The effect of iliac crest autograft on the outcome of fusion in the setting of degenerative spondylolisthesis: a subgroup analysis of the Spine Patient Outcomes Research Trial (SPORT)

Clinical Improvement After Lumbar Fusion: Using PROMIS to Assess Recovery Kinetics

STUDY DESIGN

Retrospective review of a single institution cohort.

OBJECTIVE

The goal of this study is to identify features that predict delayed achievement of minimum clinically important difference (MCID) following elective lumbar spine fusion using Patient-Reported Outcomes Measurement Information System (PROMIS) surveys.

SUMMARY OF BACKGROUND DATA

Preoperative prediction of delayed recovery following lumbar spine fusion surgery is challenging. While many studies have examined factors impacting the achievement of MCID for patient-reported outcomes in similar cohorts, few studies have assessed predictors of early functional improvement.

METHODS

We retrospectively reviewed patients undergoing elective one-level posterior lumbar fusion for degenerative pathology. Patients were subdivided into two groups based on achievement of MCID for each respective PROMIS domain either before six months ("early responders") or after six months ("late responders") following surgical intervention. Multivariable logistic regression analysis was used to determine features associated with odds of achieving distribution-based MCID before or after six months follow up.

RESULTS

147 patients were included. The average age was 64.3±13.0 years. At final follow-up, 57.1% of patients attained MCID for PI and 72.8% for PF. However, 42 patients (49.4%) reached MCID for PI by six months, compared to 44 patients (41.1%) for PF. Patients with severe symptoms had the highest probability of attaining MCID for PI (OR 10.3; P =0.001) and PF (OR 10.4; P =0.001) Preoperative PROMIS symptomology did not predict early achievement of MCID for PI or PF. Patients who received concomitant iliac crest autograft during their lumbar fusion had increased odds of achieving MCID for PI (OR 8.56; P =0.001) before six months.

CONCLUSION

Our study demonstrated that the majority of patients achieved MCID following elective one-level lumbar spine fusion at long-term follow-up, although less than half achieved this clinical benchmark for each PROMIS metric by six months. We also found that preoperative impairment was not associated with when patients would achieve MCID. Further prospective investigations are warranted to characterize the trajectory of clinical improvement and identify the risk factors associated with poor outcomes more accurately.

Biphasic Calcium Phosphate Bone Graft With a Unique Surface Topography: A Single-Center Ambispective Study for Degenerative Disease of the Lumbar Spine

STUDY DESIGN

This study is an ambispective evaluation and analysis of a single-center cohort.

OBJECTIVE

This study aimed to evaluate the performance of a novel biphasic calcium phosphate (BCP) bone graft with submicron-sized needle-shaped surface topography (BCP<µm) in interbody arthrodesis of the lumbar spine.

METHODS

This study was a single-center ambispective assessment of adult patients receiving BCP<µm as part of their lumbar interbody fusion surgery. The primary outcome was a fusion status on computed tomography (CT) 12 months postoperative. The secondary outcomes included postoperative changes in the visual analog scale (VAS), Oswestry Disability Index (ODI), Short Form 12 (SF-12), and length of stay (LOS).

RESULTS

Sixty-three patients with one- to three-level anterior (48, 76%) and lateral (15, 24%) interbody fusions with posterior instrumentation were analyzed. Thirty-one participants (49%) had three or more comorbidities, including heart disease (43 participants, 68%), obesity (31 participants, 49%), and previous lumbar surgery (23 participants, 37%). The mean ODI decreased by 24. The mean SF-12 physical health and SF-12 mental health improved by a mean of 11.5 and 6.3, respectively. The mean VAS for the left leg, right leg, and back improved by a mean of 25.75, 22.07, and 37.87, respectively. Of 101 levels, 91 (90%) demonstrated complete bridging trabecular bone fusion with no evidence of supplemental fixation failure.

CONCLUSION

The data of BCP<µm in interbody fusions for degenerative disease of the lumbar spine provides evidence of fusion in a complicated cohort of patients.

Predictors of Above Average 6-Year Citation Rates in Leading Spine-Specific Medical Journals

STUDY DESIGN

Cross-sectional.

OBJECTIVE

To identify predictors of manuscripts achieving 6-year citation rates higher than the mean in spine-specific literature.

SUMMARY OF BACKGROUND DATA

An article's citation rate demonstrates its contribution to academia and its quality. Predictors of citation rates have not yet been studied in spine-specific medical literature.

METHODS

Three leading spine-specific journals were identified by a weighted scoring system comparing various journal metrics. Research articles published in 2014 were evaluated from the following journals: Spine, European Spine Journal, and Journal of Neurosurgery: Spine. Article features analyzed included journal of origin, number of words in article title, author count, degree of first author, conflicts of interest, quantity of contributing academic institutions, country of origin, study topic, study design, level of evidence, sample size, reference count, and citation rate. Multivariate logistic regression was used to determine predictors of above average citation rate at 6 years following publication.

RESULTS

The final analysis included 1091 articles. Spine had a significantly higher citation rate than European Spine Journal (P = 0.0008); however, no significant differences were observed between Spine and Journal of Neurosurgery: Spine. Regression analysis demonstrated that studies originating in North America (OR:1.44, 95% CI:1.01-2.01, P = 0.04), those with 6 ≥ authors (OR:1.72, 95% CI:1.29-2.30, P < 0.001), sample size >100 (P < 0.001), prospective case series (OR: 2.67, 95% CI: 1.24-5.76), and retrospective case series (OR: 1.99, 95% CI: 1.07-3.73) were independent predictors of achieving above average 6-year citation rates.

CONCLUSION

Spine, European Spine Journal, and Journal of Neurosurgery: Spine had the highest 6-year citation rates of the top 10 orthopedic spine journals, with Spine being significantly higher than European Spine Journal. Studies originating in North America, those with six or more authors, sample sizes > 100, and those that are retrospective or prospective case series are independent predictors of greater citation rates at 6 years in orthopedic spine-specific medical literature.Level of Evidence: 4.

Randomized clinical trial: expanded autologous bone marrow mesenchymal cells combined with allogeneic bone tissue, compared with autologous iliac crest graft in lumbar fusion surgery

BACKGROUND CONTEXT

Although autogenous iliac crest bone graft (AICBG) is considered the gold-standard graft material for spinal fusion, new bone substitutes are being developed to avoid associated complications and disadvantages. By combining autologous bone marrow mesenchymal stromal cells (MSCs) expanded ex vivo and allogenic cancellous bone graft, we obtain a tissue-engineered product that is osteoconductive and potentially more osteogenic and osteoinductive than AICBG, owing to the higher concentration of MSCs.

PURPOSE

This study aimed to evaluate the feasibility and safety of implanting a tissue-engineered product consisting of expanded bone marrow MSCs loaded onto allograft bone (MSC+allograft) for spinal fusion in degenerative spine disease, as well as to assess its clinical and radiological efficacy.

STUDY DESIGN/SETTING

A prospective, multicenter, open-label, blinded-reader, randomized, parallel, single-dose phase I-II clinical trial.

PATIENT SAMPLE

A total of 73 adult patients from 5 hospitals, with Meyerding grade I-II L4-L5 degenerative spondylolisthesis and/or with L4-L5 degenerative disc disease who underwent spinal fusion through transforaminal lumbar interbody fusion (TLIF).

OUTCOME MEASURES

Spinal fusion was assessed by plain X-ray at 3, 6, and 12 months and by computed tomography (CT) at 6 and 12 months post-treatment. An independent radiologist performed blinded assessments of all images. Clinical outcomes were measured as change from baseline value: visual analog scale for lumbar and sciatic pain at 12 days, 3, 6, and 12 months posttreatment, and Oswestry Disability Index and Short Form-36 at 3, 6, and 12 months posttreatment.

METHODS

Patients who underwent L4-L5 TLIF were randomized for posterior graft type only, and received either MSC+allograft (the tissue-engineered product, group A) or AICBG (standard graft material, group B). Standard graft material was used for anterior fusion in all patients. Feasibility was measured primarily as the percentage of randomized patients who underwent surgery in each treatment group. Safety was assessed by analyzing treatment-emergent adverse events (AEs) for the full experimental phase and appraising their relationship to the experimental treatment. Outcome measures, both radiological and clinical, were compared between the groups.

RESULTS

Seventy-three patients were randomized in this study, 36 from the MSC+allograft group and 37 from the AICBG group, and 65 were surgically treated (31 group A, 34 group B). Demographic and comorbidity data showed no difference between groups. Most patients were diagnosed with grade I or II degenerative spondylolisthesis. MSC+allograft was successfully implanted in 86.1% of randomized group A patients. Most patients suffered treatment-emergent AEs during the study (88.2% in group A and 97.1% in group B), none related to the experimental treatment. X-ray-based rates of posterior spinal fusion were significantly higher for the experimental group at 6 months (p=.012) and 12 months (p=.0003). CT-based posterior fusion rates were significantly higher for MSC+allograft at 6 months (92.3% vs 45.7%; p=.0001) and higher, but not significantly, at 12 months (76.5% vs 65.7%; p=.073). CT-based complete response (defined as the presence of both posterior intertransverse fusion and anterior interbody fusion) was significantly higher at 6 months for MSC+allograft than for AICBG (70.6% vs 40%; p=.0038), and remained so at 12 months (70.6% vs 51.4%; p=.023). Clinical results including patient-reported outcomes improved postsurgery, although there were no differences between groups.

CONCLUSIONS

Compared with the current gold standard, our experimental treatment achieved a higher rate of posterior spinal fusion and radiographic complete response to treatment at 6 and 12 months after surgery. The treatment clearly improved patient quality of life and decreased pain and disability at rates similar to those for the control arm. The safety profile of the tissue-engineered product was also similar to that for the standard material, and no AEs were linked to the product. Procedural AEs did not increase as a result of BM aspiration. The use of expanded bone marrow MSCs combined with cancellous allograft is a feasible and effective technique for spinal fusion, with no product-related AEs found in our study.

Systematic Review of Outcomes Following 10-Year Mark of Spine Patient Outcomes Research Trial (SPORT) for Degenerative Spondylolisthesis

STUDY DESIGN

We performed a comprehensive search of PubMed, MEDLINE, and EMBASE for all English language studies of all levels of evidence pertaining to Spine Patient Outcomes Research Trial (SPORT), in accordance with Preferred Reported Items for Systematic Reviews and Meta-analyses guidelines.

OBJECTIVE

We aim to summarize the 10-year clinical outcomes of SPORT and its numerous follow-up studies for degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

The SPORT was a landmark randomized control trial including approximately 2500 patients at 13 clinics across the country. SPORT compared surgical and nonoperative management of the three most common spinal pathologies.

METHODS

Keywords used in the literature search included SPORT, spine patient outcomes research trial, degenerative spondylolisthesis, and surgical outcomes.

RESULTS

The intent-to-treat analysis failed to show a significant difference between patients treated surgically as compared to those treated nonoperatively. However, as-treated analysis revealed statically greater improvements at 6 weeks, 2 years, and 4 years in patients treated surgically. Secondary outcomes such as low back pain, leg pain, stenosis bothersome scales, overall satisfaction with current symptoms, and self-rated progress were also significantly improved in surgical patients. Regardless of the initial grade of listhesis, disk height, or mobility, patients who had surgical treatment improved more in terms of Oswestry Disability Index, bodily pain, physical function, and low back pain bothersomeness scales. Risk of reoperation increased with age, having two or three moderate or severe stenotic levels, pain predominantly localized to the back, no physical therapy, the absence of neurogenic claudication, and greater leg pain scores. Risk of reoperation was not significantly affected by type of surgery performed, smoking, diabetes, obesity, longer duration of symptoms, or workman's compensation.

CONCLUSION

Although intent-to-treat analysis failed to show significant differences in patients treated surgically, results of the as-treated analysis determined statically greater improvements in those patients with spondylolisthesis who were treated surgically as compared to those treated nonoperatively.

LEVEL OF EVIDENCE

2.

Novel Aptamer-Functionalized Nanoparticles Enhances Bone Defect Repair By Improving Stem Cell Recruitment

BACKGROUND

The restoration and repair method in the clinic of delayed fracture healing and non-union after comminuted fractures are urgently needed to improve the prognosis of patients. The recruitment of endogenous stem cells has been considered a promising approach in bone defect repair.

PROPOSE

The aim of this study was to generate a de novel MSCs aptamer and developed the first, feasible, economical, bio-compatible, and functional MSCs aptamer-directed nanoparticles without complex manufacture to recruit mesenchymal stem cells (MSCs) for bone defect regeneration.

METHODS

Whole-cell SELEX was used to generate a de novel MSCs aptamer. Flow cytometry was applied to assess the binding specificities, affinities and sorting abilities of the aptamers. Nano-Aptamer Ball (NAB) was constructed by NHS/EDC reaction. The diameter and zeta of NAB were assessed by dynamic light scattering. CCK8 assay was utilized to evaluate whether NAB could cause non-specific cytotoxicity and induce cell proliferation. To evaluate the bone repair capacity of NAB, histomorphological staining, alizarin red and micro X-ray were used to observe the repair degree of defect in vivo. ELISA was used to detect osteopontin (OPN), osteocalcin (BGP) by, and alkaline phosphatase (ALP) in peripheral blood.

RESULTS

MSCs aptamer termed as HM69 could bind with MSCs with high specificity and Kd of 9.67 nM, while has minimal cross-reactivities to other negative cells. HM69 could capture MSCs with a purity of >89%. In vitro, NAB could bind and capture MSCs effectively, whereas did not cause obvious cytotoxicity. In vivo, serum OPN, BGP, and ALP levels in the NAB group of rats were increased at both 2 and 4 weeks, indicating the repair and osteogenesis generation. The healing of bone defects in the NAB group was significantly better than control groups, the defects became blurred, and local trabecular bone growth could be observed in X-ray. The organized hematoma and cell growth in the bone marrow of the NAB group were more vigorous in bone sections staining.

CONCLUSION

These suggested that HM69 and HM69-functionalized nanoparticles NAB exhibited the ability to recruit MSCs both in vitro and in vivo and achieved a better outcome of bone defect repair in a rat model. The findings demonstrate a promising strategy of using aptamer-functionalized bio-nanoparticles for the restoration of bone defects via aptamer-introduced homing of MSCs.

Hierarchically Porous Hydroxyapatite Hybrid Scaffold Incorporated with Reduced Graphene Oxide for Rapid Bone Ingrowth and Repair

Hydroxyapatite (HA), the traditional bone tissue replacement material was widely used in the clinical treatment of bone defects because of its excellent biocompatibility. However, the processing difficulty and poor osteoinductive ability greatly limit the application of HA. Although many strategies have been reported to improve the machinability and osteointegration ability, the performance including mechanical strength, porosity, cell adhesion, etc. of material still can not meet the requirements. In this work, a soft template method was developed and a porous scaffold with hierarchical pore structure, nano surface morphology, suitable porosity and pore size, and good biomechanical strength was successfully prepared. The hierarchical pore structure is beneficial for cell adhesion, fluid transfer, and cell ingrowth. Moreover, the loaded reduced graphene oxide (rGO) can improve the adhesion and promote the proliferation and spontaneous osteogenic differentiation bone marrow mesenchymal stem cells. The scaffold is then crushed, degraded and wrapped by the newly formed bone and the newly formed bone gradually replaces the scaffold. The degradation rate of the scaffold well matches the rate of the new bone formation. The hierarchical porous HA/rGO composite scaffolds can greatly accelerate the bone ingrowth in the scaffold and bone repair in critical bone defects, thus providing a clinical potential candidate for large segment bone tissue engineering.

Impact of Iliac Crest Bone Grafting on Postoperative Outcomes and Complication Rates Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

OBJECTIVE

The relationship between bone graft technique and postoperative outcomes for minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has not been well-defined. This study aims to determine the effect of iliac crest bone grafting (ICBG) on patient-reported outcomes (PROs) and complication rates following MIS TLIF.

METHODS

Primary, single-level MIS TLIF patients were consecutively analyzed. Patients that prospectively received a percutaneous technique of ICBG were compared to patients that retrospectively received bone morphogenetic protein-2 (BMP-2). Complication rates were assessed perioperatively and up to 1 year postoperatively. Changes in Oswestry Disability Index (ODI), visual analogue scale (VAS) back, and VAS leg pain were compared. Rates of minimum clinically important difference (MCID) achievement at final follow-up for ODI, VAS back, and VAS leg scores were compared.

RESULTS

One hundred forty-nine patients were included: 101 in the BMP-2 cohort and 48 in the ICBG cohort. The ICBG cohort demonstrated increases in intraoperative blood loss and shorter lengths of stay. ICBG patients also experienced longer operative times, though this did not reach statistical significance. No significant differences in complication or reoperation rates were identified. The ICBG cohort demonstrated greater improvements in VAS leg pain at 6-week and 12-week follow-up. No other significant differences in PROs or MCID achievement rates were identified.

CONCLUSION

Patients undergoing MIS TLIF with ICBG experienced clinically insignificant increases in intraoperative blood loss and did not experience increases in postoperative pain or disability. Complication and reoperation rates were similar between groups. These results suggest that ICBG is a safe option for MIS TLIF.

Current Updates on Bone Grafting Biomaterials and Recombinant Human Growth Factors Implanted Biotherapy for Spinal Fusion: A Review of Human Clinical Studies

BACKGROUND

Owing to their great promise in the spinal surgeries, bone graft substitutes have been widely investigated for their safety and clinical potential. By the current advances in the spinal surgery, an understanding of the precise biological mechanism of each bone graft substitute is mandatory for upholding the induction of solid spinal fusion.

OBJECTIVE

The aim of the present review is to critically discuss various surgical implications and level of evidence of most commonly employed bone graft substitutes for spinal fusion.

METHOD

Data was collected via electronic search using "PubMed", "SciFinder", "ScienceDirect", "Google Scholar", "Web of Science" and a library search for articles published in peer-reviewed journals, conferences, and e-books.

RESULTS

Despite having exceptional inherent osteogenic, osteoinductive, and osteoconductive features, clinical acceptability of autografts (patient's own bone) is limited due to several perioperative and postoperative complications i.e., donor-site morbidities and limited graft supply. Alternatively, allografts (bone harvested from cadaver) have shown great promise in achieving acceptable bone fusion rate while alleviating the donor-site morbidities associated with implantation of autografts. As an adjuvant to allograft, demineralized bone matrix (DBM) has shown remarkable efficacy of bone fusion, when employed as graft extender or graft enhancer. Recent advances in recombinant technologies have made it possible to implant growth and differentiation factors (bone morphogenetic proteins) for spinal fusion.

CONCLUSION

Selection of a particular bone grafting biotherapy can be rationalized based on the level of spine fusion, clinical experience and preference of orthopaedic surgeon, and prevalence of donor-site morbidities.

Difference in the fusion rate and bone formation between artificial bone and iliac autograft inside an inter-body fusion cage - A comparison between porous hydroxyapatite/type 1 collagen composite and autologous iliac bone

BACKGROUND

Lateral inter-body fusion (LIF) using cages with a large bone grafting space can lead to a shortage of autologous grafting materials. The use of artificial bone is an option to increase the volume of grafting materials. However, the rate of bony fusion for these materials compared to that of autologous bone is unclear.

METHODS

The bone fusion rate for artificial bone (HAp/Col) and autologous iliac bone (IBG) graft among 23 patients who had undergone LIF (total 66 disc levels) combined with multilevel posterior corrective fusion for the treatment of adult spinal deformity was retrospectively evaluated. To allow comparison, one of the two separate bone grafting holes in each LIF cage was filled with HAp/Col and the other, with IBG. The change in Hounsfield units (HU) inside the implanted holes at 1-year post surgery (PO1Y) from baseline and immediately after surgery and bony fusion between adjacent vertebrae, defined by the extent of trabecular continuity at PO1Y, were evaluated using computed tomography. Differences between the convex and concave sides as well as effects of the side of approach were investigated.

RESULTS

HU values increased significantly for IBG, from 228.9 at baseline to 286.1 at PO1Y (p < 0.001), with no change for HAp/Col. The fusion rate was higher for IBG (71.2%) than for HAp/Col (19.7%; p < 0.001). A significant effect of the location of the holes on fusion rate was identified for HAp/Col but not IBG. No effects of the side of approach were identified.

CONCLUSIONS

A higher rate of fusion in LIF cages was obtained with IBG than with HAp/Col, with no effect of location of implantation (convex or concave) for IBG. Therefore, exclusive use of artificial bone, particularly on the convex side, should be avoided during LIF.

GEORG-SCHMORL-PRIZE OF THE GERMAN SPINE SOCIETY (DWG) 2016: Comparison of in vitro osteogenic potential of iliac crest and degenerative facet joint bone autografts for intervertebral fusion in lumbar spinal stenosis

PURPOSE

The promotion of spinal fusion using bone autografts is largely mediated by the osteoinductive potential of progenitors/mesenchymal stem cells (MSC) that reside in the marrow spaces of cancellous bone. Iliac crest is the common autograft donor site, but its use presents an increased risk for donor site pain, morbidity and infection. Degenerative bone samples harvested during facetectomy might provide an alternative viable source of osteoinductive autografts. In this study, we conducted an intra-individual comparison of the osteogenic potential of isolated low passage MSC from both sources.

METHODS

Iliac crest and degenerative facet joints were harvested from eight consecutive patients undergoing transforaminal lumbar interspinal fusion due to lumbar spinal stenosis. MSC were isolated by collagenase digestion, selected by plastic adherence and minimally expanded for downstream assays. Clonogenic and osteogenic potential was evaluated by colony formation assays in control and osteogenic culture medium. Osteogenic properties, including alkaline phosphatase (ALP) induction, matrix mineralization and type I collagen mRNA and protein expression were characterized using quantitative histochemical staining and reverse transcription PCR. Spontaneous adipogenesis was analysed by adipocyte enumeration and gene expression analysis of adipogenic markers.

RESULTS

Average colony-forming efficiency in osteogenic medium was equal between iliac crest (38 ± 12%) and facet joint (36 ± 11%). Osteogenic potential at the clonal level was 55 ± 26 and 68 ± 17% for iliac crest and facet joint MSC, respectively. Clonogenic and osteogenic potential were significantly negatively associated with donor age. Osteogenic differentiation led to significant induction of ALP activity in iliac crest (sixfold) and facet joint (eightfold) MSC. Matrix mineralization quantified by Alizarin red staining was increased by osteogenic differentiation, yet similar between both MSC sources. Protein expression of type I collagen was enhanced during osteogenesis and significantly greater in iliac crest MSC. Correspondingly, COL1A2 mRNA expression was higher in osteogenically differentiated MSC from iliac crest. Adipocyte numbers showed significant differences between iliac crest (63 ± 60) and facet joint (18 ± 15) MSC under osteogenic conditions. Negative (GREM1) and positive (FABP4) adipogenic markers were not differentially expressed between sources.

CONCLUSION

MSC from iliac crest and degenerative facet joints largely display similar clonogenic and osteogenic properties in vitro. Differences at the molecular level are not likely to impair the osteoinductive capacity of facet joint MSC. Bone autografts from facetectomy would be viable alternatives as bone autografts for intervertebral spinal fusion in lumbar spinal stenosis.

Iliac Crest Regeneration: A Retrospective Study of 14 Years of Follow-up

STUDY DESIGN

This is a retrospective study analysis.

OBJECTIVE

The purpose of our study was to evaluate the healing process of the ilium after being used as a bone graft donor site in the treatment of adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Iliac crest bone grafts have been proven to be the most reliable means for solid fusion in spine surgery. Nevertheless, few reports in the literature describe the ability of the iliac crest to regenerate.

METHODS

Thirty-one patients with a mean age of 15.1 years had undergone posterior spinal fusion for idiopathic scoliosis. An autogenous bone graft was harvested from the right posterior iliac crest in all cases. Computed tomography scans of the pelvis were performed preoperatively and shortly after operation to evaluate the presence of any deformity and the size of the defect formed during surgery, respectively. All patients were reexamined 14 years postoperatively, and computed tomography scans were performed to evaluate the status of ossification at the donor site.

RESULTS

In 21 cases (67.74%), bone deficits were fully restored (mean volume 12.053 cm), whereas partial regeneration was present in the remaining 10 cases (mean volume 8.766 cm). Hounsfield units (HUs) revealed that cancellous bone quality had been restored in 21 cases, whereas cysts with sclerotic bone margins were present in the remaining 10 cases. Immature patients [Risser sign (RS) 3, 4] have greater ability in restoring bone stock compared with patients with almost complete growth (RS 5; P<0.001). In addition, the gluteus maximus muscle preserved its volume and quality in cases with complete bone restoration (volume 51.3 cm, HU 55.9) compared with cases with partial regeneration (volume 43.43 cm, HU 38.35; P<0.001).

CONCLUSIONS

The iliac wing of skeletally immature patients has considerable ability to fully regenerate and could probably be used as a graft donor site again.

Burden of Surgical Site Infections Associated with Select Spine Operations and Involvement of Staphylococcus aureus

BACKGROUND

Spine operations may be indicated for treatment of diseases including vertebral injuries, degenerative spinal conditions, disk disease, spinal misalignments, or malformations. Surgical site infection (SSI) is a clinically important complication of spine surgery. Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA), is a leading cause of post-spinal SSIs.

METHODS

PubMed and applicable infectious disease conference proceedings were searched to identify relevant published studies. Overall, 343 full-text publications were screened for epidemiologic, mortality, health care resource utilization, and cost data on SSIs associated with specified spine operations.

RESULTS

Surgical site infection rates were identified in 161 studies from North America, Europe, and Asia. Pooled average SSI and S. aureus SSI rates for spine surgery were 1.9% (median, 3.3%; range, 0.1%-22.6%) and 1.0% (median, 2.0%; range, 0.02%-10.0%). Pooled average contribution of S. aureus infections to spinal SSIs was 49.3% (median, 50.0%; range, 16.7%-100%). Pooled average proportion of S. aureus SSIs attributable to MRSA was 37.9% (median, 42.5%; range, 0%-100%). Instrumented spinal fusion had the highest pooled average SSI rate (3.8%), followed by spinal decompression (1.8%) and spinal fusion (1.6%). The SSI-related mortality rate among spine surgical patients ranged from 1.1%-2.3% (three studies). All studies comparing SSI and control cohorts reported longer hospital stays for patients with SSIs. Pooled average SSI-associated re-admission rate occurring within 30 d from discharge ranged from 20% to 100% (four studies). Pooled average SSI-related re-operation rate was 67.1% (median, 100%; range, 33.5%-100%). According to two studies reporting direct costs, spine surgical patients incur approximately double the health care costs when they develop an SSI.

CONCLUSIONS

Available published studies demonstrate a clinically important burden of SSIs related to spine operations and the substantial contribution of S. aureus (including MRSA). Preventive strategies aimed specifically at S. aureus SSIs could reduce health care costs and improve patient outcomes for spine operations.

Surgical options for lumbar spinal stenosis

BACKGROUND

Hospital charges for lumbar spinal stenosis have increased significantly worldwide in recent times, with great variation in the costs and rates of different surgical procedures. There have also been significant increases in the rate of complex fusion and the use of spinal spacer implants compared to that of traditional decompression surgery, even though the former is known to incur costs up to three times higher. Moreover, the superiority of these new surgical procedures over traditional decompression surgery is still unclear.

OBJECTIVES

To determine the efficacy of surgery in the management of patients with symptomatic lumbar spinal stenosis and the comparative effectiveness between commonly performed surgical techniques to treat this condition on patient-related outcomes. We also aimed to investigate the safety of these surgical interventions by including perioperative surgical data and reoperation rates.

SEARCH METHODS

Review authors performed electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, AMED, Web of Science, LILACS and three trials registries from their inception to 16 June 2016. Authors also conducted citation tracking on the reference lists of included trials and relevant systematic reviews.

SELECTION CRITERIA

This review included only randomised controlled trials that investigated the efficacy and safety of surgery compared with no treatment, placebo or sham surgery, or with another surgical technique in patients with lumbar spinal stenosis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the studies for inclusion and performed the 'Risk of bias' assessment, using the Cochrane Back and Neck Review Group criteria. Reviewers also extracted demographics, surgery details, and types of outcomes to describe the characteristics of included studies. Primary outcomes were pain intensity, physical function or disability status, quality of life, and recovery. The secondary outcomes included measurements related to surgery, such as perioperative blood loss, operation time, length of hospital stay, reoperation rates, and costs. We grouped trials according to the types of surgical interventions being compared and categorised follow-up times as short-term when less than 12 months and long-term when 12 months or more. Pain and disability scores were converted to a common 0 to 100 scale. We calculated mean differences for continuous outcomes and relative risks for dichotomous outcomes. We pooled data using the random-effects model in Review Manager 5.3, and used the GRADE approach to assess the quality of the evidence.

MAIN RESULTS

We included a total of 24 randomised controlled trials (reported in 39 published research articles or abstracts) in this review. The trials included 2352 participants with lumbar spinal stenosis with symptoms of neurogenic claudication. None of the included trials compared surgery with no treatment, placebo or sham surgery. Therefore, all included studies compared two or more surgical techniques. We judged all trials to be at high risk of bias for the blinding of care provider domain, and most of the trials failed to adequately conceal the randomisation process, blind the participants or use intention-to-treat analysis. Five trials compared the effects of fusion in addition to decompression surgery. Our results showed no significant differences in pain relief at long-term (mean difference (MD) -0.29, 95% confidence interval (CI) -7.32 to 6.74). Similarly, we found no between-group differences in disability reduction in the long-term (MD 3.26, 95% CI -6.12 to 12.63). Participants who received decompression alone had significantly less perioperative blood loss (MD -0.52 L, 95% CI -0.70 L to -0.34 L) and required shorter operations (MD -107.94 minutes, 95% CI -161.65 minutes to -54.23 minutes) compared with those treated with decompression plus fusion, though we found no difference in the number of reoperations (risk ratio (RR) 1.25, 95% CI 0.81 to 1.92). Another three trials investigated the effects of interspinous process spacer devices compared with conventional bony decompression. These spacer devices resulted in similar reductions in pain (MD -0.55, 95% CI -8.08 to 6.99) and disability (MD 1.25, 95% CI -4.48 to 6.98). The spacer devices required longer operation time (MD 39.11 minutes, 95% CI 19.43 minutes to 58.78 minutes) and were associated with higher risk of reoperation (RR 3.95, 95% CI 2.12 to 7.37), but we found no difference in perioperative blood loss (MD 144.00 mL, 95% CI -209.74 mL to 497.74 mL). Two trials compared interspinous spacer devices with decompression plus fusion. Although we found no difference in pain relief (MD 5.35, 95% CI -1.18 to 11.88), the spacer devices revealed a small but significant effect in disability reduction (MD 5.72, 95% CI 1.28 to 10.15). They were also superior to decompression plus fusion in terms of operation time (MD 78.91 minutes, 95% CI 30.16 minutes to 127.65 minutes) and perioperative blood loss (MD 238.90 mL, 95% CI 182.66 mL to 295.14 mL), however, there was no difference in rate of reoperation (RR 0.70, 95% CI 0.32 to 1.51). Overall there were no differences for the primary or secondary outcomes when different types of surgical decompression techniques were compared among each other. The quality of evidence varied from 'very low quality' to 'high quality'.

AUTHORS' CONCLUSIONS

The results of this Cochrane review show a paucity of evidence on the efficacy of surgery for lumbar spinal stenosis, as to date no trials have compared surgery with no treatment, placebo or sham surgery. Placebo-controlled trials in surgery are feasible and needed in the field of lumbar spinal stenosis. Our results demonstrate that at present, decompression plus fusion and interspinous process spacers have not been shown to be superior to conventional decompression alone. More methodologically rigorous studies are needed in this field to confirm our results.

Mesenchymal stromal cells in spinal fusion: Current and future applications

Mesenchymal stromal cells (MSCs) have been a promising area of study for regenerative medicine. These cells can be harvested from bone marrow, adipose tissue, and other areas allowing for autologous transplantation of these cells into the area of degeneration or injury. With the proper signals, these cells may be able to regenerate healthy tissue. Recent studies have yielded promising evidence supporting translational mesenchymal stromal cell applications particularly in spinal fusion surgery.

Iliac Crest Bone Graft versus Local Autograft or Allograft for Lumbar Spinal Fusion: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

To compare the effectiveness and safety between iliac crest bone graft (ICBG) and local autologous bone and allograft in the lumbar spine.

METHODS

A systematic search of multiple major medical reference databases identified studies evaluating spinal fusion in patients with degenerative joint disease using ICBG, local autograft, or allograft in the thoracolumbar spine.

RESULTS

Six comparative studies met our inclusion criteria. A "low" strength of the overall body of evidence suggested no difference in fusion percentages in the lumbar spine between local autograft and ICBG. We found no difference in fusion percentages based on low evidence comparing allograft with ICBG autograft. There were no differences in pain or functional results comparing local autograft or allograft with ICBG autograft. Donor site pain and hematoma/seroma occurred more frequently in ICBG autograft group for lumbar fusion procedures. There was low evidence around the estimate of patients with donor site pain following ICBG harvesting, ranging from 16.7 to 20%. With respect to revision, low evidence demonstrated no difference between allograft and ICBG autograft. There was no evidence comparing patients receiving allograft with local autograft for fusion, pain, functional, and safety outcomes.

CONCLUSION

In the lumbar spine, ICBG, local autograft, and allograft have similar effectiveness in terms of fusion rates, pain scores, and functional outcomes. However, ICBG is associated with an increased risk for donor site-related complications. Significant limitations exist in the available literature when comparing ICBG, local autograft, and allograft for lumbar fusion, and thus ICBG versus other fusion methods necessitates further investigation.

Impact of a Bundled Payment System on Resource Utilization During Spine Surgery

BACKGROUND

In a bundled payment system, a single payment covers all costs associated with a single episode of care. Spine surgery may be well suited for bundled payments because of clearly defined episodes of care, but the impact on current practice has not been studied. We sought to examine how a theoretical bundled payment strategy with financial disincentives to resource utilization would impact practice patterns.

METHODS

A multiple-choice survey was administered to spine surgeons describing eight clinical scenarios. Respondents were asked about their current practice, and then their practice in a hypothetical bundled payment system. Respondents could choose from multiple types of implants, bone grafts, and other resources utilized at the surgeon's discretion.

RESULTS

Forty-three respondents completed the survey. Within each scenario, 24%-49% of respondents changed at least one aspect of management. The proportion of cases performed without implants was unchanged for four scenarios and increased in four by an average of 8%. Use of autologous iliac crest bone graft increased across all scenarios by an average of 18%. Use of neuromonitoring decreased in all scenarios by an average of 21%. Differences in costs were not statistically significant.

CONCLUSIONS

Financial disincentives to resource utilization may result in some changes to surgeons' practices but these appear limited to items with less clear benefits to patients. Choices of implants, which account for the majority of intra-operative costs, did not change meaningfully. A bundling strategy targeting peri-operative costs solely related to surgical practice may not yield substantive savings while rationing potentially beneficial treatments to patient care.

LEVEL OF EVIDENCE

5.

Laminectomy plus Fusion versus Laminectomy Alone for Lumbar Spondylolisthesis

BACKGROUND

The comparative effectiveness of performing instrumented (rigid pedicle screws affixed to titanium alloy rods) lumbar spinal fusion in addition to decompressive laminectomy in patients with symptomatic lumbar grade I degenerative spondylolisthesis with spinal stenosis is unknown.

METHODS

In this randomized, controlled trial, we assigned patients, 50 to 80 years of age, who had stable degenerative spondylolisthesis (degree of spondylolisthesis, 3 to 14 mm) and symptomatic lumbar spinal stenosis to undergo either decompressive laminectomy alone (decompression-alone group) or laminectomy with posterolateral instrumented fusion (fusion group). The primary outcome measure was the change in the physical-component summary score of the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36; range, 0 to 100, with higher scores indicating better quality of life) 2 years after surgery. The secondary outcome measure was the score on the Oswestry Disability Index (range, 0 to 100, with higher scores indicating more disability related to back pain). Patients were followed for 4 years.

RESULTS

A total of 66 patients (mean age, 67 years; 80% women) underwent randomization. The rate of follow-up was 89% at 1 year, 86% at 2 years, and 68% at 4 years. The fusion group had a greater increase in SF-36 physical-component summary scores at 2 years after surgery than did the decompression-alone group (15.2 vs. 9.5, for a difference of 5.7; 95% confidence interval, 0.1 to 11.3; P=0.046). The increases in the SF-36 physical-component summary scores in the fusion group remained greater than those in the decompression-alone group at 3 years and at 4 years (P=0.02 for both years). With respect to reductions in disability related to back pain, the changes in the Oswestry Disability Index scores at 2 years after surgery did not differ significantly between the study groups (-17.9 in the decompression-alone group and -26.3 in the fusion group, P=0.06). More blood loss and longer hospital stays occurred in the fusion group than in the decompression-alone group (P<0.001 for both comparisons). The cumulative rate of reoperation was 14% in the fusion group and 34% in the decompression-alone group (P=0.05).

CONCLUSIONS

Among patients with degenerative grade I spondylolisthesis, the addition of lumbar spinal fusion to laminectomy was associated with slightly greater but clinically meaningful improvement in overall physical health-related quality of life than laminectomy alone. (Funded by the Jean and David Wallace Foundation and others; SLIP ClinicalTrials.gov number, NCT00109213.).

Autologous bone graft harvesting: a review of grafts and surgical techniques

Spinal fusion with or without instrumentation often requires the use of bone graft. Bone graft may be autogenous or exogenous. There are various forms of bone graft which may be acquired from numerous sites. Knowledge of fusion biology is imperative for understanding the benefits and limitations of these grafts. Equally as important is the knowledge of outcome measures, management of donor-site morbidity, and potential reconstruction. This review details the methods of obtaining bone graft and details the properties of each, as well as discusses observed outcomes, donor-site morbidities, and reconstruction techniques.

Lumbar interbody fusion with porous biphasic calcium phosphate enhanced by recombinant bone morphogenetic protein-2/silk fibroin sustained-released microsphere: an experimental study on sheep model

Biphasic calcium phosphate (BCP) has been investigated extensively as a bone substitute nowadays. However, the bone formation capacity of BCP is limited owing to lack of osteoinduction. Silk fibroin (SF) has a structure similar to type I collagen, and could be developed to a microsphere for the sustained-release of rhBMP-2. In our previous report, bioactivity of BCP could be enhanced by rhBMP-2/SF microsphere (containing 0.5 µg rhBMP-2) in vitro. However, the bone regeneration performance of the composite in vivo was not investigated. Thus, the purpose of this study was to evaluate the efficacy of BCP/rhBMP-2/SF in a sheep lumbar fusion model. A BCP and rhBMP-2/SF microsphere was developed, and then was integrated into a BCP/rhBMP-2/SF composite. BCP, BCP/rhBMP-2 and BCP/rhBMP-2/SF were implanted randomly into the disc spaces of 30 sheep at the levels of L1/2, L3/4 and L5/6. After sacrificed, the fusion segments were evaluated by manual palpation, CT scan, biomechanical testing and histology at 3 and 6 months, respectively. The composite demonstrated a burst-release of rhBMP-2 (39.1 ± 2.8 %) on the initial 4 days and a sustained-release (accumulative 81.3 ± 4.9 %) for more than 28 days. The fusion rates, semi-quantitative CT scores, fusion stiffness in bending in all directions and histologic scores of BCP/rhBMP-2/SF were significantly greater than BCP and BCP/rhBMP-2 at each time point, respectively (P < 0.05). These findings indicate that the SF microspheres containing a very low dose of rhBMP-2 improve fusion in sheep using BCP constructs.

An analysis of spinopelvic sagittal alignment after lumbar lordosis reconstruction for degenerative spinal diseases: how much balance can be obtained?

STUDY DESIGN

A retrospective and radiological study of degenerative spinal diseases.

OBJECTIVE

To explore the changes in spinopelvic sagittal alignment after lumbar instrumentation and fusion of degenerative spinal diseases.

SUMMARY OF BACKGROUND DATA

Efforts have been paid to clarify the ideal postoperative sagittal profile for degenerative spinal diseases. However, little has been published about the actual changes of sagittal alignment after lumbar lordosis reconstruction.

METHODS

Radiographical analysis of 83 patients with spinal degeneration was performed by measuring sagittal parameters before and after operations. Comparative studies of sagittal parameters between short (1 level) and long (≥ 2 level) instrumentation and fusion were performed. Different variances (Δ) of these sagittal parameters before and after operations were calculated and compared. Correlative study and linear regression were performed to establish the relationship between variances.

RESULTS

No significant changes were shown in the short-fusion group postoperatively. In the long-fusion group, postoperative lumbar lordosis (LL) and sacral slope (SS) were significantly increased; pelvic tilt (PT), sagittal vertical axis (SVA), pelvic incidence minus lumbar lordosis, and PT/SS were significantly decreased. Different variances of ΔLL, ΔSS, ΔPT, ΔSVA, Δ(pelvic incidence - LL), and ΔPT/SS were significantly greater in the long-fusion group than the short-fusion group. Close correlations were mainly shown among ΔLL, ΔPT, and ΔSVA. Linear regression equations could be developed (ΔPT = -0.185 × ΔLL - 7.299 and ΔSVA = -0.152ΔLL - 1.145).

CONCLUSION

In degenerative spinal diseases, long instrumentation and fusion (≥ 2 levels) provides more efficient LL reconstruction. PT, SS, and SVA improve corresponding to LL in a linear regression model. Linear regression equations could be developed and used to predict PT and SVA change after long instrumentation and fusion for LL reconstruction.

Short-term adverse events, length of stay, and readmission after iliac crest bone graft for spinal fusion

STUDY DESIGN

Retrospective cohort study of 13,927 patients, 820 of whom received iliac crest bone graft (ICBG).

OBJECTIVE

To compare adverse events, length of stay (LOS), and readmission for patients receiving ICBG with those who did not using multivariate analysis to control for potentially confounding factors.

SUMMARY OF BACKGROUND DATA

The use of ICBG in spinal fusion has been associated with increased surgical time, LOS, and donor site morbidity. Development of expensive bone graft substitutes has been predicated on these issues. Data on the effect of bone graft harvest on LOS and readmission rate are sparse, and multivariate analysis has not been used to control for confounding factors.

METHODS

Prospectively collected data from the American College of Surgeons National Surgical Quality Improvement Project 2010-2012 database were retrospectively reviewed. This includes demographics, comorbidities, surgical data, and hospital and 30-day follow-up outcomes data including adverse events, LOS, and readmission.

RESULTS

Only 5.9% of spinal fusions use ICBG. Bivariate logistic regression (used for categorical variables) found the ICBG cohort was more likely to have a postoperative blood transfusion (11.6% vs. 5.5%, P < 0.001). Bivariate linear regression (used for continuous variables) found the ICBG cohort to have an extended operative time (+36.0 min, P < 0.001) and extended LOS (+0.6 d, P < 0.001).Multivariate analyses controlling for comorbidities, demographics, and approach-determined postoperative blood transfusion (odds ratio, 1.5), extended operative time (+22.0 min, P < 0.001), and LOS (+0.2 d, P = 0.037) to be significantly associated with ICBG use.No other adverse event was significantly associated with ICBG use. Readmission rates were not significantly different.

CONCLUSION

This study used a large national database cohort and identified increased postoperative blood transfusion, extended operative time, and increased LOS as short-term outcomes associated with ICBG on multivariate analysis. Other short-term morbidities were not significantly associated with ICBG. Readmission rates were not affected.

LEVEL OF EVIDENCE

4.

Posterior lumbar fusion: choice of approach and adjunct techniques

The choice among the many options of approach and adjunct techniques in planning a posterior lumbar fusion can be problematic. Debates remain as to whether solid fusion has an advantage over pseudarthrosis regarding long-term symptom deterioration and whether an instrumented or a noninstrumented approach will best serve clinically and/or cost effectively, particularly in elderly patients. Increased motion resulting in higher rates of nonunion and the use of nonsteroidal anti-inflammatory drugs have been studied in animal models and are presumed risk factors, despite the lack of clinical investigation. Smoking is a proven risk factor for pseudarthrosis in both animal models and level III clinical studies. Recent long-term studies and image/clinical assessment of lumbar fusions and pseudarthrosis show that, although imaging remains a key area of difficulty in assessment, including an instrumented approach and a well-selected biologic adjunct, as well as achieving a solid fusion, all carry important long-term clinical advantages in avoiding revision surgery for nonunion.

A retrospective study of iliac crest bone grafting techniques with allograft reconstruction: do patients even know which iliac crest was harvested? Clinical article

OBJECT

Considerable biological research has been performed to aid bone healing in conjunction with lumbar fusion surgery. Iliac crest autograft is often considered the gold standard because it has the vital properties of being osteoconductive, osteoinductive, and osteogenic. However, graft site pain has been widely reported as the most common donor site morbidity. Autograft site pain has led many companies to develop an abundance of bone graft extenders, which have limited proof of efficacy. During the surgical consent process, many patients ask surgeons to avoid harvesting autograft because of the reported pain complications. The authors sought to study postoperative graft site pain by simply asking patients whether they knew which iliac crest was grafted when a single skin incision was made for the fusion operation.

METHODS

Twenty-five patients underwent iliac crest autografting with allograft reconstruction during instrumented lumbar fusion surgery. In all patients the autograft was harvested through the same skin incision but with a separate fascial incision. At various points postoperatively, the patients were asked if they could tell which iliac crest had been harvested, and if so, how much pain did it cause (10-point Numeric Rating Scale).

RESULTS

Most patients (64%) could not correctly determine which iliac crest had been harvested. Of the 9 patients who correctly identified the side of the autograft, 7 were only able to guess. The 2 patients who confidently identified the side of grafting had no pain at rest and mild pain with activity. One patient who incorrectly guessed the side of autografting did have significant sacroiliac joint degenerative pain bilaterally.

CONCLUSIONS

Results of this study indicate the inability of patients to clearly define their graft site after iliac crest autograft harvest with allograft reconstruction of the bony defect unless they have a separate skin incision. This simple, easily reproducible pilot study can be expanded into a larger, multiinstitutional investigation to provide more definitive answers regarding the ideal, safe, and cost-effective bone graft material to be used in spinal fusions.

Epidural steroids: a comprehensive, evidence-based review

Epidural steroid injections (ESIs) are the most widely utilized pain management procedure in the world, their use supported by more than 45 placebo-controlled studies and dozens of systematic reviews. Despite the extensive literature on the subject, there continues to be considerable controversy surrounding their safety and efficacy. The results of clinical trials and review articles are heavily influenced by specialty, with those done by interventional pain physicians more likely to yield positive findings. Overall, more than half of controlled studies have demonstrated positive findings, suggesting a modest effect size lasting less than 3 months in well-selected individuals. Transforaminal injections are more likely to yield positive results than interlaminar or caudal injections, and subgroup analyses indicate a slightly greater likelihood for a positive response for lumbar herniated disk, compared with spinal stenosis or axial spinal pain. Other factors that may increase the likelihood of a positive outcome in clinical trials include the use of a nonepidural (eg, intramuscular) control group, higher volumes in the treatment group, and the use of depo-steroid. Serious complications are rare following ESIs, provided proper precautions are taken. Although there are no clinical trials comparing different numbers of injections, guidelines suggest that the number of injections should be tailored to individual response, rather than a set series. Most subgroup analyses of controlled studies show no difference in surgical rates between ESI and control patients; however, randomized studies conducted by spine surgeons, in surgically amenable patients with standardized operative criteria, indicate that in some patients the strategic use of ESI may prevent surgery.