0.002) and middle position (P=0.02). No difference was noted between anterior and middle positions (P=1.00). Interval analysis reveals differences in strain at 500 cycles in anterior versus anterolateral (P=0.01) and middle versus anterolateral (P=0.02). At 10,000 cycles, anterolateral strain was significantly higher (P=0.02) than anterior. No significant difference in strain was noted at 50,000 or 100,000 cycles between any of the positions. No significant differences were noted in displacement of the cages between each of the positions. Ultimate load to failure was lower (nonsignificant) in the anterolateral versus anterior position (P=0.06), but no difference was noted between anterior versus middle (P=0.57) or anterolateral versus middle (P=0.69) positions. Linear regression analysis of load-displacement curves shows significance at 500 cycles (P=0.02), approaching significance at 10,000 cycles (P=0.07), and no significant difference at 50,000 (P=0.28) or 100,000 (P=0.28) cycles. CONCLUSIONS: Positioning of interbody cages in an offset position shows higher strain upon posterior instrumentation than a central position, and quicker load to failure than an anteriorly placed cage. Biomechanical studies using shear loading, and testing of adjacent spinal levels, are necessary to further elucidate the biomechanical consequences of variable positioning of interbody cages.

Radiographic assessment of lumbar facet distance spacing and spondylolysis.

STUDY DESIGN: Spondylolytic defects at L5 are influenced by insufficient differential spacing between the inferior articular facets of L4 and superior facets of S1. These structures then impinge on the intervening L5 pars interarticularis during hyperlordosis, contributing to fracture and resorption of the pars. OBJECTIVES: Articular facet spacing was evaluated on clinical radiographs of normal and spondylolytic patients. SUMMARY OF BACKGROUND DATA: Spondylolysis ranges from a hairline fracture through the pars to a complete pseudarthrotic defect. Insufficient increase in the distance between articular facets from L4-L5 to L5-S1 has been associated with chronic lytic defects in a skeletal sample. METHODS: Anteroposterior radiographs of 39 patients with L5-S1 spondylolysis were compared with radiographs from 42 normal individuals. Differences in transverse distances between lumbar articular facets and pedicles were compared using 2-tailed t tests. RESULTS: Patients with spondylolysis exhibited a smaller increase in interfacet distance from the L3-L4 facet joints to the L5-S1 joints than do normal patients, even relative to vertebral size. CONCLUSIONS: Spondylolytic fractures at L5 are influenced by an inadequate increase in interfacet distances between adjacent vertebrae. Individuals lacking sufficient increase in lower lumbar transverse interfacet dimensions are at greater risk of developing and maintaining spondylolytic defects.

Innovations in the treatment of low back pain.

Nonoperative care of the low back pain patient has changed little over the past 15 years. However, injections to localize pain have become increasingly more sophisticated for both diagnosis and treatment. Advances in surgical treatment have been dramatic. Minimally invasive techniques shorten postoperative recovery time by decreasing local tissue trauma. Disc replacement is a new option for treating the degenerative disc; offering the prospects of rapid postoperative recovery and maintenance of range of motion.