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  • Author or Editor: Armen R. Deukmedjian x
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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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Armen R. Deukmedjian, Amir Ahmadian, Konrad Bach, Alexandros Zouzias and Juan S. Uribe

Object

Lateral minimally invasive thoracolumbar instrumentation techniques are playing an increasing role in the treatment of adult degenerative scoliosis. However, there is a paucity of data in determining the ideal candidate for a lateral versus a traditional approach, and versus a hybrid construct. The objective of this study is to present a method for utilizing the lateral minimally invasive surgery (MIS) approach for adult spinal deformity, provide clinical outcomes to validate our experience, and determine the limitations of lateral MIS for adult degenerative scoliosis correction.

Methods

Radiographic and clinical data were collected for patients who underwent surgical correction of adult degenerative scoliosis between 2007 and 2012. Patients were retrospectively classified by degree of deformity based on coronal Cobb angle, central sacral vertical line (CSVL), pelvic incidence, lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic tilt (PT), presence of comorbidities, bone quality, and curve flexibility. Patients were placed into 1 of 3 groups according to the severity of deformity: “green” (mild), “yellow” (moderate), and “red” (severe). Clinical outcomes were determined by a visual analog scale (VAS) and the Oswestry Disability Index (ODI).

Results

Of 256 patients with adult degenerative scoliosis, 174 underwent a variant of the lateral approach. Of these 174 patients, 27 fit the strict inclusion/exclusion criteria (n = 9 in each of the 3 groups). Surgery in 17 patients was dictated by their category, and 10 were treated with surgery outside of their classification. The average age was 61 years old and the mean follow-up duration was 17 months. The green and yellow groups experienced a reduction in coronal Cobb angle (12° and 11°, respectively), and slight changes in CSVL, SVA, and PT, and LL. In the green group, the VAS and ODI improved by 35 and 17 points, respectively, while in the yellow group they improved by 36 and 33 points, respectively. The red subgroup showed a 22° decrease in coronal Cobb angle, 15° increase in LL, and slight changes in PT and SVA. Three patients placed in the yellow subgroup had “green” surgery, and experienced a coronal Cobb angle and LL decrease by 17° and 10°, respectively, and an SVA and PT increase by 1.3 cm and 5°, respectively. Seven patients placed in the red group who underwent “yellow” or “green” surgery had a reduction in coronal Cobb angle of 16°, CSVL of 0.1 cm, SVA of 2.8 cm, PT of 4°, VAS of 28 points, and ODI of 12 points; lumbar lordosis increased by 15°. Perioperative complications included 1 wound infection, transient postoperative thigh numbness in 2 cases, and transient groin pain in 1 patient.

Conclusions

Careful patient selection is important for the application of lateral minimally invasive techniques for adult degenerative scoliosis. Isolated lateral interbody fusion with or without instrumentation is suitable for patients with preserved spinopelvic harmony. Moderate sagittal deformity (compensated with pelvic retroversion) may be addressed with advanced derivatives of the lateral approach, such as releasing the anterior longitudinal ligament. For patients with severe deformity, the lateral approach may be used for anterior column support and to augment arthrodesis.

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Amir Ahmadian, Armen R. Deukmedjian, Naomi Abel, Elias Dakwar and Juan S. Uribe

Object

The minimally invasive lateral transpsoas approach has become an increasingly popular means of fusion. The most frequent complication is related to lumbar plexus nerve injuries; these can be diagnosed based on distribution of neurological deficit following the motor and/or sensory nerve injury. However, the literature has failed to provide a clinically relevant description of these complications. With accurate clinical diagnosis, spine practitioners can provide more precise prognostic and management recommendations to include observation, nerve blocks, neurodestructive procedures, medications, or surgical repair strategies. The purpose of this study was to standardize the clinical findings of lumbar plexopathies and nerve injuries associated with minimally invasive lateral retroperitoneal transpsoas lumbar fusion.

Methods

A thorough literature search of the MEDLINE database up to June 2012 was performed to identify studies that reported lumbar plexus and nerve injuries after the minimally invasive lateral retroperitoneal transpsoas approach. Included studies were assessed for described neurological deficits postoperatively. Studies that did attempt to describe nerve-related complications clinically were excluded. A clinically relevant assessment of lumbar plexus nerve injury was derived to standardize early diagnosis and outline prognostic implications.

Results

A total of 18 studies were selected with a total of 2310 patients; 304 patients were reported to have possible plexus-related complications. The incidence of documented nerve and/or root injury and abdominal paresis ranged from 0% to 3.4% and 4.2%, respectively. Motor weakness ranged from 0.7% to 33.6%. Sensory complications ranged from 0% to 75%. A lack of consistency in the descriptions of the lumbar plexopathies and/or nerve injuries as well as a lack of diagnostic paradigms was noted across studies reviewed. Sensory dermal zones were established and a standardized approach was proposed.

Conclusions

There is underreporting of postoperative lumbar plexus nerve injury and a lack of standardization of clinical findings of neural complications related to the minimally invasive lateral retroperitoneal transpsoas approach. The authors provide a diagnostic paradigm that allows for an efficient and accurate classification of postoperative lumbar plexopathies and nerve injuries.

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Jotham C. Manwaring, Konrad Bach, Amir A. Ahmadian, Armen R. Deukmedjian, Donald A. Smith and Juan S. Uribe

Object

Minimally invasive (MI) fusion and instrumentation techniques are playing a new role in the treatment of adult spinal deformity. The open pedicle subtraction osteotomy (PSO) and Smith-Petersen osteotomy (SPO) are proven segmental methods for improving regional lordosis and global sagittal parameters. Recently the MI anterior column release (ACR) was introduced as a segmental method for treating sagittal imbalance. There is a paucity of data in the literature evaluating the alternatives to PSO and SPO for sagittal balance correction.

Thus, the authors conducted a preliminary retrospective radiographic review of prospectively collected data from 2009 to 2012 at a single institution. The objectives of this study were to: 1) investigate the radiographic effect of MI-ACR on spinopelvic parameters, 2) compare the radiographic effect of MI-ACR with PSO and SPO for treatment of adult spinal deformity, and 3) investigate the radiographic effect of percutaneous posterior spinal instrumentation on spinopelvic parameters when combined with MI transpsoas lateral interbody fusion (LIF) for adult spinal deformity.

Methods:

Patient demographics and radiographic data were collected for 36 patients (9 patients who underwent MI-ACR and 27 patients who did not undergo MI-ACR). Patients included in the study were those who had undergone at least a 2-level MI-LIF procedure; adequate preoperative and postoperative 36-inch radiographs of the scoliotic curvature; a separate second-stage procedure for the placement of posterior spinal instrumentation; and a diagnosis of degenerative scoliosis (coronal Cobb angle > 10° and/or sagittal vertebral axis > 5 cm). Statistical analysis was performed for normality and significance testing.

Results

Percutaneous transpedicular spinal instrumentation did not significantly alter any of the spinopelvic parameters in either the ACR group or the non-ACR group. Lateral MI-LIF alone significantly improved coronal Cobb angle by 16°, and the fractional curve significantly improved in a subgroup treated with L5–S1 transforaminal lumbar interbody fusion. Fifteen ACRs were performed in 9 patients and resulted in significant coronal Cobb angle correction, lumbar lordosis correction of 16.5°, and sagittal vertebral axis correction of 4.8 cm per patient. Segmental analysis revealed a 12° gain in segmental lumbar lordosis and a 3.1-cm correction of the sagittal vertebral axis per ACR level treated.

Conclusions

The lateral MI-LIF with ACR has the ability to powerfully restore lumbar lordosis and correct sagittal imbalance. This segmental MI surgical technique boasts equivalence to SPO correction of these global radiographic parameters while simultaneously creating additional disc height and correcting coronal imbalance. Addition of posterior percutaneous instrumentation without in situ manipulation or overcorrection does not alter radiographic parameters when combined with the lateral MI-LIF.

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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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Lawrence G. Lenke

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Jotham C. Manwaring, Devon Truong, Armen R. Deukmedjian, Carolyn M. Carey, Bruce B. Storrs, Luis F. Rodriguez, Lisa Tetreault and Gerald F. Tuite

The management of newborns with extreme macrocephaly related to hydrocephalus can be difficult; balancing the treatment of severe cranial deformity with optimal hydrocephalus management can be complicated. Excessive CSF drainage can result in significant suture overlap that leads to difficulties in patient positioning, secondary synostosis, and long-term aesthetic complications. Delayed cranial reduction and remodeling procedures carry significant risk, and the aesthetic outcomes have sometimes been poor.

The authors describe a newborn with severe macrocephaly who underwent shunt placement followed by a limited cranial reduction and fixation procedure using an absorbable plate within the 1st week of life. The procedure produced an immediate intracranial volume reduction of 49%. This novel management strategy facilitated patient positioning, simplified hydrocephalus management, and provided an excellent aesthetic outcome.

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Juan S. Uribe, Armen R. Deukmedjian, Praveen V. Mummaneni, Kai-Ming G. Fu, Gregory M. Mundis Jr., David O. Okonkwo, Adam S. Kanter, Robert Eastlack, Michael Y. Wang, Neel Anand, Richard G. Fessler, Frank La Marca, Paul Park, Virginie Lafage, Vedat Deviren, Shay Bess and Christopher I. Shaffrey

Object

It is hypothesized that minimally invasive surgical techniques lead to fewer complications than open surgery for adult spinal deformity (ASD). The goal of this study was to analyze matched patient cohorts in an attempt to isolate the impact of approach on adverse events.

Methods

Two multicenter databases queried for patients with ASD treated via surgery and at least 1 year of follow-up revealed 280 patients who had undergone minimally invasive surgery (MIS) or a hybrid procedure (HYB; n = 85) or open surgery (OPEN; n = 195). These patients were divided into 3 separate groups based on the approach performed and were propensity matched for age, preoperative sagittal vertebral axis (SVA), number of levels fused posteriorly, and lumbar coronal Cobb angle (CCA) in an attempt to neutralize these patient variables and to make conclusions based on approach only. Inclusion criteria for both databases were similar, and inclusion criteria specific to this study consisted of an age > 45 years, CCA > 20°, 3 or more levels of fusion, and minimum of 1 year of follow-up. Patients in the OPEN group with a thoracic CCA > 75° were excluded to further ensure a more homogeneous patient population.

Results

In all, 60 matched patients were available for analysis (MIS = 20, HYB = 20, OPEN = 20). Blood loss was less in the MIS group than in the HYB and OPEN groups, but a significant difference was only found between the MIS and the OPEN group (669 vs 2322 ml, p = 0.001). The MIS and HYB groups had more fused interbody levels (4.5 and 4.1, respectively) than the OPEN group (1.6, p < 0.001). The OPEN group had less operative time than either the MIS or HYB group, but it was only statistically different from the HYB group (367 vs 665 minutes, p < 0.001). There was no significant difference in the duration of hospital stay among the groups. In patients with complete data, the overall complication rate was 45.5% (25 of 55). There was no significant difference in the total complication rate among the MIS, HYB, and OPEN groups (30%, 47%, and 63%, respectively; p = 0.147). No intraoperative complications were reported for the MIS group, 5.3% for the HYB group, and 25% for the OPEN group (p < 0.03). At least one postoperative complication occurred in 30%, 47%, and 50% (p = 0.40) of the MIS, HYB, and OPEN groups, respectively. One major complication occurred in 30%, 47%, and 63% (p = 0.147) of the MIS, HYB, and OPEN groups, respectively. All patients had significant improvement in both the Oswestry Disability Index (ODI) and visual analog scale scores after surgery (p < 0.001), although the MIS group did not have significant improvement in leg pain. The occurrence of complications had no impact on the ODI.

Conclusions

Results in this study suggest that the surgical approach may impact complications. The MIS group had significantly fewer intraoperative complications than did either the HYB or OPEN groups. If the goals of ASD surgery can be achieved, consideration should be given to less invasive techniques.