John K. Song

Dynamic interspinous process technology.

Study Design. A literature review. Objectives. To evaluate the mechanisms of action and effectiveness of interspinous distraction devices in managing symptomatic lumbar spinal pathology. Summary of Background Data. Fusion operations have traditionally been used to manage many disorders of the lumbar spine related to deformity, pain, or instability. Concern over the long-term effects of fusion on adjacent segments has led to the development of the concept of dynamic stabilization. Methods. A Medline search was performed using the key words “interspinous implants,” “interspinous devices,” and “lumbar dynamic stabilization.” The abstracts of each were reviewed. Relevant articles were reviewed in detail and other appropriate references obtained. In addition, when available, nonpublished manufacturer’s information was reviewed. Results. Articles describing the following implants were included in this review: the Minns Device, the Interspinous “U,” the Diam, the Wallis Implant, and the X STOP. Conclusions. These devices continue to be evaluated in clinical trials. Early results suggest a possible role in the management of degenerative disorders of the lumbar spine.

Minimally Invasive Resection of Intradural-Extramedullary Spinal Neoplasms

OBJECTIVE: Spinal intradural-extramedullary neoplasms are uncommon lesions that usually cause pain or neurological deficit secondary to neural compression. Traditional treatment of these tumors includes open laminectomy with intradural resection. We describe an alternative minimally invasive surgical technique in a consecutive series of patients undergoing treatment for symptomatic lesions. METHODS: Six patients (four men, two women) presented with symptoms including pain (five out of six) and/or neurological deficit (two out of six) with radiographic evidence of intradural pathology. All patients underwent surgical resection using a minimally invasive, unilateral approach. Pain relief was analyzed using the visual analog scale and magnetic resonance imaging to evaluate the extent of resection. Traditional laminectomy for tumor resection disrupts the muscular, ligamentous, and bony structures of the spine, which may contribute to pain and instability. Minimally invasive resection of intradural tumors offers the option of reducing approach morbidity when resecting these lesions. Using a tubular retractor system (X-Tube, Medtronic Sofamor-Danek, Memphis, TN) and microscopic surgical techniques, we were able to resect different intradural lesions successfully. RESULTS: All patients underwent successful, complete resection of their intradural-extramedullary tumors. The average patient age was 47 years (range, 41–60 yr) with one cervical, one thoracic, and four lumbar lesions. The mean operative time was 247 minutes (range, 180–320 min), the estimated blood loss was 56 mLs (range, 40–75 mLs), and the hospital stay was 57 hours (range, 48–80 h). Histologically, five tumors were determined to be schwannomas and one was identified as a myxopapillary ependymoma. There were no complications associated with this surgical technique. Postoperative magnetic resonance imaging demonstrated complete resection in all cases. CONCLUSION: Intradural-extramedullary neoplasms can be safely and effectively treated with minimally invasive techniques. Potential reduction in blood loss, hospitalization and disruption to local tissues suggest that, in the hands of an experienced surgeon, this technique may present an alternative to traditional open tumor resection.

Recombinant Human Bone Morphogenetic Protein-2-Induced Radiculitis in Elective Minimally Invasive Transforaminal Lumbar Interbody Fusions : A Series Review

Study Design. Retrospective single center analysis. Objective. The purpose of our study is to quantify the development of a postoperative radiculitis in our minimally invasive transforaminal lumbar interbody fusion patient population. Summary of Background Data. The application of recombinant human Bone Morphogenetic Protein-2 (BMP) in spinal surgery has allowed for greater success in spinal fusions. This has led to the FDA approving its use in anterior lumbar interbody fusion. However, its well-recognized benefits have generated its “off-label” use in the cervical, thoracic, and lumbar spine. Despite its benefits, the adverse effects of its inflammatory properties are just starting to get recognized. Some clear adverse reactions have been documented in the literature in the cervical spine. However, we feel that these inflammatory properties may be present in the lumbar spine as well. Methods. We performed a retrospective chart review of 43 patients who had undergone a minimally invasive transforaminal lumbar interbody fusions. Thirty-five of these patients had BMP and 8 patients did not have BMP. We documented whether there was a preoperative radiculopathy present and whether a radiculopathy was present postoperative. We reviewed radiographic postoperative imaging to establish a structural cause for any radiculopathy. If new or increasing radicular symptoms were present, we attempted to assess the duration of these symptoms. Results. Our analysis, showed that 0 of the 8 patients of the non-BMP group had new radicular symptoms that were not attributed to structural causes. In the BMP group, 4 of the 35 patients (11.4%) had new radicular symptoms without structural etiology. Conclusion. Our analysis suggest that patients undergoing minimally invasive transforaminal lumbar interbody fusions procedures have a higher incidence of developing new radicular symptoms that could be attributed to BMP.

Efficacy of Surgical Preparation Solutions in Lumbar Spine Surgery

BACKGROUND Postoperative spinal wound infections are relatively common and are often associated with increased morbidity and poor long-term patient outcomes. The purposes of this study were to identify the common bacterial flora on the skin overlying the lumbar spine and evaluate the efficacy of readily available skin-preparation solutions in the elimination of bacterial pathogens from the surgical site following skin preparation. METHODS A prospective randomized study was undertaken to evaluate 100 consecutive patients undergoing elective lumbar spine surgery. At the time of surgery, the patients were randomized to be treated with one of two widely used, and Food and Drug Administration (FDA)-approved, surgical skin-preparation solutions: ChloraPrep (2% chlorhexidine gluconate and 70% isopropyl alcohol) or DuraPrep (0.7% available iodine and 74% isopropyl alcohol). Specimens for aerobic and anaerobic cultures were obtained prior to skin preparation (pre-preparation), after skin preparation (post-preparation), and after wound closure (post-closure). A validated neutralization solution was used for each culture to ensure that the antimicrobial activity was stopped immediately after the sample was taken. Positive cultures and specific bacterial pathogens were recorded. RESULTS Coagulase-negative Staphylococcus, Propionibacterium acnes, and Corynebacterium were the most commonly isolated organisms prior to skin preparation. The overall rate of positive cultures prior to skin preparation was 82%. The overall rate of positive cultures after skin preparation was 0% (zero of fifty) in the ChloraPrep group and 6% (three of fifty) in the DuraPrep group (p = 0.24, 95% confidence interval [CI] = 0.006 to 0.085). There was an increase in positive cultures after wound closure, but there was no difference between the ChloraPrep group (34%, seventeen of fifty) and the DuraPrep group (32%, sixteen of fifty) (p = 0.22, 95% CI = 0.284 to 0.483). Body mass index (BMI), duration of surgery, and estimated blood loss did not a show significant association with post-closure positive culture results. CONCLUSIONS ChloraPrep and DuraPrep are equally effective skin-preparation solutions for eradication of common bacterial pathogens on the skin overlying the lumbar spine.

Minimally invasive posterolateral thoracic corpectomy: cadaveric feasibility study and report of four clinical cases.

OBJECTIVETo demonstrate the feasibility of and initial clinical experience with a novel minimally invasive posterolateral thoracic corpectomy technique. METHODSSeven procedures were performed on 6 cadavers to determine the feasibility of thoracic corpectomy using a minimally invasive approach. The posterolateral thoracic corpectomies were performed with expandable 22 mm diameter tubular retractor paramedian incisions. The posterolateral aspects of the vertebral bodies were accessed extrapleurally, and complete corpectomies were performed. Intraprocedural fluoroscopy and postoperative computed tomography were used to assess the degree of decompression. In addition, 2 clinical cases of T6 burst fracture, 1 T4–T5 plasmacytoma, and 1 T12 colon cancer metastasis were treated using this minimally invasive approach. RESULTSIn the cadaveric study, an average of 93% of the ventral canal and 80% of the corresponding vertebral body were removed. The pleura and intrathoracic contents were not violated. Adequate exposure was obtained to allow interbody grafting between the adjacent vertebral bodies. The procedures were successfully performed in the 4 clinical cases using a minimally invasive technique, and the patients demonstrated good outcomes. CONCLUSIONBased on this study, minimally invasive posterolateral thoracic corpectomy safely and successfully allows complete spinal canal decompression without the tissue disruption associated with open thoracotomy. This approach may improve the complication rates that accompany open or even thoracoscopic approaches for thoracic corpectomy and may even allow surgical intervention in patients with significant comorbidities.

Cadaveric evaluation of minimally invasive posterolateral thoracic corpectomy: a comparison of 3 approaches.

Study Design A cadaver study comparing 3 different minimally invasive approaches to the anterior thoracic spine. Objective To assess the feasibility of minimally invasive thoracic corpectomy from a posterolateral approach and to compare surgical results from 3 approaches. Summary of Background Data Traditional posterolateral approaches to the thoracic spine are effective but are associated with a high rate of operative morbidity. Methods Thoracic corpectomies were performed using a modified tubular retractor starting at 3, 6, and 9 cm off of midline. Postoperative computed tomography scans were performed and analyzed to assess the extent of corpectomy and ventral decompression. Results From 3 to 6 to 9 cm, a significant difference in extent of corpectomy (65.8%, 81.5%, and 82.6%, P=0.02) and ventral decompression (83.6%, 90.4%, 94.6%, P=0.05) was noted between 3 cm and the more lateral approaches. The 9 cm approach required more rib resection and average working distances of 8.4 to 11.3 cm, which made the procedure more difficult technically and less suited to the length of standard instruments. Conclusions Minimally invasive thoracic corpectomy is feasible and a 6 cm approach off of midline appears optimal.

Minimally invasive discectomy for the treatment of disc herniation causing cauda equina syndrome

Cauda equina syndrome (CES) is a condition associated with significant morbidity that requires definitive surgical decompression of the nerve roots to prevent permanent disability. Traditionally, wide open decompression has been advocated to obtain optimal decompression with minimal complications. Some have been reluctant to employ minimally invasive strategies to treat urgent conditions. The authors present a small series of four patients who presented with CES and were treated with minimally invasive discectomy (MID). Operative length times (mean±standard deviation, 102.8±30.9 minutes) were comparable to reported operative length for open laminectomies. All patients had either stabilization or resolution of symptoms at the 6-week follow-up examination. No patients suffered a cerebrospinal fluid (CSF) leak post-operatively. This series of patients presenting with CED at a single institution treated with MID demonstrates that MID can be used to successfully treat CES. Even large fragments can be safely removed without increased risk of a CSF leak.

Incidence of graft extrusion following minimally invasive transforaminal lumbar interbody fusion

Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has been scrutinized for having a complex learning curve. Careful assessment of MI-TLIF complications and critical analyses of prevention may aid a safe adoption of this technique. The current report focuses on the incidence of interbody cage extrusions following MI-TLIF in a series of 513 patients. The authors discuss their experience with graft extrusions and provide methods to minimize this complication. This study retrospectively reviewed 513 prospectively followed patients who underwent MI-TLIF over a 10 year period. The inclusion criteria consisted of all patients who underwent one to three level MI-TLIF, from whom the incidence of cage extrusion was analyzed. Cage extrusion was defined as an interbody graft migrating outside the cephalad and caudal vertebral body posterior margin. Cage extrusions were diagnosed by comparing the intraoperative radiographs to the postoperative radiographs. Patients with >10° coronal curves, significant sagittal malalignment, infection, and preoperative instrumentation failure were excluded. Of 513 patients undergoing MI-TLIF, five patients (0.97%) were diagnosed with cage migrations. The mean follow-up duration was 13.6 ± standard deviation of 8.8 months. Complications included asymptomatic cage migration alone (two patients) neurological decline (two patients) and epidural hematoma (one patient). On average, cage migrations cost a university hospital an additional

Intraoperative and perioperative complications in minimally invasive transforaminal lumbar interbody fusion: a review of 513 patients

US17,217 for revision treatment. While the incidence of cage migrations is low (0.97%), it can lead to postoperative complications that require revision surgery and increased hospital costs. The risk for this significant complication can be minimized with proper technique and patient selection.