Douglas G. Orndorff

Reverse and pseudoreverse cortical sign in thoracolumbar burst fracture: radiologic description and distinction-a propos of three cases

In thoracolumbar burst fracture the “reverse cortical sign” is a known entity that corresponds to a fragment of the posterior wall that has been flipped 180° with the cancellous surface of the fragment facing posteriorly in the canal and the cortical surface (posterior wall) facing anteriorly. The identification of such reverse cortical fragment is crucial as ligamentotaxis is classically contraindicated as the posterior longitudinal ligament is ruptured. Recognition of such a flipped cortical fragment has relied so far on the axial CT. The advent of CT scans with sagittal reconstruction has allowed us to better describe such entities that have received little attention in the literature. The goal of this report was therefore to describe the appearance of the reverse cortical sign and its likes as they can appear on axial CT scans, sagittal reconstructions and MRI. During 1-year practice at our institution we had to treat three patients with thoracolumbar burst fracture associated with what looked like a reverse cortical sign on the axial CT scans. Further analysis of the sagittal reconstruction CT could differentiate the true reverse cortical sign from a new entity that we coined “the pseudoreverse cortical sign” as observed in two out of the three cases. In the pseudo reverse cortical sign what appears to be a flipped piece of posterior vertebral body is actually part of the superior or inferior endplate that is depressed into the comminuted vertebral body. In such cases the posterior longitudinal ligament appears to be in continuity and therefore such fracture can theoretically be treated with posterior ligamentotaxis as evidenced in one of our case. Careful analysis of the CT scan and specifically the sagittal reconstruction and MRI can differentiate two separate entities that may correspond to a different severity injury.

Interspinous Process Decompression Improves Quality of Life in Patients with Lumbar Spinal Stenosis

Lumbar spinal stenosis has been shown to negatively impact health-related quality of life. Interspinous process decompression (IPD) is a minimally invasive procedure that utilizes a stand-alone spacer to serve as a joint extension blocker to relieve neural compression in patients with spinal stenosis. Using the 5-year results from an FDA randomized controlled trial of IPD, the quality of life in 189 patients treated with the Superion® spacer was evaluated with the SF-12. Physical and mental component summary (PCS, MCS) scores were computed preoperatively and at annual intervals. For the PCS, mean scores improved from 29.4 ± 8.1 preoperatively to 41.2 ± 12.4 at 2 years (40%) and to 43.8 ± 11.6 at 5 years (49%) (p<0.001 for both comparisons). At 2 years, 81% (103 of 128) of subjects demonstrated maintenance or improvement in PCS scores. The mean MCS score improved from 50.0 ± 12.7 preoperatively to 54.4 ± 10.6 and 54.7 ± 8.6 at 2 and 5 years, respectively (p>0.10 for both comparisons). These results demonstrate that the significant impairment in physical well-being found in patients with lumbar spinal stenosis can be ameliorated, in large part, by IPD treatment.

Literature Evidence of the MIS Lateral Approach

Minimally disruptive approaches continue to gain adoption by spine surgeons in the hopes of minimizing soft tissue damage and accelerating postoperative recovery [1]. Lateral techniques such as the extreme lateral interbody fusion (XLIF®, NuVasive, Inc., San Diego, CA, USA) are one of those minimally disruptive approaches. The XLIF (XLIF®, NuVasive, Inc., San Diego, CA, USA) approach was first introduced in 2001 by Pimenta [2] and since then has gained acceptance and recognition as a spinal treatment.

Mini-Open Anterior Lumbar Interbody Fusion

Since the 1930s, an anterior surgical approach to the lumbar spine has been utilized for the surgical treatment of symptomatic lumbar disorders. A variation on the standard open technique, termed a mini-open ALIF approach, is commonly used with shorter surgical times, faster recovery, and similar fusion rates when compared to traditional anterior approaches (Saraph et al., Eur Spine J. 13(5):425–31, 2004). A mini-open ALIF approach allows for placement of an interbody graft in compression, the application of anterior instrumentation to restore the anterior tension band, and recreation of any lost lordosis without disrupting the posterior lumbar musculature, therefore aiding in higher fusion rates. Indications for a mini-open ALIF surgery include stabilization of deformity, pseudarthrosis, symptomatic degenerative disc disease, spondylolisthesis, foraminal stenosis, and infection. As with all surgical approaches, patient selection is important for clinical success. Contraindications can include prior abdominal surgery or retroperitoneal fibrosis. This chapter addresses the surgical technique, common intraoperative and postoperative complications, postoperative care, and pearls and pitfalls of a mini-open anterior approach for a lumbar interbody fusion.