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Armen R. Deukmedjian, Tien V. Le, Elias Dakwar, Carlos R. Martinez and Juan S. Uribe

Object

The minimally invasive lateral interbody fusion of the lumbar spine through a retroperitoneal transpsoas approach has become increasingly used. Although preoperative imaging is performed supine, the procedure is performed with the patient in the lateral decubitus position. The authors measured the changes in location of the psoas muscle, aorta, inferior vena cava (IVC), iliac vessels, and kidneys with regard to the fixed lumbar spine when moving from a supine to a lateral decubitus position.

Methods

Unenhanced lumbar MRI scans were performed using a 3T magnet in 10 skeletally mature volunteers in the supine, left lateral decubitus (LLD), and right lateral decubitus (RLD) positions. Positional changes in the aorta, IVC, iliac vessels, and kidneys were then analyzed at all lumbar levels when moving from supine to RLD and supine to LLD. Values are presented as group means.

Results

When the position was changed from supine to RLD, both the aorta and the IVC moved up to 6 mm to the right, with increased movement caudally at L3–4. The aorta was displaced 2 mm anteriorly at L1–2, and the IVC moved 3 mm anteriorly at L1–2 and L2–3 and 1 mm posteriorly at L3–4. The left kidney moved 22 mm anteriorly and 15 mm caudally, while the right kidney moved 9 mm rostrally.

When the position was changed from supine to LLD, the aorta moved 1.5 mm to the left at all levels, with very minimal anterior/posterior displacement. The IVC moved up to 10 mm to the left and 12 mm anteriorly, with increased movement rostrally at L1–2. The left kidney moved 3 mm anteriorly and 1 mm rostrally, while the right kidney moved 20 mm anteriorly and 5 mm caudally.

The bifurcation of the aorta was an average of 18 mm above the L4–5 disc space, while the convergence of the iliac veins to form the IVC was at the level of the disc space. The iliopsoas did not move in any quantifiable direction when the position was changed from supine to lateral; its shape, however, may change to become more flat or rounded. When the position was changed from supine to RLD, the right iliac vein moved posteriorly an average of 1.5 mm behind the anterior vertebral body (VB) line (a horizontal line drawn on an axial image at the anterior VB), while the other vessels stayed predominantly anterior to the disc space. When the position was changed from supine to LLD, the right iliac vein moved to a position 1.4 mm anterior to the anterior VB line. There was negligible movement of the other vessels in this position.

Conclusions

The authors showed that the aorta, IVC, and kidneys moved a significant distance away from the surgical corridor with changes in position. At the L4–5 level, a left-sided approach may be riskier because the right common iliac vein trends posteriorly and into the surgical corridor, whereas in a right-sided approach it trends anteriorly.

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Tien V. Le, Ali A. Baaj, Armen Deukmedjian, Juan S. Uribe and Fernando L. Vale

Object

The pediatric Chance fracture (PCF) is an uncommon injury, but it has been increasingly reported. Knowledge is limited to few case reports and short series. To understand the various aspects of this injury, the authors reviewed the current literature.

Methods

A literature search was conducted using the PubMed and Ovid online databases and relevant key words. All articles that were in English and provided information regarding PCF as a sole or part of the objective were retrieved.

Results

Seventy-three articles were found to fulfill the inclusion criteria. Relevant information about PCF collected from these articles included: 1) mode of trauma, 2) associated injuries, 3) radiological classification, and 4) treatment.

Conclusions

Chance fractures in children are potentially devastating injuries largely caused by motor vehicle collisions, and these fractures may be more common than previously thought. Concomitant intraabdominal injuries are common and should be suspected, particularly when a seat belt sign is observed. Blunt abdominal aortic injuries are rarely associated, but should be evaluated for and treated appropriately. Magnetic resonance imaging is best for defining ligamentous injury, which aids in defining the pattern of injury, facilitating appropriate treatment regimens.

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Elias Dakwar, Tien V. Le, Ali A. Baaj, Anh X. Le, William D. Smith, Behrooz A. Akbarnia and Juan S. Uribe

Object

The minimally invasive lateral transpsoas approach for interbody fusion has been increasingly employed to treat various spinal pathological entities. Gaining access to the retroperitoneal space and traversing the abdominal wall poses a risk of injury to the major nervous structures. Nerve injury of the abdominal wall can potentially lead to paresis of the abdominal musculature and bulging of the abdominal wall. Abdominal wall nerve injury resulting from the minimally invasive lateral retroperitoneal transpsoas approach has not been previously reported. The authors describe a case series of patients presenting with paresis and bulging of the abdominal wall after undergoing a minimally invasive lateral retroperitoneal approach.

Methods

The authors retrospectively reviewed all patients who underwent a minimally invasive lateral transpsoas approach for interbody fusion and in whom development of abdominal paresis developed; the patients were treated at 4 institutions between 2006 and 2010. All data were recorded including demographics, diagnosis, operative procedure, positioning, hospital course, follow-up, and complications. The onset, as well as resolution of the abdominal paresis, was reviewed.

Results

The authors identified 10 consecutive patients in whom abdominal paresis developed after minimally invasive lateral transpsoas spine surgery out of a total of 568 patients. Twenty-nine interbody levels were fused (range 1–4 levels/patient). There were 4 men and 6 women whose mean age was 54.1 years (range 37–66 years). All patients presented with abdominal paresis 2–6 weeks postoperatively. In 8 of the 10 patients, abdominal wall paresis had resolved by the 6-month follow-up visit. Two patients only had 1 and 4 months of follow-up. No long-term sequelae were identified.

Conclusions

Abdominal wall paresis is a rare but known potential complication of abdominal surgery. The authors report the first case series associated with the minimally invasive lateral transpsoas approach.

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Tien V. Le, Donald A. Smith, Mark S. Greenberg, Elias Dakwar, Ali A. Baaj and Juan S. Uribe

Object

The aim of this study was to review the authors' experience with 101 cases over the past 3 years with minimally invasive lateral interbody fusion using a lateral plate. Their main goal was to specifically look for hardware-associated complications. Three cases of hardware failure and 3 cases of vertebral body (VB) fractures associated with lateral plate placement are reported. The authors also review the literature pertaining to lateral plates and related complications.

Methods

This study is a retrospective review of a database of patients who underwent minimally invasive lateral interbody fusion in the thoracolumbar spine during a 3-year period.

Results

Six complications were identified, resulting in an incidence of 5.9%. Three hardware failures, 2 coronal plane VB fractures, and 1 lateral VB fracture were identified. All complications occurred in multilevel cases. All cases presented with recurrent back pain except one, which was identified incidentally.

Conclusions

Minimally invasive lateral interbody fusion is a safe and direct technique that is practical, especially when trying to avoid other approaches for hardware insertion, and it also avoids the complications associated with other types of instrumentation such as pedicle screws. Careful consideration during patient selection and during the operation will aid in the avoidance of complications.

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Armen R. Deukmedjian, Tien V. Le, Ali A. Baaj, Elias Dakwar, Donald A. Smith and Juan S. Uribe

Object

Traditional procedures for correction of sagittal imbalance via shortening of the posterior column include the Smith-Petersen osteotomy, pedicle subtraction osteotomy, and vertebral column resection. These procedures require wide exposure of the spinal column posteriorly, and may be associated with significant morbidity. Anterior longitudinal ligament (ALL) release using the minimally invasive lateral retroperitoneal approach with a resultant net lengthening of the anterior column has been performed as an alternative to increase lordosis. The objective of this study was to demonstrate the feasibility and early clinical experience of ALL release through a minimally invasive lateral retroperitoneal transpsoas approach, as well as to describe its surgical anatomy in the lumbar spine.

Methods

Forty-eight lumbar levels were dissected in 12 fresh-frozen cadaveric specimens to study the anatomy of the ALL as well as its surrounding structures, and to determine the feasibility of the technique. The lumbar disc spaces and ALL were accessed via the lateral transpsoas approach and confirmed with fluoroscopy in each specimen. As an adjunct, 4 clinical cases of ALL release through the minimally invasive lateral retroperitoneal transpsoas approach were reviewed. Operative technique, results, complications, and early outcomes were assessed.

Results

In the cadaveric study, sectioning of the ALL proved to be feasible from the minimally invasive lateral retroperitoneal transpsoas approach. The structures at most immediate risk during this procedure were the aorta, inferior vena cava, iliac vessels, and sympathetic plexus. The mean increase in segmental lumbar lordosis per level of ALL release was 10.2°, while global lumbar lordosis improved by 25°. Each level of ALL release took 56 minutes and produced 40 ml of blood loss on average. Visual analog scale and Oswestry Disability Index scores improved by 9 and 35 points, respectively. There were no cases of hardware failure, and as of yet no complications to report.

Conclusions

This initial experience suggests that ALL release through the minimally invasive lateral retroperitoneal transpsoas approach may be feasible, allows for improvement of lumbar lordosis without the need of an open laparotomy/thoracotomy, and minimizes the tissue disruption and morbidity associated with posterior osteotomies.

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Tien V. Le, Elias Dakwar, Shannon Hann, Euclides Effio, Ali A. Baaj, Carlos Martinez, Fernando L. Vale and Juan S. Uribe

Object

Occipital condyle screws serve as an alternative fixation point in occipital-cervical fusion. Their placement requires a thorough understanding of the anatomy of the occipital condyles and associated structures. This study is a CT-based morphometric analysis of occipital condyles as related to occipital condyle–cervical fusion.

Methods

A total of 170 patients were examined with CT scans of the craniocervical junction at a single institution, for a total of 340 occipital condyles, between March 6, 2006, and July 30, 2006. All CT scans were negative for traumatic, degenerative, and neoplastic pathological entities. Condylar anteroposterior (AP) length, transverse width, height, projected screw angle, and projected screw lengths were measured on an EBW Portal 2.5 CT Viewer Workstation (Philips Electronics).

The longest axis in the AP orientation of the occipital condyle was accepted as the length. The transverse width was a line perpendicular to the midpoint of the long axis. The height was measured in the coronal projection that had the thickest craniocaudal portion of the condyle. The screw trajectory started 5 mm lateral to the medial edge of the condyle and a line was directed anteromedially in the longest axis. The angle was measured relative to the sagittal midline. The screw length was measured from the outer cortex of the posterior wall to the outer cortex of the anterior wall.

Results

The mean ± SD values for occipital condyle measurements were as follows: AP length was 22.38 ± 2.19 mm (range 14.7–27.6 mm); width was 11.18 ± 1.44 mm (range 7.4–19.0 mm); height was 9.92 ± 1.30 mm (range 5.1–14.3 mm); screw angle was 20.30° ± 4.89° (range 8.0°–34.0°); and screw length was 20.30 ± 2.24 mm (range 13.0–27.6 mm).

Conclusions

These measurements correlate with previous cadaveric and radiographic studies of the occipital condyle, and emphasize the role of preoperative planning for the feasibility of placement of an occipital condyle screw.