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Ganesh Rao, Darrel S. Brodke, Matthew Rondina and Andrew T. Dailey

Object. To validate computerized tomography (CT) scanning as a tool to assess the accuracy of thoracic pedicle screw placement, the authors compared its accuracy with that of direct visualization in instrumented cadaveric spine specimens.

Methods. A grading scale was devised to score the placement of the pedicle screw. The grades ranged from 0 to 3 depending on the extent to which the pedicle had been violated. One hundred fifty-five pedicles were fitted with instrumentation in eight cadaveric spines. A single observer graded the appearance of the screw based on CT scans (3-mm axial sections with 1-mm overlap) and direct visualization of the specimen. The authors arrived at a Kappa value of 0.51, which suggested only moderate agreement between the two measurement techniques. Whereas CT had a positive predictive value of 95%, it had a negative predictive value of 62%.

Conclusions. The authors thus conclude that although CT scanning is the most valid tool to assess the accuracy of thoracic pedicle screw placement, it tends to overestimate the number of misplaced screws.

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Kee D. Kim, Jeffrey C. Wang, Daniel P. Robertson, Darrel S. Brodke, Mohammed BenDebba, Kathleen M. Block and Gere S. diZerega

Object

Although good surgical technique is effective in reducing postoperative epidural fibrosis, compression or tethering of the nerve root may cause recurrent radicular pain and physical impairment. The implantation of a bioresorbable gel on the dura may further decrease the amount of scar formation after surgery and thus improve the patient's ability to perform activities of daily living (ADL). This study is a 12-month evaluation of the safety and effectiveness of Oxiplex/SP Gel (FzioMed, Inc., San Luis Obispo, CA) in the reduction of pain and radiculopathy after lumbar discectomy.

Methods

A pilot randomized single-blind multicenter clinical trial was conducted to evaluate the performance of Oxiplex/SP Gel in patients who underwent surgery for unilateral herniation of the lumbar disc at L4–5 or L5–S1. Eighteen patients with severe leg pain and lower-extremity weakness (11 women and seven men) were randomly assigned intraoperatively to receive the gel at the conclusion of surgery (treatment group) or to undergo surgery alone (control group). Self-assessment questionnaires (Lumbar Spine Outcomes Questionnaire) to assess pain, symptoms, and ADL were completed preoperatively and at scheduled postoperative intervals (30 days, 90 days, 6 months, and 12 months).

The authors examined the spine and lower extremities of patients scheduled for discectomy to assess neurological function and pain. Treated patients received sufficient Oxiplex/SP Gel (1–3 ml) to coat the nerve root and fill the epidural space. Postoperative clinical evaluations were performed at 30 and 90 days. Patients completed the self-assessment questionnaires at baseline and were contacted by telephone or mail for the completion of the postoperative self-assessment questionnaires.

Surgical procedures were well tolerated; no device-related adverse events and no clinically significant laboratory results were reported. The 11 patients with severe leg pain and lower-extremity weakness who were treated with Oxiplex/SP Gel had a reduction in those symptoms at 30 days, 90 days, 6 months, and 12 months after discectomy, compared with the seven control patients who underwent surgery only.

Conclusions

Oxiplex/SP Gel was easy to use and safe in patients who underwent unilateral discectomy. A greater benefit in clinical outcome measures was seen over the 12-month follow-up period in gel-treated patients.

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Michael A. Finn, Daniel R. Fassett, Todd D. Mccall, Randy Clark, Andrew T. Dailey and Darrel S. Brodke

Object

Stabilization with rigid screw/rod fixation is the treatment of choice for craniocervical disorders requiring operative stabilization. The authors compare the relative immediate stiffness for occipital plate fixation in concordance with transarticular screw fixation (TASF), C-1 lateral mass and C-2 pars screw (C1L-C2P), and C-1 lateral mass and C-2 laminar screw (C1L-C2L) constructs, with and without a cross-link.

Methods

Ten intact human cadaveric spines (Oc–C4) were prepared and mounted in a 7-axis spine simulator. Each specimen was precycled and then tested in the intact state for flexion/extension, lateral bending, and axial rotation. Motion was tracked using the OptoTRAK 3D tracking system. The specimens were then destabilized and instrumented with an occipital plate and TASF. The spine was tested with and without the addition of a cross-link. The C1L-C2P and C1L-C2L constructs were similarly tested.

Results

All constructs demonstrated a significant increase in stiffness after instrumentation. The C1L-C2P construct was equivalent to the TASF in all moments. The C1L-C2L was significantly weaker than the C1L-C2P construct in all moments and significantly weaker than the TASF in lateral bending. The addition of a cross-link made no difference in the stiffness of any construct.

Conclusions

All constructs provide significant immediate stability in the destabilized occipitocervical junction. Although the C1L-C2P construct performed best overall, the TASF was similar, and either one can be recommended. Decreased stiffness of the C1L-C2L construct might affect the success of clinical fusion. This construct should be reserved for cases in which anatomy precludes the use of the other two.

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Alpesh A. Patel, Andrew Dailey, Darrel S. Brodke, Michael Daubs, Paul A. Anderson, R. John Hurlbert, Alexander R. Vacccaro and the Spine Trauma Study Group

Object

The authors review a novel subaxial cervical trauma classification system and demonstrate its application through a series of cervical trauma cases.

Methods

The Spine Trauma Study Group collaborated to create the Subaxial Injury Classification (SLIC) and Severity score. The SLIC system is reviewed and is applied to 3 cases of subaxial cervical trauma.

Results

The SLIC system identifies 3 major injury characteristics to describe subaxial cervical injuries: injury morphology, discoligamentous complex integrity, and neurological status. Minor injury characteristics include injury level and osseous fractures. Each major characteristic is assigned a numerical score based upon injury severity. The sum of these scores constitutes the injury severity score.

Conclusions

By addressing both discoligamentous integrity and neurological status, the SLIC system may overcome major limitations of earlier classification systems. The system incorporates a number of critical clinical variables—including neurological status, absent in earlier systems—and is simple to apply and may provide both diagnostic and prognostic information.

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Alpesh A. Patel, Andrew Dailey, Darrel S. Brodke, Michael Daubs, James Harrop, Peter G. Whang, Alexander R. Vaccaro and the Spine Trauma Study Group

Object

The aim of this study was to review the Thoracolumbar Injury Classification and Severity Score (TLICS) and to demonstrate its application through a series of spine trauma cases.

Methods

The Spine Trauma Study Group collaborated to create and report the TLICS system. The TLICS system is reviewed and applied to 3 cases of thoracolumbar spine trauma.

Results

The TLICS system identifies 3 major injury characteristics to describe thoracolumbar spine injuries: injury morphology, posterior ligamentous complex integrity, and neurological status. In addition, minor injury characteristics such as injury level, confounding variables (such as ankylosing spondylitis), multiple injuries, and chest wall injuries are also identified. Each major characteristic is assigned a numerical score, weighted by severity of injury, which is then summated to yield the injury severity score. The TLICS system has demonstrated initial success and its use is increasing. Limitations of the TLICS system exist and, in some instances, have yet to be addressed. Despite these limitations, the severity score may provide a basis to judge spinal stability and the need for surgical intervention.

Conclusions

By addressing both the posterior ligamentous integrity and the patient's neurological status, the TLICS system attempts to overcome the limitations of prior thoracolumbar classification systems. The TLICS system has demonstrated both validity and reliability and has also been shown to be readily learned and incorporated into clinical practice.

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Oren N. Gottfried and Darrel S. Brodke

Lumbar disc arthroplasty is now a common treatment for lumbar degenerative disc disease. Whereas the immediate and delayed complications in patients with artificial lumbar discs are well reported, the durability of artificial disc hardware after severe spine trauma is unknown. The authors describe the management of a rare case of a traumatic lumbar burst fracture in a patient who had undergone disc arthroplasty. This 31-year-old male contractor had undergone placement of an L4–5 Charité artificial disc (DePuy Spine) and L5–S1 anterior lumbar fusion 10 months before he fell from a roof and sustained a traumatic L-3 burst fracture with significant canal compromise and cauda equina injury. Despite the considerable compressive load on his spine, the artificial disc (L4–5) remained intact without any radiological signs of hardware failure, and the vertebrae above (L-4) and below (L-5) the artificial disc had no signs of injury. For the L-3 burst fracture the patient underwent an open decompressive laminectomy at L2–3 and posterior fusion with instrumentation from L-2 to L-4. At 24 months postinjury, he had returned to full work activities as a contractor with minimal back pain and mild right lower-extremity sensory changes and weakness left over from the trauma. The total disc arthroplasty at L4–5 is functional and has preserved motion, and there is a solid fusion at L2–4 and L5–S1. This case demonstrates that a lumbar artificial disc can tolerate a significant load from trauma and remain functional without hardware failure even after a traumatic burst fracture at the adjacent lumbar vertebral body and shows the successful treatment of this fracture, with posterior fusion preserving the motion of an artificial disc.

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Frank S. Bishop, Mical M. Samuelson, Michael A. Finn, Kent N. Bachus, Darrel S. Brodke and Meic H. Schmidt

Object

Thoracolumbar corpectomy is a procedure commonly required for the treatment of various pathologies involving the vertebral body. Although the biomechanical stability of anterior reconstruction with plating has been studied, the biomechanical contribution of posterior instrumentation to anterior constructs remains unknown. The purpose of this study was to evaluate biomechanical stability after anterior thoracolumbar corpectomy and reconstruction with varying posterior constructs by measuring bending stiffness for the axes of flexion/extension, lateral bending, and axial rotation.

Methods

Seven fresh human cadaveric thoracolumbar spine specimens were tested intact and after L-1 corpectomy and strut grafting with 4 different fixation techniques: anterior plating with bilateral, ipsilateral, contralateral, or no posterior pedicle screw fixation. Bending stiffness was measured under pure moments of ± 5 Nm in flexion/extension, lateral bending, and axial rotation, while maintaining an axial preload of 100 N with a follower load. Results for each configuration were normalized to the intact condition and were compared using ANOVA.

Results

Spinal constructs with anterior-posterior spinal reconstruction and bilateral posterior pedicle screws were significantly stiffer in flexion/extension than intact spines or spines with anterior plating alone. Anterior plating without pedicle screw fixation was no different from the intact spine in flexion/extension and lateral bending. All constructs had reduced stiffness in axial rotation compared with intact spines.

Conclusions

The addition of bilateral posterior instrumentation provided significantly greater stability at the thoracolumbar junction after total corpectomy than anterior plating and should be considered in cases in which anterior column reconstruction alone may be insufficient. In cases precluding bilateral posterior fixation, unilateral posterior instrumentation may provide some additional stability.

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Michael G. Fehlings, Justin S. Smith, Branko Kopjar, Paul M. Arnold, S. Tim Yoon, Alexander R. Vaccaro, Darrel S. Brodke, Michael E. Janssen, Jens R. Chapman, Rick C. Sasso, Eric J. Woodard, Robert J. Banco, Eric M. Massicotte, Mark B. Dekutoski, Ziya L. Gokaslan, Christopher M. Bono and Christopher I. Shaffrey

Object

Rates of complications associated with the surgical treatment of cervical spondylotic myelopathy (CSM) are not clear. Appreciating these risks is important for patient counseling and quality improvement. The authors sought to assess the rates of and risk factors associated with perioperative and delayed complications associated with the surgical treatment of CSM.

Methods

Data from the AOSpine North America Cervical Spondylotic Myelopathy Study, a prospective, multicenter study, were analyzed. Outcomes data, including adverse events, were collected in a standardized manner and externally monitored. Rates of perioperative complications (within 30 days of surgery) and delayed complications (31 days to 2 years following surgery) were tabulated and stratified based on clinical factors.

Results

The study enrolled 302 patients (mean age 57 years, range 29–86) years. Of 332 reported adverse events, 73 were classified as perioperative complications (25 major and 48 minor) in 47 patients (overall perioperative complication rate of 15.6%). The most common perioperative complications included minor cardiopulmonary events (3.0%), dysphagia (3.0%), and superficial wound infection (2.3%). Perioperative worsening of myelopathy was reported in 4 patients (1.3%). Based on 275 patients who completed 2 years of follow-up, there were 14 delayed complications (8 minor, 6 major) in 12 patients, for an overall delayed complication rate of 4.4%. Of patients treated with anterior-only (n = 176), posterior-only (n = 107), and combined anterior-posterior (n = 19) procedures, 11%, 19%, and 37%, respectively, had 1 or more perioperative complications. Compared with anterior-only approaches, posterior-only approaches had a higher rate of wound infection (0.6% vs 4.7%, p = 0.030). Dysphagia was more common with combined anterior-posterior procedures (21.1%) compared with anterior-only procedures (2.3%) or posterior-only procedures (0.9%) (p < 0.001). The incidence of C-5 radiculopathy was not associated with the surgical approach (p = 0.8). The occurrence of perioperative complications was associated with increased age (p = 0.006), combined anterior-posterior procedures (p = 0.016), increased operative time (p = 0.009), and increased operative blood loss (p = 0.005), but it was not associated with comorbidity score, body mass index, modified Japanese Orthopaedic Association score, smoking status, anterior-only versus posterior-only approach, or specific procedures. Multivariate analysis of factors associated with minor or major complications identified age (OR 1.029, 95% CI 1.002–1.057, p = 0.035) and operative time (OR 1.005, 95% CI 1.002–1.008, p = 0.001). Multivariate analysis of factors associated with major complications identified age (OR 1.054, 95% CI 1.015–1.094, p = 0.006) and combined anterior-posterior procedures (OR 5.297, 95% CI 1.626–17.256, p = 0.006).

Conclusions

For the surgical treatment of CSM, the vast majority of complications were treatable and without long-term impact. Multivariate factors associated with an increased risk of complications include greater age, increased operative time, and use of combined anterior-posterior procedures.