Comparison between posterolateral fusion with pedicle screw fixation and anterior interbody fusion with pedicle screw fixation in adult spondylolytic spondylolisthesis

Vertebral Slip Morphology in Dysplastic Spondylolisthesis as a Criterion for the Choice of the L5/S1 Support (ALIF, PLIF, Fibular Graft) in Surgical Treatment

Dysplastic spondylolisthesis is a severe pathological condition, based on dysplastic changes in the lumbosacral part of the spine, that causes the asymmetry of the lumbosacral junction. The appropriate therapeutic algorithm remains controversial. As the gold standard, the surgical reposition of the slipped vertebra and 360° fusion of the affected spinal segment is preferred. Thirty-two patients were operated on between the years 2005 and 2018. Different techniques of 360° fusion, based on the severity of the displacement of the affected vertebral segment, were used. Herein, the advantages and disadvantages of different techniques of interbody fusion are discussed. The slippage and retention after reduction in the vertebrae are evaluated prior to the operation, postoperatively, one year after the surgery, and during follow-up, which was 7 years on average (minimum 2 years for a follow-up). Complications associated with the surgery are evaluated, in addition to the operation time, blood loss, spinopelvic parameters, and patient satisfaction with the surgery. All surgical techniques improved the slippage compared to preoperative conditions. The retention of the reposition was not changed significantly in postoperative controls. The incidence of neurological complications reached 12.5%. Surgical treatment is the only treatment option that successfully addressed the pathological principle of dysplastic spondylolisthesis. All of the surgical methods used led to restoring the symmetry of the lumbar spine, and to the improvement in both radiological parameters and the alleviation of subjective difficulties. The aim of this article is to summarize surgical methods in patients having dysplastic spondylolisthesis with a slip of more than 25%, who were operated on, and to determine the optimal treatment algorithm according to the severity of the slip.

PLF+PS or ALIF+PS: which has a lower operative nonunion rate? Analysis of a cohort of 2,061 patients from a National Spine Registry

BACKGROUND CONTEXT

Although fusion rates in posterolateral lumbar fusions with pedicle screws (PLF+PS) and anterior lumbar interbody fusions with pedicle screws (ALIF+PS) have been reported, there has been no consensus on superiority with respect to clinical outcome and nonunion rates. Most studies determine nonunion rates based on radiographic studies; however, many of these nonunions are asymptomatic and may not require reoperations. Hence, a potentially more clinically useful measure is the reoperation rate for symptomatic nonunions, which we term the operative nonunion rate.

PURPOSE

To determine if there is a difference in operative nonunion rates between PLF+PS versus ALIF+PS.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

Adult patients (≥18 years old) with the diagnosis of lumbar spondylolisthesis or lumbar spinal stenosis who underwent primary elective PLF+PS and ALIF+PS for 1-level and 2-level fusions (L4-S1) between 2009 and 2018.

OUTCOME MEASURES

Reoperation rates for symptomatic nonunions (ie, operative nonunion rates).

METHODS

Patients were followed until validated operative nonunions, membership termination, death, or 03/31/2019. Descriptive statistics and 2-year incidence rates for operative nonunions were calculated by fusion-level, fusion type, and levels fused. Time-dependent multivariable Cox-Proportional Hazards regression was used to evaluate operative nonunion rates with adjustment for covariates or risk change estimates more than 10%.

RESULTS

We identified 2,061 patients (PLF+PS:1,491, ALIF+PS:570) with average follow-up time of 4.8 (±3.1) years and average time to operative nonunion of 1.3 (±1.2) yrs. Comparatively, unadjusted 1-level and 2-level incidence rates for operative nonunions were higher in PLF+PS versus ALIF+PS. For 1-level procedures these were 0.9% (95% CI=0.4-1.6) versus 0.6% (95% CI=0.1-2.1); 2-level, 2.0% (95% CI=0.8-4.0) versus 0.9% (95% CI=0.1-3.3). However, there were no observed significant differences in risks for operative nonunions in multivariable models comparing PLF+PS versus ALIF+PS (HR=0.3, 95% CI=0.1-1.1), 1-level versus 2-level fusions (HR=1.8, 95% CI=0.8-4.3), or by fusion level (L4-L5: HR=1.0, 95% CI=0.4-2.7; L5-S1: HR=2.0, 95% CI=0.7-5.4).

CONCLUSIONS

A large cohort of patients with lumbar fusions between L4 to S1 and an average follow-up of >4 years found that although there was a trend for higher operative nonunions in PLF+PS compared with ALIF+PS, this was not statistically significant. The role of spinal alignment was not investigated.

Invasive Treatments for Low Back Disorders

OBJECTIVE

This abbreviated version of the American College of Occupational and Environmental Medicine's Low Back Disorders guideline reviews the evidence and recommendations developed for invasive treatments used to manage low back disorders.

METHODS

Comprehensive systematic literature reviews were accomplished with article abstraction, critiquing, grading, evidence table compilation, and guideline finalization by a multidisciplinary expert panel and extensive peer-review to develop evidence-based guidance. Consensus recommendations were formulated when evidence was lacking and often relied on analogy to other disorders for which evidence exists. A total of 47 high-quality and 321 moderate-quality trials were identified for invasive management of low back disorders.

RESULTS

Guidance has been developed for the invasive management of acute, subacute, and chronic low back disorders and rehabilitation. This includes 49 specific recommendations.

CONCLUSION

Quality evidence should guide invasive treatment for all phases of managing low back disorders.

Functional and Radiological Outcomes of Combined Anterior-Posterior Approach Versus Posterior Alone in Management of Isthmic Spondylolisthesis. A Systematic Review and Meta-Analysis

Background

Lumbar isthmic spondylolisthesis (IS) in adults is defined as the forward slippage of a vertebra onto the top of the vertebra, resulting from a defect in the pars intraarticular, and can be low grade or high grade. Persistent back pain or neurological deficit are indications for surgical intervention. Surgery can be done from back, front, or both, with or without fusion, instrumentation, or decompression, and short or long segment.

Methods

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, several databases were searched through August 2017 for any observational or experimental studies that evaluated combined anterior-posterior approach versus posterior alone in management of IS. Primary outcome was fusion rate, whereas secondary outcomes included functional outcomes (Visual Analogue Scale [VAS] and Oswestry Disability Index [ODI] score), complication rate (infection, neurological), and reoperation rate. Descriptive, quantitative, and qualitative data were extracted. Most of the cases were low-grade IS.

Results

Of the 645 articles identified, 6 studies were eligible for the meta-analysis, with a total of 397 patients with IS, 198 in the combined (anterior interbody fusion [ALIF] + postero-lateral fusion [PLF]) group and 199 in the posterior (transformational interbody fusion [TLIF]/ postero-lateral interbody fusion [PLIF] + PLF) group, average age of 47.2 years, and 185:212 male : female ratio. Although the fusion rate reached 100% in some studies, the pooled odds ratio (OR) of fusion rate (OR = 1.02, 95% confidence interval [CI]: 0.294, 3.552, P = .972) did not reach statistical significance between (ALIF + PLF) versus (TLIF/PLIF + PLF). The estimated pooled standardized mean difference (SMD) showed less blood loss in the anterior approach compared to the posterior approach (SMD = -0.528, 95% CI: -0.777, -0.278, P < .001), with no difference in operative time and length of hospital stay. Despite both groups showing significant improvement in pain and functional scores at final follow up, ODI and VAS were not significantly different between groups with ODI (SMD = -0.644, 95% CI: -1.948, 0.621, P = .311) and VAS (SMD = 0.113, 95% CI: -0.173, 0.400, P = .439). The complication rate for the anterior approach was higher than the posterior, whereas reoperation rate was higher in the posterior approach than the anterior.

Conclusions

No significant difference between anterior and posterior approaches was found in the global assessment of fusion rate and clinical outcomes, despite a higher rate of complications using the anterior approach.

Level of Evidence

3.

Clinical Relevance

Both anterior and posterior approach are a valid option for treatment of isthemic spondylolisthesis.

A systematic review of clinical outcomes in surgical treatment of adult isthmic spondylolisthesis

BACKGROUND CONTEXT

A variety of surgical methods are available for the treatment of adult isthmic spondylolisthesis, but there is no consensus regarding their relative effects on clinical outcomes.

PURPOSE

To compare the effects of different surgical techniques on clinical outcomes in adult isthmic spondylolisthesis.

DESIGN

A systematic review was carried out.

PATIENT SAMPLE

A total of 1,538 patients from six randomized clinical trials (RCTs) and nine observational studies comparing different surgical treatments in adult isthmic spondylolisthesis.

OUTCOME MEASURES

Primary outcome measures of interest included differences in pre- versus postsurgical assessments of pain, functional disability, and overall health as assessed by validated pain rating scales and questionnaires. Secondary outcome measures of interest included intraoperative blood loss, length of hospital stay, surgery duration, reoperation rates, and complication rates.

METHODS

A search of the literature was performed in September 2017 for relevant comparative studies published in the prior 10-year period in the following databases: PubMed, Embase, Web of Science, and ClinicalTrials.gov. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed and studies were included or excluded based on strict predetermined criteria. Quality appraisal was conducted using the Newcastle-Ottawa scale (NOS) for observational studies and the Cochrane Collaboration risk of bias assessment tool for RCTs. The authors received no funding support to conduct this review.

RESULTS

A total of 15 studies (six RCTs and nine observational studies) were included for full-text review, a majority of which only included cases of low-grade isthmic spondylolisthesis. One study examined the effects of adding pedicle screw fixation (PS) to posterolateral fusion (PLF) and two studies examined the effects of adding reduction to interbody fusion (IF)+PS on clinical outcomes. Five studies compared PLF, four with PS and one without PS, with IF+PS. Additionally, three studies compared circumferential fusion (IF+PS+PLF) with IF+PS and one study compared circumferential fusion with PLF+PS. Three studies compared clinical outcomes among different IF+PS techniques (anterior lumbar IF [ALIF]+PS vs. posterior lumbar IF [PLIF]+PS vs. transforaminal lumbar IF [TLIF]+PS) without PLF. As per the Cochrane Collaboration risk of bias assessment tool, four RCTs had an overall low risk of bias, one RCT had an unclear risk of bias, and one RCT had a high risk of bias. As per the NOS, three observational studies were of overall good quality, four observational studies were of fair quality, and two observational studies were of poor quality.

CONCLUSIONS

Available studies provide strong evidence that the addition of reduction to fusion does not result in better clinical outcomes of pain and function in low-grade isthmic spondylolisthesis. Evidence also suggests that there is no significant difference between interbody fusion (IF+PS) and posterior fusion (PLF±PS) in outcomes of pain, function, and complication rates at follow-up points up to approximately 3 years in cases of low-grade slips. However, studies with longer follow-up points suggest that interbody fusion (IF+PS) may perform better in these same measures at later follow-up points. Available evidence also suggests no difference between circumferential fusion (IF+PS+PLF) and interbody fusion (IF+PS) in outcomes of pain and function in low-grade slips, but circumferential fusion has been associated with greater intraoperative blood loss, longer surgery duration, and longer hospital stays. In terms of clinical outcomes, insufficient evidence is available to assess the utility of adding PS to PLF, the relative efficacy of different interbody fusion (IF+PS) techniques (ALIF+PS vs. TLIF+PS vs. PLIF+PS), and the relative efficacy of circumferential fusion and posterior fusion (PLF+PS).

Posterolateral instrumented fusion with and without transforaminal lumbar interbody fusion for the treatment of adult isthmic spondylolisthesis: A randomized clinical trial with 2-year follow-up

BACKGROUND

Spondylolisthesis is a common cause of surgery in patients with lower back pain. Although posterolateral fusion and pedicle screw fixation are a relatively common treatment method for the treatment of spondylolisthesis, controversy exists about the necessity of adding interbody fusion to posterolateral fusion. The aim of our study was to assess the functional disability, pain, and complications in patients with spondylolisthesis treated by posterolateral instrumented fusion (PLF) with and without transforaminal lumbar interbody fusion (TLIF) in a randomized clinical trial.

MATERIALS AND METHODS

From February 2007 to February 2011, 50 adult patients with spondylolisthesis were randomly assigned to be treated with PLF or PLF+TLIF techniques (25 patients in each group) by a single surgeon. Back pain, leg pain, and disability were assessed before treatment and until 2 years after surgical treatment using visual analog scale (VAS) and oswestry disability index (ODI). Patients were also evaluated for postoperative complications such as infection, neurological complications, and instrument failure.

RESULTS

All patients completed the 24 months of follow-up. Twenty patients were females and 30 were males. Average age of the patients was 53 ± 11 years for the PLF group and 51 ± 13 for the PLF + TLIF group. Back pain, leg pain, and disability score were significantly improved postoperatively compared to preoperative scores (P < 0.001). At 3 months of follow-up, there was no statistically significant difference in VAS score for back pain and leg pain in both groups; however, after 6 months and 1 year and 2 years follow-up, the reported scores for back pain and leg pain were significantly lower in the PLF+TLIF group (P < 0.05). The ODI score was also significantly lower in the PLF+TLIF group at 1 year and 2 years of follow-up (P < 0.05). One screw breakage and one superficial infection occurred in the PLF+TLIF group, which had no statistical significance (P = 0.373).

CONCLUSION

It seems that accompanying TLIF with PLF might lead to better functional improvement and pain reduction in patients with spondylolisthesis.

Outcomes of anterior lumbar interbody fusion surgery based on indication: a prospective study

BACKGROUND

There is limited information on clinical outcomes after anterior lumbar interbody fusion (ALIF) based on the indications for surgery.

OBJECTIVE

To compare the clinical and radiological outcomes of ALIF for each surgical indication.

METHODS

This prospective clinical study included 125 patients who underwent ALIF over a 2-year period. The patients were evaluated preoperatively and postoperatively. Outcome measures included the Short Form-12, Oswestry Disability Index, Visual Analog Scale, and Patient Satisfaction Index.

RESULTS

After a mean follow-up of 20 months, the clinical condition of the patients was significantly better than their preoperative status across all indications. A total of 108 patients had a Patient Satisfaction Index score of 1 or 2, indicating a successful clinical outcome in 86%. Patients with degenerative disk disease (with and without radiculopathy), spondylolisthesis, and scoliosis had the best clinical response to ALIF, with statistically significant improvement in the Short Form-12, Oswestry Disability Index, and Visual Analog Scale. Failed posterior fusion and adjacent segment disease showed statistically significant improvement in all of these clinical outcome scores, although the mean changes in the Short Form-12 Mental Component Summary, Oswestry Disability Index, and Visual Analog Scale (back pain) were lower. The overall radiological fusion rate was 94.4%. Superior radiological outcomes (fusion >90%) were observed in patients with degenerative disk disease (with and without radiculopathy), spondylolisthesis, and failed posterior fusion, whereas in adjacent segment disease, it was 80%.

CONCLUSION

ALIF is an effective treatment for degenerative disk disease (with and without radiculopathy) and spondylolisthesis. Although results were promising for scoliosis, failed posterior fusion, and adjacent segment disease, further studies are necessary to establish the effectiveness of ALIF in these conditions.

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.

Segmental stiffness achieved by three types of fixation for unstable lumbar spondylolytic motion segments

Objective The objective of this study was to compare the relative stability in lumbar spondylolysis (SP) of a rigid anterior plate (with a novel compression slot) versus traditional posterior pedicle screw (PS) fixation. Summary of Background Data Arthrodesis has been a mainstay of treatment for symptomatic isthmic spondylolisthesis in adults. Posterior PS fixation has become a commonly used adjunct. Some have advocated anterior lumbar interbody fixation (ALIF) plate as an alternative. The relative stability afforded by ALIF in SP has not been well characterized, nor has the contribution afforded by a compression screw slot in an ALIF plate. Methods Calf spine segments were characterized in the normal state, after sectioning the pars (SP model), then after reconstruction with an interbody spacer and either PS/rods, or an ALIF plate, or both. Results ALIF plate conferred stability on the spondylolytic segment only comparable to that of the normal functional spinal unit (FSU). Posterior fixation was more stable than anterior fixation in all testing modes. Addition of an ALIF plate conferred a significant additional stability in those that already had posterior fixation. The utilization of an anterior compression screw conferred additional stability in extension testing only. Conclusions ALIF plate reconstruction in the setting of SP may not confer enough segmental stability to predictably encourage fusion beyond that of the uninstrumented intact FSU. The utilization of an integral compression screw in an ALIF plate may not confer clinically significant additional construct stability in SP.

Comparison of instrumented posterolateral fusion versus percutaneous pedicle screw fixation combined with anterior lumbar interbody fusion in elderly patients with L5-S1 isthmic spondylolisthesis and foraminal stenosis

OBJECT

The purpose of this study was to compare the clinical and radiological outcomes of treating L5-S1 isthmic spondylolisthesis and foraminal stenosis in elderly patients with instrumented posterolateral fusion (PLF) versus percutaneous pedicle screw fixation (PSF) combined with anterior lumbar interbody fusion (ALIF).

METHODS

Forty-nine patients older than 65 years of age with L5-S1 isthmic spondylolisthesis and symptomatic foraminal stenosis who underwent ALIF were retrospectively analyzed. An ALIF with instrumented PLF (Group A) was performed in 23 patients, and ALIF with percutaneous PSF (Group B) was performed in 26 patients. Data were collected preoperatively and at 3 months, 6 months, 1 year, and every subsequent year. A comparative analysis was made between the 2 groups using clinical (visual analog pain scale [VAS] and modified MacNab criteria) and radiological (dynamic plain radiographs and CT scans) measures.

RESULTS

The mean follow-up duration was 30.3 months (range 24-47 months). The mean preoperative scores on the VAS for low-back pain in Groups A and B were 5.9 and 5.7, respectively, decreasing to 1.4 and 3.6, respectively, at 6 months after surgery (p = 0.001), whereas VAS scores for low-back pain in Groups A and B at 2 years postoperatively were 1.3 and 2.3, respectively (p = 0.005). The mean preoperative scores on the VAS for leg pain in Groups A and B were 7.5 and 7.8, respectively, decreasing at 6 months after surgery to 1.2 and 1.6, respectively (p = 0.201), whereas VAS scores for leg pain in Groups A and B at 2 years postoperatively were 1.3 and 1.4, respectively (p = 0.803). The rates of patients with excellent or good outcomes in terms of the modified MacNab criteria in Groups A and B were 91.3% and 69.2%, respectively, at 6 months after surgery (p = 0.010). Those rates in Groups A and B at 2 years after the operation were 91.3% and 84.6%, respectively (p = 0.203). The fusion rates in Groups A and B were 91.3% and 57.7%, respectively, at 6 months after surgery (p = 0.008), whereas the fusion rates in Groups A and B were 91.3% and 76.9%, respectively, at 2 years after surgery (p = 0.103). There was no significant difference in terms of the complication rate between Group A (4.3%) and B (3.8%) (p = 0.691).

CONCLUSIONS

A relatively longer time until, and lower rate for, fusion in the patients treated with ALIF and percutaneous PSF were noted, which may be correlated with a relatively lower rate of patients with excellent or good outcomes. These results seem to favor ALIF with instrumented PLF rather than ALIF with percutaneous PSF in the treatment of elderly patients with L5-S1 isthmic spondylolisthesis and foraminal stenosis. However, additional long-term follow-up, a larger number of patients, and well-designed studies are necessary for a more rigorous evaluation of the outcome of patients treated using these surgical techniques.

Posterior versus anterior lumbar interbody fusion with anterior tension band plating: retrospective analysis

Over the past 2 decades, posterior lumbar interbody fusion (PLIF) with pedicle screw instrumentation has gained popularity. Anterior fusion techniques, however, have evolved over time and currently allow for minimally invasive anterior retroperitoneal diskectomy, interbody graft placement, and rigid instrumentation. A direct comparison of anterior lumbar interbody fusion (ALIF) with anterior tension band plating to that of instrumented PLIF has not been previously reported. This retrospective uncontrolled cohort comparison included 59 patients with low back pain and 1- or 2-level lumbar degenerative disk disease from L3 to S1 who underwent PLIF with pedicle screw instrumentation or ALIF with anterior tension band plating. Outcome measures included estimated blood loss, surgical time, radiographic evidence of fusion at 6 to 9 months postoperatively, and pre- and postoperative Oswestry Disability Index scores. Fusion rates for the 2 procedures were similar. Posterior lumbar interbody fusion patients had significantly higher estimated blood loss and longer surgical time than ALIF-ATB patients. Oswestry Disability Index scores were similar between the 2 groups at all postoperative time points, except at 3 months postoperatively when PLIF patients had lower scores than ALIF-ATB patients. These findings suggest that ALIF-ATB has similar fusion and functional outcomes as PLIF, but with shorter surgical time and decreased blood loss.

Novel concepts in the evaluation and treatment of high-dysplastic spondylolisthesis. Eur Spine J. 2009;18 Suppl 1:133-142. [PMID: 19399535 DOI: 10.1007/s00586-009-0984-y]

The classification system of spondylolisthesis proposed by Marchetti and Bartolozzi is the most practical regarding prognosis and treatment and includes the description of both low- and high-dysplastic developmental spondylolisthesis (HDDS). Unfortunately, it does not provide strict criteria on how to differentiate between these two subtypes. The accepted treatment for HDDS is surgical. However, there is no consensus on how to surgically stabilize this subtype of spondylolisthesis, and although the concept of reducing spinal deformity before fusion is attractive, the issue of surgical reduction versus in situ fusion remains controversial, especially for HDDS (Meyerding Grades III and IV). The purpose of this study was (1) to describe the severity index (SI) as a simple method that can be used in the identification of low-dysplastic developmental spondylolisthesis from HDDS allowing earlier surgical stabilization to prevent slip progression, (2) to provide guidelines for using the unstable zone for the inclusion of L4 in stabilization, and (3) to describe a surgical technique in the reduction and stabilization of this challenging surgical entity in an attempt to decrease the risk of iatrogenic L5 neurologic injury. The concepts of SI and unstable zone in the evaluation and treatment of HDDS are relatively new. In our study, patients with an SI value >20% were classified as having HDDS and surgical stabilization was offered. In addition, all vertebrae that were contained in the defined unstable zone were surgically instrumented and fused with attempts at anatomic reduction. This case series involved the retrospective radiological review of 25 consecutive patients surgically treated for HDDS between April 2000 and September 2004 by two senior surgeons. All 25 patients had a minimum 3-year follow-up. Reduction of slip, lumbosacral kyphosis, sacral inclination, fusion rate, maintenance of reduction, and iatrogenic L5 neurologic injury were evaluated. Twenty-two patients underwent a single-level L5-S1 fusion. Three patients had extension of the L5-S1 fusion to include L4 because it fell into the unstable zone. Slip improved from 67.2 to 13.6%, focal L5-S1 kyphosis improved from +17.5 degrees to -6.4 degrees . There were no pseudoarthroses and all patients had radiographic evidence of solid bony fusion at latest follow-up. To date, there have been no re-operations secondary to progression of deformity or loss of fixation. Two re-operations were performed, one for a superficial wound infection, the other for further laparoscopic decompression for continued L5 nerve root symptoms after the index surgery. One patient developed an iatrogenic L5 radiculopathy with dysaesthesiae 3 days postoperatively which completely resolved over 6 weeks. HDDS is best treated surgically. Early identification and stabilization of this challenging surgical entity could prevent the progression of slip and deformity making the index surgery less technically demanding. Vertebrae that are contained in the unstable zone can be instrumented and stabilized so that progression of the deformity and re-operation might be avoided. The authors suggested surgical technique can provide a way to restore sagittal balance, provide an environment for successful fusion, and decrease the risk of iatrogenic L5 neurologic injury.

Surgical treatment for unstable low-grade isthmic spondylolisthesis in adults: a prospective controlled study of posterior instrumented fusion compared with combined anterior-posterior fusion

BACKGROUND CONTEXT

The surgical treatment for low-grade isthmic spondylolisthesis in adults with intractable lumbar pain is usually spinal fusion. It has been postulated that anterior column reconstruction may be relatively advantageous in those patients with unstable slips.

PURPOSE

To compare the early and medium term treatment efficacy of two common fusion techniques in isthmic spondylolisthesis.

STUDY DESIGN/SETTING

Prospective controlled trial comparing single-level posterior-lateral instrumented fusion with combined anterior and posterior-lateral instrumented fusion in sequential matched cohorts of patients with radiographically unstable isthmic spondylolisthesis.

OUTCOME MEASURES

Primary outcome measure of success was an Oswestry Disability Index (ODI)<or=20. Secondary outcome measures included patient determined minimum-acceptable outcome on four questionnaires: pain intensity (visual analog scale), ODI, medication intake, and work status. Radiographic outcome of fusion was determined by radiographic union and motion on flexion/extension X-rays. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated for primary outcome of success for combined fusion compared with posterior fusion.

METHODS

The study was conducted over a 6-year period. The first cohort of 50 consecutive patients was treated with a single-level instrumented posterior-lateral fusion; the second sequential cohort was treated with an anterior interbody fusion and the same posterior operation. Observations were made at baseline, 6 months, 1 year, and 2 years after surgery. Final radiographic assessment was made at 2 years after surgery.

RESULTS

Baseline demographic and clinical factors were well-matched in the two cohorts. At 2 years, 46 posterior-only fusion subjects and 47 combined fusion subjects completed the full follow-up regimen. Outcomes were better by all measures at 6 months and 12 months in the anterior-posterior cohort. Comparing the primary outcome measure (ODI outcome<or=20) in the posterior versus the combined groups, success was achieved at 6 months in 11 versus 30 (RR=2.67, 95% CI 1.53, 4.67; p=.0001); at 1 year, 20 versus 34 (RR=1.66, 95% CI 1.14, 2.42; p<.005); and at 2 years, 29 versus 36 subjects (RR=1.21, 95% CI 0.93, 1.59; p=.14). At 6 months, 13 posterior-only and 25 combined group subjects had returned to work (RR 1.88, 95% CI 1.10, 3.21; p=.01). More patients achieved their preoperatively determined minimum-acceptable outcome at each time point. There were three nonunions in the posterior-alone cohort and one in the combined group. Serious complications and reoperations were similar in both groups.

CONCLUSION

Outcomes up to 2 years were superior by clinically important differences after a combined anterior-posterior operation compared with posterior-alone surgery for unstable spondylolisthesis; however, between-group differences attenuated appreciably after 6 months. The apparent clinical and occupational benefits of combined fusion should be considered along with possible increases in minor complications and procedure-related costs.

Treatment of instability and spondylolisthesis: surgical versus nonsurgical treatment

Spondylolisthesis is a common cause of lower-back pain, radiculopathy, and neurogenic claudication among the adult population. Treatment should begin with nonoperative measures that may include physical therapy, aerobic exercise, epidural steroid injections, and homeopathic remedies. If these treatments fail, surgical intervention may provide the patient pain relief and improvement in neurologic symptoms. The use of instrumentation for posterolateral fusions as well as interbody fusion may improve clinical outcomes for those having surgical intervention. We discuss the current nonoperative modalities and surgical techniques treating degenerative spondylolisthesis.

LEVEL OF EVIDENCE

Level V: Expert Opinion. See the Guidelines for Authors for a complete description of the levels of evidence.

In vitro, biomechanical comparison of an anterior lumbar interbody fusion with an anteriorly placed, low-profile lumbar plate and posteriorly placed pedicle screws or translaminar screws

STUDY DESIGN

An in vitro biomechanical comparison of anteriorly placed lumbar plates, pedicle screws, and translaminar screws in the anterior lumbar interbody fusion (ALIF) setting.

OBJECTIVES

To determine whether an anteriorly placed lumbar plate reduces the flexibility in terms of neutral zone and range of motion of a simulated ALIF, and to compare this reduction in flexibility to that provided by posteriorly placed pedicle screws and translaminar screws.

SUMMARY OF BACKGROUND DATA

Pedicular and translaminar facet fixation add stability and increase fusion rates, compared with ALIF alone. An anteriorly placed lumbar plate has been introduced to provide stability without the need for a secondary approach. However, this plate has not been evaluated biomechanically.

METHODS

Seven intact, cadaveric lumbar motion segments were tested to +/- 7.5 Nm in flexion-extension, lateral bending, and axial torsion. Specimens were retested after ALIF, and after subsequent instrumentation with pedicle screws, translaminar screws, and anterior lumbar plates. The range of motion and neutral zone were measured from resulting flexibility curves.

RESULTS

Mean (+/- standard deviation) flexion-extension range of motion for intact segments (9.9 degrees +/- 3.1 degrees ) was significantly reduced to 7.7 degrees +/- 1.8 degrees after ALIF (P = 0.02), and was further reduced to 3.0 degrees +/- 0.9 degrees with lumbar plates (P < 0.001), 1.5 degrees +/- 0.6 degrees with pedicle screws (P < 0.001), and 0.9 degrees +/- 0.4 degrees with translaminar screws (P < 0.001). All 3 devices also reduced flexion-extension neutral zone and torsion neutral zone and range of motion, compared with ALIF alone (P < 0.05). Lumbar plates did not decrease lateral bending range of motion or neutral zone (P > 0.05), whereas pedicle and translaminar screws did (P < 0.05).

CONCLUSIONS

Although not as rigid as pedicle or translaminar screws, anterior lumbar plating does add significant stability to an ALIF and may provide a valuable, single-approach alternative to supplemental posterior fixation.

A critical analysis of the literature regarding surgical approach and outcome for adult low-grade isthmic spondylolisthesis

OBJECTIVE

A systematic review of the radiographic and clinical outcomes of adult patients undergoing surgery for low-grade isthmic spondylolisthesis was performed to determine whether conclusions could be made regarding the optimal choice of surgically managing adult low-grade isthmic spondylolisthesis.

METHODS

We tabulated the radiographic and clinical outcomes of patients who underwent a posterior procedure alone, an anterior procedure alone, or a combined anterior and posterior procedure. We also evaluated the influence of covariates such as laminectomy, spinal internal fixation, smoking, and secondary gain issues on these outcomes. Patients were pooled, and a chi analysis was performed to determine the relationship between surgical approach and patient outcome. A covariate analysis was performed to determine the influence of a laminectomy, spinal fixation, smoking, and secondary gain issues on these outcomes.

RESULTS

The available literature consisted primarily of retrospective case series, with only 4 of 34 reports being prospective randomized controlled studies. Patients with combined anterior and posterior procedures were most likely to achieve a solid fusion and a successful clinical outcome. The use of spinal fixation also increased the chance of fusion and successful clinical outcome.

CONCLUSIONS

A pooling of the surgical literature on adult low-grade spondylolisthesis indicates that a combined anterior and posterior procedure most reliably achieves fusion and a successful clinical outcome. The literature, however, is primarily retrospective and heterogeneous with respect to indications for surgery and methods of evaluating outcome, providing a compelling rationale for a prospective randomized controlled trial of the various surgical approaches to this problem.

Adult low-grade acquired spondylolytic spondylolisthesis: evaluation and management

STUDY DESIGN

Literature review.

OBJECTIVE

To discuss the presentation and evaluation of adult patients with acquired spondylolytic spondylolisthesis of low-grade severity and to review surgical treatment options.

SUMMARY OF BACKGROUND DATA

Low-grade adult acquired spondylolytic spondylolisthesis is one of the most common forms of spondylolisthesis.

METHODS

Literature review.

RESULTS

Adults with symptomatic low-grade spondylolytic spondylolisthesis are treated predominantly nonoperatively, with activity modification, physiotherapy, nonsteroidal anti-inflammatory agents, and local injections. Surgical treatment is reserved for individuals with intractable back pain and/or radicular symptoms. A number of surgical options exist, including direct pars repair, and fusion with or without decompression. Fusion can be achieved by providing anterior column support alone, posterior support alone, or a combined circumferential approach; the optimal method by which fusion should be achieved has not been established.

CONCLUSIONS

The management of low-grade acquired spondylolytic spondylolisthesis requires a thoughtful and individualized approach, recognizing the frequently benign natural history of the deformity and the potentially good clinical outcomes from surgery in those select patients with intolerable back and leg pain. While fusion is the mainstay of surgical management, a prospective randomized study would be extremely useful to delineate the optimal fusion technique.

Posterior lumbar interbody fusion for lytic spondylolisthesis: restoration of sagittal balance using insert-and-rotate interbody spacers

BACKGROUND CONTEXT

The role of surgical correction of sagittal plane deformity in cases of lytic spondylolisthesis remains controversial. While some early evidence is emerging of the possible short- and long-term benefits of restoring spinal balance, many surgeons have been concerned about the associated risks. The insert-and-rotate posterior lumbar interbody fusion (PLIF) technique, first described by Jaslow in 1946, may enable surgeons to safely and effectively correct sagittal balance through a single posterior approach.

PURPOSE

To determine whether the focal kyphosis and subluxation associated with a lytic lumbosacral spondylolisthesis can be safely and effectively corrected using a single-stage posterior distraction/reduction technique and insert-and-rotate interbody fusion spacers.

STUDY DESIGN/SETTING

A prospective, single cohort, observational study of the clinical outcomes and retrospective radiological review, in a series of 18 consecutive patients with lytic spondylolisthesis Grades I to IV, operated between September 2000 and December 2002.

PATIENT SAMPLE

Mean age of 50.2 years (range, 15.5 to 77.8 years). Principal indication for surgery was relief of radicular pain secondary to foraminal stenosis in 16 of 18 patients, and back pain was the principal symptom in 2 patients. Mean preoperative slip was 30.2% (range, 9% to 78%). Mean preoperative focal lordosis was 10.6 degrees (range, -12 to 33 degrees).

OUTCOME MEASURES

Minimum 12-month follow-up was available on all patients except one, who died of unrelated causes after his 6-month visit. Patients completed Visual Analogue Pain Score (VAS), Low Back Outcome Score (LBOS), Short Form (SF)-12 and patient satisfaction questionnaires. Pre- and postoperative measurements of the percentage slip and lumbar lordosis of the involved segments were available on 13 patients. SURGICAL METHODS: Decompressive laminectomy was followed by reduction of the spondylolisthesis with the aid of intervertebral disc space spreaders and supplementary pedicle screw instrumentation. The vertebral bodies were supported with bilateral intervertebral lordotic spacers made from carbon fiber, titanium mesh or polyether-ether-ketone (Medtronic Sofamor Danek, Memphis, TN). These were inserted on their sides and rotated 90 degrees before placing bone graft to either side of them, within the disc space.

RESULTS

Mean follow-up was 17.3 months. Mean preoperative measures of VAS and LBOS of 5.0+/-2.3 and 29.3+/-16.4, respectively, improved to 2.9+/-3.0 (p=.01) and 42.6+/-20.1 (p=.005) at last follow-up. Fifteen of 18 patients (83.3%) considered their outcome to be good or excellent. Mean preoperative slip reduced from 30.2% to 6.2% (p=.001). Mean focal lordosis improved from 10.6 to 18.1 degrees (p=.02). Lumbar lordosis (L1-S1) did not change, but the lordosis of the lumbar segments above the fusion reduced from 46.8 to 34.9 degrees (p=.02). There were no serious implant or procedural complications. Postoperatively, there was a delayed and temporary weakness of ankle dorsiflexion in a patient with Grade IV spondylolisthesis.

CONCLUSIONS

This series suggests that PLIF using an insert-and-rotate technique can yield satisfactory clinical outcomes and substantial deformity correction using a posterior only approach and with low levels of serious or permanent complications. Longer-term clinical outcome and comparative studies are required regarding the importance of the restoration of spinal balance.

Biomechanical testing of the lumbar facet interference screw

STUDY DESIGN

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

OBJECTIVES

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSIONS

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