Anterior spinal fusion or deranged lumbar intervertebral disc

Iliolumbar vein: a challenge for the exposure of the L4-5 disc in the anterior approach to the lumbar spine

PURPOSE

Anterior lumbar spine arthrodesis has been increasingly prescribed. In order to obtain better exposure of the intervertebral discs, it is necessary to identify vascular structures depending on the level to be approached. Systematic ligation of the iliolumbar vein has been suggested for access to the L4-L5 level, which may be technically challenging. The goal of the present study was to determine a safe limit for separating the iliolumbar vein safely without the need for its ligation.

METHODS

In total, 2284 patients involving the topography of the iliolumbar vein were included. If this vein was up to 5 mm distant from the inferior border of the L4-L5 intervertebral disc, its ligature was performed. In cases that the distance was greater than 5 mm, only the retraction was performed without ligature.

RESULTS

A total of 115 ligatures were necessary (5% of cases). Among the 2169 cases with no ligature, bleeding due to ruptures occurred during traction in only 55 patients (3% of cases). The time taken for ligation ranged from five minutes to thirty-two minutes, with an average of 18.3 min per ligature. In cases in which ligatures were needed (distance less than 5 mm), there was loosening of the ligatures leading to bleeding in 23 cases (20% of ligatures).

CONCLUSIONS

Systematic ligature is not necessary for accessing the anterior route to the L4-L5 level, leading to a reduction in the time of surgery and avoiding serious vascular injuries that can occur.

Internal lumbar disc derangement with instability catch from monosegmental discopathy. The forgotten mechanical and kinetic surgical back pain syndrome

STUDY DESIGN

This is a retrospective cohort experience reported with concurrent survey PROM outcomes.

OBJECTIVE

To describe the results of open PLIF reconstruction for a select group of mechanical back pain patients who have mono- or bi-segmental discopathy on MRI imaging, a clinical history of repeated severe and disabling acute mechanical back pain symptoms, and the irregular lumbar motion pattern in returning erect from the flexed position known as the "instability catch".

SUMMARY OF BACKGROUND DATA

The literature of fusion surgery for back pain relief in "mechanical" back pain reveals inconsistent results and in the majority presents only a vague description of these syndromes. Internal Lumbar Disc Degeneration with Instability catch "ILDDIC" may be one subset of these patients who are uniquely benefitted from spine stabilization.

METHODS

The senior author (DAB) in midsummer 2015 began to offer smaller fusion procedures to selected patients on an overnight-stay basis using a standard perioperative care protocol. For practice audit, in December 2020 a mailed survey questionnaire requesting VAS pain scores and SF-36 physical function scores was sent out to all 111 patients who had been treated this way, which group included 30 cases of ILDDIC. We report here on the success of open PLIF reconstruction in achieving back pain relief for these patients.

RESULTS

Some 24 of 30 patients returned the mailed survey questionnaire, and the remaining six could not be reached. All 24 responders reported significant relief of back pain and improved physical function, at a mean of 30 months from surgery. Review of the available clinical records (LFU < 1 year) from the six nonresponders also recorded positive early benefit.

CONCLUSION

The diagnosis of ILDDIC requires both imaging and clinical correlates and may define a subgroup of the mechanical back pain population uniquely suited to achieve pain relief through lumbar fusion.

Intraoperative Neuromonitoring and Lumbar Spinal Instrumentation: Indications and Utility

Multimodal intraoperative neurophysiologic monitoring (IONM) can be utilized as an adjunct to lumbar spinal instrumentation in order to aid with avoidance of neurologic complications. The most commonly utilized modalities include somatosensory-evoked potentials, motor-evoked potentials, and electromyography. Somatosensory-evoked potentials (SSEPs) allow for continuous assessment of the dorsal columns of the spinal cord and are therefore most useful during procedures with a posterior approach to the cervical and thoracic spine. Motor-evoked potentials (MEPs) and electromyography (EMG) can be applied intermittently to assess motor nerve function. The utility of each individual modality can be largely dependent on the surgical approach. Approaches to lumbar spinal instrumentation can be generally categorized as anterior, lateral, and posterior. For lateral approaches, electromyography can be helpful in identifying neural structures crossing the surgical field to prevent injury. In posterior and anterior approaches, somatosensory-evoked potentials and motor-evoked potentials can be used to assess nerve injury during and after maneuvers for decompression and instrumentation. Additionally, during the placement of pedicle screws, direct stimulation with triggered electromyography can be used to detect the pedicle cortex's breach. The efficacy of intraoperative neuromonitoring is dependent on prompt and accurate recognition of changes in signals. This is then followed by accurate recognition of the cause for these changes and appropriate responses by the surgeon, anesthesiologist, and monitoring personnel to correct the change.

Previously unreported complications associated with integrated cage screws following anterior lumbar interbody fusion: report of 2 cases

Anterior lumbar interbody fusion (ALIF) is a widely performed surgical treatment for various lumbar spine pathologies. The authors present the first reports of virtually identical cases of complications with integrated screws in stand-alone interbody cages. Two patients presented with the onset of S-1 radiculopathy due to screw misplacements following an ALIF procedure. In both cases, an integrated screw from the cage penetrated the dorsal aspect of the S-1 cortical margin of the vertebra, extended into the neural foramen, and injured the traversing left S-1 nerve roots. Advanced neuroimaging findings indicated nerve root impingement by the protruding screw tip. After substantial delays, radiculopathic symptoms were treated with removal of the offending instrumentation, aggressive posterior decompression of the bony and ligamentous structures, and posterolateral fusion surgery with pedicle screw fixation. Postoperative radiographic findings demonstrated decompression of the symptomatic nerve roots via removal of the extruded screw tips from the neural foramina.

Understanding Retroperitoneal Anatomy for Lateral Approach Spine Surgery

Lateral approach spine surgery provides effective interbody stabilization, and correction and indirect neural decompression with minimal-incision and less invasive surgery compared with conventional open anterior lumbar fusion. It may also avoid the trauma to paraspinal muscles or facet joints found with transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. However, because lateral approach surgery is fundamentally retroperitoneal approach surgery, it carries potential risk to intra- and retroperitoneal structures, as seen in a conventional open anterior approach. There is an innovative lateral approach technique that reveals different anatomical views; however, it requires reconsideration of the traditional surgical anatomy in more detail than a traditional open anterior approach. The retroperitoneum is the compartmentalized space bounded anteriorly by the posterior parietal peritoneum and posteriorly by the transversalis fascia. The retroperitoneum is divided into three compartments by fascial planes: anterior and posterior pararenal spaces and the perirenal space. Lateral approach surgery requires mobilization of the peritoneum and its content and accurate exposure to the posterior pararenal space. The posterior pararenal space is confined anteriorly by the posterior renal fascia, anteromedially by the lateroconal fascia, and posteriorly by the transversalis fascia. The posterior renal fascia, the lateroconal fascia or the peritoneum should be detached from the transversalis fascia and the psoas fascia to allow exposure to the posterior pararenal space. The posterior pararenal space, however, does not allow a clear view and identification of these fasciae as this relationship is variable and the medial extent of the posterior pararenal space varies among patients. Correct anatomical recognition of the retroperitoneum is essential to success in lateral approach surgery. Spine surgeons must be aware that the retroperitoneal membrane and fascia is multilayered and more complex than is commonly understood. Preoperative abdominal images would facilitate more efficient surgical considerations of retroperitoneal membrane and fascia in lateral approach surgery.

Stand-alone anterior lumbar interbody fusion for treatment of degenerative spondylolisthesis

We sought to evaluate the clinical and radiologic efficacy of stand-alone anterior lumbar interbody fusion (ALIF) for low grade degenerative spondylolisthesis, the favoured surgical management approach at our institution. The optimal approach for surgical management of spondylolisthesis remains contentious. We performed a prospective analysis of all consecutive patients with low grade lumbar spondylolisthesis who underwent ALIF between 2009 and 2013 by a single surgeon (n=27). The mean age was 64.9 years with a male to female ratio of 14:13. There were 32 levels operated and the average preoperative spondylolisthesis was 14.8%, which reduced to 6.4% postoperatively and 9.4% at the latest follow-up (p=0001). Postoperative disc height was increased to 175% of preoperative values and was statistically significant (p<0.001) and remained improved with an overall change of 139% at the latest follow-up. The radiological fusion rate was 91%. The 12-Item Short Form Health Survey (SF-12) mental and physical component summary improved from 31.7 to 43.0 (p=0.007) and from 35.4 to 51.7 (p=0.0026), respectively. The mean visual analogue scale pain score improved from 7.6 to 2.2 (p<0.001), and the mean Oswestry disability index improved from 56.9 to 17.8% (p<0.0001). The overall clinical success rate was 93%. The posterior disc height correlated with spondylolisthesis reduction (p=0.04) and the only clinical factor affecting reduction was body mass index (p=0.04). The present study provides encouraging short term results for stand-alone ALIF as a procedure for low grade lumbar degenerative spondylolisthesis. Future studies should include adequately powered, prospective, multicentre registry studies with long term follow-up to allow a better assessment of the relative benefits and risks.

Indications for anterior lumbar interbody fusion

Anterior lumbar interbody fusion (ALIF) has become a widely recognized surgical technique for degenerative pathology of the lumbar spine. Spinal fusion has evolved dramatically ever since the first successful internal fixation by Hadra in 1891 who used a posterior approach to wire adjacent cervical vertebrae in the treatment of fracture-dislocation. Advancements were made to reduce morbidity including bone grafting substitutes, metallic hardware instrumentation and improved surgical technique. The controversy regarding which surgical approach is best for treating various pathologies of the lumbar spine still exists. Despite being an established treatment modality, current indications of ALIF are yet to be clearly defined in the literature. This article discusses the current literature on indications on ALIF surgery.

Complications during anterior surgery of the lumbar spine: an anatomically based study and review

Procedures involving anterior surgical decompression and fusion are being performed with increasing frequency for the treatment of a variety of pathological processes of the spine including trauma, deformity, infection, degenerative disease, failed-back syndrome, discogenic pain, metastases, and primary spinal neoplasms. Because these operations involve anatomy that is often unfamiliar to many neurological and orthopedic surgeons, a significant proportion of the associated complications are not related to the actual decompressive or fusion procedure but instead to the actual exposure itself. To understand the nature of these injuries, a detailed anatomical study and dissection was undertaken in six cadaveric specimens. Critical structures at risk in the abdomen and retroperitoneum were identified, and their anatomical relationships were categorized and photographed. These structures included the psoas muscle, kidneys, ureters, diaphragm and crura, esophageal hiatus, thoracic duct, greater splanchnic nerves, phrenic nerves, sympathetic chains, medial arcuate ligament, superior and inferior hypogastric plexus, segmental and radicular vertebral vessels, aorta, vena cava, median sacral artery, common iliac vessels, iliolumbar veins, lumbosacral plexus, and presacral hypogastric plexus. Based on these dissections and an extensive review of the literature, the authors provide a detailed anatomically based discussion of the complications associated with anterior lumbar surgery.

The memory metal minimal access cage: a new concept in lumbar interbody fusion-a prospective, noncomparative study to evaluate the safety and performance

Study Design/Objective. A single-centre, prospective, non-comparative study of 25 patients to evaluate the performance and safety of the Memory Metal Minimal Access Cage (MAC) in Lumbar Interbody Fusion. Summary of Background Data. Interbody fusion cages in general are designed to withstand high axial loads and in the meantime to allow ingrowth of new bone for bony fusion. In many cages the contact area with the endplate is rather large leaving a relatively small contact area for the bone graft with the adjacent host bone. MAC is constructed from the memory metal Nitinol and builds on the concept of sufficient axial support in combination with a large contact area of the graft facilitating bony ingrowth and ease in minimal access implantation due to its high deformability. Methods. Twenty five subjects with a primary diagnosis of disabling back and radicular leg pain from a single level degenerative lumbar disc underwent an interbody fusion using MAC and pedicle screws. Clinical performance was evaluated prospectively over 2 years using the Oswestry Disability Index (ODI), Short Form 36 questionnaire (SF-36) and pain visual analogue scale (VAS) scores. The interbody fusion status was assessed using conventional radiographs and CT scan. Safety of the device was studied by registration of intra- and post-operative adverse effects. Results. Clinical performance improved significantly (P < .0018), CT scan confirmed solid fusion in all 25 patients at two year follow-up. In two patients migration of the cage occurred, which was resolved uneventfully by placing a larger size at the subsequent revision. Conclusions. We conclude that the Memory Metal Minimal Access Cage (MAC) resulted in 100% solid fusions in 2 years and proved to be safe, although two patients required revision surgery in order to achieve solid fusion.

Good functional outcome and adjacent segment disc quality 10 years after single-level anterior lumbar interbody fusion with posterior fixation

We reviewed the records of a prospective consecutive cohort to evaluate the clinical performance of anterior lumbar interbody fusion with a titanium box cage and posterior fixation, with emphasis on long-term functional outcome. Thirty-two patients with chronic low back pain underwent anterior lumbar interbody fusion and posterior fixation. Radiological and functional results (visual analogue scale [VAS] and Oswestry score) were evaluated. Adjacent segment degeneration (ASD) was evaluated radiologically and by magnetic resonance imaging (MRI). Twenty-five patients (78%) were available for follow-up. Functional scores showed significant improvement in pain and function up to the 2-year follow-up observation. At 4 years, there was some deterioration of the clinical results. At 10-year follow-up, results remained stable compared with 4-year results. MRI showed ASD in 3/25 (12%) above and 2/10 (20%) below index level (compared with absent preoperatively). ASD could not be related to clinical outcome in this study. Anterior lumbar interbody fusion and posterior fixation is safe and effective. Initial improvement in VAS and Oswestry scores is partly lost at the 4-year follow-up. Good clinical results are maintained at 10-year follow-up and are not related to adjacent segment degeneration.

A multicenter study to evaluate the safety and efficacy of a stand-alone anterior carbon I/F Cage for anterior lumbar interbody fusion: two-year results from a Food and Drug Administration investigational device exemption clinical trial

STUDY DESIGN

Two-year prospective multicenter clinical trial.

OBJECTIVE

To determine the safety and efficacy of the anterior I/F Cage in the primary treatment of single-level degenerative disc disease.

SUMMARY OF BACKGROUND DATA

A carbon fiber-reinforced polymer cage was designed to replace the traditional allograft/autograft structural graft used in an anterior lumbar interbody fusion (ALIF). Although the outcomes of various types of ALIF cages have previously been reported, the safety and efficacy of the I/F cage are unknown.

METHODS

Between June 2000 and June 2004, 112 patients were prospectively enrolled at 12 study sites for the current study. Efficacy was evaluated clinically and radiographically. "Patient success" was declared only when the following 4 criteria were present at final follow-up: (1) "clinical success": improvement of 15 points on Oswestry Disability Index, (2) absence of a new neurologic abnormality, (3) successful radiographic fusion, and (4) no subsequent secondary surgical intervention at 24-month follow-up. Safety was inferred by way of an objective summary of complications and adverse events, as reported at regular intervals throughout the course of the study.

RESULTS

A total of 112 patients (mean age: 41.7 years) underwent a single-level ALIF procedure (L5-S1: 95 patients, L4-L5: 17 patients). The mean surgical time was 126 minutes, the mean estimated blood loss was 134 mL, and the mean duration of hospitalization was 3.3 days. There were 80 patients available for 24-month follow-up. Overall patient success was 25% (20/80). Clinical success was present in 46.3% (37/80), fusion success was 57.5% (46/80), and 87.5% of patients (70/80) avoided a subsequent secondary surgical intervention. Disc space height had significantly increased after surgery, and this increase was maintained at 2 years follow-up period. Complications and adverse events included the following: 8 infections (7.1%) (7 superficial, 1 deep), 2 vascular injuries (1.8%) (left common iliac vein), and 12 secondary surgical interventions (15%).

CONCLUSION

This safety and efficacy study suggests that the anterior I/F Cage is a safe surgical option in the treatment of single-level lumbar degenerative disc disease. As a stand-alone construct, the I/F Cage yields suboptimal radiographic and clinical outcomes. Additional benefit may be gained from adjunctive posterior stabilization.

The Correlation Between Preoperative Disc Space Height and Clinical Outcomes After Anterior Lumbar Interbody Fusion

OBJECTIVE

To determine whether preoperative disc space height (DSH) influences the clinical outcomes of patients diagnosed with single-level symptomatic discogenic disease and treated with a stand-alone anterior lumbar interbody fusion with two tapered threaded fusion cages, we performed a retrospective analysis of 392 patients.

METHODS

Preoperative radiographs were used to establish four study groups based on the patients' DSH: the tall disc group: DSH >15 mm; the intermediate tall group: DSH ranging from 10 to 15 mm; the intermediate collapsed group: DSH ranging from 5 to 10 mm; and the collapsed disc group: DSH <5 mm.

RESULTS

All of the patient groups exhibited improvement in their clinical outcomes. However, patients in the collapsed disc group (DSH of <5 mm) tended to have earlier and greater improvement in Oswestry Disability Index scores, Physical Component Summary scores of the Short Form-36, and Visual Analog Scale scores for low back pain.

CONCLUSION

Symptomatic disc degeneration can be readily identified with plain radiographic findings, and patients' symptoms can often be relieved predictably with a stand-alone interbody fusion procedure.

Use of rhBMP-2 in combination with structural cortical allografts: clinical and radiographic outcomes in anterior lumbar spinal surgery

BACKGROUND

Recombinant human bone morphogenetic protein-2 soaked into an absorbable collagen sponge (rhBMP-2/ACS) has been shown in a nonhuman primate study and in a pilot study in humans to promote new bone formation and incorporation of an allograft device when implanted in patients undergoing anterior lumbar interbody arthrodesis. However, a larger series with longer follow-up is needed to demonstrate its superiority to autogenous iliac crest bone graft.

METHODS

Between 1998 and 2001, a two-part, prospective, randomized, multicenter study of 131 patients was conducted to determine the safety and efficacy of the use of rhBMP-2/ACS as a replacement for autogenous iliac crest bone graft in anterior lumbar spinal arthrodesis with threaded cortical allograft dowels. Patients were randomly assigned to a study group that received rhBMP-2/ACS or to a control group that received autograft. The clinical and radiographic outcomes were determined with use of well-established instruments and radiographic assessments.

RESULTS

The patients in the study group had significantly better outcomes than the control group with regard to the average length of surgery (p < 0.001), blood loss (p < 0.001), and hospital stay (p = 0.020). Fusion rates were significantly better in the study group (p < 0.001). The average Oswestry Disability Index scores, Short-Form-36 physical component summary scores, and low-back and leg-pain scores were significantly better in the study group (p < 0.05).

CONCLUSIONS

In patients undergoing anterior lumbar interbody arthrodesis with threaded allograft cortical bone dowels, rhBMP-2/ACS was an effective replacement for autogenous bone graft and eliminated the morbidity associated with graft harvesting.

Good outcome and restoration of lordosis after anterior lumbar interbody fusion with additional posterior fixation

STUDY DESIGN

Fifty-two patients with degenerative disc disease underwent single- or double-level anterior lumbar interbody fusion with SynCage and additional posterior fixation as treatment for degenerative disc disease and were prospectively followed for 4 years.

OBJECTIVES

To test the clinical performance of anterior lumbar interbody fusion with SynCage, with emphasis on the safety and efficacy of the surgical procedure and the ability to restore anatomy and fuse the motion segment.

SUMMARY OF BACKGROUND DATA

Anterior lumbar interbody fusion using femoral allograft and/or autologous bone has a high complication rate. With cage technology, some of these complications can be avoided. The design characteristics of the SynCage offer advantages in restoring and maintaining intervertebral height and restoration of lumbar lordosis.

METHODS

Thirty-three patients underwent single-level and 19 patients double-level anterior lumbar interbody fusion with SynCage and additional posterior fixation (translaminar screws, n = 32 or pedicle screws, n = 10). Radiologic and functional results (VAS and Oswestry score) were evaluated.

RESULTS

Intervertebral height was corrected from an average of 8.7 to 17.6 mm. Lordosis of the fused segment was significantly increased (average 10.6 degrees for the fused segment and 8 degrees for lumbosacral lordosis). After 2 years, there was radiologic evidence for fusion in 70 of 71 (98.6%) levels. Functional scores showed a significant improvement in pain and function up to the 2-year follow-up observation. At the 4-year follow-up observation, there was some loss of the initial improvement in VAS and Oswestry scores. Despite this loss, they remained significantly better than the preoperative scores.

CONCLUSIONS

Anterior lumbar interbody fusion with SynCage and additional posterior fixation is a safe and effective procedure. Intervertebral height is corrected, and lumbosacral lordosis is restored. An initial improvement in VAS and Oswestry scores is partly lost at the 4-year follow-up observation, but 4-year results are still significantly better than the preoperative scores.

Comparison of methods for determining the presence and extent of anterior lumbar interbody fusion

STUDY DESIGN

Titanium alloy interbody fusion devices with autogenous bone were placed in the L5-L6 disc space of 31 adult pig-tailed monkeys through an anterolateral (retroperitoneal) approach. Anteroposterior and lateral radiographs, CT imaging, and histologic analysis of the specimens were performed.

OBJECTIVES

This study compared the accuracy of plain film radiographs and CT imaging for determining bony fusion of a titanium interbody device implanted in a non-human primate model. The accuracy of the assessments was determined by comparison to histologic analysis.

SUMMARY OF BACKGROUND DATA

Interbody fusion assessment is often difficult to compare in clinical studies because of differences in definition of fusion criteria. In addition, the accuracy of plain film radiographs and CT imaging assessments of fusion are debated because of device material radiopacity and introduction of artifacts.

METHODS

A uniform grading system evaluating both the presence and extent of bony fusion was applied to all evaluation techniques. Matched-pair nonparametric t tests were used to determine differences in scoring.

RESULTS

The radiographic and histologic presence of fusion grades was equivalent in only 13 of 29 cases (45%), while the CT imaging was equivalent to histologic assessment in 24 of 29 cases (83%). However, the extent of bony fusion in CT imaging and histologic assessment was equivalent in only 4 of 29 cases (14%). Grading of CT images significantly overestimated the extent of fusion.

CONCLUSIONS

This study demonstrated CT imaging techniques to be superior to plain film radiographs in determining the presence of bony fusion. However, CT imaging did not accurately determine the extent of bony fusion present as confirmed by histologic analysis.

Direct current stimulation of titanium interbody fusion devices in primates

BACKGROUND CONTEXT

The fusion rate for anterior lumbar interbody fusion (ALIF) varies widely with the use of different interbody devices and bone graft options. Adjunctive techniques such as electrical stimulation may improve the rate of bony fusion.

PURPOSE

To determine if direct current (DC) electrical stimulation of a metallic interbody fusion device enhanced the incidence or extent of anterior bony fusion.

STUDY DESIGN/SETTING

ALIF was performed using titanium alloy interbody fusion devices with and without adjunctive DC electrical stimulation in nonhuman primates.

METHODS

ALIF was performed through an anterolateral approach in 35 macaques with autogenous bone graft and either a titanium alloy (Ti-6Al-4V) fusion device or femoral allograft ring. The fusion devices of 19 animals received high (current density 19.6 microA/cm2) or low (current density 5.4 microA/cm2) DC electrical stimulation using an implanted generator for a 12- or 26-week evaluation period. Fusion sites were studied using serial radiographs, computed tomography imaging, nondestructive mechanical testing and qualitative and semiquantitative histology.

RESULTS

Fusion was achieved with the titanium fusion device and autogenous bone graft. At 12 weeks, the graft was consolidating and early to moderate bridging callus was observed in and around the device. By 26 weeks, the anterior callus formation was more advanced with increased evidence of bridging trabeculations and early bone remodeling. The callus formation was not as advanced or abundant for the allograft ring group. Histology revealed the spinal fusion device had an 86% incidence of bony fusion at 26 weeks compared with a 50% fusion rate for the allograft rings. DC electrical stimulation of the fusion device had a positive effect on anterior interbody fusion by increasing both the presence and extent of bony fusion in a current density-dependent manner.

CONCLUSIONS

Adjunctive DC electrical stimulation of the fusion device improved the rate and extent of bony fusion compared with a nonstimulated device. The fusion device was equivalent to or better than the femoral allograft ring in all evaluations. The use of adjunctive direct current electrical stimulation may provide a means of improving anterior interbody fusion.

Anterior lumbar interbody fusion for the management of chronic lower back pain: current strategies and concepts

In a retrospective analysis of two large multicenter clinical studies, 321 patients with degenerative lumbar disc disease were divided into two groups who underwent anterior lumbar interbody fusion using two threaded titanium fusion cages. To determine whether differences in surgical procedures and cage design affect anterior and posterior annular distraction and clinical outcomes, the authors evaluated the clinical and radiographic outcomes of patients treated with a stand-alone ALIF procedure. End-plate preservation techniques were associated with improved anterior and posterior disc space distraction compared with standard end-plate preparation techniques. Similarly, the use of the LT-CAGE device led to greater improvements in restoration of segmental lordosis than did the use of standard cylindric cages. Furthermore, these surgical benefits resulted in improved clinical outcomes as early as 3 months and were maintained over a 2-year follow-up period in patients with improved postoperative disc space distraction and lordosis. Placing cylindric cages in a lordotic or trapezoidal disc space can be accomplished only through asymmetric reaming of the vertebral end plates. In a lordotic disc space, the posterior portion of the disc must be reamed more than the anterior portion. This over-reaming inhibits distraction of the posterior disc space and limits restoration of neuroforaminal height. Reduced reaming and symmetric reaming of the vertebral end plates enable the surgeon to restore anatomic segmental lordosis across the disc space. The tapered cage configuration aids in maintaining segmental lordosis. Anatomic restoration of disc space contours has an impact on a patient's outcome after stand-alone anterior interbody fusion surgery.

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.

Comparison of instrumented anterior interbody fusion with instrumented circumferential lumbar fusion

Posterior lumbar interbody fusion (PLIF) restores disc height, the load bearing ability of anterior ligaments and muscles, root canal dimensions, and spinal balance. It immobilizes the painful degenerate spinal segment and decompresses the nerve roots. Anterior lumbar interbody fusion (ALIF) does the same, but could have complications of graft extrusion, compression and instability contributing to pseudarthrosis in the absence of instrumentation. The purpose of this study was to assess and compare the outcome of instrumented circumferential fusion through a posterior approach [PLIF and posterolateral fusion (PLF)] with instrumented ALIF using the Hartshill horseshoe cage, for comparable degrees of internal disc disruption and clinical disability. It was designed as a prospective study, comparing the outcome of two methods of instrumented interbody fusion for internal disc disruption. Between April 1994 and June 1998, the senior author (N.R.B.) performed 39 instrumented ALIF procedures and 35 instrumented circumferential fusion with PLIF procedures. The second author, an independent assessor (S.M.), performed the entire review. Preoperative radiographic assessment included plain radiographs, magnetic resonance imaging (MRI) and provocative discography in all the patients. The outcome in the two groups was compared in terms of radiological improvement and clinical improvement, measured on the basis of improvement of back pain and work capacity. Preoperatively, patients were asked to fill out a questionnaire giving their demographic details, maximum walking distance and current employment status in order to establish the comparability of the two groups. Patient assessment was with the Oswestry Disability Index, quality of life questionnaire (subjective), pain drawing, visual analogue scale, disability benefit, compensation status, and psychological profile. The results of the study showed a satisfactory outcome (score< or =30) on the subjective (quality of life questionnaire) score of 71.8% (28 patients) in the ALIF group and 74.3% (26 patients) in the PLIF group (P>0.05). On categorising Oswestry Index scores into "excellent", "better", "same", and "worse", we found no difference in outcome between the two groups: 79.5% (n=31) had satisfactory outcome with ALIF and 80% (n=28) had satisfactory outcome with PLIF. The rate of return to work was no different in the two groups. On radiological assessment, we found two nonunions in the circumferential fusion (PLIF) group (94.3% fusion rate) and indirect evidence of no nonunions in the ALIF group. There was no significant difference between the compensation rate and disability benefit rate between the two groups. There were three complications in ALIF group and four in the PLIF (circumferential) group. On the basis of these results, we conclude that it is possible to treat discogenic back pain by anterior interbody fusion with Hartshill horseshoe cage or with circumferential fusion using instrumented PLIF.

Reduction of disc space distraction after anterior lumbar interbody fusion with autologous iliac crest graft

STUDY DESIGN

A retrospective review with long-term clinical and radiologic assessment was conducted.

OBJECTIVE

To assess the severity and reasons for the reduction of disc space distraction after successful autograft fusion of the lumbar spine and its clinical consequences.

SUMMARY OF BACKGROUND DATA

Anterior lumbar interbody fusion is an established treatment for lumbar disc degeneration. It is not firmly established whether the grafted level narrows after surgery, and if so, what the clinical consequences are.

METHODS

This study assessed 67 patients who underwent anterior lumbar interbody fusion at L4-L5 with autologous iliac crest graft. The disc space height and angle between L4 and L5 were serially measured. Times until fusion and the presence of symptoms before and after surgery and at the latest follow-up assessment were noted.

RESULTS

The mean follow-up period was 14 years (range, 2.5-32 years). The fusion rate was 96% (64 of 67 patients), and the mean time to fusion was 9 months. In the group that had successful fusion, there was an initial increase in disc space distraction followed by a reduction in 55 patients (86%). The mean preoperative disc space height was 12.1 mm, which increased immediately after surgery to 16.2 mm, but had been reduced to 12.6 mm at the latest follow-up assessment. The reduction in distraction occurred within the first 3 months after surgery and was correlated with age, but not with recurrence of symptoms, the amount of initial distraction, or the gender of the individual. A similar trend was seen with L4-L5 segmental angulation.

CONCLUSIONS

Reduction of disc space distraction after anterior lumbar interbody fusion using tricortical iliac crest bone graft is a common finding. Despite this, the fusion rate is high, and there is no association with symptom recurrence.

Video-assisted versus open anterior lumbar spine fusion surgery: a comparison of four techniques and complications in 135 patients

STUDY DESIGN

A retrospective review involved 135 patients undergoing anterior interbody fusion using four different approaches: transperitoneal video-assisted surgery with insufflation, retroperitoneal endoscopic video-assisted surgery, minilaparotomy retroperitoneal surgery, and traditional oblique muscle-splinting retroperitoneal surgery.

OBJECTIVE

To describe and compare the operative procedure and perioperative complications of four different interbody fusion techniques.

SUMMARY OF BACKGROUND DATA

Although anterior lumbar interbody fusion surgery has a long history, several new and innovative approaches have been introduced recently. In contrast to the traditional oblique muscle-splitting retroperitoneal flank incision, the following have been used: a "minilaparotomy" open extraperitoneal approach through a small midline incision, a transperitoneal video-assisted insufflation technique, and a video-assisted gasless retroperitoneal endoscopic technique.

METHODS

A retrospective review was performed using the hospital records, operating room records, and clinic charts of 135 consecutive patients (50 men and 85 women) who underwent surgery between December 1993 and February 1998. Cases were included if either bone grafts alone or cylindrical cages with bone graft inside were used. Cases with anterior instrumentation using plates or rods were excluded. Diagnoses included degenerative disc disease, spondylolisthesis, or pseudarthrosis of a previous lumbosacral fusion. Patients with tumors or infection were excluded. The patients all were adults ranging in age from 17 to 83 years. Among the 135 patients, 12 had undergone previous anterior spine fusion surgery and 64 had undergone prior abdominal surgery.

RESULTS

The onset of new radicular pain or numbness, not experienced by the patient before surgery, occurred in six patients (18%; all with transperitoneal video-assisted surgery using insufflation). Vascular problems occurred in five patients (3.7% overall): two in the transperitoneal video-assisted group (5.9% of the group) and three in the minilaparotomy group (8.7% of the group). Retrograde ejaculation occurred in 4 of the 50 male patients (8% of the group): three in the transperitoneal video-assisted group (25% of the group) and one in the minilaparotomy group (2% of the group). Two patients had ureteral injuries (1.5% overall): one each in the retroperitoneal endoscopic and minilaparotomy groups. Conversion to open procedures was performed in seven patients (11% of the video-assisted procedures). The reasons for conversion included two major vessel lacerations and five peritoneal tears in the retroperitoneal video-assisted group.

CONCLUSIONS

A comparative analysis of four techniques for approaching the lower lumbar spine to perform arthrodesis in 135 patients showed an incidence of complications consistent with the literature for video-assisted techniques, but higher than for open techniques. For these and other reasons, the video-assisted approaches have been abandoned by the surgeons of this report.

Single-level lumbar spine fusion: a comparison of anterior and posterior approaches

This study is a retrospective review of 122 patients who underwent single-level lumbar spine fusion. The objectives were to directly compare perioperative morbidity and early results of single-level anterior interbody posterolateral intertransverse process lumbar spine fusion and to provide objective findings that may be useful in selecting surgical method. Lumbar spinal fusion is a well-recognized surgical treatment of intractable low back pain resulting from DDD or spondylolisthesis. Assessments of techniques, results, and outcomes have been published, but detailed head-to-head comparisons of anterior posterior approaches with objective operative and postoperative data are not available in the literature. A retrospective review of 122 patients who underwent either an anterior interbody or posterolateral intertransverse process (average follow-up 22 and 26 months, respectively) single-level instrumented lumbar spinal fusion was performed. Surgical, perioperative, and follow-up data were obtained directly from medical records. The findings compared included estimated blood loss, need for blood transfusion, number of units transfused, operative time, number of days in hospital, need for transitional facility care, complications, need for further surgery, radiographic fusion, and clinical results. There was significantly less blood loss, need for transfusion, amount of blood transfused, operative time, and hospital stay for patients with anterior fusion procedures (p < 0.01). There was no significant difference in need for transitional facility care, complication rates, and given follow-up period in radiographic fusion rate and clinical outcome. Clinical results were significantly worse for those undergoing revision primary fusion (p < 0.01). The anterior approach to single-level lumbar fusion is associated with less morbidity than the posterolateral approach. This may in turn affect surgical outcome and hospital cost. However, both approaches to single-level lumbar fusion produce similar early fusion rates and clinical results. Revision fusions had poor early results regardless of approach.

Spinal cage retrieval and assessment of biologic response

Implant retrieval programs have been effective in understanding implant failure and biomaterial compatibility in joint arthroplasty; however, its application has not been extended extensively to the assessment of spinal constructs and implants. The objective of this study is to determine the efficacy of implant retrieval analysis as a standard for the assessment of explanted spinal implants. The limitations of clinical radiographic assessment of fusion through metal interbody devices are also identified. The implant analysis protocol is shown through a case report of a titanium mesh spinal fusion cage retrieved from a 54-year-old woman who had a pseudoarthrosis at the T12 cage interface. The implant analysis techniques include backscattered electron imaging, high-resolution contact radiography, histology, and fluorochrome analysis. An implant retrieval analysis program similar to the one discussed in the presented case study will enable an accurate assessment of outcomes of these commonly used implants and will guide future development.

Bone graft incorporation in radiographically successful human intervertebral body fusion cages

STUDY DESIGN

Biopsies were obtained from within radiographically successful human intervertebral body fusion cages to document the histology of remodeling bone graft.

OBJECTIVES

The purpose of this study is to describe the tissue within successful human interbody cages with special reference to the viability of bone and the presence or absence of debris particles.

SUMMARY OF BACKGROUND DATA

The use of interbody fusion cages is gaining rapid acceptance, but there is little histologic documentation of the nature of tissue within successful human interbody fusion cages.

METHODS

Needle biopsies were obtained of tissue within radiographically successful intervertebral body fusion cages at the time of pedicle screw removal for back pain or fusion of adjacent spinal level in nine spinal levels of eight patients. Preoperative diagnoses of these eight adult patients included disease conditions in the sagittal plane: spondylosis (5), degenerative disc disease (6), failed laminectomy and discectomy (2), radiculopathy (1), and spondylolisthesis (1). In all cases the cages had been packed with autograft (iliac crest 7, local 1) at the time of insertion. Cage implantation was performed with anterior (anterior lumbar interbody fusion 4, corpectomy and plate fixation 1), and posterior (posterior lumbar interbody fusion 4), segmental instrumentation (plate 1, or pedicle screws 8). All cases except one cervical case had posterolateral fusion or bilateral facet fusion. The cages were composed of carbon fiber-reinforced polymer (Brantigan cage; DePuy AcroMed, Raynham, MA, n = 5) or titanium mesh (Harms Cage; DePuy AcroMed, Raynham, MA, n = 4). Cages had been in situ from 8 to 72 months (mean 28 months). All nine biopsies from eight patients were obtained from within the center of the cages. Specimens were decalcified, routinely embedded in paraffin, stained with hematoxylin and eosin, and viewed qualitatively with transmitted and polarized light.

RESULTS

All needle biopsies were obtained from within the center of the cages, and no patient developed spinal instability after the biopsy. All nine biopsies showed small fragments of necrotic bone associated with viable bone and restoration of hematopoietic bone marrow. Numerous cement lines demarcated the edges of previous cycles of remodeling. The ratio of necrotic to viable bone varied greatly among cases. Small particles of debris were associated with four of the five carbon-fiber cages and one of the four specimens from titanium cages, but there was no visible bone resorption or inflammation.

CONCLUSIONS

Autogenous bone graft was incorporated in these radiographically successful human intervertebral body fusion cages. A few debris particles were observed, but there was no histologic evidence of particle-induced bone resorption or inflammation.

The vascular anatomy anterior to the L5-S1 disk space

STUDY DESIGN

Dissection of 37 human cadavers was performed to assess the variability in the vascular anatomy anterior to the L5-S1 disc space.

OBJECTIVES

To determine the variability of the anterior vascular anatomy at the L5-S1 disc space, and to assess its reliability as an anatomic landmark for the placement of anterior interbody fusion devices.

SUMMARY OF BACKGROUND DATA

Although multiple studies have defined both the lumbar spinal anatomy and the anatomy of the great vessels, the relation of the great vessels to the anterior L5-S1 disc space has not been quantified directly.

METHODS

This study investigated 35 human cadavers (17 males and 18 females). The anterior L5-S1 disc space and great vessel bifurcation were exposed through a transabdominal approach. Two independent observers each obtained 10 measurements in each specimen.

RESULTS

The middle sacral artery was present in 100% of the specimens, averaging 2.5 mm in width. Its location in relation to the midline was quite variable, with a range greater than 2 cm in both the top and bottom of the disc. The distance from the bifurcation to the top of the L5-S1 disc averaged 18 mm (range, 7-36 mm). The total width between the left common iliac vein and the right common iliac artery averaged 33.5 mm (range, 12-50 mm).

CONCLUSIONS

The middle sacral artery, present in 100% of the specimens, is a poor anatomic landmark for locating the midline at L5-S1. Because the average space available between the left common iliac vein and the right common iliac artery is 33.5 mm, and because the left common iliac vein averages only 12 mm from midline, the surgeon must be prepared to mobilize the local vasculature in most cases to expose the L5-S1 disc space adequately.

Lumbar interbody fusion using the Brantigan I/F cage for posterior lumbar interbody fusion and the variable pedicle screw placement system: two-year results from a Food and Drug Administration investigational device exemption clinical trial

STUDY DESIGN

A carbon fiber-reinforced polymer cage implant filled with autologous bone was designed to separate the mechanical and biologic functions of posterior lumbar interbody fusion.

OBJECTIVES

To test the safety and efficacy of the carbon cage with pedicle screw fixation in a 2-year prospective study performed at six centers under a protocol approved by the Food and Drug Administration, and to present the data supporting the Food and Drug Administration approved indications.

SUMMARY OF BACKGROUND DATA

The success of posterior lumbar interbody fusion has been limited by mechanical and biologic deficiencies of the donor bone. Some failures of pedicle screw fixation may be attributable to the absence of adequate load sharing through the anterior column. Combining an interbody fusion device with pedicle screw fixation may address some limitations of posterior lumbar interbody fusion or pedicle screw fixation in cases that are more complex mechanically.

METHODS

This clinical study of posterior lumbar interbody fusion with pedicle screw fixation involved a prospective group of 221 patients.

RESULTS

Fusion success was achieved in 176 (98.9%) of 178 patients. In the management of degenerative disc disease in patients with prior failed discectomy surgery, clinical success was achieved in 79 (86%) of 92 patients, and radiographic bony arthrodesis in 91 (100%) of 91 patients. Disc space height, averaging 7.9 mm before surgery, was increased to 12.3 mm at surgery and maintained at 11.7 mm at 2 years. Fusion success was notdiminished over multiple fusion levels. These results were significantly better than those reported in prior literature. Although significant surgical complications occurred, those attributable to the implant devices occurred less frequently and generally were minor.

CONCLUSIONS

The Brantigan I/F Cage for posterior lumbar interbody fusion and the Variable Screw Placement System are safe and effective for the management of degenerative disc disease.

Spine fusion for discogenic low back pain: outcomes in patients treated with or without pulsed electromagnetic field stimulation

Sixty-one randomly selected patients who underwent lumbar fusion surgeries for discogenic low back pain between 1987 and 1994 were retrospectively studied. All patients had failed to respond to preoperative conservative treatments. Forty-two patients received adjunctive therapy with pulsed electromagnetic field (PEMF) stimulation, and 19 patients received no electrical stimulation of any kind. Average follow-up time was 15.6 months postoperatively. Fusion succeeded in 97.6% of the PEMF group and in 52.6% of the unstimulated group (P < .001). The observed agreement between clinical and radiographic outcome was 75%. The use of PEMF stimulation enhances bony bridging in lumbar spinal fusions. Successful fusion underlies a good clinical outcome in patients with discogenic low back pain.

Autogenic versus allogenic bone grafts in anterior lumbar interbody fusion

Between 1987 and 1993, 94 consecutive patients with painful spondylolisthesis underwent combined anterior and posterior fusion. The average age at operation was 40 years (range, 16-65 years). Posterior fusion was performed in all patients using pedicle screw systems, and anterior fusion was accomplished with autogenic or allogenic bone grafts. Patients retrospectively were assigned to two groups. In Group 1, anterior fusion was performed with autogenic bone grafts harvested from the iliac crest (n = 65; 146 segments) and in Group 2 allogenic bone grafts were taken from femoral heads (n = 39; 86 segments). The incidence of pseudarthrosis was evaluated on lateral tomograms 24 months after surgery. The mean clinical followup time was 4 years (range, 3-8 years). Pseudarthrosis was found in seven fused levels (3%) managed with autogenic bone grafts (Group 1) and in seven patients (8%) managed with allogenic bone grafts (Group 2). This incidence of pseudarthrosis was not significantly different between the two groups. Considering the possible complications associated with harvesting iliac crest bone, the use of allogenic bone appears justified.

Laparoscopic fusion of the lumbar spine: minimally invasive spine surgery. A prospective multicenter study evaluating open and laparoscopic lumbar fusion

STUDY DESIGN

Two hundred-forty consecutive patients underwent laparoscopic instrumented interbody fusion using custom-designed instrumentation and BAK (Sulzer Spine Tech, Minneapolis, MN) fusion cages. The surgeries were performed at eight spine centers during U.S. Food and Drug Administration investigational device evaluation clinical trials. This cohort was compared with 591 consecutive patients undergoing open anterior fusion with the same device.

OBJECTIVES

To investigate the feasibility and safety of the laparoscopic approach compared with that of open procedures.

SUMMARY OF BACKGROUND DATA

In other areas of medicine, advances in laparoscopic surgical procedures have resulted in reduced morbidity, expense, and pain when compared with results of the open counterpart.

METHODS

The open anterior procedure was performed using a retroperitoneal approach. The laparoscopic procedure was performed transperitoneally with carbon dioxide insufflation to provide visualization using a 10-mm endoscope. Two hollow, titanium, threaded interbody implants packed with autologous bone were inserted into the diseased interspace.

RESULTS

The laparoscopy group had a shorter hospital stay and reduced blood loss but had increased operative time. Operative time improved in the laparoscopy group as surgeons' experience increased. Operative complications were comparable in both groups, with an occurrence of 4.2% in the open approach and 4.9% in the laparoscopic approach. Overall, the device-related reoperation rate was higher in the laparoscopy group (4.7% vs. 2.3%), primarily as a result of intraoperative disc herniation. Conversion to open procedure in the laparoscopy group was 10%, with most cases predictable and preventable.

CONCLUSIONS

The laparoscopic procedure is associated with a learning curve, but once mastered, it is effective and safe when compared with open techniques of fusion.

The Bagby and Kuslich method of lumbar interbody fusion. History, techniques, and 2-year follow-up results of a United States prospective, multicenter trial

STUDY DESIGN

A prospective, multicenter trial of the Bagby and Kuslich method of lumbar interbody stabilization for chronic discogenic low back pain, with follow-up evaluation at 3 months, 6 months, and yearly thereafter, with independent radiographic analysis.

OBJECTIVES

To report the history of development, the surgical techniques, and results of the Bagby and Kuslich method when used to manage discogenic pain of the lumbar spine in humans.

SUMMARY OF BACKGROUND DATA

Disabling chronic low back pain frequently is resistant to conservative management. The "Bagby Basket" effectively has fused the equine and baboon spine. The results of biomechanical and animal studies performed over the last 20 years have suggested that a similar but improved design--the Bagby and Kuslich device--would be useful in stabilizing the human spine.

METHODS

From 1992 to 1995, 947 patients with chronic discogenic low back pain were treated by Bagby and Kuslich interbody fusion in a strict, multicenter, prospective clinical trial by using either the open anterior or open posterior approach. The study involved 42 surgeons at 19 medical centers. The authors of the current report analyzed the fusion rates, pain relief, functional status, and complications occurring in patients who underwent long-term follow-up observation.

RESULTS

The Bagby and Kuslich method is safe and effective when compared with methods described in previous reports of posterior and anterior lumbar interbody arthrodesis performed by using bone graft alone. Fusion occurred in 91% of patients at 24 months after surgery, and pain was eliminated or reduced in 84%. Function was improved in 91%. There were no device-related deaths, cases of major paralyses, device failures, or deep infections.

CONCLUSIONS

Carefully selected middle-aged patients with chronic low back pain secondary to degenerative disc disease can be treated effectively and safely by skilled surgeons using the Bagby and Kuslich device for one- and two-level interbody fusion.

Anterior lumbar interbody fusion. A minimum 10-year follow-up

STUDY DESIGN

One hundred eight patients from a consecutive series of 125 anterior lumbar interbody fusions were invited to take part in a clinical outcome assessment (including plain radiography and magnetic resonance imaging of the lumbosacral spine) more than 10 years after the original surgery.

OBJECTIVES

By standardizing the reporting of outcome, to determine whether the duration of patient follow-up influences the outcome of surgery, with particular reference to the effects of compensation and psychological status.

SUMMARY OF BACKGROUND DATA

The success rates of lumbar spinal fusion surgery reported in the literature vary widely. The lack of standardization of measures of patient outcome limits the value of study comparisons. Evaluation of the efficacy of spinal fusion is further compounded by the adverse effects of both compensation and psychological disturbance on the reporting of outcome.

METHODS

One hundred three patients agreed to take part in a clinical outcome assessment by completing a comprehensive low-back questionnaire that included demographic, compensation, and employment details. Eighty-seven of these cases also agreed to undergo radiographic evaluation and magnetic resonance imaging of the lumbar spine. Subjective assessment of outcome was based on a 10-point analog pain scale as well as patient opinion regarding the success of surgery. A more objective assessment of outcome was made using the Low-Back Outcome Score. Psychological status was determined by combining the Modified Somatic Perception Questionnaire and the Zung Depression Scale. The effects of radiologic fusion, compensation status, psychological status, and reoperation on the various outcome measures were assessed and compared with the results reported in a separate but similar series of patients with a minimum follow-up of 2 years.

RESULTS

Seventy-eight percent of patients rated themselves as having "complete relief" or "a good deal of relief," but only 34% fell into the "excellent" or "good" category using the Low-Back Outcome Score. The clinical outcome was not associated with the presence of radiologic fusion and was not influenced by the compensation status. Psychological disturbance at review and reoperation, however, did influence the reporting of outcome and were significantly correlated with the Low-Back Outcome Score. With the exception of the effects of compensation, these results were remarkably similar to the findings in the 2-year study.

CONCLUSIONS

The findings of the study suggest that the assessment of outcome of lumbar interbody fusion is strongly compounded by the psychological make-up of the patient and that this effect is maintained in the long term. However, the negative effect of compensation observed at 2 years seems to dissipate with time and becomes insignificant at 10 years.

Pedicle screw fixation in spinal disorders: a European view

Continuing controversy over the use of pedicular fixation in the United States is promoted by the lack of governmental approval for the marketing of these devices due to safety and efficacy concerns. These implants have meanwhile become an invaluable part of spinal instrumentation in Europe. With regard to the North American view, there is a lack of comprehensive reviews that consider the historical evolution of pedicle screw systems, the rationales for their application, and the clinical outcome from a European perspective. This literature review suggests that pedicular fixation is a relatively safe procedure and is not associated with a significantly higher complication risk than non-pedicular instrumentation. Pedicle screw fixation provides short, rigid segmental stabilization that allows preservation of motion segments and stabilization of the spine in the absence of intact posterior elements, which is not possible with non-pedicular instrumentation. Fusion rates and clinical outcome in the treatment of thoracolumbar fractures appear to be superior to that achieved using other forms of treatment. For the correction of spinal deformity (i.e., scoliosis, kyphosis, spondylolisthesis, tumor), pedicular fixation provides the theoretical benefit of rigid segmental fixation and of facilitated deformity correction by a posterior approach, but the clinical relevance so far remains unknown. In low-back pain disorders, a literature analysis of 5,600 cases of lumbar fusion with different techniques reveals a trend that pedicle screw fixation enhances the fusion rate but not clinical outcome. The most striking finding in the literature is the large range in the radiological and clinical results. For every single fusion technique poor and excellent results have been described. This review argues that European spine surgeons should begin to back up the evident benefits of pedicle screw systems for specific spinal disorders by controlled prospective clinical trials. This may prevent forthcoming medical licensing authorities from restricting the use of pedicle screw devices and dictating the practice of spinal surgery in Europe in the near future.

The outcome of posterolateral fusion in highly selected patients with discogenic low back pain

STUDY DESIGN

A prospective analysis of the clinical outcome of a consecutive series of patients treated with posterior lumbar arthrodesis. Preoperative data were collected retrospectively by chart review.

OBJECTIVES

To measure by independent review the clinical outcome of posterolateral intertransverse fusion as a treatment for discogenic low back pain in a highly selected group of patients.

SUMMARY OF BACKGROUND DATA

Although numerous studies have reported on the surgical management of degenerative disc disease, they have been difficult to interpret because they lack patient-oriented outcome assessment and objective pain measurement criteria, independent review, and include patients with diagnoses other than degenerative disc disease.

METHODS

Between 1991 and February 1993 all patients seen by a single surgeon, evaluated with magnetic resonance imaging and discography, and treated with posterolateral lumbar fusion were reviewed by independent investigation. Outcome was assessed in the areas of radiographic fusion, pain, function, and patient satisfaction.

RESULTS

Twenty-three patients (12 women, 11 men; 100% follow-up an average of 47 months after surgery [range, 24-84 months]) met the inclusion criteria. Overall, 39% had a good or excellent result, 13% fair, and 48% poor. Nine of 10 patients receiving worker's compensation had a poor result, four of five patients with radiographic pseudarthrosis had a poor result. Statistically significant improvement in the visual analogue scale was noted in the good and excellent group (P = 0.0001) and the fair group (P = 0.002) with no change in the poor group. Patients out of work more than 3 months before surgery tended to have poor results. Overall, 56% of patients were extremely satisfied with the result of their surgery.

CONCLUSION

Posterolateral intertransverse fusion can be used to successfully manage chronic discogenic back pain. However, patient selection remains a challenge, and successful outcome appears to be limited in the subset of patients receiving worker's compensation and those chronically disabled. Prospective and randomized study with objective pain criteria, independent review, and patient-oriented outcome is recommended.

Sense of coherence and outcome of anterior low-back fusion. A 5- to 13-year follow-up of 85 patients

Eighty-five patients were followed up for more than 5 years after an anterior low-back fusion which was performed for a chronically painful low-back condition. The mean age of the patients at the time of the index operation was 35 years, the mean duration of their symptoms was 8 years, and 50 (59%) had undergone previous low-back surgery. Preoperatively the patients were on average severely disabled according to the Oswestry scale, and the self-rated improvement at the follow-up on average 7.4 years after surgery was significant, the mean index being 24%. In 29 (34%) patients, the Oswestry index was 10% or below, reflecting none or very little discomfort as a result of the surgery. In all age groups, women had better results than men. The best outcome was found in patients with no previous low-back surgery. Half of the patients returned to work. Thirteen patients needed new surgery because of nonunion. The use of transpedicular fixation did not produce better results. The sense of coherence scale assessing the patient's successful coping capability had a very good predictive value in the whole series, and this predictive value was especially good in patients between 35 and 50 years of age. Also, the shorter duration of symptoms was an important predictor of a successful outcome, and the end results in patients who had a longer duration of preoperative low-back symptoms tended to be poor.

The Graf stabilisation system: early results in 50 patients

The results of the first 50 consecutive patients using the Graf stabilisation system are presented. The average age of the patients was 41 years; there were 32 women and 18 men in the group. All patients suffered from intractable symptomatic degenerative disc disease which could be localised to one or more levels. All patients gave a history of chronic back pain, but the mean period of severe disability was 24 months. The mean preoperative disability score (Oswestry questionnaire) was 59%. The average period of follow-up was 24 months (range 19-36 months). At the latest review, the mean disability score was 31%. The clinical results were classified as "excellent" or "good" in 72% of patients, "fair" in 10%, "the same" in 16% and "worse" in 2%. All but three patients felt that surgery was worthwhile. The results have not deteriorated over the period of follow-up.

Anterior spondylodesis for spondylolisthesis: isthmic and degenerative types

We studied the influence of instability of the spondylolisthetic segment upon anterior interbody fusion (AIF) rates. A one-level AIF of the lumbar spine by the modified extraperitoneal Bailey-Badgley fusion construct was performed in 26 patients with chronic or recurring acute low-back pain and/or other symptoms due to grades I and II spondylolisthesis. Sixteen were degenerative type, and 10 were isthmic type. Seventeen were female and 9, male. The average age was 41.2 years. The number of cases of spondylolisthesis at the level of L4-5 and L5-S1 as 18 and 8, respectively. In the 16 cases of degenerative type, 13 were grade I slip, and 3 were grade II slip, while in the 10 cases of isthmic type, 8 were grade I slip, and 2 were grade II slip. The average postoperative follow-up was 6 years (range 2-10 years). Solid fusion was obtained in 15 (93.8%) of the cases of degenerative spondylolisthesis and in 6 of the cases of isthmic type. Thus, the overall fusion rate was 80.7% (21 cases). However, some graft crumbling and redisplacement developed in 1 of the cases of degenerative type and 6 of the cases of isthmic type. Non-union developed in 4 (57.1%) of those 7 cases of graft crumbling (3 isthmic and 1 degenerative type). Fusion took 7 months on average (range 5-9 months). It is hypothesised that the isthmic-type spondylolisthesis had more instability than the degenerative one. Therefore, AIF in the case of degenerative spondylolisthesis is a useful procedure, while in the isthmic type it is not advisable as a routine procedure.

Painful internal disc derangements of the lumbosacral spine: discographic diagnosis and treatment by posterior lumbar interbody fusion

Results of surgical or non-surgical treatment of patients with chronic persistent low back pain, but without clearly demonstrable diagnosis of disc herniation, spinal stenosis, or spinal instability, range between 50% to 80% of success rates in the literature. Between 1984 and 1988, the authors reviewed 25 consecutive cases of internal derangements of the lumbar disc treated by subtotal disc excision and interbody fusion. All patients had chronic, persistent, or frequently recurring low back pain resistant to active nonoperative treatments for a minimum of 3 months (mean: 16); no evidence of disc herniation, stenosis, or instability; no previous operation; single level of the pathologic condition in L-S spine; and diagnosis made by clinical information, CT, MRI, and/or discography. Ages ranged from 25 to 51 (mean: 38 to 40). Average follow up was 2 years (range: 13 to 57 months). In addition, 20 patients (32 discographics) who had available information of discography, MRI, and CT scan of the L-S spine, were reviewed for the relationship between disc morphology, pressure, volume, and pain response during discography. Overall clinical results for the 25 patients were: 58% excellent (15 of 26), 31% good (8 of 26), and 11% fair (3 of 26). No patients were in the "poor" category. The successful fusion rate was 95%.

Retroperitoneal fibrosis after anterior spinal fusion

Three patients with lumbar anterior spinal fusion (two with Dwyer instrumentation) developed retroperitoneal fibrosis in relation to the operative site. This complication is possibly a reaction to the retroperitoneal insult. Haematoma, low-grade infection and metallic implant are other likely contributory factors. Its occurrence is affected by the laterality of surgical approach and extent of dissection. Radiologists should be aware of such a complication when investigating post-fusion patients. Early diagnosis and treatment prevent further renal damage.