Tien V. Le

Minimally Invasive Surgery for Traumatic Spinal Pathologies A Mini-Open, Lateral Approach in the Thoracic and Lumbar Spine

Study Design. Prospective registry. Objective. The objective of this study was to examine patient outcomes using a mini-open, lateral approach for the treatment of traumatic thoracic and lumbar fractures. Summary of Background Data. The high-quality published studies that examine treatment methods for acute traumatic thoracic and lumbar fractures are few and a few that are present contain insufficient samples to make broad conclusions. Despite this, we know that conventional surgical techniques often include large, morbid exposures. More recent advancements in less invasive surgical techniques have greatly decreased the associated morbidities of conventional approaches, namely, thoracotomy. Methods. A total of 52 patients were treated at 1 of 2 institutions for traumatic thoracic or lumbar fractures with a mini-open lateral approach for corpectomy. Patients were prospectively followed for clinical outcomes, with treatment and in-hospital complications collected retrospectively. Results. The majority of patients (94.2%) presented with traumatic burst fractures with instability and neurologic deficit. Patients were treated with mini-open, lateral corpectomies from T7 to L4, the majority at T12 and L1, and were followed 2 years after surgery. Supplemental internal fixation was used in all patients: 75% anterolateral plating and 46.1% transpedicular fixation (11 [21.2%] patients with combined). Median operative time, estimated blood loss, and hospital stay were 128 minutes, 300 mL, and 4 days, respectively. Complications were observed in 13.5% of patients and no reoperations occurred. Neurologic status, assessed using American Spinal Injury Association categorization, improved significantly postoperatively, with 73% of patients either completely neurologically intact or with only slight residual deficits (American Spinal Injury Association E or D). No patient experienced neurologic deterioration. Expandable wide-footprint titanium cages were used in 34.6% of patients, which resisted radiographic subsidence seen in some patients treated with expandable cylindrical titanium cages. Conclusion. The mini-open lateral approach for thoracic and lumbar corpectomy was shown to be safe and effective in this series while avoiding many of the associated morbidities of thoracotomies for anterior column reconstruction and open posterior approaches.

Subsidence of Polyetheretherketone Intervertebral Cages in Minimally Invasive Lateral Retroperitoneal Transpsoas Lumbar Interbody Fusion

Study Design. A retrospective review. Objective. The objective is to evaluate subsidence related to minimally invasive lateral retroperitoneal lumbar interbody fusion by reviewing our experience with this procedure. Summary of Background Data. Polyetheretherketone intervertebral cages of different lengths, widths, and heights filled with various allograft types are commonly used as spacers in lumbar fusions. Subsidence is a potential complication. To date, there are no published reports specifically addressing subsidence, because it relates to a series of patients undergoing minimally invasive lateral retroperitoneal transpsoas lumbar interbody fusion. Methods. An institutional review board–approved, retrospective review of a prospectively collected database was conducted. One hundred forty consecutive patients who underwent this procedure between L1 and L5 during a 2-year period were included. All patients had T scores of −2.5 or more. Postoperative radiographs during routine follow-ups were reviewed for subsidence, defined as any violation of the vertebral end plate. Results. Radiographical subsidence occurred in 14.3% (20 of 140), whereas clinical subsidence occurred in 2.1%. Subsidence occurred in 8.8% (21 of 238) of levels fused. Construct length had a significant positive correlation with increasing subsidence rates. Subsidence rates decreased progressively with lower levels in the lumbar spine, but had a higher than expected rate at L4–L5. Subsidence rates of 14.1% (19 of 135) and 1.9% (2 of 103) were associated with 18-and 22-mm-wide cages, respectively. No significant trends were observed with cage lengths. Supplemental lateral plates had a higher rate of subsidence than bilateral pedicle screws. Subsidence occurred at the superior end plate 70% of the time. Conclusion. The use of wider intervertebral cages leads to a significantly lower rate of subsidence, but a longer cage does not necessarily offer a similar advantage. Wide cages are protective against subsidence, and the widest cages should be used whenever feasible for interbody fusion in the lumbar spine to protect indirect compression and promote arthrodesis.

Minimally invasive surgery treatment for thoracic spine tumor removal: a mini-open, lateral approach.

Study Design. Prospective registry. Objective. The objective of this study is to examine procedural and long-term outcomes of a mini-open, lateral approach for tumor removal in the thoracic spine. Summary of Background Data. The majority of spinal tumors present as metastatic tumors in the thoracic spine. Conventional surgical treatments have been associated with high rates of approach-related morbidities as well as difficult working windows for complete tumor excision. Recent advances in minimally invasive techniques, particularly mini-open (minimally invasive, not endoscopic) approaches, help to reduce the morbidities of conventional procedures with comparable outcomes. Methods. Twenty-one consecutively treated patients at 2 institutions were treated between 2007 and 2009. Treatment variables, including operating time, estimated blood loss, length of hospital stay, and complications were collected, as were outcome measures, including the visual analog scale for pain and the Oswestry disability index. Results. Twenty-one patients with thoracic spinal tumors were successfully treated with a minimally invasive lateral approach. Operating time, estimated blood loss, and length of hospital stay were 117 minutes, 291 mL, and 2.9 days, respectively. One (4.8%) perioperative complication occurred (pneumonia). Mean follow-up was 21 months. Two patients had residual tumor at last follow-up. Two patients died during the study as the result of other metastases (spine tumor was secondary). Visual analog scale improved from 7.7 to 2.9 and Oswestry disability index improved from 52.7% to 24.9% from preoperative to the last follow-up. Conclusion. The mini-open lateral approach described here can be performed safely and without many of the morbidities and difficulties associated with conventional and endoscopic procedures. Proper training in minimally invasive techniques and the use of direct-visualization minimally invasive retractors are required to safely and reproducibly treat these complex indications.

Anterior longitudinal ligament release using the minimally invasive lateral retroperitoneal transpsoas approach: a cadaveric feasibility study and report of 4 clinical cases

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.

Postoperative lumbar plexus injury after lumbar retroperitoneal transpsoas minimally invasive lateral interbody fusion.

Study Design. Retrospective review. Objective. To evaluate the motor and sensory deficit rate after the lumbar retroperitoneal transpsoas minimally invasive lateral interbody fusion (MIS LIF) by reviewing a single surgeons experience. Summary of Background Data. The MIS LIF is an increasingly used alternative to traditional open anterior or posterior operations to treat a host of spinal disorders. It has many advantages, but the potential for immediate postoperative thigh numbness, pain, and potential motor weakness has been reported. Published rates range widely in part because previous studies have based patient outcomes on data from different surgeons using different techniques. Methods. An institutional review board-approved, retrospective review of a prospectively collected database was conducted. Seventy-one consecutive patients who underwent this procedure between L1 and L5 during a 3-year period met criteria and were included. Postoperative clinical examinations immediately after surgery and during routine follow-up intervals were examined. Results. There was a 19.1% (14/71) rate of immediate postoperative ipsilateral thigh numbness during the study period. The annual rates of numbness progressively decreased annually. There was a 26.1% (6/23), 25% (5/20), and 10.7% (3/28) rate for 2008, 2009, and 2010, respectively. All patients with numbness had a fusion construct that involved L4–L5. More than half the patients, 54.9% (39/71), had immediate postoperative ipsilateral iliopsoas or quadriceps weakness. Of these, the vast majority had resolution by 3 months (92.3%), and all had complete resolution by 2 years. Conclusion. The lumbar retroperitoneal transpsoas MIS LIF is a safe alternative to traditional open operations for many spinal conditions. As with most minimally invasive techniques, there is a learning curve to be overcome to minimize the risk of iatrogenic nerve injuries. Our refined technique of the MIS LIF during a 3-year period has led to a significant reduction of the incidence of postoperative numbness of nearly 60% (from 26.1%–10.7%).

Abdominal wall paresis as a complication of minimally invasive lateral transpsoas interbody fusion

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.

The Effect of the Retroperitoneal Transpsoas Minimally Invasive Lateral Interbody Fusion on Segmental and Regional Lumbar Lordosis

Background. The minimally invasive lateral interbody fusion (MIS LIF) in the lumbar spine can correct coronal Cobb angles, but the effect on sagittal plane correction is unclear. Methods. A retrospective review of thirty-five patients with lumbar degenerative disease who underwent MIS LIF without supplemental posterior instrumentation was undertaken to study the radiographic effect on the restoration of segmental and regional lumbar lordosis using the Cobb angles on pre- and postoperative radiographs. Mean disc height changes were also measured. Results. The mean follow-up period was 13.3 months. Fifty total levels were fused with a mean of 1.42 levels fused per patient. Mean segmental Cobb angle increased from 11.10° to 13.61° (P < 0.001) or 22.6%. L2-3 had the greatest proportional increase in segmental lordosis. Mean regional Cobb angle increased from 52.47° to 53.45° (P = 0.392). Mean disc height increased from 6.50 mm to 10.04 mm (P < 0.001) or 54.5%. Conclusions. The MIS LIF improves segmental lordosis and disc height in the lumbar spine but not regional lumbar lordosis. Anterior longitudinal ligament sectioning and/or the addition of a more lordotic implant may be necessary in cases where significant increases in regional lumbar lordosis are desired.

Complications of the mini-open anterolateral approach to the thoracolumbar spine

The mini-open anterolateral approach to the thoracolumbar spine is gaining popularity as a minimally-invasive alternative to traditional open thoracolumbar approaches. Published studies reporting and discussing the complications associated with this minimally invasive approach, however, are limited. We performed a retrospective review of patients undergoing the mini-open lateral approach to the thoracolumbar spine for corpectomy/fusion. Intraoperative and postoperative complications are reported and analyzed. Eighty consecutive patients underwent the mini-open lateral approach with corpectomy and fusion for trauma (71%), tumor (26%) and infection (3%). Total complication rate was 12.5% (dural tear 2.5%, intercostal neuralgia 2.5%, deep vein thrombosis 2.5%, pleural effusion 1.3%, wound infection 1.3%, hardware failure 1.3%, hemothorax 1.3%). Two patients needed a re-operation to address the complication (hardware failure, hemothorax). There were no postoperative neurological complications. The mini-open anterolateral approach to the thoracolumbar spine is an appealing alternative to the traditional open approaches. This technique, however, is technically demanding and requires proficiency in the use of minimally invasive spinal surgery instruments and retractors.

Occipital condyle screw placement and occipitocervical instrumentation using three-dimensional image-guided navigation

Occipital condyle (OC) screws are an alternative cephalad fixation point in occipitocervical fusion. Safe placement of occipital, C1 lateral mass, and C2 pars screws have been described previously, but not OC screws. The craniocervical junction is complex, and a thorough understanding of the anatomy is needed. Three-dimensional (3D) image-guided navigation was used in six patients. There were no complications related to image-guided navigation during the placement of 12 OC screws and we found that this navigation can serve as a useful adjunct when placing an OC screw. Technical considerations of placing OC and C1 lateral mass screws are discussed with particular reference to patient positioning and the StealthStation® S7™ image-guided navigational platform (Medtronic, Minneapolis, MN, USA). The reference arc is attached to the head-clamp and faces forward. The optical camera and monitor are positioned at the head of the table for a direct, non-obstructed line-of-sight. To minimize intersegmental movement, the OC should not be drilled until all other screws have been placed. We conclude that 3D image-guided navigation is a useful adjunct that can be safely and effectively used for placement of instrumentation of the upper cervical spine including the OC.

Computed tomography–based morphometric analysis of the human occipital condyle for occipital condyle–cervical fusion

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.