Management of degenerative disc disease above an L5-S1 segment requiring arthrodesis

In vitro investigation of two connector types for continuous rod construct to extend lumbar spinal instrumentation

PURPOSE

Instrumentation of the lumbar spine is a common procedure for treating pathologic conditions. Studies have revealed the risks of pathologies in the adjacent segments, with the incidence rate being up to 36.1%. Revision procedures are often required, including extension of the instrumentation by the use of connectors to adjacent levels. The aim of this study was to determine the stiffness of side-to-side and end-to-end connectors for comparison with the use of continuous rods.

METHODS

Ten human lumbar spine specimens (L1-S1) were tested about the three axes under pure moment loading of ± 7.5 Nm. Nine conditions were used to investigate the functions of the extensions for different instrumentation lengths (L3-S1 and L2-S1) and different connector levels (L3/4 and L2/3). The intersegmental range of motion (iROM) and intersegmental neutral zone as well as total range of motion (tROM) and total neutral zone (tNZ) were analyzed.

RESULTS

The application of the spinal system significantly decreased the tROMs (- 44 to - 83%) and iROMs in levels L2/3 (- 56 to - 94%) and L3/4 (- 68 to - 99%) in all the tested directions, and the tNZ under flexion/extension (- 63 to - 71%) and axial rotation (- 34 to - 72%). These decreases were independent of the employed configuration (p < 0.05). The only significant changes in the iROM were observed under lateral bending between the continuous rod and the side-to-side connector at level L3/4 (p = 0.006).

CONCLUSION

From a biomechanical viewpoint, the tested connectors are comparable to continuous rods in terms of ROM and NZ. These slides can be retrieved under Electronic Supplementary Material.

Single- versus multilevel fusion for single-level degenerative spondylolisthesis and multilevel lumbar stenosis: four-year results of the spine patient outcomes research trial

STUDY DESIGN

A subanalysis study.

OBJECTIVE

To compare surgical outcomes and complications of multilevel decompression and single-level fusion with multilevel decompression and multilevel fusion for patients with multilevel lumbar stenosis and single-level degenerative spondylolisthesis (DS).

SUMMARY OF BACKGROUND DATA

In patients with DS who are treated surgically, decompression and fusion provide a better clinical outcome than decompression alone. Surgical treatment for multilevel lumbar stenosis and DS typically includes decompression and fusion of the spondylolisthesis segment and decompression with or without fusion for the other stenotic segments. To date, no study has compared the results of these 2 surgical options for single-level DS with multilevel stenosis.

METHODS

The results from a multicenter randomized and observational study, the Spine Patient Outcomes Research Trial comparing multilevel decompression and single-level fusion and multilevel decompression and multilevel fusion for spinal stenosis with spondylolisthesis, were analyzed. The primary outcome measures were the bodily pain and physical function scales of the Medical Outcomes Study 36-item Short-Form General Health Survey (SF-36) and the modified Oswestry Disability Index at 1, 2, 3, and 4 years postoperatively. Secondary analysis consisted of stenosis bothersomeness index, low back pain bothersomeness, leg pain, patient satisfaction, and self-rated progress.

RESULTS

Overall, 207 patients were enrolled for the study, 130 had multlilevel decompression with 1 level fusion and 77 patients had multilevel decompression and multilevel fusion. For all primary and secondary outcome measures, there were no statistically significant differences in surgical outcomes between the 2 surgical techniques. However, operative time and intraoperative blood loss were significantly higher in the multilevel fusion group.

CONCLUSION

Decompression and single-level fusion and decompression and multilevel fusion provide similar outcomes in patients with multilevel lumbar stenosis and single-level DS.

Decision making in surgical treatment of chronic low back pain: the performance of prognostic tests to select patients for lumbar spinal fusion

Chronic low back pain (CLBP) is one of the main causes of disability in the western world with a huge economic burden to society. As yet, no specific underlying anatomic cause has been identified for CLBP. Imaging often reveals degenerative findings of the disc or facet joints of one or more lumbar motion segments. These findings, however, can also be observed in asymptomatic people. It has been suggested that pain in degenerated discs may be caused by the ingrowth of nerve fibers into tears or clefts of the annulus fibrosus or nucleus pulposus, and by reported high levels of pro-inflammatory mediators. As this so-called discogenic pain is often exacerbated by mechanical loading, the concept of relieving pain by spinal fusion to stabilise a painful spinal segment, has been developed. For some patients lumbar spinal fusion indeed is beneficial, but its results are highly variable and hard to predict for the individual patient. To identify those CLBP patients who will benefit from fusion, many surgeons rely on tests that are assumed to predict the outcome of spinal fusion. The three most commonly used prognostic tests in daily practice are immobilization in a lumbosacral orthosis, provocative discography and trial immobilization by temporary external transpedicular fixation. Aiming for consensus on the indications for lumbar fusion and in order to improve its results by better patient selection, it is essential to know the role and value of these prognostic tests for CLBP patients in clinical practice. The overall aims of the present thesis were: 1) to evaluate whether there is consensus among spine surgeons regarding the use and appreciation of prognostic tests for lumbar spinal fusion; 2) to verify whether a thoracolumbosacral orthosisis (TLSO) truly minimises lumbosacral motion; 3) to verify whether a TLSO can predict the clinical outcome of fusion for CLBP; 4) to assess whether provocative discography of adjacent segments actually predicts the long-term clinical outcome fusion; 5) to determine the incidence of postdiscography discitis, and whether there is a need for routine antibiotic prophylaxis; 6) to assess whether temporary external transpedicular fixation (TETF) can help to predict the outcome of spinal fusion; 7) to determine the prognostic accuracy of the most commonly used tests in clinical practice to predict the outcome of fusion for CLBP. The results of a national survey among spine surgeons in the Netherlands were presented in Study I. The surgeons were questioned about their opinion on prognostic factors and about the use of predictive tests for lumbar fusion in CLBP patients. The comments were compared with findings from the prevailing literature. The survey revealed a considerable lack of uniformity in the use and appreciation of predictive tests. Prognostic factors known from the literature were not consistently incorporated in the surgeons' decision making process either. This heterogeneity in strategy is most probably caused by the lack of sound scientific evidence for current predictive tests and it was concluded that currently there is not enough consensus among spine surgeons in the Netherlands to create national guidelines for surgical decision making in CLBP. In Study II, the hypothesized working mechanism of a pantaloon cast (i.e., minimisation of lumbosacral joint mobility) was studied. In patients who were admitted for a temporary external transpedicular fixation test (TETF), infrared light markers were rigidly attached to the protruding ends of Steinman pins that were fixed in two spinal levels. In this way three-dimensional motion between these levels could be analysed opto-electronically. During dynamic test conditions such as walking, a plaster cast, either with or without unilateral hip fixation, did not significantly decrease lumbosacral joint motion. Although not substantiated by sound scientific support, lumbosacral orthoses or pantaloon casts are often used in everyday practice as a predictor for the outcome of fusion. A systematic review of the literature supplemented with a prospective cohort study was performed (Study III) in order to assess the value of a pantaloon cast in surgical decision-making. It appeared that only in CLBP patients with no prior spine surgery, a pantaloon cast test with substantial pain relief suggests a favorable outcome of lumbar fusion compared to conservative treatment. In patients with prior spine surgery the test is of no value. It is believed by many spine surgeons that provocative discography, unlike plain radiographs or magnetic resonance imaging, is a physiologic test that can truly determine whether a disc is painful and relevant in a patient's pain syndrome, irrespective of the morphology of the disc. It has been suggested that in order to achieve a successful clinical outcome of lumbar fusion, suspect discs should be painful and adjacent control discs should elicit no pain on provocative discography. For this reason, a cohort of patients in whom the decision to perform lumbar fusion was based on an external fixation (TETF) trial, was analysed retrospectively in Study IV. The results of preoperative discography of solely the levels adjacent to the fusion were compared with the clinical results after spinal fusion. It appeared that in this select group of patients the discographic status of discs adjacent to a lumbar fusion did not have any effect on the clinical outcome. The most feared complication of lumbar discography is discitis. Although low in incidence, this is a serious complication for a diagnostic procedure and prevention by the use of prophylactic antibiotics has been advocated. In search for clinical guidelines, the risk of postdiscography discitis was assessed in Study V by means of a systematic literature review and a cohort of 200 consecutive patients. Without the use of prophylactic antibiotics, an overall incidence of postdiscography discitis of 0.25% was found. To prove that antibiotics would actually prevent discitis, a randomised trial of 9,000 patients would be needed to reach significance. Given the possible adverse effects of antibiotics, it was concluded that the routine use of prophylactic antibiotics in lumbar discography is not indicated. In Study VI, the middle- and long-term results of external fixation (TETF) as a test to predict the clinical outcome of lumbar fusion were studied in a group of back pain patients for whom there was doubt about the indication for surgery. The test included a placebo trial, in which the patients were unaware whether the lumbar segmental levels were fixed or dynamised. Using strict and objective criteria of pain reduction on a visual analogue scale, the TETF test failed to predict clinical outcome of fusion in this select group of patients. Pin track infection and nerve root irritation were registered as complications of this invasive test. It was concluded that in chronic low back pain patients with a doubtful indication for fusion, TETF is not recommended as a supplemental tool for surgical decision-making. In Study VII, a systematic literature review was performed regarding the prognostic accuracy of tests that are currently used in clinical practice and that are presumed to predict the outcome of lumbar spinal fusion for CLBP. The tests of interest were magnetic resonance imaging (MRI), TLSO immobilisation, TETF, provocative discography and facet joint infiltration. Only 10 studies reporting on three different index tests (discography, TLSO immobilisation and TETF) that truly reported on test qualifiers, such as sensitivity, specificity and likelihood ratios, could be selected. It appeared that the accuracy of all prognostic tests was low, which confirmed that in many clinical practices patients are scheduled for fusion on the basis of tests, of which the accuracy is insufficient or at best unknown. As the overall methodological quality of included studies was poor, higher quality trials that include negatively tested as well as positively tested patients for fusion, will be needed. It was concluded that at present, best evidence does not support the use of any prognostic test in clinical practice. No subset of patients with low back pain could be identified, for whom spinal fusion is a reliable and effective treatment. In literature, several studies have reported that cognitive behavioural therapy or intensive exercise programs have treatment results similar to those of spinal fusion, but with considerably less complications, morbidity and costs. As the findings of the present thesis show that the currently used tests do not improve the results of fusion by better patient selection, these tests should not be recommended for surgical decision making in standard care. Moreover, spinal fusion should not be proposed as a standard treatment for chronic low back pain. Causality of nonspecific spinal pain is complex and CLBP should not be regarded as a diagnosis, but rather as a symptom in patients with different stages of impairment and disability. Patients should be evaluated in a multidisciplinary setting or Spine Centre according to the so-called biopsychosocial model, which aims to identify underlying psychosocial factors as well as biological factors. Treatment should occur in a stepwise fashion starting with the least invasive treatment. The current approach of CLBP, in which emphasis is laid on self-management and empowerment of patients to take an active course of treatment in order to prevent long-term disability and chronicity, is recommended.

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.

Is the T9, T11, or L1 the more reliable proximal level after adult lumbar or lumbosacral instrumented fusion to L5 or S1?

STUDY DESIGN

A retrospective comparison study.

OBJECTIVE

To compare the postoperative proximal junctional change and revision prevalence as influenced by 3 different proximal levels after adult lumbar deformity instrumented fusion from the distal thoracic/upper lumbar spine (T9-L2) to L5 or S1.

SUMMARY OF BACKGROUND DATA

Few comparative studies on postoperative sagittal plane change and revision prevalence as influenced by 3 different proximal levels after adult lumbar deformity instrumented fusion from the distal thoracic/upper lumbar spine (T9-L2) to L5 or S1 have been published. Many surgeons have hypothesized that stopping proximally in the upper lumbar spine (L1 or L2) or the thoracolumbar junction (T11 or T12) would lead to a high percentage of rapid proximal degeneration, kyphosis, and decompensation because of the concentration of stress on these relatively mobile segments. Therein, many surgeons have felt it is unsafe to stop at these regions of the spine and it is better to always stop proximally at T9 or T10.

METHODS

A clinical and radiographic assessment in addition to revision prevalence of 125 adult lumbar deformity patients (average age 57.1 year) who underwent long (average 7.1 vertebrae) segmental posterior spinal instrumented fusion from the distal thoracic/upper lumbar spine (T9-L2) to L5 or S1 with a minimum 2-year follow-up (2-19.8 year follow-up) were compared as influenced by T9-T10 (group 1, n = 37), T11-T12 (group 2, n = 49), and L1-L2 (group 3, n = 39) proximal fusion levels. The revision prevalence and sagittal Cobb angle change at the proximal junction after surgery were compared.

RESULTS

Three groups demonstrated nonsignificant differences in the prevalence of proximal junctional kyphosis (group 1 51% vs. group 2 55% vs. group 3 36%, P = 0.20) and revision (group 1 24% vs. group 2 24% vs. group 3 26%, P = 0.99) at the ultimate follow-up. Subsequent proximal junctional angle and sagittal vertical axis changes between the ultimate follow-up and preoperative (P = 0.10 and 0.46 respectively) were not significantly different. The SRS total and all subscale outcomes scores among the 3 groups did not demonstrate significant differences (P > 0.50).

CONCLUSION

Three different proximal fusion levels did not demonstrate significant radiographic and clinical outcomes or revision prevalence after surgery. Therefore the more distal proximal fusion level at a neutral and stable vertebra may be satisfactory.

Provocative discography and lumbar fusion: is preoperative assessment of adjacent discs useful?

STUDY DESIGN

A cohort study of clinical outcomes of lumbar fusion patients with preoperative assessment of adjacent levels by provocative discography.

OBJECTIVE

To evaluate whether the preoperative status of the adjacent discs, as determined by provocative discography, has an impact on the clinical outcome of lumbar fusion in chronic low back pain (LBP) patients.

SUMMARY OF BACKGROUND DATA

The results of lumbar fusion in chronic LBP patients vary considerably and are hard to predict. It is believed that degenerative levels adjacent to a fused spinal segment may be a cause of continuing pain. In this respect, it is important to know whether preoperative degenerative or symptomatic adjacent levels have an adverse effect on patient outcomes after lumbar fusion.

METHODS

In 197 patients with an equivocal indication for lumbar fusion (two thirds were patients with prior spine surgery), the decision for either lumbar fusion or conservative management was determined by a temporary external transpedicular fixation trial. During the diagnostic workup, all patients had undergone provocative discography that included the assessment of the discs adjacent to the intended fusion levels. The individual changes in pain on a visual analog scale, assessed before treatment and at follow-up, and patient satisfaction were the measures of outcome.

RESULTS

In the 82 patients who underwent a lumbar fusion, no difference in outcome was found between those patients with degenerative or symptomatic discs adjacent to the fusion and those with normal adjacent discs.

CONCLUSION

In this cohort study of chronic LBP patients with an uncertain indication for lumbar fusion, the preoperative status of adjacent levels as assessed by provocative discography did not appear to be related to the clinical outcome after fusion.

A prospective randomized study of unilateral versus bilateral instrumented posterolateral lumbar fusion in degenerative spondylolisthesis

STUDY DESIGN

Prospective randomized study on 82 patients with degenerative lumbar spondylolisthesis, having undergone posterolateral fusion with bilateral or unilateral instrumentation.

OBJECTIVE

To determine the effectiveness of unilateral pedicle instrumentation in clinical outcome and rate of union in comparison with the classic bilateral system.

SUMMARY OF BACKGROUND DATA

Instrumentation has proved to have advantages and disadvantages related to its rigidity. The use of less rigid systems applied to posterior lumbar fusions proved promising according to the results achieved in both experimental and clinical field.

METHODS

Eighty-two patients were randomized into 2 groups: Group 1 (n = 42) had had bilateral instrumentation, and Group 2 (n = 40) had only had unilateral instrumentation. One case from Group 1, L3-S1 dropped out; only fusions of 1 or 2 levels remained in the study. Length of time spent on operating, blood loss, blood transfusion, hospital stay, complications, clinical results measured by SF-36v2, and radiologic assessment of union and of loss of height of adjacent discs were analyzed and compared by means of chi2 test, t test, and Fisher exact test.

RESULTS

Statistically, there was no significant difference between the 2 groups in relation to demographics, blood loss, need of transfusion, hospital stay, complications, clinical results, rate of union, and effect on adjacent discs. The operating time needed for Group 2 was significantly shorter in than the time needed for Group 1 (P < 0.001). In Group 1, 3 of 186 screws violated the pedicle cortex requiring reoperation because root irritation versus no complication on a total of 90 screws in Group 2.

CONCLUSION

Unilateral instrumentation used for the treatment of degenerative lumbar spondylolisthesis is as effective as bilateral instrumentation when performed in addition to 1- or 2-level posterolateral fusion. The cost of this method is lower, saves time, and reduces possible risk inserting screws in only one side.

An analysis of sagittal spinal alignment following long adult lumbar instrumentation and fusion to L5 or S1: can we predict ideal lumbar lordosis?

STUDY DESIGN

A retrospective study.

OBJECTIVE

To determine factors controlling sagittal spinal balance after long adult lumbar instrumentation and fusion from the thoracolumbar spine to L5 or S1.

SUMMARY OF BACKGROUND DATA

To our knowledge, no study on postoperative sagittal balance following long adult spinal instrumentation and fusion to L5 or S1 has been published.

METHODS

A clinical and radiographic assessment of 80 patients with adult lumbar deformity (average age 53.4 years) who underwent long (average 7.6 vertebrae, 5-11 vertebrae) segmental posterior spinal instrumentation and fusion from the thoracolumbar spine to the L5-S1 (average 4.5 years, 2-15.8-year follow-up) was performed. We defined the optimal sagittal balance (n = 42) group, the distance from C7 plumb to superior posterior endplate of S1 < or = 3.0 cm, and the suboptimal sagittal balance (n = 38) group, the distance from C7 plumb to superior posterior endplate of S1 > 3.0 cm at ultimate follow-up.

RESULTS

The optimal sagittal balance group (C7 plumb, average -0.6 +/- 2.5 cm) had the larger average angle differences between lumbar lordosis and thoracic kyphosis (P < 0.0001), preoperative smaller pelvic incidence (P = 0.007), smaller average thoracolumbar junctional angle (T10-L2) increase (P < 0.0001), and bigger lumbar lordosis angle increase (P = 0.014) at ultimate follow-up. Patients with optimal sagittal balance at ultimate follow-up had significantly higher total Scoliosis Research Society 24 outcome scores than those with suboptimal sagittal balance (P = 0.015). Risk factors that were statistically significant for the suboptimal sagittal balance group included pelvic incidence compared with lumbar lordosis (> or = 45 degrees) before surgery (vs. < 45 degrees, P = 0.009), smaller lumbar lordosis compared with thoracic kyphosis (< 20 degrees) at 8 weeks postoperatively (vs. > or = 20 degrees, P = 0.013), and older than 55 years of age at surgery (vs. 55 years or younger, P = 0.024).

CONCLUSION

A sagittal Cobb angle difference between lumbar lordosis and thoracic kyphosis of > 20 degrees (higher lumbar lordosis) is advisable in most circumstances to achieve optimal sagittal balance.

Sagittal thoracic decompensation following long adult lumbar spinal instrumentation and fusion to L5 or S1: causes, prevalence, and risk factor analysis

STUDY DESIGN

Retrospective study.

OBJECTIVE

To analyze the causes, prevalence of, and risk factors for sagittal thoracic decompensation in adult lumbar spinal instrumentation and fusion (from distal thoracic or upper lumbar spine) to L5 or S1.

SUMMARY OF BACKGROUND DATA

To our knowledge, no studies on sagittal thoracic decompensation following long adult lumbar spinal instrumentation and fusion (from distal thoracic or upper lumbar spine) to L5 or S1 have been published.

METHODS

A clinical and radiographic assessment of 99 patients with adult lumbar spinal deformity (average age 56.7 years) who underwent long (> or = 4 vertebrae; range 4-10/average 6.7) spinal instrumentation and fusion (from lower thoracic or upper lumbar spine to L5 or S1) at a single institution between 1985 and 2003 with a minimum 2-year follow-up (average 4.5 years) was performed. We defined sagittal thoracic decompensation as a progressive kyphotic deformity of the thoracic spine without pseudarthrosis after a long lumbar fusion, which subsequently resulted in a C7 plumb relative to the posterior aspect of the L5-S1 disc > or = 8 cm.

RESULTS

The prevalence of sagittal thoracic decompensation after long adult lumbar spinal instrumentation and fusion (from distal thoracic or upper lumbar spine) to L5 or S1 was 23% (23/99 cases). The etiologies were 14 acute sharp angular kyphoses and 9 long sweeping kyphoses above the instrumented fusion. Of the 14 sharp angular kyphoses, 10 occurred from severe disc degeneration and 4 were caused by compression fractures at the uppermost instrumented vertebra.

CONCLUSION

Risk factors for sagittal thoracic decompensation developing were sagittal imbalance at 8 weeks postoperatively (> or = 5 cm), smaller lumbar lordosis compared with thoracic kyphosis (< 10 degrees) at 8 weeks postoperatively, preoperative sagittal imbalance (> or = 5 cm), age at surgery (older than 55 years), and associated comorbidities. Sagittal thoracic decompensation adversely affected Scoliosis Research Society 24 outcomes scores.

T-Coupler: a method of in situ coupling of plate-plate and rod-plate: a technical report

BACKGROUND CONTEXT

With the existing VSP plate using "no-cut," or low profile screws, with a 5-mm spacer on the screw, it is difficult or impossible to stack a second plate onto the existing in situ plate. In order to extend a fusion above or below, the plate must be explanted and replaced with a longer plate.

PURPOSE

Situations exist where it would be advantageous to leave an existing plate in situ and couple a second plate onto the existing plate. A new device is described for in situ coupling of a plate to plate and a rod to plate using the VSP and lsola systems.

STUDY DESIGN

A T-Coupler was designed to permit coupling of plate-to-plate and rod-to-plate. The T-Coupler was implanted into patients who were prospectively followed clinically and radiographically for a minimum of 2 years.

PATIENT SAMPLE

Seventeen patients were selected who were deemed candidates for the above procedure. In each case, the patient had an existing fusion with Steffee plate and required extension of the fusion above or below the existing plate.

OUTCOME MEASURES

The patients were followed clinically and radiographically for a minimum 2 years.

METHODS

After obtaining FDA 510K clearance and appropriate mechanical testing, the T-Coupler was implanted into patients who were deemed appropriate candidates. In each case the patient had an existing fusion with a Steffee plate and required an extension of the fusion above or below. The patients were followed with anterior-posterior and flexion/extension lateral films every 3 months for 2 years and then every 6 months. The patient's clinical progress was also evaluated.

RESULTS

The T-Coupler was used in 18 operations in 17 patients with a minimum follow-up of 24 months, an average follow-up of 49.6 months with a range of 24 to 84 months. Three patients underwent reexploration with direct visualization of the T-Coupler. There was no evidence of loosening or breakage, and radiographically all patients went on to solid fusions.

CONCLUSIONS

The T-Coupler is a safe and effective device for the stacking of plates or rods onto an existing plate in selected patients. The T-Coupler may improve patient care by reducing the need to explant long constructs thereby reducing operating time, blood loss, and risk of infection.

Degenerative spondylolisthesis: review of current trends and controversies

STUDY DESIGN

A literature-based review.

OBJECTIVES

To review management and controversies and to present authors recommendations.

SUMMARY OF BACKGROUND DATA

There is considerable controversy regarding indication for surgery, role for decompression alone, and decompression with fusion with or without instrumentation.

METHODS

Review of English language medical literature.

RESULTS

The condition may stabilize itself with the collapse of the disc spaces and osteophytes but may continue to progress in nearly a third of the cases. It may cause predominantly back pain due to segmental instability, or radicular pain/neurogenic claudication secondary to root entrapment or spinal stenosis. When conservative treatment fails, the mainstay of surgical treatment is decompressive laminectomy and fusion, with or without instrumentation.

CONCLUSIONS

Decompression primarily relieves radicular symptoms and neurogenic claudication whereas fusion primarily relieves back pain by elimination of instability. The goals for instrumentation are to promote fusion and to correct deformity. Fusion has a better long-term outcome than decompression alone. There is evidence that instrumentation improves fusion rate but does not improve clinical outcome in a relatively short-term follow-up. However, outcome of pseudarthrosis cases deteriorates over time and solid fusion produces better long-term outcome. The benefit of instrumentation comes with a price of higher postoperative morbidity and complication rate. Bone morphogenetic proteins are being tried to increase the rate of fusion, without increasing the complication rate, but the cost is prohibitive. More recently, dynamic stabilization with instrumentation but without fusion has been introduced as an alternative treatment. The current trends of surgical treatment and controversies are discussed.

The impact of adjacent level disc degeneration on health status outcomes following lumbar fusion

STUDY DESIGN

A retrospective review of patient outcomes after lumbar spinal fusion.

OBJECTIVE

To determine whether patients with a fusion ending adjacent to a "degenerated disc" (DDD group) had worse clinical outcomes than patients with fusions ending adjacent to "normal" discs (NL group).

SUMMARY OF BACKGROUND DATA

Although it has been suggested that creating a rigid motion segment adjacent to a degenerated segment may negatively impact clinical outcomes after lumbar fusion, this question has not been addressed to our knowledge in the English literature.

METHODS

Twenty-five consecutive patients treated with lumbar fusion for degenerative instability who had preoperative lumbar spine magnetic resonance imaging, who completed health status questionnaire Short Form 36 (SF-36), and were seen in the office for radiographic follow-up at least 2 years following surgical treatment formed the study group. The magnetic resonance images were reviewed independently by two spine surgeons and rated for the presence of any degenerative changes. Statistical analysis of the SF-36 data was performed with chi2 and Mann-Whitney U testing.

RESULTS

Of the 25 patients, 20 were fused adjacent to at least one degenerated level (DDD group), whereas 5 were fused adjacent to a normal level (NL group). At follow-up, SF-36 scores were higher for the DDD group in all eight subgroups, contrary to the research hypothesis. A power analysis demonstrated with at least 98% certainty that if patients in the DDD group had even a 10% lower score in any of the 8 SF-36 subgroups, this study would have detected it.

CONCLUSION

This retrospective review of patients who underwent lumbar fusion for degenerative instability demonstrated no adverse impact on clinical outcomes when the lumbar fusion ended adjacent to a degenerative motion segment. Although a power analysis validated these results with 98% certainty, larger prospective studies are needed to confirm that there is no benefit to include degenerated adjacent segments in a lumbar fusion for degenerative instability.

Lumbar spinal stenosis. Treatment strategies and indications for surgery

Initially, all patients with degenerative lumbar spinal stenosis should be treated conservatively. Rapid deterioration is unlikely. The majority of patients may either improve or remain stable over a long-term follow-up with nonoperative treatment. Surgery should be an elective decision by the patients who fail to improve after conservative treatment. Medical evaluation is mandatory in those elderly patients with frequent comorbidities. For central spinal stenosis, without significant grade I spondylolisthesis or deformity, decompression is the surgical treatment of choice. Iatrogenic instability must be avoided during decompression surgery by preserving the facet joint and the pars interarticularis. Limited decompression with laminotomy may be indicated for lateral canal stenosis. A limited decompression may avoid postoperative instability but is associated with more frequent neurologic sequelae. Postlaminectomy instability is uncommon, and too little decompression is a more frequent mistake than too much. Decompression is usually associated with good or excellent outcome in 80% of patients. Deterioration of initial post-operative improvement may occur over long-term follow-up. When spinal stenosis is associated with instability, degenerative spondylolisthesis, deformity, postoperative instability, or recurrent stenosis, fusion is often recommended. Instrumentation often improves the fusion rate but does not influence the clinical outcome. Generous decompression but selective fusion of the unstable segment only are preferable for degenerative spondylolisthesis and type I degenerative scoliosis with minimal rotation of the spine.

Surgical management of adjacent level degeneration following lumbar spine fusion

Thirty-eight patients who underwent extension of a prior lumbar fusion for treatment of adjacent level degeneration were retrospectively evaluated. Patient age, pain relief with the initial surgical procedure, and distal level of fusion significantly affected outcome. Overall, this study suggests that adjacent level fusion yields results that are not optimal but provides sigificant clinical improvement for patients with symptomatic adjacent level degeneration.