A prospective, randomised controlled trial of femoral ring allograft versus a titanium cage in circumferential lumbar spinal fusion with minimum 2-year clinical results

How much are patients willing to pay for spine surgery? An evaluation of attitudes toward out-of-pocket expenses and cost-reducing measures

BACKGROUND CONTEXT

With rising healthcare expenditures in the United States, patients and providers are searching to maintain quality while reducing costs.

PURPOSE

The aim of this study was to investigate patient willingness to pay for anterior cervical discectomy and fusion (ACDF), degenerative lumbar spinal fusions (LF), and adult spine deformity (ASD) surgery.

STUDY DESIGN/SETTING

A survey was developed and distributed to anonymous respondents through Amazon Mechanical Turk (MTurk).

METHODS

The survey introduced 3 procedures: ACDF, LF, and ASD surgery. Respondents were asked sequentially if they would pay at each increasing price option. Respondents were then presented with various cost-saving methods and asked to select the options that made them most uncomfortable, even if those would save them out-of-pocket costs.

RESULTS

In total, 979 of 1,172 total responses (84%) were retained for analysis. The average age was 36.2 years and 44% of participants reported a household income of $50,000 to 100,000. A total of 63% used Medicare and 13% used Medicaid. A total of 40% stated they had high levels of financial stress. A total of 30.1% of participants were willing to undergo an ACDF, 30.3% were willing to undergo a LF, and 29.6% were willing to undergo ASD surgery for the cost of $3,000 (p=.98). Regression demonstrated that for ACDF surgery, a $100 increase in price resulted in a 2.1% decrease in willingness to pay. This is comparable to degenerative LF surgery (1.8% decrease), and ASD surgery (2%). When asked which cost-saving measures participants were least comfortable with for ACDF surgery, 60% stated "Use of the older generation implants/devices" (LF: 51%, ASD: 60%,), 61% stated "Having the surgery performed at a community hospital instead of at a major academic center" (LF: 49%, ASD: 56%), and 55% stated "Administration of anesthesia by a nurse anesthetist" (LF: 48.01%, ASD: 55%). Conversely, 36% of ACDF patients were uncomfortable with a "Video/telephone postoperative visit" to cut costs (LF: 51%, ASD: 39%).

CONCLUSIONS

Patients are unwilling to contribute larger copays for adult spinal deformity correction than for ACDF and degenerative lumbar spine surgery, despite significantly higher procedural costs and case complexity/invasiveness. Patients were most uncomfortable forfeiting newer generation implants, receiving the operation at a community rather than an academic center, and receiving care by physician extenders. Conversely, patients were more willing to convert postoperative visits to telehealth and forgo neuromonitoring, indicating a potentially poor understanding of which cost-saving measures may be implemented without increasing the risk of complications.

Evolution of materials for implants in metastatic spine disease till date - Have we found an ideal material?

"Metastatic Spine Disease" (MSD) often requires surgical intervention and instrumentation with spinal implants. Ti6Al4V is widely used in metastatic spine tumor surgery (MSTS) and is the current implant material of choice due to improved biocompatibility, mechanical properties, and compatibility with imaging modalities compared to stainless steel. However, it is still not the ideal implant material due to the following issues. Ti6Al4V implants cause stress-shielding as their Young's modulus (110 gigapascal [GPa]) is higher than cortical bone (17-21 GPa). Ti6Al4V also generates artifacts on CT and MRI, which interfere with the process of postoperative radiotherapy (RT), including treatment planning and delivery. Similarly, charged particle therapy is hindered in the presence of Ti6Al4V. In addition, artifacts on CT and MRI may result in delayed recognition of tumor recurrence and postoperative complications. In comparison, polyether-ether-ketone (PEEK) is a promising alternative. PEEK has a low Young's modulus (3.6 GPa), which results in optimal load-sharing and produces minimal artifacts on imaging with less hinderance on postoperative RT. However, PEEK is bioinert and unable to provide sufficient stability in the immediate postoperative period. This issue may possibly be mitigated by combining PEEK with other materials to form composites or through surface modification, although further research is required in these areas. With the increasing incidence of MSD, it is an opportune time for the development of spinal implants that possess all the ideal material properties for use in MSTS. Our review will explore whether there is a current ideal implant material, available alternatives and whether these require further investigation.

Efficacy of Biocage in treating single-segment lumbar degenerative disease in patients with high risk of non-fusion: a prospective controlled study with at least 2 years' follow-up

Objective

To evaluate the clinical efficacy of an allogeneic bone cage (Biocage; Beijing Datsing Bio-Tech Co., Ltd., Beijing, China) for treatment of single-segment lumbar degenerative disease in patients with a high risk of non-fusion.

Methods

From January 2013 to December 2016, 67 patients who underwent lumbar fusion were divided into the Biocage group (n = 33) and polyether ether ketone (PEEK) group (n = 34). The patients were followed up for 24 to 48 months. The mean intervertebral height of the fusion level, fusion rate, height of the intervertebral foramen, visual analog scale score, and Oswestry disability index were compared.

Results

The PEEK group had a lower fusion rate than the Biocage group (88.24% vs. 90.91%), although the difference was not statistically significant. During follow-up, the height of the intervertebral space was similar between the Biocage and PEEK groups (12.88 ± 0.45 and 12.84 ± 1.01 mm, respectively). The height of the intervertebral foramen was larger in the Biocage than PEEK group (20.67 ± 1.34 vs. 20.00 ± 2.05 mm). Good clinical efficacy was achieved in both groups.

Conclusion

The Biocage is efficient and safe for treatment of single-segment lumbar degenerative disease in patients with a high risk of non-fusion.

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.

Risk Factors Associated With Femoral Ring Allograft Breakage in ALIF

STUDY DESIGN

This is a retrospective chart review.

OBJECTIVES

To identify the incidence of, and variables correlated with, femoral ring allograft (FRA) fracture following anterior lumbar interbody fusion (ALIF).

METHODS

All patients who underwent ALIF using FRAs at an academic institution over 10 years were included. Postoperative radiographs were reviewed by both the primary and senior authors; fracture and no-fracture groups were created for comparison. Patient and surgical characteristics were extracted from electronic medical records. Frequency data comparisons were performed using contingency table analysis; comparisons of means were analyzed for continuous variables. A multivariate linear regression model was developed using screw use, graft height <12 mm, index level, and weight as variables.

RESULTS

A total of 76 FRAs in 59 patients were identified, 13 (17%) of which fractured. Age, sex, smoking status, use of buttress screws, weight, index level, and presence of spondylolisthesis were not correlated with incidence of fracture (P > .05). There was a significant correlation between the height of FRA and incidence of fracture; 2% (1/52) of grafts ≥12 mm and 50% (12/24) of grafts <12 mm fractured (P < .0001). Using ordinary least-squares regression, this result was independent of patient weight, use of screws, and index level. Of 10 patients, 9 did not require revision surgery to achieve fusion.

CONCLUSIONS

Graft height was the only variable correlated with incidence of FRA fracture. Graft height <12 mm is an independent risk factor for FRA fracture in patients undergoing ALIF, and their use should be avoided in ALIF procedures.

Follow-up of a new titaniumcoated polyetheretherketone cage for the cervical spine

Poly-ether-ether-ketone (PEEK) cages have lower modulus of elasticity when compared with Titanium (TTN) cages. This suggests that PEEK-cages could show a lower rate of subsidence after anterior cervical discectomy-fusion (ACDF) and might lead to a lower loss of correction. We investigated the one to five year-results of standalone PEEK-TTN-porous coated cages in a patient cohort from 2014 to 2017. The patients underwent single-level ACDF for disc herniation and degenerative discopathy. Clinical and radiological outcome were assessed in 50 eligible patients after a mean of 27 months. Results: Solid arthrodesis was found in 84%. Neck disability index (NDI), and visual analogue scale (VAS) of neck and arm show comparable results to the literature. Conclusions: Clinical and radiological outcomes of ACDF with PEEK-body-cages with a porous coated surface show good bony integration. The modulus of elasticity, design, shape, size, cage surface architecture, as well as bone density, endplate preparation, radical microdiscectomy and distraction during surgery should be considered as important factors influencing the clinical results. One main advantage, over titanium cages, is the absence of MRI artifacts, allowing an excellent postoperative follow-up.

Raman Biomarkers Are Associated with Cyclic Fatigue Life of Human Allograft Cortical Bone

BACKGROUND

Structural bone allografts are an established treatment method for long-bone structural defects resulting from such conditions as traumatic injury and sarcoma. The functional lifetime of structural allografts depends on resistance to cyclic loading (cyclic fatigue life), which can lead to fracture at stress levels well below the yield strength. Raman spectroscopy biomarkers can be used to non-destructively assess the 3 primary components of bone (collagen, mineral, and water), and may aid in optimizing allograft selection to decrease fatigue fracture risk. We studied the association of Raman biomarkers with the cyclic fatigue life of human allograft cortical bone.

METHODS

Twenty-one cortical bone specimens were machined from the femoral diaphyses of 4 human donors (a 63-year old man, a 61-year-old man, a 51-year-old woman, and a 48-year-old woman) obtained from the Musculoskeletal Transplant Foundation. Six Raman biomarkers were analyzed: collagen disorganization, mineral maturation, matrix mineralization, and 3 water compartments. The specimens underwent cyclic fatigue testing under fully reversed conditions (35 and 45 MPa), during which they were tested to fracture or to 30 million cycles ("runout"), simulating 15 years of moderate activity. A tobit censored linear regression model for cyclic fatigue life was created.

RESULTS

The multivariate model explained 60% of the variance in the cyclic fatigue life (R = 0.604, p < 0.001). Increases in Raman biomarkers for disordered collagen (coefficient: -2.74×10, p < 0.001) and for loosely collagen-bound water compartments (coefficient: -2.11×10, p < 0.001) were associated with a decreased cyclic fatigue life. Increases in Raman biomarkers for mineral maturation (coefficient: 3.50×10, p < 0.001), matrix mineralization (coefficient: 2.32×10, p < 0.001), tightly collagen-bound water (coefficient: 1.19×10, p < 0.001), and mineral-bound water (coefficient: 3.27×10, p < 0.001) were associated with an increased cyclic fatigue life. Collagen disorder accounted for 44% of the variance in the cyclic fatigue life, mineral maturation accounted for 6%, and all bound water compartments accounted for 3%.

CONCLUSIONS

Increasing baseline collagen disorder was associated with a decreased cyclic fatigue life and had the strongest correlation with the cyclic fatigue life of human cortical donor bone. This model should be prospectively validated.

CLINICAL RELEVANCE

Raman analysis is a promising tool for the non-destructive evaluation of structural bone allograft quality for load-bearing applications.

PEEK versus metal cages in posterior lumbar interbody fusion: a clinical and radiological comparative study

BACKGROUND

Low back pain and sciatica represent a common disabling condition with a significant impact on the social, working and economic lives of patients. Transforaminal lumbar interbody fusion (TLIF) is a surgical procedure used in degenerative spine conditions. Several types of cages were used in the TLIF procedure.

PURPOSE

To determine whether there is a difference in terms of symptomatology improvement, return to daily activities and fusion rate between metal cages and polyetheretherketone (PEEK) cages.

METHODS

We have retrospectively reviewed 40 patients who have undergone TLIF from October 2015 to May 2016. All patients were clinically evaluated with questionnaires and were assessed with CT scan and standing X-ray films of the full-length spine.

RESULTS

We found no significant functional differences in the two groups. At 1-year follow-up, osteolysis was present in 50% of cases of the PEEK cages and in 10% cases of the metal cages. The degree of fusion at 1  year was evaluated as complete in 40% cases of the metal cages and 15% cases of the PEEK cages.

CONCLUSIONS

We have found a better fusion rate and prevalence of fusion in the group treated with metal cages, reflecting the well-known osteoinductive properties of titanium and tantalum.

Total Disc Replacement Versus Anterior-Posterior Interbody Fusion in the Lumbar Spine and Lumbosacral Junction: A Cost Analysis

STUDY DESIGN

Prospective observational cohort study.

OBJECTIVES

To analyze clinical and economic results in patients with degenerative disc disease in the lumbar area for patients who received combined anterior and posterior fusion or total disc replacement (TDR).

METHODS

The study included 75 patients, 38 in the fusion group and 37 in the TDR group, who received either anterior/posterior fusion or TDR for lumbar disc disease from January 2005 to December 2008 with a minimum follow-up of 24 months. We collected data with regard to clinical parameters, demographics, visual analogue scale scores, Oswestry Disability Index scores, SF-36 and SF-6D data, surgery time, amount of blood loss, transfusion of blood products, number of levels, duration of hospital stay, and complications. For cost analysis, general infrastructure, theatre costs, as well as implant costs were examined, leading to primary hospital costs. Furthermore, average revision costs were examined, based on the actual data. Statistical analysis was performed using t tests for normal contribution and Mann-Whitney test for skew distributed values. The significance level was set to .05.

RESULTS

There was a higher surgery time, more blood loss, and longer hospital stay for the fusion group, compared with the TDR group. In addition, the hospital costs for the primary procedure and revision were 35% higher in the fusion group. The clinical data in terms of SF-36 and SF-6D showed no difference between these 2 groups.

CONCLUSIONS

TDR is a good alternative to anterior and posterior lumbar fusion in terms of short follow-up analysis for clinical data and cost analysis. General advice cannot be given due to missing data for long-term costs in terms of surgical treatment of adjacent level or further fusion techniques.

A Cost-Effectiveness Analysis of Intradiscal Electrothermal Therapy Compared with Circumferential Lumbar Fusion

STUDY DESIGN

Cost-effectiveness analysis.

OBJECTIVE

To evaluate the cost-effectiveness of intradiscal electrothermal therapy (IDET) relative to circumferential lumbar fusion with femoral ring allograft (FRA) in the United Kingdom.

SUMMARY OF BACKGROUND DATA

Circumferential lumbar fusion is an established treatment for discogenic low back pain. However, IDET could be a cost-effective treatment alternative as it can be carried out as a day case.

METHODS

Patient-level data were available for patients with discogenic low back pain treated with FRA (n = 37) in a randomized trial of FRA vs. titanium cage, and for patients recruited to a separate study evaluating the use of IDET (n = 85). Both studies were carried out at a single institution in the United Kingdom. Patients were followed-up for 24 months, with data collected on low back disability (Oswestry Disability Index), back and leg pain (visual analog scale), quality of life (Short Form 36), radiographic evaluations, and U.K. National Health Service (NHS) resource use. Cost-effectiveness was measured by the incremental cost per quality-adjusted life year (QALY) gained.

RESULTS

Both treatments produced statistically significant improvements in outcome at 24-month follow-up. NHS costs were significantly lower with IDET due to a shorter mean procedure time (377.4 minutes vs. 49.9 minutes) and length of stay (7 days vs. 1.2 days). At a threshold of £20,000 per QALY, the probability that IDET is cost effective is high.

CONCLUSIONS

Both treatments led to significant improvements in patient outcomes that were sustained for at least 24 months. Costs were lower with IDET, and for appropriate patients IDET is an effective and cost-effective treatment alternative.

"Steel-Concrete" Inspired Biofunctional Layered Hybrid Cage for Spine Fusion and Segmental Bone Reconstruction

In this paper we report a "steel-concrete" inspired layered hybrid spine cage combining a titanium mesh and a bioceramic scaffold, which were welded together through a bioglass bonding layer using a novel multistep manufacturing methodology including three-dimensional slip deposition, gel casting, freeze-drying, and cosintering. The interfacial welding strength achieved 27 ± 0.7 MPa, indicating an excellent structural integrity of the hybrid cage construct. The biocramic scaffold layer consisting of wollastonite and hydroxyapatite had an interconnected, highly porous structure with a pore size of 100-500 μm and a porosity of >85%, well fufilling the structural requirements of bone regeneration. Simulated body fluid immersion assay showed that the hybrid cage exhibited excellent biodegradability to facilitate rapid bone-like apatite formation. In vitro studies demonstrated that the bioceramic scaffold on the hybrid cage supported attachment, spreading, growth, and migration of bone/vessel-forming cells and triggered osteogenic differentiation of human mesenchymal stem cells. In vivo studies further suggested that the bioceramic scaffold on the hybrid cage could actively promote fast generation of new bone tissues within 12 weeks of implantation in a rabbit femoral condyle model. This study has provided a new design and fabrication methodology of hybrid cages by integrating strong mechanical properties with excellent biological activities including osteoinductivity and bone regeneration ability, for spine fusion and segmental bone reconstruction.

Quality and Quantity of Published Studies Evaluating Lumbar Fusion during the Past 10 Years: A Systematic Review

Study Design Systematic review. Clinical Questions (1) Has the proportion and number of randomized controlled trials (RCTs) as an indicator of quality of evidence regarding lumbar fusion increased over the past 10 years? (2) Is there a difference in the proportion of RCTs among the four primary fusion diagnoses (degenerative disk disease, spondylolisthesis, deformity, and adjacent segment disease) over the past 10 years? (3) Is there a difference in the type and quality of clinical outcomes measures reported among RCTs over time? (4) Is there a difference in the type and quality of adverse events measures reported among RCTs over time? (5) Are there changes in fusion surgical approach and techniques over time by diagnosis over the past 10 years? Methods Electronic databases and reference lists of key articles were searched from January 1, 2004, through December 31, 2013, to identify lumbar fusion RCTs. Fusion studies designed specifically to evaluate recombinant human bone morphogenetic protein-2 or other bone substitutes, revision surgery studies, nonrandomized comparison studies, case reports, case series, and cost-effectiveness studies were excluded. Results Forty-two RCTs between January 1, 2004, and December 31, 2013, met the inclusion criteria and form the basis for this report. There were 35 RCTs identified evaluating patients diagnosed with degenerative disk disease, 4 RCTs evaluating patients diagnosed with degenerative spondylolisthesis, and 3 RCTs evaluating patients with a combination of degenerative disk disease and degenerative spondylolisthesis. No RCTs were identified evaluating patients with deformity or adjacent segment disease. Conclusions This structured review demonstrates that there has been an increase in the available clinical database of RCTs using patient-reported outcomes evaluating the benefit of lumbar spinal fusion for the diagnoses of degenerative disk disease and degenerative spondylolisthesis. Gaps remain in the standardization of reportage of adverse events in such trials, as well as uniformity of surgical approaches used. Finally, continued efforts to develop higher-quality data for other surgical indications for lumbar fusion, most notably in the presence of adult spinal deformity and revision of prior surgical fusions, appear warranted.

The need for structural allograft biomechanical guidelines

Because of their osteoconductive properties, structural bone allografts retain a theoretic advantage in biologic performance compared with artificial interbody fusion devices and endoprostheses. Present regulations have addressed the risks of disease transmission and tissue contamination, but comparatively few guidelines exist regarding donor eligibility and bone processing issues with a potential effect on the mechanical integrity of structural allograft bone. The lack of guidelines appears to have led to variation among allograft providers in terms of processing and donor screening regarding issues with recognized mechanical effects. Given the relative lack of data on which to base reasonable screening standards, we undertook basic biomechanical evaluation of one source of structural bone allograft, the femoral ring. Of our tested parameters, the minimum and maximum cortical wall thicknesses of femoral ring allograft were most strongly correlated with the axial compressive load to failure of the graft, suggesting that cortical wall thickness may be a useful screening tool for compressive resistance expected from fresh cortical bone allograft. Development of further biomechanical and clinical data to direct standard development appears warranted.

Application of titanium and polyetheretherketone cages in the treatment of pyogenic spondylodiscitis

OBJECTIVE

Surgical treatment of a pyogenic spondylodiscitis (PSD) involves a fixation and debridement of the affected segment combined with a specific antibiotic therapy. To achieve a proper stability and to avoid pseudarthrosis and kyphotic malposition many surgeons favour the interposition of an anterior graft. Besides autologous bone grafts titanium (TTN) cages have gained acceptance in the treatment of PSD. Polyetheretherketone (PEEK) cages have a more favourable modulus of elasticity than TTN. We compared both cage types. Primary endpoints were the rate of reinfection and radiological results.

METHODS

From 2004 to 2013 51 patients underwent surgery for PSD with fixation and TTN or PEEK cage-implantation. While lumbar patients underwent a partial discectomy by the posterior approach, discs of the cervical and thoracic patients had been totally removed from anterior. Clinical and radiological parameters were assessed in 37 eligible patients after a mean of 20.4 months. 21 patients received a PEEK- and 16 patients a TTN-cage.

RESULTS

A reinfection after surgery and 3 months of antibiotic therapy was not observed. Solid arthrodesis was found in 90.5% of the PEEK-group and 100% of the TTN-group. A segmental correction could be achieved in both groups. Nonetheless, a cage subsidence was observed in 70.3% of all cases. Comparison of radiological results revealed no differences between both groups.

CONCLUSIONS

A debridement and fixation with anterior column support in combination with an antibiotic therapy appear to be the key points for successful treatment of PSD. The application of TTN- or PEEK-cages does not appear to influence the radiological outcome or risk of reinfection, neither does the extent of disc removal in this clinical subset.

Bone mineral density and donor age are not predictive of femoral ring allograft bone mechanical strength

While metal or plastic interbody spinal fusion devices are manufactured to appropriate mechanical standards, mechanical properties of commercially prepared structural allograft bone remain relatively unassessed. Robust models predicting compressive load to failure of structural allograft bone based on easily measured variables would be useful. Three hundred twenty seven femoral rings from 34 cadaver femora were tested to failure in axial compression. Predictive variables included age, gender, bone mineral density (BMD), position along femoral shaft, maximum/minimum wall thickness, outer/inner diameter, and area. We used support vector regression and 10-fold cross-validation to develop robust nonlinear predictive models for load to failure. Model performance was measured by the root-mean-squared-deviation (RMSD) and correlation coefficients (r). A polynomial model using all variables had RMSD = 7.92, r = 0.84, indicating excellent performance. A model using all variables except BMD was essentially unchanged (RMSD = 8.12, r = 0.83). Eliminating both age and BMD produced a model with RMSD = 8.41, r = 0.82, again essentially unchanged. Compressive strength of structural allograft bone can be estimated using easily measured geometric parameters, without including BMD or age. As DEXA is costly and cumbersome, and setting upper age-limits for potential donors reduces the supply, our results may prove helpful to increase the quality and availability of structural allograft.

Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 3: assessment of economic outcome

A comprehensive economic analysis generally involves the calculation of indirect and direct health costs from a societal perspective as opposed to simply reporting costs from a hospital or payer perspective. Hospital charges for a surgical procedure must be converted to cost data when performing a cost-effectiveness analysis. Once cost data has been calculated, quality-adjusted life year data from a surgical treatment are calculated by using a preference-based health-related quality-of-life instrument such as the EQ-5D. A recent cost-utility analysis from a single study has demonstrated the long-term (over an 8-year time period) benefits of circumferential fusions over stand-alone posterolateral fusions. In addition, economic analysis from a single study has found that lumbar fusion for selected patients with low-back pain can be recommended from an economic perspective. Recent economic analysis, from a single study, finds that femoral ring allograft might be more cost-effective compared with a specific titanium cage when performing an anterior lumbar interbody fusion plus posterolateral fusion.

Incidence and outcome of graft resorption in anterior lumbar interbody fusion: using femoral ring allografts and recombinant human bone morphogenetic protein-2

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To determine the incidence of resorption after anterior lumbar interbody fusion (ALIF) and its effect on outcome.

SUMMARY OF BACKGROUND DATA

Recombinant human bone morphogenetic protein-2 (rhBMP-2) used in ALIF has been associated with a 0.5% to 82% incidence of resorption. This has been described as either a complication or part of the natural history. We postulate that early resorption (≤4 mo) in ALIF using femoral ring allograft augmented with rhBMP-2 supplemented with posterior instrumentation has no effect on outcome.

METHODS

Institutional review board-approved retrospective 60 chart cohort study of ALIF using femoral ring allograft-augmented rhBMP-2 supplemented with posterior instrumentation from May 5, 2005, to April 6, 2010. Two groups were based upon the presence or absence of early graft resorption (≤4 mo). Patients were seen prior to surgery and postoperatively until 29 ± 20 months (last visit). Follow-up visual analogue scale pain scores and radiographical evidence of fusion were measured and compared between the 2 groups.

RESULTS

Sixty patients, 27 females and 33 males had follow-up for 29 ± 20 months. Group 1 (33 patients, 45 levels) and group 2 (27 patients, 36 levels) were identical in age (P = 0.62), sex distribution (P = 0.43), preoperative pain score (P = 0.63), and in the rhBMP-2 dose per level (P = 0.77). There were no significant group differences in postoperative visual analogue scale scores but a trend to higher fusion rate in group 1 was seen (P = 0.07) at 6 months. There was a 40% incidence of early resorption with no significant differences in visual analogue scale scores or fusion rate between both groups.

CONCLUSION

There is a 40% incidence of early resorption (≤4 mo) that had no significant effect on pain score or fusion rate. Resorption should be considered part of the fusion process and not necessarily a complication.

LEVEL OF EVIDENCE

3.

Diagnostic criteria and treatment of discogenic pain: a systematic review of recent clinical literature

BACKGROUND CONTEXT

Pain innate to intervertebral disc, often referred to as discogenic pain, is suspected by some authors to be the major source of chronic low back and neck pain. Current management of suspected discogenic pain lacks standardized diagnosis, treatment, and terminology.

PURPOSE

In an attempt to determine whether patterns existed that may facilitate standardization of care, we sought to analyze the terminologies used and the various modes of diagnosis and treatment of suspected discogenic pain.

STUDY DESIGN

A systematic review of the recent literature.

METHODS

A Medline search was performed using the terms degenerative disc disease, discogenic pain, internal disc disruption while using the limits of human studies, English language, and clinical trials, for the last 10 years. The search led to a total of 149 distinct citations, of which 53 articles, where the intervertebral disc itself was considered the principal source of patient's pain and was the main target of the treatment, were retained for further analysis.

RESULTS

The results of this review confirm and help quantify the significant differences that existed in the terminology and all the areas of diagnosis and treatment of presumed discogenic pain.

CONCLUSIONS

Our findings show that suspected discogenic pain, despite its extensive affirmation in the literature and enormous resources regularly devoted to it, currently lacks clear diagnostic criteria and uniform treatment or terminology.

Twenty-year perspective of randomized controlled trials for surgery of chronic nonspecific low back pain: citation bias and tangential knowledge

BACKGROUND CONTEXT

After decades of clinical research, the role of surgery for chronic nonspecific low back pain (CNLBP) remains equivocal. Despite significant intellectual, human, and economic investments into randomized controlled trials (RCTs) in the past two decades, the role of surgery in the treatment for CNLBP has not been clarified.

PURPOSE

To delineate the historical research agenda of surgical RCTs for CNLBP performed between 1993 and 2012 investigating whether conclusions from earlier published trials influenced the choice of research questions of subsequent RCTs on elucidating the role of surgery in the management of CNLBP.

STUDY DESIGN

Literature review.

METHODS

We searched the literature for all RCTs involving surgery for CNLBP. We reviewed relevant studies to identify the study question, comparator arms, and sample size. Randomized controlled trials were classified as "indication" trials if they evaluated the effectiveness of surgical therapy versus nonoperative care or as "technical" if they compared different surgical techniques, adjuncts, or procedures. We used citation analysis to determine the impact of trials on subsequent research in the field.

RESULTS

Altogether 33 technical RCTs (3,790 patients) and 6 indication RCTs (981 patients) have been performed. Since 2007, despite the unclear benefits of surgery reported by the first four indication trials published in 2001 to 2006, technical trials have continued to predominate (16 vs. 2). Of the technical trials, types of instrumentation (13 trials, 1,332 patients), bone graft materials and substitutes (11 trials, 833 patients), and disc arthroplasty versus fusion (5 trials, 1,337 patients) were the most common comparisons made. Surgeon authors have predominantly cited one of the indication trials that reported more favorable results for surgery, despite a lack of superior methodology or sample size. Trials evaluating bone morphogenic protein, instrumentation, and disc arthroplasty were all cited more frequently than the largest trial of surgical versus nonsurgical therapy.

CONCLUSIONS

The research agenda of RCTs for surgery of CNLBP has not changed substantially in the last 20 years. Technical trials evaluating nuances of surgical techniques significantly predominate. Despite the publication of four RCTs reporting equivocal benefits of surgery for CNLBP between 2001 and 2006, there was no change in the research agenda of subsequent RCTs, and technical trials continued to outnumber indication trials. Rather than clarifying what, if any, indications for surgery exist, investigators in the field continue to analyze variations in surgical technique, which will probably have relatively little impact on patient outcomes. As a result, clinicians unfortunately have little evidence to advise patients regarding surgical intervention for CNLBP.

Two-Level Circumferential Lumbar Fusion Comparing Midline and Paraspinal Posterior Approach: 5-Year Interim Outcomes of a Randomized, Blinded, Prospective Study

STUDY DESIGN

A prospective randomized and blinded comparative study of 2 patient groups with >5-year follow-up.

OBJECTIVE

To compare the clinical outcomes and postoperative posterior muscle changes in patients with advanced degenerative disk disease undergoing 2-level circumferential spinal fusion using a posterior midline versus a paraspinal approach.

SUMMARY OF BACKGROUND DATA

Lumbar spinal fusion is often performed using a circumferential (anterior and posterior) technique. Paraspinal muscle alterations occur during the retraction of the muscles required for posterior instrumentation and fusion bed preparation, which may adversely affect outcomes.

METHODS

Patients with advanced 2-level lumbar degenerative disk disease were randomized into 2 groups of 25 each for the approach to the posterior spine for their anterior-posterior fusion. A midline posterior skin incision was universal, but all patients were blinded to the fascial incision and exposure to the posterior spine. All had intertransverse and facet joint fusions with pedicle screw instrumentation. Outcomes (visual analog back and leg pain scale, pain drawing, Oswestry disability index, and self-assessment of procedure success) were assessed at various periods postoperatively. Preoperative and >1-year postoperative magnetic resonance images (MRI), including paraspinal muscles, were read by a radiologist who was blinded to the surgical approach and outcomes.

RESULTS

No difference in operative time, blood loss, implant costs, or any other intraoperative parameter existed between the 2 patient groups. Although clinical improvement for all outcome scales was significant for both groups postoperatively, there was no difference between groups. Postoperative MRI T2 relaxation values were significantly increased at the operative levels and distally, but the changes were similar for both groups.

CONCLUSIONS

Midline and paraspinal approaches result in similar outcomes in 2-level spinal fusions. We were unable to demonstrate that a paraspinal muscle-splitting approach to 2-level fusion was superior to the muscle-stripping midline approach. However, the study has low statistical power.

Fresh-frozen femoral head allograft as lumbar interbody graft material allows high fusion rate without subsidence

BACKGROUND

Circumferential lumbar spinal fusion is widely used to increase fusion rate, but little data is available using fresh-frozen femoral head allograft (FFFHA) as a structural interbody graft alternative.

HYPOTHESIS

Circumferential lumbar arthrodesis using FFFHA as interbody graft material could be an alternative to achieve interbody fusion without graft subsidence.

METHODS

A retrospective review of 47 patients (56 levels) treated with lumbar circumferential fusion using FFFHA as interbody material. Consolidation was independently assessed by the two authors using a 3-type scale; interbody bone graft subsidence was also evaluated.

RESULTS

Forty-four of the 47 patients (93.6%), and 53 of the 56 levels (94.6%) obtained consolidation, without differences between smokers and nonsmokers. Three levels (in three patients) did not fuse; one of them (2.1%) required revision. No patient presented graft dislodgment, signs of infection or graft subsidence at the last follow-up.

DISCUSSION

FFFHA use as lumbar interbody graft in circumferential arthrodesis exhibited a 94% fusion rate, without graft subsidence. FFFHA may be considered a valid alternative to achieve interbody fusion.

LEVEL OF EVIDENCE

Level IV. Retrospective study.

Lumbar spine fusion for chronic low back pain due to degenerative disc disease: a systematic review

STUDY DESIGN

Systematic literature review.

OBJECTIVE

To categorize published evidence systematically for lumbar fusion for chronic low back pain (LBP) in order to provide an updated and comprehensive analysis of the clinical outcomes.

SUMMARY OF BACKGROUND DATA

Despite a large number of publications of outcomes of spinal fusion surgery for chronic LBP, there is little consensus on efficacy.

METHODS

A MEDLINE and Cochrane database search was performed to identify published articles reporting on validated patient-reported clinical outcomes measures (2 or more of visual analogue scale, Oswestry Disability Index, Short Form [36] Health Survey [SF-36] PCS, and patient satisfaction) with minimum 12 months of follow-up after lumbar fusion surgery in adult patients with LBP due to degenerative disc disease. Twenty-six total articles were identified and stratified by level of evidence: 18 level 1 (6 studies of surgery vs. nonoperative treatment, 12 studies of alternative surgical procedures), 2 level 2, 2 level 3, and 4 level 4 (2 prospective, 2 retrospective). Weighted averages of each outcomes measure were computed and compared with established minimal clinically important difference values.

RESULTS

Fusion cohorts included a total of 3060 patients. The weighted average improvement in visual analogue scale back pain was 36.8/100 (standard deviation [SD], 14.8); in Oswestry Disability Index 22.2 (SD, 14.1); in SF-36 Physical Component Scale 12.5 (SD, 4.3). Patient satisfaction averaged 71.1% (SD, 5.2%) across studies. Radiographical fusion rates averaged 89.1% (SD, 13.5%), and reoperation rates 12.5% (SD, 12.4%) overall, 9.2% (SD, 7.5%) at the index level. The results of the collective studies did not differ statistically in any of the outcome measures based on level of evidence (analysis of variance, P > 0.05).

CONCLUSION

The body of literature supports fusion surgery as a viable treatment option for reducing pain and improving function in patients with chronic LBP refractory to nonsurgical care when a diagnosis of disc degeneration can be made.

Anterior cervical discectomy and fusion: comparison of titanium and polyetheretherketone cages

BACKGROUND

Titanium (TTN) cages have a higher modulus of elasticity when compared with polyetheretherketone (PEEK) cages. This suggests that TTN-cages could show more frequent cage subsidence after anterior cervical discectomy and fusion (ACDF) and therefore might lead to a higher loss of correction. We compared the long term results of stand-alone PEEK- and TTN-cages in a comparable patient collective that was operated under identical operative settings.

METHODS

From 2002 to 2007 154 patients underwent single-level ACDF for degenerative disc disease (DDD). Clinical and radiological outcome were assessed in 86 eligible patients after a mean of 28.4 months. 44 patients received a TTN- and 42 patients a PEEK-cage.

RESULTS

Solid arthrodesis was found in 93.2% of the TTN-group and 88.1% of the PEEK-group. Cage subsidence was observed in 20.5% of the TTN- and 14.3% of the PEEK-group. A significant segmental lordotic correction was achieved by both cage-types. Even though a loss of correction was found at the last follow-up in both groups, it did not reach the level of statistical significance. Statistical analysis of these results revealed no differences between the TTN- and PEEK-group.When assessed with the neck disability index (NDI), the visual analogue scale (VAS) of neck and arm pain and Odom's criteria the clinical data showed no significant differences between the groups.

CONCLUSIONS

Clinical and radiological outcomes of ACDF with TTN- or PEEK-cages do not appear to be influenced by the chosen synthetic graft. The modulus of elasticity represents only one of many physical properties of a cage. Design, shape, size, surface architecture of a cage as well as bone density, endplate preparation and applied distraction during surgery need to be considered as further important factors.

The Memory Metal Spinal System in a Posterior Lumbar Interbody Fusion (PLIF) Procedure: A Prospective, Non-Comparative Study to Evaluate the Safety and Performance

Study Design:

A prospective, non-comparative study of 27 patients to evaluate the safety and performance of the Memory Metal Spinal System used in a PLIF procedure in the treatment of spondylolisthesis, symptomatic spinal stenosis or degenerative disc disease (DDD).

Objective:

To evaluate the clinical performance, radiological outcome and safety of the Memory Metal Spinal System, used in a PLIF procedure, in the treatment of spondylolisthesis, symptomatic spinal stenosis or degenerative disc disease in human subjects.

Summary of Background Data:

Spinal systems that are currently available for correction of spinal deformities or degeneration such as lumbar spondylosis or degenerative disc disease, use components manufactured from stainless steel or titanium and typically comprise two spinal rods with associated connection devices. The Memory Metal Spinal System consists of a single square spinal rod made from a nickel titanium alloy (Nitinol) used in conjunction with connection devices. Nitinol is characterized by its shape memory effect and is a more flexible material than either stainless steel or titanium. With current systems there is loss of achieved reposition due to the elastic properties of the spine. By using a memory metal in this new system the expectation was that this loss of reposition would be overcome due to the metal’s inherent shape memory properties. Furthermore, we expect a higher fusion rate because of the elastic properties of the memory metal.

Methods:

Twenty-seven subjects with primary diagnosis of spondylolisthesis, symptomatic spinal stenosis or degenerative disc disease (DDD) were treated with the Memory Metal Spinal System in conjunction with the Brantigan IF® Cage in two consecutive years. Clinical performance of the device was evaluated over 2 years using the Oswestry Disability Index (ODI), Short Form 36 questionnaire (SF-36) and pain visual analogue scale (VAS) scores. Safety was studied by collection of adverse events intra-operative and during the followup. Interbody fusion status was assessed using radiographs and a CT scan.

Results:

The mean pre-operative ODI score of 40.9 (±14.52) significantly improved to 17.7 (±16.76) at 24 months postoperative. Significant improvement in the physical component from the SF36 questionnaire was observed with increases from the baseline result of 42.4 to 72.7 at 24 months (p<.0001); The emotional component in the SF36 questionnaires mean scores highlighted a borderline significant increase from 56.5 to 81.7 at 24 months (p=0.0441). The average level of leg pain was reduced by more than 50% postoperation (VAS values reduced from 5.7 (±2.45) to 2.2 (±2.76) at 24 month post-operation with similar results observed for back pain. CT indicated interbody fusion rate was not significantly faster compared to other devices in literature. No device related adverse events were recorded in this study.

Conclusions:

The Memory Metal Spinal System, different from other devices on the market with regard to material and the one rod configuration, is safe and performed very well by improving clinically important outcomes in the treatment of spondylolisthesis, symptomatic spinal stenosis or degenerative disc disease. In addition the data compares favorably to that previously reported for other devices in the literature.

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.

Factors affecting clinical outcomes in treating patients with grade 1 degenerative spondylolisthesis using interspinous soft stabilization with a tension band system: a minimum 5-year follow-up

STUDY DESIGN

Retrospective clinical study.

OBJECTIVE

To explore the factors influencing the clinical outcomes and motion-preserving stabilization after interspinous soft stabilization (ISS) with a tension band system for grade 1 degenerative spondylolisthesis (DS).

SUMMARY OF BACKGROUND DATA

Despite increasing recognition of the benefits of dynamic stabilization systems for treating lumbar degenerative disorders, the factors affecting the clinical and radiological outcomes of these systems have rarely been identified.

METHODS

Sixty-five patients (mean age, 60.3 years) who underwent ISS with a tension band system between 2002 and 2004 were analyzed. The mean follow-up period was 72.5 months. The patients were divided according to the postsurgical clinical improvements into the optimal (n = 44) and suboptimal groups (n = 21), and the radiological intergroup differences were analyzed. Multiple linear regression analysis was performed to determine the impact of the radiological factors on the clinical outcomes.

RESULTS

Significant intergroup differences were observed on the follow-up clinical examination. Radiologically, total lumbar lordosis (TLL) and segmental lumbar lordosis (SLL) were significantly improved only in the optimal group, resulting in significant intergroup differences in TLL (P = 0.023), SLL (P = 0.001), and the L1 tilt (P = 0.002). All these measures were closely associated with postoperative segmental lumbar lordosis, which also was the most influential radiological variable for the clinical parameters.

CONCLUSION

In the patients with grade 1 DS, the back pain relief and functional improvement following ISS were affected by the improvements in the sagittal spinal alignment through the achievement of segmental lumbar lordosis. ISS can be an alternative treatment to fusion surgery for grade 1 DS in patients who do not require fixation or reduction.

Relationship of donor variables and graft dimension on biomechanical performance of femoral ring allograft

Structural femoral ring allograft is commonly used in interbody spinal arthrodesis. Fractures of implanted femoral ring allograft have been reported. Data to guide donor screening and tissue processing by allograft tissue banks for factors that affect graft strength are incomplete. Fresh frozen human femora from 34 cadaveric donors were sectioned into ten 20-mm thick specimens. Bone mineral density (BMD), donor age, and graft dimensions were recorded for each specimen. Three hundred twenty-seven specimens were tested in quasi-static axial compression. Linear regression models compared load to failure with BMD, sex-specific donor age, minimum/maximum cortical wall thickness, and minimum/maximum outer ring diameter. Correlations between minimum and maximum cortical wall thickness and load to failure were significant (r = 0.73, p < 0.001 and r = 0.74, p < 0.001, respectively). BMD showed a weaker negative correlation with load to failure (r = -0.11, p = 0.05). Correlations between load to failure and minimum and maximum outer ring diameter and age (r = 0.06, p = 0.31) were not significant. We found that the minimum and maximum cortical wall thicknesses of femoral ring allograft are strongly correlated with the axial compressive load to failure of the graft. Other tested parameters did not prove to be effective predictors of resistance to axial loading.

Evaluating the correlation and responsiveness of patient-reported pain with function and quality-of-life outcomes after spine surgery

STUDY DESIGN

Systematic review.

OBJECTIVE

To determine the correlation of patient-reported pain with physical function and health-related quality of life (HRQoL) after spine surgery and to determine the responsiveness of pain, physical function, and HRQoL after spine surgery.

SUMMARY OF BACKGROUND DATA

Several validated outcome instruments are available to assess the success of treatment for chronic low back pain. These patient-centered tools include measurements for pain based on numeric scales, validated condition-specific functional outcomes measures, and HRQoL outcomes measures. It is unclear whether these three types of patient-reported outcomes are measuring different constructs and whether all three should be measured after spine surgery. In addition, it is unclear which of these outcomes measures is most sensitive to change after spine surgery for low back pain.

METHODS

A systematic search was conducted in MEDLINE, EMBASE, and the Cochrane Collaboration Library for literature published through December 2010. The correlation between pain (visual analog scale, VAS), physical function (Oswestry Disability Index, ODI), and HRQoL (36-Item Short Form Health Survey [SF-36] and European Quality of Life [EQ-5D]) change scores was performed using the Spearman rank correlation coefficients. To compare the responsiveness of pain, function, and HRQoL scores after spine surgery, we calculated effect sizes by dividing change scores by the SD of the baseline scores. This standardized method allowed us to compare the responsiveness of each outcome measure directly and reported an effect size of 0.2 to 0.3 as a "small" effect, around 0.5 a "medium" effect and 0.8 to infinity, a "large" effect. To determine whether the differences in effect sizes measuring responsiveness were significantly different, we conducted a Wilcoxon signed-rank test between each of the three measurements of pain, function, and HRQoL scores when there was enough data to perform the test.

RESULTS

None of the correlations exceeded 0.70 using the Spearman rank correlation coefficients, suggesting that these outcomes are measuring different constructs. The strongest correlations were between the VAS back pain change scores and the SF-36 physical composite score change scores (ρ = 0.67) and VAS back pain change scores and ODI change scores (ρ = 0.69). The pooled mean effect sizes for the five studies that reported a pain measure and the ODI were 1.4 ± 0.57 and 1.1 ± 0.39, respectively. Both are considered "large" effect sizes. The pooled mean effect sizes for the three studies reporting the SF-36 physical and mental composite scores were 0.66 ± 0.39 and 0.54 ± 0.36, respectively. Both are considered "medium" effect sizes. The pooled mean effect sizes for the single studies reporting the EQ-5D and SF-36 total score were 0.78 ± 0.12 and 0.34 ± 0.21. These were "medium" and "small," respectively.

CONCLUSION

We observed little correlation between the change in pain and the change in HRQoL outcomes measures. The strongest correlation was between VAS pain and ODI but was still not considered strong (0.69). These findings suggest that these three outcomes (pain, function, and HRQoL) are measuring different constructs. With respect to responsiveness, VAS pain and ODI were the only outcomes measures that demonstrated a large effect after lumbar spine surgery. None of the HRQoL tools were as sensitive to the treatment. The EQ-5D, SF physical composite, and SF mental composite outcomes demonstrated a medium effect, while the SF-36 total score demonstrated a small effect. The responsive measure shows that the more specific the outcomes tool, the more sensitive the response.

CLINICAL RECOMMENDATIONS

Recommendation 1: When surgically treating CLBP, we recommend administering both a VAS for pain and a condition-specific physical measure such as the ODI before and after surgical intervention as these outcomes are the most treatment specific and responsive to change. Strength of recommendation: Strong.Recommendation 2: When evaluating the surgical outcomes for CLBP in the clinical-research setting, we recommend selecting a shorter version for measuring general HRQoL (e.g., SF-12, EQ-5D) to minimize clinician and patient burden. Strength of recommendation: Strong.

Intervertebral disc properties: challenges for biodevices

Intervertebral disc biodevices that employ motion-preservation strategies (e.g., nucleus replacement, total disc replacement and posterior stabilization devices) are currently in use or in development. However, their long-term performance is unknown and only a small number of randomized controlled trials have been conducted. In this article, we discuss the following biodevices: interbody cages, nuclear pulposus replacements, total disc replacements and posterior dynamic stabilization devices, as well as future biological treatments. These biodevices restore some function to the motion segment; however, contrary to expectations, the risk of adjacent-level degeneration does not appear to have been reduced. The short-term challenge is to replicate the complex biomechanical function of the motion segment (e.g., biphasic, viscoelastic behavior and nonlinearity) to improve the quality of motion and minimize adjacent level problems, while ensuring biodevice longevity for the younger, more active patient. Biological strategies for regeneration and repair of disc tissue are being developed and these offer exciting opportunities (and challenges) for the longer term. Responsible introduction and rigorous assessment of these new technologies are required. In this article, we will describe the properties of the disc, explore biodevices currently in use for the surgical treatment of low back pain (with an emphasis on lumbar total disc replacement) and discuss future directions for biological treatments. Finally, we will assess the challenges ahead for the next generation of biodevices designed to replace the disc.

Anterior interbody arthrodesis with percutaneous posterior pedicle fixation for degenerative conditions of the lumbar spine

This is a retrospective case series to evaluate clinical variables, complications and outcome of 50 patients who underwent anterior lumbar interbody fusion (ALIF) supplemented with posterior percutaneous pedicle screw fixation for degenerative conditions of the lumbar spine. Twenty-four patients underwent single-level fusion and 26 patients had a two-level fusion for a total of 76 levels fused. The mean lengths of the anterior and posterior (including repositioning) portions of the procedure were 131 and 102 min, respectively. The mean estimated blood loss for the entire procedure was 288 ml. The overall adverse event rate was 12%. The mean VAS score for leg pain, VAS score for back pain and mean ODI all improved postoperatively. This study found that ALIF using allograft bone and rhBMP-2 combined with percutaneous pedicle screw fixation had a high fusion rate and a low incidence of perioperative complications. Patient outcomes showed significant improvements in back and leg pain and physical functioning.

Health-related quality of life improvements in patients undergoing lumbar spinal fusion as a revision surgery

STUDY DESIGN

Retrospective cohort analysis.

OBJECTIVE

To investigate health-related quality of life improvements in patients undergoing lumbar fusion to revise a previous lumbar spine surgery.

SUMMARY OF BACKGROUND DATA

Spinal fusion is often used as a surgical intervention in patients who have previously undergone lumbar surgery. Prior studies suggest results that are inferiorto primary fusions. However, most of these studies are based on subjective surgeon evaluations, lack patient-reported outcomes, and include various diagnoses such as prior discectomy, adjacent level degeneration, and nonunion.

METHODS

From a single-center database, we identified 171 patients who underwent lumbar fusion to revise a previous lumbar spine surgery. All had prospectively collected outcome measures at a minimum 2-year follow-up. The study group included 91 patients who had previous discectomy or laminectomy, 42 patients undergoing revision for adjacent segment degeneration (ASD) and 38 patients undergoing revision for nonunion. All patients completed the Oswestry Disability Index (ODI), MOS Short Form 36 (SF-36), and back and leg pain numerical rating scores before surgery and at 1 and 2 years after surgery. We compared mean changes in outcome measures and percentage of patients reaching the minimum clinically important difference (MCID) threshold in the 3 groups. Logistic regression analysis was performed to identify preoperative factors which could predict significant improvement.

RESULTS

Statistically significant improvements were noted in back pain, leg pain, and ODI in all 3 groups. Postdecompression and ASD patients demonstrated significant improvements in SF-36 PCS at 2 years, while nonunion patients did not. A total of 49% of postdecompression patients, 38% of ASD patients, and 29% of nonunion patients reached the MCID for ODI. About 46% of postdecompression patients, 40% of ASD patients, and 24% of nonunion patients reached the MCID for SF-36 PCS. Significant improvement from index surgery was the only factor which able to predict reaching the MCID for ODI, while worker's compensation and narcotic use predicted failure to reach the MCID for SF-36 PCS.

CONCLUSION

The current study demonstrates that patients undergoing lumbar fusion as a revision of a prior lumbar surgery can expect only modest improvements in health-related quality of life. Postdecompression patients achieved moderate improvements in clinical outcome measures, whereas ASD and nonunion patients showed only modest improvements. Further investigation is needed to identify preoperative predictors that will assist the selection of patients who will benefit from revision lumbar fusion.

Complications and concerns with osteobiologics for spine fusion in clinical practice

STUDY DESIGN

Literature-based topic review.

OBJECTIVE

To review the complications and the concerns that may be associated with all of the commonly used osteobiologic options for spine fusion.

SUMMARY OF BACKGROUND DATA

Obtaining a solid arthrodesis is an important objective in many lumbar surgical procedures, and a wide array of bone graft materials may be used in an attempt to achieve this goal. Iliac crest bone graft, as well as all of the available osteobiologic alternatives, carries potential risks and concerns for both patient and surgeon.

METHODS

Review of literature and expert opinion.

CONCLUSION

Some of the potential complications associated with osteobiologic materials used in spinal fusion are well understood and clearly documented whereas others require further study and clarification. In any given clinical situation, the patient and surgeon need to balance the benefits and performance characteristics of the graft material with the risk profile to optimize clinical management.

Enhancing allograft bone healing through gene therapy

STUDY DESIGN

A review and synopsis of recent literature pertinent to allograft bone healing.

OBJECTIVE

To review the basic principles and primary issues regarding the healing of allograft bone. To review progress made in understanding the molecular mechanisms of healing, and efforts being made to manipulate these processes to enhance healing.

SUMMARY OF BACKGROUND DATA

Bone grafting with both autografts and allografts is a common reconstructive procedure. Failure to heal and catastrophic failure of seemingly healed structural grafts occur. There is currently a great deal of excitement about the potential of bone marrow-derived cells to enhance healing. Gene transfer techniques have been developed which allow the insertion of desired deoxyribonucleic acid-encoded messages into cells. Such messages can result in the production of therapeutic proteins. Gene therapy has been used to enhance the healing of allografts in a murine model.

METHODS

Literature review.

RESULTS

Autografts heal by endochondral ossification at the graft-host interface and by intramembranous bone formation over the surface of the graft. Allografts heal predominately by endochondral ossification at the graft-host interface. The living periosteum of a graft contains progenitor cells that have an important role in graft healing. The addition of bone marrow-derived cells to an allograft does not improve healing unless they are genetically modified to express bone morphogenetic protein 2. Gene therapy to induce expression of several other proteins (VEGF and RANKL, caALK2) can also result in markedly improved allograft healing.

CONCLUSION

Gene therapy techniques can create revitalized allografts in a mouse model. These revitalized grafts heal faster, more completely, more durably, and stronger than allografts.

Interbody device endplate engagement effects on motion segment biomechanics

BACKGROUND CONTEXT

Stand-alone nonbiologic interbody fusion devices for the lumbar spine have been used for interbody fusion since the early 1990s. However, most devices lack the stability found in clinically successful circumferential fusion constructs. Stability results from cage geometry and device/vertebral endplate interface integrity. To date, there has not been a published comparative biomechanical study specifically evaluating the effects of endplate engagement of interbody devices.

PURPOSE

Lumbar motion segments implanted with three different interbody devices were tested biomechanically to compare the effects of endplate engagement on motion segment rigidity. The degree of additional effect of supplemental posterior and anterior fixation was also investigated.

STUDY DESIGN/SETTING

A cadaveric study of interbody fusion devices with varying degrees of endplate interdigitation.

OUTCOME MEASURES

Implanted motion segment range of motion (ROM), neutral zone (NZ), stiffness, and disc height.

METHODS

Eighteen human L23 and L45 motion segments were distributed into three interbody groups (n=6 each) receiving a polymeric (polyetheretherketone) interbody spacer with small ridges; a modular interbody device with endplate spikes (InFix, Abbott Spine, Austin, TX, USA); or dual tapered threaded interbody cages (LT [Lordotic tapered] cage; Medtronic, Memphis, TN, USA). Specimens were tested intact using a 7.5-Nm flexion-extension, lateral bending, and axial torsion flexibility protocol. Testing was repeated after implantation of the interbody device, anterior plate fixation, and posterior interpedicular fixation. Radiographic measurements determined changes in disc height and intervertebral lordosis. ROM and NZ were calculated and compared using analysis of variance.

RESULTS

The interbody cages with endplate spikes or threads provided a statistically greater increase in disc height versus the polymer spacer (p=.01). Relative to intact, all stand-alone devices significantly reduced ROM in lateral bending by a mean 37% to 61% (p< or =.001). The cages with endplate spikes or threads reduced ROM by approximately 50% and NZ by approximately 60% in flexion-extension (p< or =.02). Only the cage with endplate spikes provided a statistically significant reduction in axial torsion ROM compared with the intact state (50% decrease, p<.001). Posterior fixation provided a significant reduction in ROM in all directions versus the interbody device alone (p<.001). Anterior plating decreased ROM over interbody device alone in flexion-extension and torsion but did not have additional effect on lateral bending ROM.

CONCLUSION

The cages with endplate spikes or threads provide substantial motion segment rigidity compared with intact in bending modes. Only the cages with endplate spikes were more rigid than intact in torsion. All devices experienced increased rigidity with anterior plating and even greater rigidity with posterior fixation. It appears that the endplate engagement with spikes may be beneficial in limiting torsion, which is generally difficult with other "stand-alone" devices tested in the current and prior reports.

The contribution of RCTs to quality management and their feasibility in practice

The randomized controlled trial (RCT) is generally accepted as the most reliable method of conducting clinical research. To obtain an unbiased evaluation of the effectiveness of spine surgery, patients should be randomly assigned to either new or standard treatment. The aim of the present article is to provide a short overview of the advantages and challenges of RCTs and to present a summary of the conclusions of the Cochrane Reviews in spine surgery and later published trials in order to evaluate their contribution to quality management and feasibility in practice. From the searches, 130 RCTs were included, 95 from Cochrane Reviews and systematic reviews, and 35 from additional search. No study comparing surgery with sham surgery was identified. The first RCT in spine surgery was published in 1974 and compared debridement and ambulatory treatment in tuberculosis of the spine. The contribution of RCTs in spinal surgery has markedly increased over the last 10 years, which indicates that RCTs are feasible in this field. The results demonstrate missing quality specifications. Despite the number of published trials there is conflicting or limited evidence to support various techniques of instrumentation. The only intervention that receives strong evidence is discectomy for faster relief in carefully selected patients due to lumbar disc prolapse with sciatica. For future trials, authors, referees, and editors are recommended to follow the CONSORT statement. RCTs provide evidence to support clinical opinions before implementation of new techniques, but the individual clinical experience is still important for the doctor who has to face the patient.

Fusion and nonsurgical treatment for symptomatic lumbar degenerative disease: a systematic review of Oswestry Disability Index and MOS Short Form-36 outcomes

BACKGROUND CONTEXT

Although numerous studies have been published, controversy still exists regarding fusion and nonsurgical treatment for symptomatic degenerative lumbar spine conditions. Definite conclusions are difficult to draw because of differences in patient inclusion criteria, fusion technique, nonoperative treatment regimen, and clinical outcome measures used to determine success.

PURPOSE

The objective of this study was to evaluate lumbar fusion and nonsurgical interventions for various degenerative spine disorders using the Oswestry Disability Index (ODI) as a primary outcome measure in a systematic review. A secondary objective was to determine whether there is a difference in clinical outcomes based on the specific diagnosis.

STUDY DESIGN/SETTING

Systematic review.

PATIENT SAMPLE

Patients with low back pain of at least 12 weeks duration and older than 18 years, with prospectively collected ODI scores and at least a 12-month follow-up.

OUTCOME MEASURES

ODI and Short Form-36 (SF-36).

METHODS

A MEDLINE, HealthSTAR, CINAHL, and Cochrane database search was done using the search strategy recommended by the Cochrane Back Review Group. Proceedings from annual meetings of various spine societies and reference lists from review articles and retrieved articles were evaluated for possible inclusion. Criteria for inclusion were prospective randomized clinical trials in patients with low back pain of at least 12 weeks duration and older than 18 years; with prospectively collected ODI scores and at least a 12-month follow-up. The methodological quality of the studies was assessed using the van Tulder criteria. Data extracted from each study included demographics, study design, diagnosis, baseline and change in ODI, and baseline and change in SF-36 Physical Composite Score (PCS). The data were pooled and analyzed based on the primary reported inclusion diagnosis: degenerative disc disease (DDD), chronic low back pain (CLBP), and spondylolisthesis; and treatment: fusion (unspecified, posterior, anterior, combined) and nonsurgical.

RESULTS

Twenty-five studies met the inclusion criteria. The distribution of sex and smokers was similar across diagnoses and treatments. Patients with spondylolisthesis were older than patients with DDD and CLBP. Patients with spondylolisthesis had the greatest ODI improvement followed by patients with DDD and CLBP. The three fusion types produced similar amounts of improvement in ODI. Nonsurgical patients did not improve as much but had a lower baseline ODI. Improvements in the SF-36 PCS were fairly consistent across diagnostic groups and treatment types.

CONCLUSIONS

Substantial improvement can be expected in patients treated with fusion, regardless of technique, when an established indication such as spondylolisthesis or DDD exists. CLBP patients are less disabled and experience less improvement.

The myth of lumbar instability: the importance of abnormal loading as a cause of low back pain

Spinal fusion became what has been termed the "gold standard" for the treatment of mechanical low back pain, yet there was no scientific basis for this. Operations of fusion for low back pain were initially done at the beginning of the last century for back pain thought to be related to congenital abnormalities or for past spinal infection. The recognition of the disc as a cause of sciatica, commonly associated with back pain, and the recognition that a degenerate disc led to abnormal movement suggested the concept that this abnormal movement was the cause of pain, and this abnormal movement came to be called "instability". Much biomechanical expertise confirmed the fact that degenerate discs led to abnormal movement, there were many hypothesis as to why this caused pain. However clinical results of fusion for back pain were unpredictable. The failure of pedicle screws and cage fusion to improve the clinical results of fusion despite near 100% fusion success, and the introduction of "flexible stabilization" and artificial discs, which demonstrated that despite the often unpredictable movement permitted by of these devices, clinical success was similar to fusion, directed attention to the other role of the disc, that of load transfer, which these devices also affected. Abnormal load transfer was already known to be critical in other joints in the body and had led to the use of osteotomy to realign joints. The relevance of load transfer to the future design of spinal implants used in the treatment of low back pain is discussed, and some finite element studies are reported demonstrating the likely effect of abnormal loading beneath an incompletely incorporated plate of an artificial disc, perhaps explaining in part the somewhat disappointing clinical results to date of the implantation of artificial discs.

ISSLS prize winner: cost-effectiveness of two forms of circumferential lumbar fusion: a prospective randomized controlled trial

STUDY DESIGN

Economic evaluation alongside a prospective, randomized controlled trial from a secondary care National Health Service (NHS) perspective.

OBJECTIVE

To determine the cost-effectiveness of titanium cages (TC) compared with femoral ring allografts (FRA) in circumferential lumbar spinal fusion.

SUMMARY OF BACKGROUND DATA

A randomized controlled trial has shown the use of TC to be clinically inferior to the established practice of using FRA in circumferential lumbar fusion. Health economic evaluation is urgently needed to justify the continued use of TC, given that this treatment is less effective and, all things being equal, is assumed more costly than FRA.

METHODS

Eighty-three patients were randomly allocated to receive either the TC or FRA as part of a circumferential lumbar fusion between 1998 and 2002. NHS costs related to the surgery and revision surgery needed during the trial period were monitored and adjusted to the base year (2005-2006 Pounds Sterling). The Short Form-6D (SF-6D) was administered before surgery and at 6, 12 and 24 months in order to elicit patient utility and subsequently Quality-Adjusted Life Years (QALYs) for the trial period. Return to paid employment was also monitored. Bootstrapped mean differences in discounted costs and benefits were generated in order to explore cost-effectiveness.

RESULTS

A significant cost difference of pound 1950 (95% CI, pound 849 to pound 3145) in favor of FRA was found. Mean QALYs per patient over the 24-month trial period were 0.0522 (SD, 0.0326) in the TC group and 0.1914 (SD, 0.0398) in the FRA group, producing a significant difference of -0.1392 (95% CI, -0.2349 to -0.0436). With regard to employment, incremental productivity costs were estimated at pound 185,171 in favor of FRA.

CONCLUSION

From an NHS perspective, the trial data show that TC is not cost-effective in circumferential lumbar fusion. The use of FRA was both cheaper and generated greater QALY gains. In addition, FRA patients reported a greater return to work rate.

Surgery for degenerative lumbar spondylosis

BACKGROUND

Surgical investigations and interventions account for large health care utilisation and costs, but the scientific evidence for most procedures is still limited.

OBJECTIVES

Degenerative conditions affecting the lumbar spine are variously described as lumbar spondylosis or degenerative disc disease (which we regarded as one entity) and may be associated with back pain and associated leg symptoms, instability, spinal stenosis and/or degenerative spondylolisthesis. The objective of this review was to assess current scientific evidence on the effectiveness of surgical interventions for degenerative lumbar spondylosis.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, PubMed, Spine and ISSLS abstracts, with citation tracking from the retrieved articles. We also corresponded with experts. All data found up to 31 March 2005 are included.

SELECTION CRITERIA

Randomised (RCTs) or quasi-randomised trials of surgical treatment of lumbar spondylosis.

DATA COLLECTION AND ANALYSIS

Two authors assessed trial quality and extracted data from published papers. Additional information was sought from the authors if necessary.

MAIN RESULTS

Thirty-one published RCTs of all forms of surgical treatment for degenerative lumbar spondylosis were identified. The trials varied in quality: only the more recent trials used appropriate methods of randomization, blinding and independent assessment of outcome. Most of the earlier published results were of technical surgical outcomes with some crude ratings of clinical outcome. More of the recent trials also reported patient-centered outcomes of pain or disability, but there is still very little information on occupational outcomes. There was a particular lack of long term outcomes beyond two to three years. Seven heterogeneous trials on spondylolisthesis, spinal stenosis and nerve compression permitted limited conclusions. Two new trials on the effectiveness of fusion showed conflicting results. One showed that fusion gave better clinical outcomes than conventional physiotherapy, while the other showed that fusion was no better than a modern exercise and rehabilitation programme. Eight trials showed that instrumented fusion produced a higher fusion rate (though that needs to be qualified by the difficulty of assessing fusion in the presence of metal-work), but any improvement in clinical outcomes is probably marginal, while there is other evidence that it may be associated with higher complication rates. Three trials with conflicting results did not permit any conclusions about the relative effectiveness of anterior, posterior or circumferential fusion. Preliminary results of two small trials of intra-discal electrotherapy showed conflicting results. Preliminary data from three trials of disc arthroplasty did not permit any firm conclusions.

AUTHORS' CONCLUSIONS

Limited evidence is now available to support some aspects of surgical practice. Surgeons should be encouraged to perform further RCTs in this field.