Posterior open-wedge anterior longitudinal ligament release: Cadaveric technique analysis.

Anterior column release is a powerful surgical technique for achieving spinopelvic balance in adult patients with sagittal plane deformities. We present an alternative strategy for focal deformity correction from a posterior-only approach. The purpose of this study was to evaluate the feasibility and efficacy of a novel surgical technique called posterior open-wedge diskectomy and anterior longitudinal ligament (ALL) release (POWAR). A cadaveric torso underwent POWARs at the L1-L4 intervertebral disc spaces. Baseline measurements of end-plate angle (EPA), anterior intervertebral disc height (ADH), and posterior intervertebral disc height (PDH) were obtained. These measurements were repeated after three stages of correction: posterior column compression alone, posterior column compression following Schwab grade 2 osteotomies, and posterior column compression following POWAR. A second cadaver underwent posterolateral spinal dissection to demonstrate the pertinent anatomical features relevant to this novel procedure. With each stage of correction, a sequential increase in EPA and ADH and a decrease in PDH were demonstrated. The large increase in ADH seen following POWAR confirmed successful release of the ALL. In situ investigation of the aorta and inferior vena cava following anterior exposure revealed no injury to the great vessels or surrounding structures. Ex vivo testing of the aorta and inferior vena cava took place at the L3-4 level. This testing demonstrated no injury or tears to either vessel. POWAR is a new surgical technique that can provide an alternative to three-column osteotomy for surgeons performing spinal reconstructions in adults through an open, posterior-only approach. Clin. Anat. 32:348-353, 2019. © 2018 Wiley Periodicals, Inc.

Safety and Accuracy of Freehand Versus Navigated Iliac Screws: Results From 222 Screw Placements.

STUDY DESIGN: Retrospective review. OBJECTIVE: To compare the safety and accuracy of the freehand technique versus stereotactic navigation for placement of iliac screws. SUMMARY OF BACKGROUND DATA: Iliac screw fixation is often used to augment lumbosacral reconstruction in advanced spine disease to increase the likelihood of successful arthrodesis. Iliac screws can be placed with image guidance, using either intraoperative fluoroscopy or computed tomography (CT) to guide navigation. However, these imaging modalities add radiation exposure and can disrupt workflow. The freehand technique is an alternative strategy that decreases radiation exposure and workflow disruption but may compromise safety and accuracy. METHODS: A retrospective review was performed for a consecutive series of adult patients with degenerative spine conditions who underwent posterior reconstruction with iliac screw placement between 2011 and 2016. Clinical and radiographic data were collected and analyzed. The accuracy of iliac screw placement was determined with either intraoperative/postoperative CT imaging or anteroposterior/lateral radiography when CT was not performed. RESULTS: Bilateral iliac screws were placed in all 111 patients, for a total of 222 iliac screws. Eighty screws were placed with the freehand technique and 142 with the intraoperative navigation technique. CT imaging was used to assess placement accuracy of 124 screws (46 freehand [37%], 78 navigated [63%]). Accuracy was similar for the freehand group (89%, 41/46) and the navigated group (96%, 75/78) (P = 0.12). For patients without intraoperative/postoperative CT imaging, radiography was used to assess placement accuracy of 98 screws (34 freehand, 64 navigated) and the placement accuracy rate for the freehand group (100%, 34/34) was comparable to that for the navigated group (98%, 63/64) (P = 0.46). No complications attributable to iliac screw placement occurred in either group. CONCLUSION: Overall, there was no difference in the safety and accuracy between the freehand and navigated techniques. LEVEL OF EVIDENCE: 4.

Transdural retrieval of a retropulsed lumbar interbody cage: Technical case report.

The purpose of this case report was to describe a novel method to retrieve a herniated lumbar interbody cage. Transforaminal lumbar interbody fusion (TLIF) is an increasingly popular method of spinal fixation and fusion. Unexpected retropulsion of an interbody is a rare event that can result in intractable pain or motor compromise necessitating surgical retrieval of the interbody. Both anterior and posterior approaches to removing migrated cages may be associated with significant surgical morbidity and mortality. A 60-year-old woman underwent an L4-S1 TLIF coupled with pedicle screw fixation at a previous hospital 5 years prior to admission. She noted sudden-onset bilateral lower extremity weakness and right-sided foot drop. Magnetic resonance imaging and radiographs were notable for purely centrally herniated interbody. A posterior, midline transdural approach was used to retrieve the interbody. Situated in between nerve rootlets to the ventral canal, this virgin corridor allowed us to easily visualize and protect neurological structures while safely retrieving the interbody. The patient experienced an immediate improvement in symptoms and was discharged on postoperative day 3. At 12-month follow-up, she had no evidence of cerebrospinal fluid (CSF) leak and had returned to normal activities of daily living. While the risk of CSF leak may be higher with a transdural approach, we maintain that avoiding unnecessary retraction of the nerve roots may outweigh this risk. To our knowledge, this is the first case report of a transdural approach for the retrieval of a retropulsed lumbar interbody cage.