A prospective comparison of surgical approach for anterior L4-L5 fusion: laparoscopic versus mini anterior lumbar interbody fusion

Preoperative phlebography in anterior L4-L5 disc approach. Clinical experience about 63 cases

INTRODUCTION

The anterior approach of the L4-L5 disc requires a perfect knowledge of the venous anatomy. Some configurations make this approach hazardous. The purpose of this study is to classify configurations of the iliocava junction and the iliolumbar vein relative to L4-L5 and to analyze vascular complications.

MATERIALS AND METHODS

The preoperative phlebographies of 63 patients (30 men, 33 women, mean age 42years) undergoing a L4-L5 disc replacement were reviewed. The height of the iliocava junction was calculated as a ratio of the distance between the discs L4-L5 and L5-S1. The position of the left iliac vein was classified into three thirds across the width of L5. The number of branches of the iliolumbar vein was noted. Surgical reports were reviewed for complications.

RESULTS

The height of the iliocava junction was very high in six, high in 25, low in 26 and very low in six patients. The position of the left iliac vein was medial in 20, intermediate in 28 and lateral in 15 patients. The iliolumbar vein had one branch in 37, two in 20, three in three patients. It was not visualized in three cases. Variants of the venous anatomy included eight duplications of the left iliac vein, four wide diameters and one iliolumbar vein network pattern. Intraoperatively, three lacerations of iliolumbar veins occurred.

CONCLUSION

The iliocava anatomy is very variable: the safety of an anterior approach to the L4-L5 disc depends on it. The information of preoperative phlebography can help to plan a more accessible antero-lateral approach or to switch on a posterior fusion if the anatomical situation is deemed too dangerous, such as duplicated left iliac veins.

LEVEL OF EVIDENCE

Level IV. Diagnostic study.

A comparison of complication rate between anterior and lateral approaches to the lumbar spine

AIM

The aim of this study was to compare the complication rate of traditional minimally invasive anterior with the new minimally invasive lateral trans-psoatic retroperitoneal approaches to the intervertebral discs at levels T12-L5.

METHODS

A review of all cases of minimally invasive anterior (ALIF) and lateral (XLIF) intervertebral disc surgery at levels T12-L5, treated at the Department of Neurosurgery from January 1996 to September 2011. The ALIF group consisted of 120 and the XLIF group consisted of 88 patients. Preoperative diagnoses were: degenerative disc disease, failed back surgery syndrome, spondylolisthesis, retrolisthesis and posttraumatic disc injury. The surgical steps are described. All surgical intraoperative and postoperative complications directly related to the spinal surgery were prospectively documented. The outcome measure was rate of complications.

RESULTS

In the ALIF group there were no major complications, only 35 minor intra- and postoperative complications in 32 patients (26.6%). The main complication was lumbar post-sympathectomy syndrome in 19 patients (15.8%). In the XLIF group there were 26 complications in 22 patients (25%). One major intraoperative complication was partial and transient injury to the L5 nerve root (1.1%). There were 25 minor postoperative complications in the XLIF group in 21 patients (23.9%), mainly transient pain of the left groin or anterior thigh in 11 patients (12.5%) or numbness in the same dermatomas in 9 patients (10.2%). Statistically there was no difference between the ALIF and XLIF groups in complication rate.

CONCLUSION

Anterolateral and lateral retroperitoneal minimally invasive approaches to levels T12-L5 disc spaces are safe procedures with only minor complications and one exception. The rate of complications was similar in both groups. In the case of ALIF, the particular complication was post-sympathectomy syndrome. The main complication of XLIF was transient nerve root injury in one patient due to underestimation of the procedure in the outset. Intraoperative neuromonitoring during XLIF surgery is fully recommended.

Complications and Morbidities of Mini-open Anterior Retroperitoneal Lumbar Interbody Fusion: Oblique Lumbar Interbody Fusion in 179 Patients

STUDY DESIGN

A retrospective study including 179 patients who underwent oblique lumbar interbody fusion (OLIF) at one institution.

PURPOSE

To report the complications associated with a minimally invasive technique of a retroperitoneal anterolateral approach to the lumbar spine.

OVERVIEW OF LITERATURE

Different approaches to the lumbar spine have been proposed, but they are associated with an increased risk of complications and a longer operation.

METHODS

A total of 179 patients with previous posterior instrumented fusion undergoing OLIF were included. The technique is described in terms of: the number of levels fused, operative time and blood loss. Persurgical and postsurgical complications were noted.

RESULTS

Patients were age 54.1 ± 10.6 with a BMI of 24.8 ± 4.1 kg/m(2). The procedure was performed in the lumbar spine at L1-L2 in 4, L2-L3 in 54, L3-L4 in 120, L4-L5 in 134, and L5-S1 in 6 patients. It was done at 1 level in 56, 2 levels in 107, and 3 levels in 16 patients. Surgery time and blood loss were, respectively, 32.5 ± 13.2 minutes and 57 ± 131 ml per level fused. There were 19 patients with a single complication and one with two complications, including two patients with postoperative radiculopathy after L3-5 OLIF. There was no abdominal weakness or herniation.

CONCLUSIONS

Minimally invasive OLIF can be performed easily and safely in the lumbar spine from L2 to L5, and at L1-2 for selected cases. Up to 3 levels can be addressed through a 'sliding window'. It is associated with minimal blood loss and short operations, and with decreased risk of abdominal wall weakness or herniation.

The presacral retroperitoneal approach for axial lumbar interbody fusion

The presacral retroperitoneal approach for axial lumbar interbody fusion (presacral ALIF) is not widely reported, particularly with regard to the mid-term outcome. This prospective study describes the clinical outcomes, complications and rates of fusion at a follow-up of two years for 26 patients who underwent this minimally invasive technique along with further stabilisation using pedicle screws. The fusion was single-level at the L5-S1 spinal segment in 17 patients and two-level at L4–5 and L5-S1 in the other nine. The visual analogue scale for pain and Oswestry Disability Index scores were recorded pre-operatively and during the 24-month study period. The evaluation of fusion was by thin-cut CT scans at six and 12 months, and flexion-extension plain radiographs at six, 12 and 24 months. Significant reductions in pain and disability occurred as early as three weeks postoperatively and were maintained. Fusion was achieved in 22 of 24 patients (92%) at 12 months and in 23 patients (96%) at 24 months. One patient (4%) with a pseudarthrosis underwent successful revision by augmentation of the posterolateral fusion mass through a standard open midline approach.

There were no severe adverse events associated with presacral ALIF, which in this series demonstrated clinical outcomes and fusion rates comparable with those of reports of other methods of interbody fusion.

Robot-assisted resection of paraspinal Schwannoma

Resection of retroperitoneal tumors is usually performed using the anterior retroperitoneal approach. Our report presents an innovative method utilizing a robotic surgical system. A 50-yr-old male patient visited our hospital due to a known paravertebral mass. Magnetic resonance imaging showed a well-encapsulated mass slightly abutting the abdominal aorta and left psoas muscle at the L4-L5 level. The tumor seemed to be originated from the prevertebral sympathetic plexus or lumbosacral trunk and contained traversing vessels around the tumor capsule. A full-time robotic transperitoneal tumor resection was performed. Three trocars were used for the robotic camera and working arms. The da Vinci Surgical System® provided delicate dissection in the small space and the tumor was completely removed without damage to the surrounding organs and great vessels. This case demonstrates the feasibility of robotic resection in retroperitoneal space. Robotic surgery offered less invasiveness in contrast to conventional open surgery.

Intraoperative and early postoperative complications in extreme lateral interbody fusion: an analysis of 600 cases

STUDY DESIGN

Prospective analysis of 600 extreme lateral interbody fusion (XLIF) approach procedures for intraoperative and perioperative complications.

OBJECTIVE

To delineate and describe complications in a large, prospective series of minimally invasive lateral lumbar fusion procedures (XLIF).

SUMMARY OF BACKGROUND DATA

While some small series of lateral lumbar fusion have discussed complications, no results from large studies have been reported.

METHODS

A total of 600 patients were treated with a lateral approach to fusion (XLIF) for degenerative spinal conditions. Data were collected prospectively on all patients and analyzed for demographic, diagnostic, and hospitalization information to identify operative and early postoperative complications. Documented complication types and rates in this large series were compared with smaller prior reports on lateral approach fusions, as well as other minimally invasive (mini-anterior lumbar interbody fusion and minimally invasive surgical [MIS] transforaminal lumbar interbody fusion) and more traditional fusion approaches (posterior intertransverse fusion, anterior lumbar interbody fusion, posterior lumbar interbody fusion, transforaminal lumbar interbody fusion).

RESULTS

Seven hundred forty-one levels were treated, 80.8% single level, 15.0% 2 level, 4.0% 3 level, 0.2% 4 level; 59.3%, including the L4 to L5 levels. A total of 99.2% included supplemental internal fixation; 83.2% included pedicle screw fixation (predominantly unilateral). Hemoglobin change from pre- to postoperation averaged 1.38. Hospital stay averaged 1.21 days. The overall incidence of perioperative complications (intraoperation and out to 6 weeks postoperation) was 6.2%: 9 (1.5%) in-hospital surgery-related events, 17 (2.8%) in-hospital medical events, 6 (1.0%) out-of-hospital surgery-related events, and 5 (0.8%) out-of-hospital medical events. There were no wound infections, no vascular injuries, no intraoperative visceral injuries, and 4 (0.7%) transient postoperative neurologic deficits. Eleven events (1.8%) resulted in additional procedures/reoperation.

CONCLUSIONS

Compared with traditional open approaches, the MIS lateral approach to fusion by using the XLIF technique resulted in a lower incidence of infection, visceral and neurologic injury, and transfusion as well as markedly shorter hospitalization. Complications in MIS XLIF compare favorably with those from other MIS fusion procedures; duration of hospitalization is shorter than with any previously reported technique.

An MRI study of psoas major and abdominal large vessels with respect to the X/DLIF approach

Extreme/direct lateral interbody fusion (X/DLIF) has been used to treat various lumbar diseases. However, it involves risks to injure the lumbar plexus and abdominal large vessels when it gains access to the lumbar spine via lateral approach that passes through the retroperitoneal fat and psoas major muscle. This study was aimed to determine the distribution of psoas major and abdominal large vessels at lumbar intervertebral spaces in order to select an appropriate X/DLIF approach to avoid nerve and large vessels injury. Magnetic resonance imaging scanning on lumbar intervertebral spaces was performed in 48 patients (24 males, 24 females, 54.2 years on average). According to Moro's method, lumbar intervertebral space was divided into six zones A, I, II, III, IV and P. Thickness of psoas major was measured and distribution of abdominal large vessels was surveyed at each zone. The results show vena cava migrate from the right of zone A to the right of zone I at L1/2-L4/5; abdominal aorta was located mostly to the left of zone A at L1/2-L3/4 and divided into bilateral iliac arteries at L4/5; Psoas major was tenuous and dorsal at L1/2 and L2/3, large and ventral at L3/4 and L4/5. Combined with the distribution of nerve roots reported by Moro, X/DLIF approach is safe via zones II-III at L1/2 and L2/3, and via zone II at L3/4. At L4/5, it is safe via zones I-II in left and via zone II in right side, respectively.

Complications in spine surgery

OBJECT

The overall incidence of complications or adverse events in spinal surgery is unknown. Both prospective and retrospective analyses have been performed, but the results have not been critically assessed. Procedures for different regions of the spine (cervical and thoracolumbar) and the incidence of complications for each have been reported but not compared. Authors of previous reports have concentrated on complications in terms of their incidence relevant to healthcare providers: medical versus surgical etiology and the relevance of perioperative complications to perioperative events. Few authors have assessed complication incidence from the patient's perspective. In this report the authors summarize the spine surgery complications literature and address the effect of study design on reported complication incidence.

METHODS

A systematic evidence-based review was completed to identify within the published literature complication rates in spinal surgery. The MEDLINE database was queried using the key words "spine surgery" and "complications." This initial search revealed more than 700 articles, which were further limited through an exclusion process. Each abstract was reviewed and papers were obtained. The authors gathered 105 relevant articles detailing 80 thoracolumbar and 25 cervical studies. Among the 105 articles were 84 retrospective studies and 21 prospective studies. The authors evaluated the study designs and compared cervical, thoracolumbar, prospective, and retrospective studies as well as the durations of follow-up for each study.

RESULTS

In the 105 articles reviewed, there were 79,471 patients with 13,067 reported complications for an overall complication incidence of 16.4% per patient. Complications were more common in thoracolumbar (17.8%) than cervical procedures (8.9%; p < 0.0001, OR 2.23). Prospective studies yielded a higher incidence of complications (19.9%) than retrospective studies (16.1%; p < 0.0001, OR 1.3). The complication incidence for prospective thoracolumbar studies (20.4%) was greater than that for retrospective series (17.5%; p < 0.0001). This difference between prospective and retrospective reviews was not found in the cervical studies. The year of study publication did not correlate with the complication incidence, although the duration of follow-up did correlate with the complication incidence (p = 0.001).

CONCLUSIONS

Retrospective reviews significantly underestimate the overall incidence of complications in spine surgery. This analysis is the first to critically assess differing complication incidences reported in prospective and retrospective cervical and thoracolumbar spine surgery studies.

Migrated XLIF cage: case report and discussion of surgical technique

Extreme lateral interbody fusion (XLIF; NuVasive, Inc, San Diego, California) is a minimally invasive technique developed to avoid complications associated with traditional or minimally invasive anterior or posterior approaches to lumbar interbody fusion. It uses a direct lateral, retroperitoneal, transpsoas approach for placement of an interbody cage. To date, no reports of cage-related complications or procedures for revising an XLIF have been published. This article describes a case of a complication unique to this procedure and the surgical technique used to treat it. A 49-year-old woman underwent XLIF at L3-4 with supplemental posterior pedicle fixation for treatment of a pseudarthrosis of a previous fusion performed for junctional degeneration below an old scoliosis construct. One month postoperatively, she reported increasing leg pain, and imaging studies demonstrated the cage to have extruded laterally. The cage was revised using a mini-open lateral approach. The presence of neurologic symptoms (leg pain) necessitated the cage to first be reimpacted before it could be safely extracted. A new cage was placed with the addition of a lateral plate. The patient's leg pain resolved shortly after the revision, and at 1-year follow-up, she appeared to have a solid fusion with no further complications. If required, XLIF may be safely and effectively revised through a minimally invasive or mini-open lateral approach. Use of a lateral plate as a buttress should be considered in cases associated with significant coronal deformity or lateral listhesis, even when planning use of supplemental posterior instrumentation.

Two-year clinical and radiographic success of minimally invasive lateral transpsoas approach for the treatment of degenerative lumbar conditions

Background

The lateral transpsoas approach to interbody fusion is a less disruptive but direct-visualization approach for anterior/anterolateral fusion of the thoracolumbar spine. Several reports have detailed the technique, the safety of the approach, and the short term clinical benefits. However, no published studies to date have reported the long term clinical and radiographic success of the procedure.

Materials and methods

The current study is a retrospective chart review of prospectively collected clinical and radiographic outcomes in 62 patients having undergone the Anterolateral transpsoas procedure at a single institution for anterior column stabilization as treatment for degenerative conditions, including degenerative disk disease, spondylolisthesis, scoliosis, and stenosis. Only patients who were a minimum of 2 years postoperative were included in this evaluation. Clinical outcomes measured included visual analog pain scales (VAS) and Oswestry disability index (ODI). Radiographic outcomes included identification of successful arthrodesis.

Results

Sixty-two patients were treated with lateral interbody fusion between 2003 and December 2006. Twenty-six patients (42%) were single-level, 13 (21%) 2-level, and 23 (37%) 3- or more levels. Forty-five (73%) included supplemental posterior pedicle fixation, 4 (6%) lateral fixation, and 13 (21%) were stand-alone. Pain scores (VAS) decreased significantly from preoperative to 2 years follow-up by 37% (P < .0001). Functional scores (ODI) decreased significantly by 39% from preoperative to 2 years follow-up (P < .0001). Clinical success by ODI-change definition was achieved in 71% of patients. Radiographic success was achieved in 91% of patients, with 1 patient with pseudarthrosis requiring posterior revision.

Conclusion

The lateral transpsoas approach is similar to a traditional anterior lumbar interbody fusion, in that access is obtained through a retroperitoneal, direct-visualization exposure, and a large implant can be placed in the interspace to achieve disk height and alignment correction. The 2 years plus clinical and radiographic success rates are similar to or better than those reported for traditional anterior and posterior approach procedures, which, coupled with significant short-term benefits of minimal morbidity, make the lateral approach a safe and effective treatment option for anterior/anterolateral lumbar fusions.

Presacral retroperitoneal approach to axial lumbar interbody fusion: a new, minimally invasive technique at L5-S1: Clinical outcomes, complications, and fusion rates in 50 patients at 1-year follow-up

BACKGROUND

The presacral retroperitoneal approach to an axial lumbar interbody fusion (ALIF) is a percutaneous, minimally invasive technique for interbody fusion at L5-S1 that has not been extensively studied, particularly with respect to long-term outcomes.

OBJECTIVE

The authors describe clinical and radiographic outcomes at 1-year follow-up for 50 consecutive patients who underwent the presacral ALIF.

METHODS

Our patients included 24 males and 26 females who underwent the presacral ALIF procedure for interbody fusion at L5-S1. Indications included mechanical back pain and radiculopathy. Thirty-seven patients had disc degeneration at L5-S1, 7 had previously undergone a discectomy, and 6 had spondylolisthesis. A 2-level L4-S1 fusion was performed with a transforaminal lumbar interbody fusion at L4-5 in 15 patients. AxiaLIF was performed as a stand-alone procedure in 5 patients and supplemented with pedicle screws in 45 patients. Pre- and postoperative visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were evaluated and complications were tracked. Fusion was evaluated by an independent neuro-radiologist.

RESULTS

At 1-year follow-up, VAS and ODI scores had significantly improved by 49% and 50%, respectively, versus preoperative scores. By high-resolution computer tomography (CT) scans, fusion was achieved in 44 (88%) patients, developing bone occurred in 5 (10%), and 1 (2%) patient had pseudoarthrosis. One patient suffered a major operative complication-a bowel perforation with a pre-sacral abscess that resolved with treatment.

CONCLUSION

Our initial 50 patients who underwent presacral ALIF showed clinical improvement and fusion rates comparable with other interbody fusion techniques; its safety was reflected by low complication rates. Its efficacy in future patients will continue to be monitored, and will be reported in a 2-year follow-up study of fusion.

Anterior lumbar interbody fusion with stand-alone interbody cage in treatment of lumbar intervertebral foraminal stenosis : comparative study of two different types of cages

OBJECTIVE

This retrospective study was performed to evaluate the clinical and radiological results of anterior lumbar interbody fusion (ALIF) using two different stand-alone cages in the treatment of lumbar intervertebral foraminal stenosis (IFS).

METHODS

A total of 28 patients who underwent ALIF at L5-S1 using stand-alone cage were studied [Stabilis(R) (Stryker, Kalamazoo, MI, USA); 13, SynFix-LR(R) (Synthes Bettlach, Switzerland); 15]. Mean follow-up period was 27.3 +/- 4.9 months. Visual analogue pain scale (VAS) and Oswestry disability index (ODI) were assessed. Radiologically, the change of disc height, intervertebral foraminal (IVF) height and width at the operated segment were measured, and fusion status was defined.

RESULTS

Final mean VAS (back and leg) and ODI scores were significantly decreased from preoperative values (5.6 +/- 2.3 --> 2.3 +/- 2.2, 6.3 +/- 3.2 --> 1.6 +/- 1.6, and 53.7 +/- 18.6 --> 28.3 +/- 13.1, respectively), which were not different between the two devices groups. In Stabilis(R) group, postoperative immediately increased disc and IVF heights (10.09 +/- 4.15 mm --> 14.99 +/- 1.73 mm, 13.00 +/- 2.44 mm --> 16.28 +/- 2.23 mm, respectively) were gradually decreased, and finally returned to preoperative value (11.29 +/- 1.67 mm, 13.59 +/- 2.01 mm, respectively). In SynFix-LR(R) group, immediately increased disc and IVF heights (9.60 +/- 2.82 mm --> 15.61 +/- 0.62 mm, 14.01 +/- 2.53 mm --> 21.27 +/- 1.93 mm, respectively) were maintained until the last follow up (13.72 +/- 1.21 mm, 17.87 +/- 2.02 mm, respectively). The changes of IVF width of each group was minimal pre- and postoperatively. Solid arthrodesis was observed in 11 patients in Stabilis group (11/13, 84.6%) and 13 in SynFix-LR(R) group (13/15, 86.7%).

CONCLUSION

ALIF using stand-alone cage could assure good clinical results in the treatment of symptomatic lumbar IFS in the mid-term follow up. A degree of subsidence at the operated segment was different depending on the device type, which was higher in Stabilis(R) group.

Changes in abdominal vascular tension associated with various leg positions in the anterior lumbar approach: cadaver study

STUDY DESIGN

A descriptive cadaveric study measuring arterial tension.

OBJECTIVE

Anterior lumbar surgery is technically challenging due to perioperative vascular complications. Many studies suggest approaches based on the anatomy of the abdominal vessel for safe vascular mobilization. However, the tension in the vascular structure is also important for adequate exposure of the target lesion. It has been established that the tension in the lumbar nerve at the root level can be changed by a straight leg raise test and that the structure of the vascular connection is similar to that of the neural connection. Consequently, a change in leg position could affect the tension of lumbosacral vessels. The purpose of this study was to evaluate the effect of leg position on the tension of lumbosacral vessels.

METHODS

We dissected 10 unembalmed cadavers using the method described by Gumbs et al, using the Synframe system to expose the abdominal artery and vein. The left iliac artery and the distal abdominal aorta were retracted to the right side at the L4-L5 disc level by a measuring retractor to which a strain gauge was attached. The tension was checked at various angles of the hip joint and the motions of the abdominal arteries were monitored in 4 unembalmed cadavers using a C-arm fluoroscope.

RESULTS

The tension in the abdominal aorta at L4-L5 level was decreased by 2.9% to 21.8% in the hip-flexion position, and the motion of the arteries showed proximal displacement of the external iliac artery and the common iliac artery during the hip-flexed position and veins also showed the same pattern of displacement as artery.

CONCLUSION

The results of this study would be useful for not only spinal surgery but also other vascular surgeries, particularly, in cases where patients with conditions such as atherosclerosis or stenosis.

Vascular injury in elective anterior lumbosacral surgery

STUDY DESIGN

Systematic review.

OBJECTIVE

To document the incidence and consequences of vascular injury in lumbosacral surgery, to identify factors contributing to this injury, and to determine whether there are any effective measures to decrease the occurrence of vascular injury.

SUMMARY OF BACKGROUND DATA

Anterior lumbosacral surgery encompasses all aspects of spine surgery, including trauma, deformity, and degenerative conditions. Although it has theoretical advantages, anterior lumbosacral surgery carries with it certain definite risks, one of the most critical of which is injury to the surrounding vasculature. It is important for both the patient and the surgeon to understand the risks, patterns, and outcomes of injury to the vascular structures associated with this surgery.

METHODS

A systematic review of the English-language literature was undertaken for articles published between January 1993 and December 2008. Electronic databases and reference lists of key articles were searched to identify published studies examining vascular injury in anterior lumbosacral surgery. Vascular injury was defined as any case in which a suture was required to control bleeding. Two independent reviewers assessed the strength of literature using the Grading of Recommendations Assessment, Development, and Evaluation criteria assessing quality, quantity, and consistency of results. Disagreements were resolved by consensus.

RESULTS

A total of 88 articles were initially screened, and 40 ultimately met the predetermined inclusion criteria. Vascular injuries after anterior lumbosacral surgeries were rare (<5%). Venous laceration was more common than arterial laceration, and most venous injuries occurred during retraction of the great vessels. In most cases, the overall clinical outcome after vascular injury was not adversely affected. L4-L5 exposure was associated with increased vascular injury in some studies but not others. Vascular injury occurred more frequently in laparoscopic compared with open anterior lumbar interbody fusion.

CONCLUSION

Vascular injury in anterior lumbosacral surgery remains low, with reports being <5%. The consequences of injury seem rare, but may include thrombosis, pulmonary embolism, and prolonged hospitalization. Exposure and surgery at L4-L5 may be associated with a higher risk of injury than that at L5-S1, though the data are not consistent.

Design and finite-element evaluation of a versatile assembled lumbar interbody fusion cage

INTRODUCTION

When an interbody cage is inserted into a human being's lumbar spine, not only the design, but also the material used is considerably crucial, particularly when minimally invasive lumbar fusion (MILIF) approaches are considered. The purpose of this study was to design a multi-function cage (either for MILIF or open lumbar interbody fusion) and also to evaluate the strength of the design based on a finite-element model analysis.

METHOD

Three-dimensional finite-element models that were instrumental in the reproduction of post-operative conditions under which different cages, such as assembled lumbar interbody fusion cages (ALIFC) and the separated ones, could be examined and traced after implantation were developed. Simulations were run to realize various loading conditions including axial compression, flexion, extension, lateral bending and rotation under a constant compressive preload. Meanwhile, the evaluation results derived from FEMs data focused on endplate stress distribution, peak stress of von Mises and stress of cage. Stress distributions on the bone surface were evaluated and discussed as well.

RESULTS

The consequences of cage insertion, high strains and stresses, were concentrated in the areas where the cage and endplate were in contact with each other. Simultaneously, contact stresses around the implants seemed to be concentrated around the periphery of the device. After implantation of ALIFC, the stiffness of the new cages was similar to that of traditional cages in an assemble condition, according to the biomechanical data dealing with FEM. Once a separated cage was in the place of an assembled cage, the stresses would get symmetrically distributed in the lateral areas of the endplate and decrease significantly at the center where the separated cage was not in contact with the endplate. The stress of the cage was going to be high once being rotating; most significant difference of stresses distribution due to the alternative choice has been found in the state of rotation. On comparison of peak von Mises stresses on the endplates in the new cage, the stresses were symmetrically distributed in the lateral areas of the endplate when a separated cage was used in place of an assembled cage.

CONCLUSION

The new cage was more advantages with regard to endplate stress distribution, peak stress of von Mises and stress of cage than the assembled state. ALIFC can provide sufficient primary stability for lumbar intervertebral fusion and the new cage may be regarded as a suitable device for load-bearing implantation.

Robot-assisted anterior lumbar interbody fusion (ALIF) using retroperitoneal approach

BACKGROUND

Over the past few years, robot-assisted surgery has become increasingly popular, affecting virtually all surgical fields. It has been proven to overcome pitfalls of laparoscopic procedures, such as high complication rates and steep learning curve. We have, therefore, performed experimental anterior lumbar interbody fusion (ALIF) using retroperitoneal approach in swine model to test the feasibility of robot-assisted surgery in spinal surgery.

METHOD

In this report, we describe the setup with the da Vinci surgical system, operative method, result and discuss technical aspects and the future of robot-assisted ALIF.

FINDINGS

Experimental retroperitoneal dissection using robotic surgical system was successfully performed with great visual cue, minimal retraction and minimal bleeding.

CONCLUSION

Although retroperitoneal approach for spinal fusion has never been attempted with robotic surgical system, we could demonstrate the possibility with swine model. Further studies and development of appropriate instruments will bring minimally invasive spine surgery to a new era.

[Minimally invasive spine arthrodesis in degenerative spinal disorders]

BACKGROUND AND PURPOSE

As in many other surgical fields, new minimally invasive techniques have been developed over the past 20 years, with reducing the muscular trauma associated with the traditional surgical approach and reducing related morbidity as the main goals. Initially limited to the laparoscopic or video-assisted approaches of the anterior spine, these techniques have been extended to the posterior transmuscular access of the lumbar spine. This article reviews the value of these approaches in the treatment of degenerative lumbar spine disorders.

METHODS

We describe the main techniques used in minimally invasive lumbar spine surgery, including posterior pedicle screwing as well as anterior (ALIF), posterior (PLIF), transforaminal (TLIF), extreme lateral (XLIf), and presacral (AxiaLIF) interbody fusion. The results of recently published series are reported.

RESULTS

Percutaneous pedicle screwing is reported to be an effective technique of lumbar spine arthrodesis associated with a low rate of screw misplacement. Minimally invasive PLIF, TLIF, and ALIF have been associated with shorter mean operative time, less postoperative pain, reduction of the estimated blood loss, a shorter hospital stay, and quicker functional recovery. Despite these encouraging early clinical results, no prospective, randomized published scientific study has proved that minimally invasive techniques are better than standard techniques. Larger clinical series with a longer follow-up could fill this gap.

Endoscope-based hybrid navigation system for minimally invasive ventral spine surgeries

The availability of high-resolution, magnified, and relatively noise-free endoscopic images in a small workspace, 4-10 cm from the endoscope tip, opens up the possibility of using the endoscope as a tracking tool. We are developing a hybrid navigation system in which image-analysis-based 2D-3D tracking is combined with optoelectronic tracking (Optotrak) for computer-assisted navigation in laparoscopic ventral spine surgeries. Initial results are encouraging and confirm the ability of the endoscope to serve as a tracking tool in surgical navigation where sub-millimetric accuracy is mandatory.

An analysis of general surgery-related complications in a series of 412 minilaparotomic anterior lumbosacral procedures

OBJECT

Anterior lumbar surgery is associated with certain perioperative visceral and vascular complications. The aim of this study was to document all general surgery-related adverse events and complications following minilaparotomic retroperitoneal lumbar procedures and to discuss strategies for their management or prevention.

METHODS

The authors analyzed data obtained in 412 patients who underwent anterior lumbosacral surgery between 2003 and 2005. The series comprised 114 men and 298 women whose mean age was 56 years (range 34-79 years). Preoperative diagnoses were as follows: isthmic spondylolisthesis (32%), degenerative spondylolisthesis (24%), instability/stenosis (15%), degenerative disc disease (15%), failed-back surgery syndrome (7%), and lumbar degenerative kyphosis or scoliosis (7%). A single level was exposed in 264 patients (64%), 2 in 118 (29%), and 3 or 4 in 30 (7%). The average follow-up period was 16 months.

RESULTS

Overall, 52 instances of complications and adverse events occurred in 50 patients (12.1%), including sympathetic dysfunction in 25 (6.06%), vascular injury repaired with/without direct suture in 12 (2.9%), ileus lasting > 3 days in 5 (1.2%), pleural effusion in 4 (0.97%), wound dehiscence in 2 (0.49%), symptomatic retroperitoneal hematoma in 2 (0.49%), angina in 1 (0.24%), and bowel laceration in 1 patient (0.24%). There was no instance of retrograde ejaculation in male patients, and most complications had no long-term sequelae.

CONCLUSIONS

This report presents a detailed analysis of complications related to anterior lumbar surgery. Although the incidence of complications appears low considering the magnitude of the procedure, surgeons should be aware of these potential complications and their management.

Cosmetic and functional outcomes following paramedian and anterolateral retroperitoneal access in anterior lumbar spine surgery

Object

In this paper, the authors review the functional and cosmetic outcomes and complications in 300 patients who underwent treatment for lumbar spine disease via either an anterior paramedian or conventional anterolateral retroperitoneal approach.

Methods

Seven surgeons performed anterior lumbar surgeries in 300 patients between August 2004 and December 2006. One hundred and eighty patients were treated with an anterior paramedian approach, and 120 patients with an anterolateral retroperitoneal approach. An access surgeon was used in 220 cases (74%). Postoperative evaluation in all patients consisted of clinic visits, assessment with the modified Scoliosis Research Society–30 instrument, as well as a specific questionnaire relating to wound appearance and patient satisfaction with the wound.

Results

At a mean follow-up of 31 months (range 12–47 months), the mean Scoliosis Research Society–30 score (out of 25) was 21.2 in the patients who had undergone the anterior paramedian approach and 19.4 in those who had undergone the anterolateral retroperitoneal approach (p = 0.005). The largest differences in quality of life measures were observed in the areas of pain control (p = 0.001), self-image (p = 0.004), and functional activity (p = 0.003), with the anterior paramedian group having higher scores in all 3 categories. Abdominal bulging in the vicinity of the surgical site was the most common wound complication observed and was reported by 22 patients in the anterolateral retroperitoneal group (18%), and 2 patients (1.1%) in the anterior paramedian group. Exposures of ≥ 3 levels with the anterolateral approach were associated with abdominal bulging (p = 0.04), while 1- or 2-level exposures were not (p > 0.05). Overall satisfaction with incisional appearance was higher in patients with an anterior paramedian incision (p = 0.001) and with approaches performed by an access surgeon (p = 0.004).

Conclusions

Patients who undergo an anterior paramedian approach to the lumbar spine have a higher quality of life and better cosmetic outcomes than patients undergoing an anterolateral retroperitoneal approach.

Minimally invasive techniques for lumbar interbody fusions

Lumbar spinal fusions have been performed for nearly a century for a variety of spinal conditions and include posterior/posterolateral and anterior lumbar interbody fusions. Traditionally, the ability to achieve adequate exposure to perform these procedures required an open surgical approach; however, the advent of newer techniques and technology, combined with an improved understanding of surgical anatomy, has resulted in newer minimally invasive techniques. Posterior approaches include posterior and transforaminal lumbar interbody fusions, whereas anterior techniques include retroperitoneal and transperitoneal anterior lumbar interbody fusion approaches. More recently, the extreme lateral interbody fusion and axial lumbar interbody fusion have been described. This article provides a general review of the history, indications, brief overview, and description of the more common minimally invasive spine surgery techniques used for achieving a lumbar interbody fusion.

Open anterior approaches for lumbar spine procedures

With the advent of anterior lumbar interbody fusion (ALIF) and artificial discs as common procedures for the treatment many spinal problems such as pseudoarthrosis, degenerative disc disease and internal disc disruption from trauma, anterior exposure has become an increasingly popular procedure for the general, thoracic, urologic and vascular surgeon. Despite this, the body of literature describing this procedure is lacking. Dividing the approach for anterior spinal surgery into the thoracolumbar, mid-lumbar, and lumbosacral regions, we describe the basic techniques and anatomy needed to perform these open approaches, specifically, repairs of disc spaces T12-L2, L2-5, and L5-S1, respectively. The technique for the retroperitoneal approach will be discussed in detail; however, issues involved with indications for transperitoneal approach and technical "pearls" will also be discussed.

Minimally invasive lumbar spinal fusion

Minimally invasive techniques for lumbar spine fusion have been developed in an attempt to decrease the complications related to traditional open exposures (eg, infection, wound healing problems). Anterior minimally invasive procedures include laparoscopic and mini-open anterior lumbar interbody fusion as well as the lateral transpsoas and percutaneous presacral approaches. Posterior techniques typically use a tubular retractor system that avoids the muscle stripping associated with open procedures. These techniques can be applied to both posterior and transforaminal lumbar interbody fusion procedures. Many initial reports have shown similar clinical results in terms of spinal fusion rates for both traditional open and minimally invasive posterior approaches. However, the anterior minimally invasive procedures are often associated with significantly greater incidence of complications and technical difficulty than their associated open approaches. There is a steep learning curve associated with minimally invasive techniques, and surgeons should not expect to master them in the first several cases.

Revision open anterior approaches for spine procedures

BACKGROUND CONTEXT

Anterior exposure has become an increasingly popular procedure for the general and vascular surgeon due to the increased use of anterior lumbar interbody fusion and artificial disc replacement for the treatment of many spinal problems.

PURPOSE

Because of this increase, revision operations have become increasing necessary. Despite this, there is almost no literature dealing with the issues related to these complex revision operations.

STUDY DESIGN

A retrospective review of charts was performed on patients operated on from April 2002 until October 2004 in two tertiary care hospitals.

METHODS

In total, 218 open exposures for anterior lumbar spinal approaches were performed of which 9 patients required revision lumbar spinal operations. Seven patients were approached again anteriorly (78%), and 2 (22%) patients required a combined anterior and posterior approach.

RESULTS

The nine cases were the number of revision procedures performed over the 16-month period of this study. The average age was 44 overall (range, 25-89) and 53 (33-73) for the revision operations, p>.05. All revision operations attempted were successful. Seven (78%) of the secondary procedures could be approached retroperitoneally whereas 2 (22%) patients required transperitoneal approaches owing to the degree of adhesions. The average length until revision surgery was 13 months (range 6-24). No patients required early revision defined as surgery within 30 days from the primary surgery. Early complications occurred in 4 patients (44%), and included dural tear, median nerve dysthesia, left common femoral nerve palsy further complicated by prolonged postoperative ileus and retrograde ejaculation. Late complications occurred in one patient and consisted of a deep venous thrombosis and urinary tract infection. The average length of stay was 6 days (SD 2.7 days) (range 4-12) compared with 4 days (SD 2.3 days) (range 2-22) for the index operations, p>.05.

CONCLUSION

Revision anterior open exposure to the lumbar and lumbosacral vertebral bodies can be performed safely, but is associated with an increased rate of early complications. Nonetheless, these complications are self-limited and highlight the importance of a multidisciplinary approach in maximizing the various surgical skills of spine (orthopedic and neurosurgical) and exposure (vascular and general) surgeons in reducing serious complications in revision anterior lumbar spinal surgery.

Variation in reported safety of lumbar interbody fusion: influence of industrial sponsorship and other study characteristics

STUDY DESIGN

Systematic review.

OBJECTIVE

To quantify variability in undesirable outcomes among studies of lumbar interbody fusion using stand-alone cage devices, and to determine whether author conflicts of interest contribute to variability.

SUMMARY OF BACKGROUND DATA

Promising early studies of lumbar fusion with stand-alone cage devices led to rapid uptake of the technique, but some surgeons later expressed reservations regarding efficacy and safety.

METHODS

We systematically identified studies of lumbar interbody fusion with stand-alone cage devices that reported at least one undesirable outcome among 10 or more adult subjects. We performed meta-analyses of rates of 7 prespecified outcomes (nonunion, reoperation, major vessel injury, retrograde ejaculation, neurologic injury, dural injury, and infection). Heterogeneity in outcome rates was quantified as I2 (the proportion of variance due to differences among studies rather than random variation). Random-effects meta-regression identified sources of observed heterogeneity, including potential conflicts of interest.

RESULTS

We identified 30 eligible studies, including a total of 3228 subjects. A potential conflict of interest was identified in 18 (60%). We observed marked heterogeneity in rates of nonunion, reoperation, and neurologic injury (I2 > 85%; P < 0.001), and substantial heterogeneity in rates of dural injury (I2 = 63%; P < 0.01) and major vessel injury (I2 = 38%; P = 0.09). Among 24 studies reporting fusion status after 6 months of follow-up, nonunion rates ranged from 2.3% to 83.3% (median, 8.3%) and exceeded 45% in 4 studies. Potential author conflict of interest was associated with significantly lower rates of nonunion (P = 0.001). Heterogeneity in rates of other undesirable outcomes was not significantly associated with author conflicts of interest or other study characteristics.

CONCLUSION

We quantified substantial unexplained variation in reported complication rates of undesirable outcomes of lumbar interbody fusion with stand-alone cage devices. Authors with potential conflicts of interest, however, reported significantly lower rates of nonunion.

The use of computed tomography angiography to define the prevertebral vascular anatomy prior to anterior lumbar procedures

STUDY DESIGN

Prospective cohort.

OBJECTIVE

To determine the efficacy of a single-slice computed tomography (CT) angiogram to define the prevertebral anatomy in patients undergoing an anterior lumbar spine procedure.

SUMMARY OF BACKGROUND DATA

Preoperative planning with precise prevertebral anatomic details can help in mini-open anterior lumbar approaches.

METHODS

A total of 76 consecutive patients undergoing a minimal incision approach for anterior lumbar surgery were evaluated before surgery with CT angiography. The prevertebral anatomy was documented, and the patients were observed during treatment.

RESULTS

There were no complications related to CT angiography. This study directly influenced surgical decision making and the treatment options in 21% of patients. The vena caval confluence limited access to the L5-S1 disc in 3% of patients and at the L4-L5 disc in 92% of the patients. Prevertebral anatomic anomalies were found in 11.8% of patients. Atherosclerotic disease was discovered in 17% of the patients. The major complication rate was 7.5%. CT angiography correlated with intraoperative vascular anatomy in all cases.

CONCLUSION

Preoperative CT angiography before anterior approaches was determined to be effective in evaluating the prevertebral vascular anatomy.

An evaluation of vascular anatomy for minilaparotomic anterior L4–5 procedures

Object

The complexity of the vascular anatomy pertinent to the L4–5 intervertebral disc space has led to difficulties when performing the anterior approach to the lumbar spine. The purpose of the present study was to evaluate the variations of the great vessels to match the imaging-documented axial anatomy with the surgical exposure.

Methods

The authors analyzed data obtained in 223 patients who had undergone mini–open anterior lumbar surgery involving the L4–5 disc. The preoperative magnetic resonance images or computed tomography scans were evaluated by examiners blinded to the surgical approach to determine the vascular configuration. All complications of the procedures were described.

Two major variations of the vascular configuration were delineated according to the location of the bifurcation of the inferior vena cava. On images showing the lower margin of the L-4 vertebra, the anatomy in 182 patients (81%) was classified as Type A because the inferior vena cava (IVC) was not bifurcated; in 38 patients (17%) it was classified as Type B because the IVC was bifurcated. Type A could be subdivided into Types A1 and A2 according to whether the aorta was bifurcated (A2) or not (A1) on the same image. The surgical exposure used was above the bifurcations (in Type A) and below the bifurcations (in Type B). The major complications were three venous injuries, and the leading complication was sympathetic dysfunction in 14 patients, which in most cases resolved spontaneously.

Conclusions

Careful preoperative evaluation of the vascular anatomy is essential to conducting successful anterior lumbar surgery. The determination of an appropriate approach can contribute to a reduction of unnecessary vascular retraction and a consequent decrease in vascular complications.

Access strategies for revision or explantation of the Charité lumbar artificial disc replacement

BACKGROUND

Several lumbar disc prostheses are being developed with the goal of preserving mobility in patients with degenerative disc disease. The disadvantage of lumbar artificial disc replacement (ADR) compared with anterior interbody fusion (ALIF) is the increased potential for displacement or component failure. Revision or removal of the device is complicated by adherence of the aorta, iliac vessels, and the ureter to the operative site. Because of these risks of anterior lumbar procedures, vascular surgeons usually provide access to the spine. We report our experience with secondary exposure of the lumbar spine for revision or explantation of the Charité disc prosthesis.

METHODS

Between January 2001 and May 2006, 19 patients with prior implantation of Charité Artificial Discs required 21 operations for repositioning or removal of the device. Two patients had staged removal of prostheses at two levels. One patient had simultaneous explantation at two levels. The mean age was 49 years (range, 31 to 69 years; 56% men, 42% women). The initial ADR was performed at our institution in 14 patients (74%). The mean time from implantation to reoperation was 7 months (range, 9 days to 4 years). The levels of failure were L3-4 in one, L4-5 in nine, and L5-S1 in 12.

RESULTS

The ADR was successfully removed or revised in all patients that underwent reoperation. Three of the 12 procedures at L5-S1 were performed through the same retroperitoneal approach as the initial access. One of these three, performed after a 3-week interval, was converted to a transperitoneal approach because of adhesions. The rest of the L5-S1 prostheses were exposed from a contralateral retroperitoneal approach. Four of the L4-5 prostheses were accessed from the original approach and five from a lateral, transpsoas exposure (four left, one right). The only explantation at L3-4 was from a left lateral transpsoas approach. Nineteen of the 22 ADR were converted to ALIF. Two revisions at L5-S1 involved replacement of the entire prosthesis. One revision at L4-5 required only repositioning of an endplate. Access-related complications included, in one patient each, iliac vein injury, temporary retrograde ejaculation, small-bowel obstruction requiring lysis, and symptomatic, large retroperitoneal lymphocele. There were no permanent neurologic deficits, deep vein thromboses, or deaths.

CONCLUSIONS

Owing to vascular and ureteral fixation, anterior exposure of the lumbar spine for revision or explantation of the Charité disc replacement should be performed through an alternative approach unless the procedure is performed < or = 2 weeks of the index procedure. The L5-S1 level can be accessed through the contralateral retroperitoneum. Reoperation at L3-4 and L4-5 usually requires explantation and fusion that is best accomplished by way of a lateral transpsoas exposure.

Laparoscopic approach for lumbar spinal fusion

Several recent articles suggest that utilization of the laparoscopic anterior lumbar interbody fusion (ALIF) is decreasing in this country. After reviewing the published evidence in support and in opposition to this approach, we felt that the topic warranted additional study. We began a prospective study utilizing the known techniques to help reduce serious complications. These techniques were previously reported but not widely utilized according to the available literature. We report our early results of eleven patients along with a detailed description of the approach itself with the emphasis aimed at the laparoscopic approach surgeon. One patient was converted to open, with adequate exposure achieved in all. No bleeding complications were seen. Early postoperative results are encouraging. Our conclusions are that the laparoscopic anterior approach to the lumbar spine can be safely performed by approach-surgeons skilled in advanced laparoscopic techniques and those who have also received additional training in laparoscopic anterior lumbar exposures. We feel that improvement over the open approach may be achievable with increased experience.

Perioperative complications in transforaminal lumbar interbody fusion versus anterior-posterior reconstruction for lumbar disc degeneration and instability

OBJECTIVES

Multiple different approaches are used to treat lumbar degenerative disc disease and spinal instability. Both anterior-posterior (AP) reconstructive surgery and transforaminal lumbar interbody fusion (TLIF) provide a circumferential fusion and are considered reasonable surgical options. The purpose of this study was to quantitatively assess clinical parameters such as surgical blood loss, duration of the procedure, length of hospitalization, and complications for TLIF and AP reconstructive surgery for lumbar fusion.

METHODS

A retrospective analysis was completed on 167 consecutive cases performed between January 2002 and March 2004. TLIF surgical procedure was performed on 124 patients, including 73 minimally invasive and 51 open cases. AP surgery was performed on 43 patients. Patients were treated for painful degenerative disc disease, facet arthropathy, degenerative instability, and spinal stenosis.

RESULTS

The mean operative time for AP reconstruction was 455 minutes, for minimally invasive TLIF 255 minutes, and open TLIF 222 minutes. The mean blood loss for AP fusion surgery was 550 mL, for minimally invasive TLIF 231 mL, and open TLIF 424 mL. The mean hospitalization time for AP reconstruction was 7.2 days, for minimally invasive TLIF 3.1 days, and open TLIF 4.1 days. The total rate of complications was 76.7% for AP reconstruction, including 62.8% major and 13.9% minor complications. The minimally invasive TLIF patients group had the total 30.1% rate of complications, 21.9% of which were minor and 8.2% major complications. There were no major complications in the open TLIF patients group, with 35.3% minor complications.

CONCLUSIONS

AP lumbar interbody fusion surgery is associated with a more than two times higher complication rate, significantly increased blood loss, and longer operative and hospitalization times than both percutaneous and open TLIF for lumbar disc degeneration and instability.

Extreme Lateral Interbody Fusion (XLIF): a novel surgical technique for anterior lumbar interbody fusion

BACKGROUND

Minimally disruptive approaches to the anterior lumbar spine continue to evolve in a quest to reduce approach-related morbidity. A lateral retroperitoneal, trans-psoas approach to the anterior disc space allows for complete discectomy, distraction, and interbody fusion without the need for an approach surgeon.

PURPOSE

To demonstrate the feasibility of a minimally disruptive lateral retroperitoneal approach and the advantages to patient recovery.

METHODS/RESULTS

The extreme lateral approach (Extreme Lateral Interbody Fusion [XLIF]) is described in a step-wise manner. There have been no complications thus far in the author's first 13 patients.

CONCLUSIONS

The XLIF approach allows for anterior access to the disc space without an approach surgeon or the complications of an anterior intra-abdominal procedure. Longer-term follow-up and data analysis are under way, but initial findings are encouraging.

Intraoperative adverse events and related postoperative complications in spine surgery: implications for enhancing patient safety founded on evidence-based protocols

STUDY DESIGN

Prospective observational study.

OBJECTIVE

To assess the incidence and clinical consequence of intraoperative adverse events from a wide variety of spinal surgical procedures.

SUMMARY OF BACKGROUND DATA

In this study, adverse events were defined as any unexpected or undesirable event(s) occurring as a result of spinal surgery. A complication was defined as a disease or disorder, which, as a consequence of a surgical procedure, will negatively affect the outcome of the patient. We hypothesized that most adverse events would not result in complications that would be normally flagged through traditional practice audit approaches. By defining the incidence and types of adverse events seen in a spine surgical practice, we hope to develop preventative approaches to enhance patient safety.

METHODS

All postoperative clinical sequelae (i.e., complications) were prospectively identified, classified as to type, and graded (0 [none] to IV [death]) in 700 consecutive patients who underwent spine surgery (excluding > 300-day surgery microdiscectomies) at a university center from January 2002 to June 2003. To confirm data accuracy and assess the clinical sequelae of any adverse events, the medical records of these 700 patients were reviewed.

RESULTS

The overall incidence of intraoperative adverse events was 14% (98/700). A total of 23 adverse events led to postoperative clinical sequelae for an overall intraoperative complication incidence of 3.2% (23/700). Specific adverse events included dural tears (n = 58), spinal instrumentation-related events (n = 12), blood loss exceeding 5000 mL (n = 10), anesthesia/medical (n = 4), suspected or actual vertebral artery injury (n = 3), approach-related events (n = 3), esophageal/pharyngeal injury (n = 2), and miscellaneous (n = 6).

CONCLUSIONS

Adverse events can frequently occur (14%) during spinal surgery, however, the majority (76.5%) are not associated with complications. Improved patient safety can only be maximized by independent practice audit and the development of prospective methods to record adverse event data so that enhanced, evidence-based, clinical protocols can be developed.

Recombinant human bone morphogenetic protein-2 in open tibial fractures. A subgroup analysis of data combined from two prospective randomized studies

BACKGROUND

The use of recombinant human bone morphogenetic protein-2 (rhBMP-2) to improve the healing of open tibial shaft fractures has been the focus of two prospective clinical studies. The objective of the current study was to perform a subgroup analysis of the combined data from these studies.

METHODS

Two prospective, randomized clinical studies were conducted. A total of 510 patients with open tibial fractures were randomized to receive the control treatment (intramedullary nail fixation and routine soft-tissue management) or the control treatment and an absorbable collagen sponge impregnated with one of two concentrations of rhBMP-2. The rhBMP-2 implant was placed over the fracture at the time of definitive wound closure. For the purpose of this analysis, only the control treatment and the Food and Drug Administration-approved concentration of rhBMP-2 (1.50 mg/mL) were compared. Patients who anticipated receiving planned bone-grafting as part of a staged treatment were excluded from enrollment.

RESULTS

Fifty-nine trauma centers in twelve countries participated, and patients were followed for twelve months postoperatively. Two subgroups were analyzed: (1) the 131 patients with a Gustilo-Anderson type-IIIA or IIIB open tibial fracture and (2) the 113 patients treated with reamed intramedullary nailing. The first subgroup demonstrated significant improvements in the rhBMP-2 group, with fewer bone-grafting procedures (p = 0.0005), fewer patients requiring invasive secondary interventions (p = 0.0065), and a lower rate of infection (p = 0.0234), compared with the control group. The second subgroup analysis of fractures treated with reamed intramedullary nailing demonstrated no significant difference between the control and the rhBMP-2 groups.

CONCLUSIONS

The addition of rhBMP-2 to the treatment of type-III open tibial fractures can significantly reduce the frequency of bone-grafting procedures and other secondary interventions. This analysis establishes the clinical efficacy of rhBMP-2 combined with an absorbable collagen sponge implant for the treatment of these severe fractures.

Vascular injury and complication in neurosurgical spine surgery

Vascular injury is an uncommon, but not rare complication of spine surgery. The consequence of vascular injury may be quite devastating, but its incidence can be reduced by understanding the mechanisms of injury. Properly managing vascular injury can reduce mortality and morbidity of patients. A review of the literature was conducted to provide an update on the etiology and management of vascular injury and complication in neurosurgical spine surgery. The vascular injuries were categorized according to each surgical procedure responsible for the injury, i.e., anterior screw fixation of the odontoid fracture, anterior cervical spine surgery, posterior C1-2 arthrodesis, posterior cervical spine surgery, anterolateral approach for thoracolumbar spine fracture, posterior thoracic spine surgery, scoliosis surgery, anterior lumbar interbody fusion (ALIF), lumbar disc arthroplasty, lumbar discectomy, and posterior lumbar spine surgery. The incidence, mechanisms of injury, and reparative measures were discussed for each surgical procedure. Detailed coverage was especially given to vascular injury associated with ALIF, which may have been underestimated. The accumulation of anatomical knowledge and advanced imaging studies has made complex spine surgery safer and more reliable. It is not clear, however, whether the incidence of vascular injury has been reduced significantly in all procedures of spine surgery. Emerging new techniques, such as microendoscopic discectomy and lumbar disc arthroplasty, seem to be promising, but we need to keep in mind their safety issues, including vascular injury and complication.

Direct percutaneous gene delivery to enhance healing of segmental bone defects

BACKGROUND

Healing of segmental bone defects can be induced experimentally with genetically modified osteoprogenitor cells, an ex vivo strategy that requires two operative interventions and substantial cost. Direct transfer of osteogenic genes offers an alternative, clinically expeditious, cost-effective approach. We evaluated its potential in a well-established, critical-size, rat femoral defect model.

METHODS

A critical-size defect was created in the right femur of forty-eight skeletally mature Sprague-Dawley rats. After twenty-four hours, each defect received a single, intralesional, percutaneous injection of adenovirus carrying bone morphogenetic protein-2 (Ad.BMP-2) or luciferase cDNA (Ad.luc) or it remained untreated. Healing was monitored with weekly radiographs. At eight weeks, the rats were killed and the femora were evaluated with dual-energy x-ray absorptiometry, micro-computed tomography, histological analysis, histomorphometry, and torsional mechanical testing.

RESULTS

Radiographically, 75% of the Ad.BMP-2-treated femora showed osseous union. Bone mineral content was similar between the Ad.BMP-2-treated femora (0.045 +/- 0.020 g) and the contralateral, intact femora (0.047 +/- 0.003 g). Histologically, 50% of the Ad.BMP-2-treated defects were bridged by lamellar, trabecular bone; the other 50% contained islands of cartilage. The control (Ad.luc-treated) defects were filled with fibrous tissue. Histomorphometry demonstrated a large difference in osteogenesis between the Ad.BMP-2 group (mean bone area, 3.25 +/- 0.67 mm(2)) and the controls (mean bone area, 0.65 +/- 0.67 mm(2)). By eight weeks, the Ad.BMP-2-treated femora had approximately one-fourth of the strength (mean, 0.07 +/- 0.04 Nm) and stiffness (mean, 0.5 +/- 0.4 Nm/rad) of the contralateral femora (0.3 +/- 0.08 Nm and 2.0 +/- 0.5 Nm/rad, respectively).

CONCLUSIONS

A single, percutaneous, intralesional injection of Ad.BMP-2 induces healing of critical-size femoral bone defects in rats within eight weeks. At this time, the repair tissue is predominantly trabecular bone, has normal bone mineral content, and has gained mechanical strength.

Minimally disruptive decompression and transforaminal lumbar interbody fusion

BACKGROUND

Posterior spinal procedures through tubular exposures have been described. However, tubes restrain visibility and require co-axial instrument manipulation, increasing difficulty and potentially compromising surgical results. An independent-blade retractor system overcomes the obstacles of working through a tube and has been used to perform minimally-disruptive decompression and instrumented tranforaminal lumbar interbody fusion (TLIF).

PURPOSE

To evaluate the advantages to patient recovery and surgical efficacy of this technique.

METHODS/RESULTS

Retrospective review of technique employing a minimally-disruptive approach to decompression and transforaminal lumber interbody fusion (TLIF).

CONCLUSIONS

Minimally-disruptive decompression and instrumented TLIF can be performed in a safe and effective manner using an independent-blade retractor system. Relative to traditional-open techniques, surgical goals can be accomplished, but with the benefits of minimally-disruptive surgery.

Clinical and radiological outcomes with the Charité artificial disc: a 10-year minimum follow-up

This is the first report of clinical and radiologic outcomes for the CHARITE artificial disc with a minimum follow-up of 10 years. A total of 107 patients indicated for total lumbar disc replacement were implanted with the CHARITE prosthesis. Of these 107, 100 were followed for a minimum of 10 years (range 10-13.4 years). A total of 147 prostheses were implanted with 54 one-level and 45 two-level procedures and 1 three-level procedure. The prostheses were placed through a standard anterior retroperitoneal approach. Clinically, 62% had an excellent outcome, 28% had a good outcome, and 10% had a poor outcome. Of the 95 eligible to return to work, 88 (91.5%) either returned to the same job as prior to surgery or a different job. These included 63.2% (12) of those working in heavy labor employment returning to the same job. Mean flexion/extension motion was 10.3 degrees for all levels (12.0 degrees at L3-L4, 9.6 degrees at L4-L5, 9.2 degrees at L5-S1). Mean lateral motion was 5.4 degrees . In the sagittal plane, 9 (6.1%) were anterior of geometric center, 50 (34.0%) were centered, and 88 (59.9%) were posterior of center. In the frontal plane, 110 (75%) were centered, and 37 (25%) were noted to be lateral to center. Slight subsidence was observed in two patients, but they did not require further surgery. No subluxation of the prostheses and no cases of spontaneous arthrodesis were identified. There was one case of disc height loss of 1 mm. Five patients required a secondary posterior arthrodesis. A good or excellent clinical outcome rate of 90% and a return to work rate of 91.5% compare favorably with results described in the literature for fusion for the treatment of lumbar degenerative disc disease. With a minimum follow-up of 10 years, the CHARITE artificial disc demonstrated excellent flexion/extension and lateral range of motion with no significant complications.

Minimally-invasive technique for transforaminal lumbar interbody fusion (TLIF)

Minimal access surgical techniques have been described for diskectomy and laminectomy procedures performed through tubular exposures. Tubular exposures, however, restrain visibility to a fixed diameter and require co-axial instrument manipulation. An independent blade retractor system has been developed to overcome the obstacles of working through a tube. Decompression and circumferential fusion can be accomplished through this minimal access exposure via a combination of laminectomy and transforaminal lumbar interbody fusion (TLIF) coupled with minimally invasive pedicle screw fixation. Herein, we describe a minimally-invasive technique for TLIF exposure. Illustrations, intraoperative photographs, and fluoroscopic images supplement this technique. We found that the described minimally-invasive system provides comparable exposure to the traditional-open techniques with the benefits of minimally-invasive techniques. Additionally, it does not have the added constraints of a tubular system. We were able to perform TLIFs without any additional complications. Minimal access decompression and TLIF can be performed safely and effectively using this minimally-invasive system. Besides the retractor system, no additional specialized instruments are required. An operative microscope is not required, in fact, all our cases were performed using operative loupes. The light attachment provides superb visbility without the discomfort of having to wear a headlight. Thus far we have found no added risks or complications using this system. We are currently working on long-term analysis and follow-up to further evaluate this system's efficacy.

Standard and minimally invasive approaches to the spine

With the advent of minimally invasive surgical approaches to the spine, the ability to adequately expose the desired anatomic structures while minimizing the disadvantages of excessive soft tissue stripping, dissection, and prolonged retraction has become increasingly popular. A minimally invasive one- or two-level posterior exposure of the spine is now safely attainable with the latest minimal-access systems that exploit the biomechanics of an adjustable blade retractor. As the clinical use of these developing systems escalates, more outcomes data will become available to determine the safety and value of these minimally invasive procedures.

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 11: interbody techniques for lumbar fusion

The majority of reviewed medical evidence suggests that interbody techniques are associated with higher fusion rates compared with PLF when applied to patients with low-back pain due to DDD limited to one or two levels. The evidence is generally of poor quality and retrospective in nature. Conflicting evidence exists supporting the role of interbody graft placement for improvement of functional outcomes; however, there is no Class I or II evidence to suggest that the use of an interbody graft is associated with worse outcomes, and Class II evidence exists to suggest that outcomes are improved. Complication rates of interbody graft placement, particularly of circumferential procedures, are higher in most series. Many complications, however, are associated with pedicle screw fixation and not with interbody graft placement per se. In the context of a single-level stand-alone ALIF or ALIF with posterior instrumentation, there does not appear to be a substantial benefit to the addition of a PLF. The addition of a PLF to a construct that already includes an interbody graft is, however, associated with increased costs and complications. Therefore, although the addition of supplemental fixation (a 270 degrees fusion) may be necessary for biomechanical reasons, it may not be appropriate to subject the patient to the morbidity of a full posterior exposure for placement of graft material. Significant differences in clinical outcomes between the various interbody techniques have not been convincingly demonstrated. No general recommendation can therefore be made regarding the technique that should be used to achieve interbody fusion.

Biomechanical testing of the lumbar facet interference screw

STUDY DESIGN

An in vitro study was conducted to determine the biomechanical properties of a new simple, percutaneous, posterior fixation technique for the lumbar spine involving a new implant, the so-called Lumbar Facet Interference Screw.

OBJECTIVES

The purpose of this study was to compare the biomechanical properties of this new fixation device with translaminar and pedicle screw fixation.

SUMMARY OF BACKGROUND DATA

Several techniques were described to perform a minimal invasive posterior stabilization of the lumbar spine after an anterior lumbar interbody fusion procedure. Yet, due to the high complexity of these minimally invasive surgical procedures, currently, hardly any of these percutaneous posterior fixation techniques is carried out routinely.

METHODS

Ten human lumbar spines were tested in flexion, extension, axial rotation, and lateral bending using a nonconstrained testing method. First, all motion segments were evaluated intact (group 1). After complete discectomy of L4-L5, the following stabilization techniques were tested sequentially (n = 10/group): group 2: "stand-alone" cage; group 3: cage plus translaminar screws; group 4: cage plus Lumbar Facet Interference Screw; and group 5: cage plus pedicle screws. Stiffness, ranges of motion, and neutral and elastic zones were determined.

RESULTS

In comparison to the intact motion segment, the "stand-alone" cage showed a significantly higher (P < 0.05) range of motion, neutral zone, and elastic zone and a significantly lower (P < 0.05) stiffness in extension and rotation. Generally, all fixation techniques using cages plus posterior stabilization decreased range of motion, neutral zone, and elastic zone and increased stiffness in comparison to the "stand-alone" cage group. There was no significant difference between the cage plus interference screw and the cage plus translaminar screw group in all test modes. In comparison to the 2 facet joint stabilization techniques, pedicle screw stabilization decreased (P < 0.01) range of motion, neutral zone, and elastic zone and increased (P < 0.01) stiffness significantly in flexion and rotation.

CONCLUSIONS

Results of this study indicate that the new Lumbar Facet Interference Screw fixation yields initial biomechanical stability similar to translaminar screw fixation, yet inferior biomechanical stability compared to pedicle screw fixation. Although these results are encouraging, additional biomechanical studies including cyclic loading tests have to evaluate the mid- and long-term stabilization capacity of this new minimally invasive fixation technique before human application.

Posterolateral transforaminal selective endoscopic discectomy and thermal annuloplasty for chronic lumbar discogenic pain: a minimal access visualized intradiscal surgical procedure

BACKGROUND CONTEXT

Chronic lumbar discogenic pain (CLDP) impairs the patient's physical abilities to function within the normal physiologic loading ranges of activities of daily living. The pathogenesis of CLDP is multifactorial and not well understood. Conservative therapeutic regimens often fail to achieve sufficient pain relief. Surgical options vary greatly in surgical invasiveness as well as outcome. Definitive surgical treatment is often 360-degree fusion. The morbidity associated with this approach is significant, considering that only 65% to 80% of patients obtain satisfactory clinical results. This has spawned interest in minimally invasive surgical options, such as intradiscal electrothermal therapy (IDET; ORATEC Interventions, Inc., Menlo Park, CA), but results are conflicting.

PURPOSE

The authors describe their surgical technique of minimal access posterolateral transforaminal selective endoscopic discectomy (SED) and bipolar radiofrequency thermal annuloplasty to treat CLDP. The procedure's rationale is based on the hypothesis that annular defects are the focal points of chronic exposure between neural sensory receptors in the defect and the inflammatogenic nucleus pulposus. In contrast to other percutaneous procedures, this technique allows direct visualization and targeting of the disc nucleus and annular fissures. Our 2-year clinical result is reported.

STUDY DESIGN/SETTING

This is a retrospective review of consecutive surgical cases performed by one surgeon (ATY). The procedures were carried out from January 1997 to December 1999. Each patient has a minimum postoperative follow-up of 2 years.

PATIENT SAMPLE

A total of 113 patients met the generally accepted clinical criteria for chronic lumbar discogenic pain and were selected for the procedure.

OUTCOME MEASURES

Two outcome measures were used for clinical assessment: a surgeon-based modified MacNab method and a patient-based questionnaire. A mandatory poor result was given to any patient who had repeat spine surgery at the same level or has indicated dissatisfaction with the surgical result on the questionnaire response.

METHOD

After meeting CLDP selection criteria, provocation contrast/indigo carmine dye discography was performed. This test was used to confirm the suspected discs as pain generators. The subject surgery then followed. Only cases with one and two levels of confirmed painful discs were entered into the study. The nonoperating author (PMT) analyzed the data.

RESULTS

Using the surgeon assessment method, 17 patients (15%) had excellent results, 32 patients (28.3%) had good results, 34 patients (30.1%) had fair results and 30 patients (26.5%) had poor results. Of the 30 patients in the poor result group, 12 reported either no improvement or worsening, and refused further surgical treatment. Of the remaining 18 patients in the poor group, 8 had spinal fusion, 3 had laminectomy and 7 had repeat spinal endoscopic surgery. The patient-based questionnaire yielded similar percentages in each category. However, only 73.5% of the 113 patients returned the survey questionnaire. There were no aborted procedures, unexpected hemorrhage, device-related complications, neurologic deficits, perioperative deaths or late instability.

CONCLUSIONS

Posterolateral transforaminal SED and radiofrequency thermal annuloplasty were used to interrupt the purported annular defect pain sensitization process, thought to be necessary in the genesis of chronic lumbar discogenic pain. Lack of clinical benefit from the subject procedure did not degrade any subsequent surgical or nonsurgical treatment options. The experience gained from this study warrants further investigation into the cellular and molecular processes that provided back pain relief in these patients.

Comparison of conventional versus minimally invasive extraperitoneal approach for anterior lumbar interbody fusion

The purpose of the study was to compare conventional versus minimally invasive extraperitoneal approach for anterior lumbar interbody fusion (ALIF). Fifty-six consecutive patients with spondylolisthesis, lumbar instability, or failed back syndrome were treated with ALIF between 1991 and 2001. The patients were retrospectively evaluated and divided in two groups: Group 1, consisting 33 patients, was treated with ALIF using the conventional retroperitoneal approach, and Group 2, consisting of 23 patients, was operated with the minimally invasive muscle-splitting approach for ALIF. The groups were comparable as regards age, indication of fusion, and diagnosis. All patients in both groups had fusion with autologous iliac crest grafts and posterior instrumentation with posterolateral fusion in the same sitting. Clinical evaluation was done by two questionnaires: the North American Spine Society (NASS) Lumbar Spine Outcome Assessment Instrument and the Nottingham Health Profile (NHP). Fusion rate was evaluated radiologically. Mean clinical follow-up was 5.5 years. There was no statistical difference in the occurrence of complications with both approaches nor with the fusion rates of 92% in group 1 and 84% in group 2 respectively. The minimally invasive extraperitoneal approach for ALIF was associated with significantly less intraoperative blood loss, operation time, and length of the skin incision. In addition, this approach showed significant improvement in postoperative back pain in comparison to the conventional approach for ALIF.

"Does size matter?"A comparison of balloon-assisted less-invasive vs conventional retroperitoneal approach for anterior lumbar interbody fusion

This is a case-series comparison of two approaches to anterior lumbar interbody fusion. A conventional open approach (COA) was compared with a balloon-assisted minimally invasive approach (BMI). Outcome measures included operating time, blood loss and complications. Secondary outcome measures included analgesia requirements, time to mobilization and inpatient stay. There were 17 females (7 COA, 10 BMI) and 18 males (9 COA and 9 BMI). Forty-five discs (21 COA, 24 BMI) in total were fused in 35 patients. There were significant differences (in favour of the BMI) in the overall operating time between the COA and the BMI, and the single level COA and the BMI. There was no inter-group difference in the PCA requirements either overall or between one or two-level operations. The less invasive approach did have a benefit in earlier mobilization of the single-level fusions.

Comparative study of laparoscopic L5-S1 fusion versus open mini-ALIF, with a minimum 2-year follow-up

Anterior lumbar interbody fusion (ALIF) is a widely accepted tool for management of painful degenerative disc disease. Recently, the modern laparoscopic surgical technique has been combined with ALIF procedure, with good early postoperative results being reported. However, the benefit of laparoscopic fusion is poorly defined compared with its open counterpart. This study aimed to compare perioperative parameters and minimum 2-year follow-up outcome for laparoscopic and open anterior surgical approach for L5-S1 fusion. The data of 54 consecutive patients who underwent anterior lumbar interbody fusion (ALIF) of L5-S1 from 1997 to 1999 were collected prospectively. More than 2-years' follow-up data were available for 47 of these patients. In all cases, carbon cage and autologous bone graft were used for fusion. Twenty-five patients underwent a laparoscopic procedure and 22 an open mini-ALIF. Three laparoscopic procedures were converted to open ones. For perioperative parameters only, the operative time was statistically different (P=0.001), while length of postoperative hospital stay and blood loss were not. The incidence of operative complications was three in the laparoscopic group and two in the open mini-ALIF group. After a follow-up period of at least 2 years, the two groups showed no statistical difference in pain, measured by visual analog scale, in the Oswestry Disability Index or in the Patient Satisfaction Index. The fusion rate was 91% in both groups. The laparoscopic ALIF for L5-S1 showed similar clinical and radiological outcome when compared with open mini-ALIF, but significant advantages were not identified, despite its technical difficulty.

Adapting innovative motion-preserving technology to spinal surgical practice: what should we expect to happen?

STUDY DESIGN

A literature-based review of approach-related morbidity and a conjectural analysis of potential complications of disc arthroplasty based on experience with total joint arthroplasty.

OBJECTIVE

To describe predictable complications of disc arthroplasty and possible strategies for minimizing or treating these complications.

SUMMARY OF BACKGROUND DATA

There is a significant experience with anterior approach-related morbidity in spinal surgery. There is also extensive experience with extremity total joint arthroplasty. The combination of these experiences should predict certain occurrences that will occur with the advent of disc arthroplasty in the spine.

METHODS

Review of the medical literature associated with anterior approach to the lumbar spine for spinal fusion was done. Sequential steps for performance of disc arthroplasty and possible problems with each step were evaluated and possible complications identified. Parallel experience in total joint arthroplasty was reviewed for possible predictive experience.

RESULTS

There are definable approach-related morbidities that will occur, regardless of prosthesis design and implantation technique. Prosthesis design involves a series of tradeoffs for risks and benefits. Revisions are inevitable; rate of revision and time to revision remain to be determined.

CONCLUSIONS

Disc arthroplasty will offer benefits over current fusion techniques. It will come at a cost and certain complications are entirely predictable. There will be deaths from the procedure, due to thromboembolic phenomenon or due to uncontrollable hemorrhage from irreparable vascular injury, especially on repeat operations. There will be prostheses that dislodge. There will be infections that require device removal, a very high-risk procedure. There will be a deterioration of results in the hands of the general medical community as opposed to the hands of the initial investigators, a learning curve if you will. The access surgeon will be critical to minimizing morbidity. Design considerations compete with anatomic constraints. Material choices all have pros and cons. Spine surgeons as a whole are excited about this opportunity, but we must be diligent to minimize these predictable adverse events to make the risk benefit profile the best that it can be for our patients.