A Prospective Randomized Clinical Trial Comparing Bone Union Rate Following Anterior Cervical Discectomy and Fusion Using a Polyetheretherketone Cage: Hydroxyapatite/B-Tricalcium Phosphate Mixture versus Hydroxyapatite/Demineralized Bone Matrix Mixture

Complications With Demineralized Bone Matrix, Hydroxyapatite and Beta-Tricalcium Phosphate in Single and Two-Level Anterior Cervical Discectomy and Fusion Surgery

STUDY DESIGN

Systematic literature review.

OBJECTIVES

To analyze the evidence available reporting complications in single or two-level anterior cervical discectomy and fusion (ACDF) using a demineralized bone matrix (DBM), hydroxyapatite (HA), or beta-tricalcium phosphate (β-TCP).

METHODS

A systematic review of the literature using PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov databases was performed in August 2020 to identify studies reporting complications in one or two-level ACDF surgery using DBM, HA, or β-TCP. The study was reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines.

RESULTS

A total of 1857 patients were included, 981 male and 876 female, across 17 articles; 5 prospective, and 12 retrospectives. We noted heterogeneity among the included studies concerning the study design and combination of graft materials utilized in them. However, we noted a higher incidence of adjacent segment disease (17.7%) and pseudoarthrosis (9.3%) in fusion constructs using DBM. Studies using β-TCP reported a higher incidence of pseudoarthrosis (28.2%) and implant failures (17.9%).

CONCLUSIONS

Degenerative cervical conditions treated with one or two-level ACDF surgery using DBM, HA, or β-TCP with or without cervical plating are associated with complications such as adjacent segment disease, dysphagia, and pseudarthrosis. However, consequent to the study designs and clinical heterogeneity of the studies, it is not possible to correlate these complications accurately with any specific graft material employed. Further well-designed prospective studies are needed to correctly know the related morbidity of each graft used for achieving fusion in ACDF.

Demineralized Bone Matrix and Fibers in Spinal Fusion

Formation of bony fusion after arthrodesis depends on osteoinduction, osteoconduction, and osteogenesis. Traditionally, the patient's own bone, or autograft, has been used to provide biological material necessary for these steps. However, the amount of autograft obtainable is often inadequate. Modern spine surgery has adopted the use of many autograft extenders or replacements, such as demineralized bone matrix or fibers. The present article covers the history of bone grafting, the production and technical details of demineralized bone matrix, and the evidence supporting its use in spine fusions.

Anterior Cervical Discectomy and Fusion Performed Using a CaO-SiO2-P2O5-B2O3 Bioactive Glass Ceramic or Polyetheretherketone Cage Filled with Hydroxyapatite/β-Tricalcium Phosphate: A Prospective Randomized Controlled Trial

A CaO-SiO₂-P₂O₅-B₂O₃ bioactive glass-ceramic (BGS-7) spacer provides high mechanical stability, produces a chemical bond to the adjacent endplate, and facilitates fusion after spine surgery. This prospective, randomized, single-blind, non-inferiority trial aimed to evaluate the radiographic outcomes and clinical efficacy of anterior cervical discectomy and fusion (ACDF) using a BGS-7 spacer for treating cervical degenerative disorders. Thirty-six patients underwent ACDF using a BGS-7 spacer (Group N), and 40 patients underwent ACDF using polyetheretherketone (PEEK) cages filled with a mixture of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) for the treatment of cervical degenerative disorders. The spinal fusion rate was assessed 12 months postoperatively using three-dimensional computed tomography (CT) and dynamic radiographs. Clinical outcomes included patient-reported outcome measures, visual analog scale scores for neck and arm pain, and scores from the neck disability index (NDI), European Quality of Life-5 Dimensions (EQ-5D), and 12-item Short Form Survey (SF-12v2). All participants were randomly assigned to undergo ACDF using either a BGS-7 spacer or PEEK cage filled with HA and β-TCP. The primary outcome was the fusion rate on CT scan image at 12 months after ACDF surgery based on a per-protocol strategy. Clinical outcomes and adverse events were also assessed. The 12-month fusion rates for the BGS-7 and PEEK groups based on CT scans were 81.8% and 74.4%, respectively, while those based on dynamic radiographs were 78.1% and 73.7%, respectively, with no significant difference between the groups. There were no significant differences in the clinical outcomes between the two groups. Neck pain, arm pain, NDI, EQ-5D, and SF-12v2 scores significantly improved postoperatively, with no significant differences between the groups. No adverse events were observed in either group. In ACDF surgery, the BGS-7 spacer showed similar fusion rates and clinical outcomes as PEEK cages filled with HA and β-TCP.

Use of biphasic calcium phosphate versus demineralized bone matrix: retrospective clinical and CT analysis of posterolateral fusion results

PURPOSE

Bone graft extenders have been developed to prevent donor site morbidity associated with iliac crest bone graft, but few studies compared the efficacy of various substitutes. Our purpose was to determine fusion rate and clinical outcome in patients undergoing lumbar arthrodesis using demineralized bone matrix (DBM) and biphasic calcium phosphate (BCP).

METHODS

Patients with degenerative spondylolisthesis undergoing one-level or two-level arthrodesis of lumbar spine were retrospectively reviewed. Two treatment groups placed either BCP or DBM, in addition to local autograft in lumbar posterolateral space. Three-dimensional CT exam and dynamic flexion-extension radiographs at postoperative 2-year were assessed for posterolateral fusion status and pain scale and Oswestry Disability Index (ODI) for clinical outcome.

RESULTS

Of the 148 patients reviewed (including 23 in one- and 58 patients in two-level in BCP group, and 47 in one- and 20 patients in two-level in DBM group), no significant differences were found in terms of age, sex, BMI, smoking, diabetes, steroids, number of level fused, non-union rate or revision surgery between BCP and DBM groups. Significantly improved pain scale of back and leg and ODI were found in both groups postoperatively without group difference. We found a comparable fusion rate in one-level surgery (100% versus 93.6%) and a superior fusion rate of BCP group in two-level surgery (98.3% versus 80.0%, p = 0.01).

CONCLUSION

Being a bone graft extender without osteoinductive property, with local autograft, BCP is comparable to DBM for one- and superior for two-level fusion. No significant difference was found in clinical outcomes.

Complications of Anterior Cervical Discectomy and Fusion

Anterior cervical discectomy and fusion (ACDF) is the most common surgery performed on the cervical spine, and the number of its cases has tripled over the last two decades. Although this intervention is typically safe and effective, it carries an inherent complication risk, which should not be underestimated. Improvements in surgical techniques and advances in interbody fusion devices and plating systems have certainly reduced the rate of postoperative morbidity, but despite such progress, surgeons need to beware consistently of the potential complications, inform the patient of their possibility, and have a management strategy as they develop. This review discusses postoperative morbidity encountered in recently reported large studies on ACDF and highlights the senior author's own single-surgeon experience with 2579 such procedures performed between 1998 and 2017. In his clinical series, which is the largest one reported to date, the overall complication rate was 7.0% (180 cases), and dysphagia (1.9% of cases), graft/hardware failures (1.3% of cases), and postoperative hematomas (0.9% of cases) were noted most frequently. Understanding of the risk and clinical impact of complications after ACDF is very important and every effort should be put on their possible avoidance and on appropriate management when they do occur.

Hydroxyapatite Use in Spine Surgery—Molecular and Clinical Aspect

Hydroxyapatite possesses desirable properties as a scaffold in tissue engineering: it is biocompatible at a site of implantation, and it is degradable to non-toxic products. Moreover, its porosity enables infiltration of cells, nutrients and waste products. The outcome of hydroxyapatite implantation highly depends on the extent of the host immune response. Authors emphasise major roles of the chemical, morphological and physical properties of the surface of biomaterial used. A number of techniques have been applied to transform the theoretical osteoconductive features of HAp into spinal fusion systems—from integration of HAp with autograft to synthetic intervertebral implants. The most popular uses of HAp in spine surgery include implants (ACDF), bone grafts in posterolateral lumbar fusion and transpedicular screws coating. In the past, autologous bone graft has been used as an intervertebral cage in ACDF. Due to the morbidity related to autograft harvesting from the iliac bone, a synthetic cage with osteoconductive material such as hydroxyapatite seems to be a good alternative. Regarding posterolateral lumbar fusion, it requires the graft to induce new bone growth and reinforce fusion between the vertebrae. Hydroxyapatite formulations have shown good results in that field. Moreover, the HAp coating has proven to be an efficient method of increasing screw fixation strength. It can decrease the risk of complications such as screw loosening after pedicle screw fixation in osteoporotic patients. The purpose of this literature review is to describe in vivo reaction to HAp implants and to summarise its current application in spine surgery.

Demineralized Bone Matrix in Spine Surgery: A Review of Current Applications and Future Trends

BACKGROUND

Graft augmentation for spinal fusion is an area of continued interest, with a wide variety of available products lacking clear recommendations regarding appropriate use. While iliac crest autograft has long been considered the "gold standard", suboptimal fusion rates along with harvest-related concerns continue to drive the need for graft alternatives. There are now multiple options of products with various characteristics that are available. These include demineralized bone matrix (DBM) and demineralized bone fibers (DBF), which have been used increasingly to promote spine fusion. The purpose of this review is to provide an updated narrative on the use of DBM/DBF in spine surgery.

METHODS

Literature review.

RESULTS

The clinical application of DBM in spine surgery has evolved since its introduction in the mid-1900s. Early preclinical studies demonstrated its effectiveness in promoting fusion. When used in the cervical, thoracic, and lumbar spine, more recent clinical data suggest similar rates of fusion compared with autograft, although clinical studies are primarily limited to level III or IV evidence with few level I studies. However, significant variability in surgical technique and type of product used in the literature limits its interpretation and overall application.

CONCLUSIONS

DBM and DBF are bone graft options in spine surgery. Most commonly used as graft extenders, they have the ability to increase the volume of traditional grafting techniques while potentially inducing new bone formation. While the literature supports good fusion rates when used in the lumbar spine and when used with adjuvant cages or additional grafting techniques in the cervical spine, care should be taken when using as a stand-alone product. As new literature emerges, DBM and DBF can be a useful method in a surgeon's armamentarium for fusion-based procedures.

In Vitro and In Vivo Study of a Novel Nanoscale Demineralized Bone Matrix Coated PCL/β-TCP Scaffold for Bone Regeneration

Bone defects remains a challenge for surgeons. Bone graft scaffold can fill the defect and enhance the bone regeneration. Demineralized bone matrix (DBM) is an allogeneic bone graft substitute, which can only be used as a filling material rather than a structural bone graft. Coating of the scaffolds with nanoscale DBM may enhance the osteoinductivity or osteoconductivity. Herein the lyophilization method is presented to coat the nano-DBM on surface of the porous polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP) scaffolds fabricated by 3D printing technology. The morphology, elastic modulus, in vitro cell biocompatibility, and in vivo performance are investigated. Scanning electron microscope (SEM) shows DBM particle clusters with size of 200-500 nm are observed on scaffolds fibers after coating. MC3T3-E1 cells on nano-DBM coated PCL/β-TCP scaffold show better activity than on PCL/β-TCP scaffold. In vivo tests show better infiltration of new bone tissue in nano-DBM coated PCL/β-TCP scaffold than PCL/β-TCP scaffold via the interface. These results show the presence of nano-DBM coating on PCL/β-TCP scaffold could enhance the attachment, proliferation, and viability of cells and benefit for the new bone formation surrounding and deep inside the scaffolds. Nano-DBM could potentially be used as a new kind of biomaterial for bone defect treatment.

Anterior Cervical Arthrodesis With Polyetheretherketone Spacers: What is the Role of the Grafting Material?

STUDY DESIGN

This was a retrospective study of 2 surgeons' use of a single polyetheretherketone (PEEK) device.

OBJECTIVE

Our objective was to investigate the fusion adjunct placed within PEEK devices to examine the likelihood of an arthrodesis, regardless of the PEEK interbody device itself.

SUMMARY OF BACKGROUND DATA

The effectiveness of PEEK interbody devices in anterior cervical arthrodesis has been questioned.

METHODS

The authors retrospectively reviewed the results of 121 patients with demineralized bone matrix (DBM) and 96 with local autograft bone placed within identical PEEK devices for anterior cervical arthrodesis (from 2011 to 2018); 1 surgeon used DBM and another local autograft bone. Arthrodesis was determined independently by a surgeon and 2 blinded neuroradiologists.

RESULTS

For DBM versus autograft; mean age was 60 versus 61 years, smoking status 42.1% versus 31%, diabetes mellitus 18.2% versus 28%, mean body mass index 31 versus 30, and follow up averaged 17 months in both groups. For DBM versus autograft; a radiographic arthrodesis was observed in 22.3% versus 76% of patients. Refusion at the index level was required in 5.8% of the DBM and 0% of the autograft patients.

CONCLUSIONS

A PEEK interbody device filled with local autograft resulted in a higher radiographic fusion rate and a lower need for reoperation at the index level than an identical device filled with DBM. Caution is warranted in assigning fusion failure to the PEEK device alone in anterior cervical discectomy and fusion surgery.

Structural Allograft Versus PEEK Implants in Anterior Cervical Discectomy and Fusion: A Systematic Review

STUDY DESIGN

Systematic literature review.

OBJECTIVE

Our primary objective was to compare reported fusion rates after anterior cervical discectomy and fusion (ACDF) using structural allograft versus polyetheretherketone (PEEK) interbody devices in patients with cervical spine degeneration. Our secondary objectives were to compare differences in rates of subsidence and reoperation and in patient-reported outcomes between the 2 groups.

METHODS

Through a systematic review of the English-language literature using various databases, we identified 4702 articles. After we applied inclusion and exclusion criteria, 14 articles (7 randomized controlled trials, 4 prospective studies, and 3 retrospective studies) reporting fusion rates of structural allograft or PEEK interbody devices were eligible for our analysis. No randomized controlled trials compared outcomes of structural allograft versus PEEK interbody devices. Extracted data included authors, study years, study designs, sample sizes, patient ages, duration of follow-up, types of interbody devices used, fusion rates, definition of fusion, reoperation rates, subsidence rates, and patient-reported outcomes.

RESULTS

Fusion rates were 82% to 100% for allograft and 88% to 98% for PEEK interbody devices. The reported data were insufficient to perform meta-analysis. Structural allograft had the highest reported rate of reoperation (14%), and PEEK interbody devices had the highest reported subsidence rate (18%). Patient-reported outcomes improved in both groups. There was insufficient high-quality evidence to compare the associations of various PEEK modifications with fusion rates.

CONCLUSION

Fusion rates were similar between structural allograft and PEEK interbody devices when used for ACDF for cervical spine degeneration. Currently, there is insufficient high-quality evidence to assess associations of PEEK modifications with fusion rates.

LEVEL OF EVIDENCE

II.

A Long-Term Follow-up, Multicenter, Comparative Study of the Radiologic, and Clinical Results Between a CaO-SiO2-P2O5-B2O3 Bioactive Glass Ceramics (BGS-7) Intervertebral Spacer and Titanium Cage in 1-Level Posterior Lumbar Interbody Fusion

STUDY DESIGN

This is a prospective, stratified randomized, multicenter, 4-year follow-up study.

OBJECTIVE

The authors aimed to evaluate the long-term clinical efficacy and safety of CaO-SiO2-P2O5-B2O3 glass ceramics (BGS-7) spacers in 1-level posterior lumbar interbody fusion (PLIF) at a 4-year follow-up.

SUMMARY OF BACKGROUND DATA

According to 1-year follow-up results, BGS-7 spacer showed similar fusion rates and clinical outcomes compared with titanium cage. A long-term follow-up study beyond 2 years is necessary to investigate the status of intervertebral bone graft volumes. Moreover, longer follow-up is mandatory to also evaluate the safety and efficacy of BGS-7 spacers, because they remain in the intervertebral space for a long time.

MATERIALS AND METHODS

In this prospective, randomized, multicenter, 4-year follow-up study, we evaluated 62 of the 74 patients who underwent 1-level PLIF. During 1-level PLIF, titanium cages filled with autologous local bone were inserted into the control group patients and BGS-7 spacers were inserted to the experimental group patients. Bone fusion was evaluated by plain radiography and thin-section computed tomography. Visual Analog Scale (VAS), the Oswestry Disability Index (ODI), Short Form-36 Health Survey (SF-36), and evaluation of safety were conducted after 48 months.

RESULTS

Computed tomography scan showed a bone fusion rate of 90.6% in the BGS-7 spacer group and 93.3% in the control group, with no significant differences between groups. The BGS-7 spacer group showed a significantly larger area directly fused to the endplate than the control group (P<0.001). The BGS-7 spacer group showed a significant increase in the fused area compared with the titanium group at 1- and 4-year follow-up. The ODI, SF-36, back pain, and lower limb pain in both groups showed significant improvement after surgery, and no significant differences were observed between the groups. Both groups showed no additional adverse events.

CONCLUSIONS

The 4-year follow-up study showed similar fusion rates and clinical outcomes in both the BGS-7 spacer and autologous bone with a titanium cage in 1-level PLIF. However, the BGS-7 spacer implants showed a larger area of fusion with the endplates than that of autologous bone with a titanium cage. Therefore, the results demonstrated that the BGS-7 spacer can be considered as a novel intervertebral spacer to achieve successful spinal fusion without safety concerns for long-term use.

Superiority Claims for Spinal Devices: A Systematic Review of Randomized Controlled Trials

STUDY DESIGN

Systematic review.

OBJECTIVES

Superiority claims for medical devices are commonly derived from noninferiority trials, but interpretation of such claims can be challenging. This study aimed to (a) establish the prevalence of noninferiority and superiority designs among spinal device trials, (b) assess the frequency of post hoc superiority claims from noninferiority studies, and (c) critically evaluate the risk of bias in claims that could translate to misleading conclusions.

METHODS

Study bias was assessed using the Cochrane Risk of Bias Tool. The risk of bias for the superiority claim was established based on post hoc hypothesis specification, analysis of the intention-to-treat population, post hoc modification of a priori primary outcomes, and sensitivity analyses.

RESULTS

Forty-one studies were identified from 1895 records. Nineteen (46%) were noninferiority trials. Fifteen more (37%) were noninferiority trials with a secondary superiority hypothesis specified a priori. Seven (17%) were superiority trials. Of the 34 noninferiority trials, 14 (41%) made superiority claims. A medium or high risk of bias was related to the superiority claim in 9 of those trials (64%), which was due to the analyzed population, lacking sensitivity analyses, claims not being robust during sensitivity analyses, post hoc hypotheses, or modified endpoints. Only 4 of the 14 (29%) noninferiority studies provided low bias in the superiority claim, compared with 3 of the 5 (60%) superiority trials.

CONCLUSIONS

Health care decision makers should carefully evaluate the risk of bias in each superiority claim and weigh their conclusions appropriately.

Bone Graft Substitutes in Single- or Double-Level Anterior Cervical Discectomy and Fusion: A Systematic Review

STUDY DESIGN

Systematic review OBJECTIVE.: To undertake a systematic review of published literature to evaluate efficacy of bone graft substitutes on radiographic and clinical outcomes in single- or double-level anterior cervical discectomy and fusion (ACDF) for degenerative disease.

SUMMARY OF BACKGROUND DATA

ACDF is one of the most common spinal surgeries completed in the United States. Today bone graft substitutes including ceramic-based synthetic bone grafts, allografts, bone morphogenetic proteins (BMPs), mesenchymal stem cells, and bone marrow aspirate are widely used to enhance fusions; even though the efficacy of these substitutes is poorly defined. Critical evaluation of these products is necessary to optimize radiographic and clinical outcomes for ACDF in degenerative disease.

METHODS

A systematic literature review of 22 published articles was conducted. All articles reported results on patients who underwent a single- or double-level ACDF performed using a bone graft substitute and reported results on radiographic fusion rates at least 6 months after surgery.

RESULTS

All studies using BMP showed 100% fusion rate despite length of the study or whether additional bone graft substitutes were used. Use of only ceramic-based synthetics had the lowest fusion rate, 80.5%. Use of only mesenchymal stem cells resulted in an average fusion rate of 87.7%. When used alone, allograft resulted in an average fusion rate of 87.3%. This was significantly influenced by one outlier, Kim et al, which when removed, increased the fusion rate to 93.5%. Clinical outcomes were improved postoperatively irrespective of the graft used, although dysphagia was significantly greater in studies using BMP (P < 0.001).

CONCLUSION

Allograft alone has the lowest cost with similar fusion rates and clinical outcomes compared to other bone graft substitutes. Physicians should consider this when choosing to use bone graft substitutes for routine ACDFs.

LEVEL OF EVIDENCE

4.

Evaluation of bony fusion after anterior cervical discectomy: a systematic literature review

PURPOSE

Anterior cervical discectomy and fusion (ACDF) has proven effective in treating radicular arm pain. Post-operatively, cervical spine stability is temporarily challenged, but data on bony fusion and speed of fusion are ambiguous; optimum evaluation method and criteria are debated.

AIM

To study bony fusion accomplishment and to obtain an overview of methods to evaluate fusion.

METHODS

A literature search was performed in PubMed and Embase. Included studies had to report original data concerning 1- or 2-level ACDF with intervertebral device or bone graft, where bony fusion was assessed using CT scans or X-rays.

RESULTS

A total of 146 articles comprising 10,208 patients were included. Bony fusion was generally defined as "the presence of trabecular bridging" and/or "the absence of motion". Fusion was accomplished in 90.1% of patients at the final follow-up. No gold standard for assessment could be derived from the results. Addition of plates and/or cages with screws resulted in slightly higher accomplishment of fusion, but differences were not clinically relevant. Eighteen studies correlated clinical outcome with bony fusion, and 3 found a significant correlation between accomplishment and better clinical outcome.

CONCLUSIONS

In approximately 90% of patients, bony fusion is accomplished one year after ACDF. As there is no generally accepted definition of bony fusion, different measuring techniques cannot be compared to a gold standard and it is impossible to determine the most accurate method. Variations in study design hamper conclusions on optimising the rate of bony fusion by choice of material and/or additives. Insufficient attention is paid to correlation between bony fusion and clinical outcome. These slides can be retrieved from electronic supplementary material.

Clinical and CT Analysis of Lumbar Spine Arthrodesis: β-Tricalcium Phosphate Versus Demineralized Bone Matrix

Background

Bone graft substitutes have been developed to circumvent donor site morbidity associated with iliac crest bone graft, but sparse literature compares the efficacy of various substitutes. Two commonly used bone graft substitutes used in lumbar fusion are β-tricalcium phosphate (BTP) and demineralized bone matrix (DBM).

Methods

A retrospective review of patients who underwent instrumented posterolateral lumbar fusion was conducted by a single surgeon from January 2013 to December 2016. Patients were divided into two groups based on whether DBM or BTP as graft in conjunction with local autograft. Clinical outcomes scores were collected at a minimum of 1-year follow-up. Postoperative CT scans were evaluated to assess fusion.

Results

Forty-one patients (DBM, 21 and BTP, 20) were reviewed. No significant differences were found in terms of age, sex, body mass index, smoking, diabetes, steroids, osteoporosis, American Society of Anesthesiologists classification, number of levels fused, estimated blood loss, length of stay, or surgical time between the DBM and BTP groups. A trend was found toward lower revision surgery (zero versus 15%), improved visual analog scale scores (postoperative change of 1.81 versus 3.25; P = 0.09), and higher rates of fusion (90% versus 70%; P = 0.09) in the DBM group compared with the BTP group.

Conclusions

No significant difference was found in clinical outcomes at 1 year, with a trend toward a higher fusion rate and lower revision surgery with DBM.

Clinical Application of Ceramics in Anterior Cervical Discectomy and Fusion: A Review and Update

STUDY DESIGN

Narrative review.

OBJECTIVES

Anterior cervical discectomy and fusion (ACDF) is a reliable procedure, commonly used for cervical degenerative disc disease. For interbody fusions, autograft was the gold standard for decades; however, limited availability and donor site morbidities have led to a constant search for new materials. Clinically, it has been shown that calcium phosphate ceramics, including hydroxyapatite (HA) and tricalcium phosphate (TCP), are effective as osteoconductive materials and bone grafts. In this review, we present the current findings regarding the use of ceramics in ACDF.

METHODS

A review of the relevant literature examining the clinical use of ceramics in anterior cervical discectomy and fusion procedures was conducted using PubMed, OVID and Cochrane.

RESULT

HA, coralline HA, sandwiched HA, TCP, and biphasic calcium phosphate ceramics were used in combination with osteoinductive materials such as bone marrow aspirate and various cages composed of poly-ether-ether-ketone (PEEK), fiber carbon, and titanium. Stand-alone ceramic spacers have been associated with fracture and cracks. Metallic cages such as titanium endure the risk of subsidence and migration. PEEK cages in combination with ceramics were shown to be a suitable substitute for autograft.

CONCLUSION

None of the discussed options has demonstrated clear superiority over others, although direct comparisons are often difficult due to discrepancies in data collection and study methodologies. Future randomized clinical trials are warranted before definitive conclusions can be drawn.

Anterior cervical fusion with interbody cage containing beta-tricalcium phosphate: Clinical and radiological results

Aim

Beta tricalcium phosphate (beta-TCP) is an osteoconductive, resorbable material. Its clinical effectiveness has been proved in many indications. This study was clinical and radiographic study report obtained in patients undergoing anterior cervical discectomy and fusion ACDF in which PEEK cages were filled beta-TCP in an injectable form.

Material and methods

Between January 2010 and June 2011, 16 consecutive patients underwent ACDF using PEEK cages with beta-TCP. The cohort compromised 10 men and 6 women with a mean age of 45.2 years. The surgery was performed when the patient had myelopathy or radiculopathy with progressive neurological deficit, or failure of conservative treatment (a minimum of 3 months). The patients were evaluated by Odom criteria preoperatively and postoperative 3rd, 6th, 12th and 24th months. Preop and postop pain was evaluated with visual analogue scala (VAS). Disc height and fusion success rates were evaluated.

Results

Preoperative average VAS score was 7.9 (7–10) for neck pain and 8 (7–10) for arm pain. At the final follow-up, these scores became 1.5 and 1.4 for neck and arm pain, respectively. The average improvement rate was 81% for neck pain and 82.5% for arm pain. Postop ODOM's criteria main rate was 3.4. Bone fusion was achieved in 14 segments (70%) at 3rd month, 19 segments (95%) at 12th month follow-up assessment.

Conclusion

Clinical and radiological results revealed that B-TCP is a good alternative synthetic fusion material for cervical interbody fusion.

Level of evidence: Level IV, therapeutic study.

The Influences of Different Ratios of Biphasic Calcium Phosphate and Collagen Augmentation on Posterior Lumbar Spinal Fusion in Rat Model

PURPOSE

To determine the influence of different ratios of hydroxyapatite (HA)/beta tricalcium phosphate (β-TCP) and collagen augmentation for posterior lumbar fusion in a rat model.

MATERIALS AND METHODS

We generated a posterior lumbar fusion model in 50 rats and divided it into five groups of equal number as follows; 1) autologous bone graft as group A, 2) 70% HA+30% β-TCP as group B, 3) 70% HA+30% β-TCP+collagen as group C, 4) 30% HA+70% β-TCP as group D, and 5) 30% HA+70% β-TCP+collagen as group E. Rats were euthanized at 12 weeks after surgery and fusion was assessed by manual palpation, quantitative analysis using microCT and histology.

RESULTS

The score of manual palpation was significantly higher in group C than group E (3.1±1.1 vs. 1.8±0.8, p=0.033). However, in terms of microCT analysis, group D showed significantly higher scores than group B (5.5±0.8 vs. 3.1±1.1, p=0.021). According to quantitative volumetric analysis, 30% HA+70% β-TCP groups (group D and E) showed significantly reduced fusion mass at 12 weeks after surgery (123±14.2, 117±46.3 vs. 151±27.3, p=0.008, 0.003, respectively). Collagen augmentation groups revealed superior results in terms of both microCT score and histologic grade.

CONCLUSION

A 7:3 HA/β-TCP ratio with collagen augmentation rather than a 3:7 HA/β-TCP ratio could be a more favorable graft substitute for lumbar spinal fusion. There was positive role of collagen as an adjunct for spinal bone fusion process.

Bone Union Rate Following Instrumented Posterolateral Lumbar Fusion: Comparison between Demineralized Bone Matrix versus Hydroxyapatite

Study Design

Retrospective study.

Purpose

To compare the union rate of posterolateral lumbar fusion (PLF) using demineralized bone matrix (DBM) versus hydroxyapatite (HA) as bone graft extender.

Overview of Literature

To our knowledge, there has been no clinical trial to compare the outcomes of DBM versus HA as a graft material for PLF.

Methods

We analyzed prospectively collected data from consecutive 79 patients who underwent instrumented PLF. Patients who received DBM were assigned to group B (n=38), and patients who received HA were assigned into group C (n=41). The primary study outcome was fusion rate assessed with radiographs. The secondary outcomes included pain intensity using a visual analogue scale, functional outcome using Oswestry disability index score, laboratory tests of inflammatory profiles and infection rate.

Results

One year postoperatively, bone fusion was achieved in 73% in group B and 58% in group C without significant difference between the groups (p=0.15). There were no differences between the groups with respect to secondary outcomes.

Conclusions

DBM would provide noninferior outcomes compared to the HA as a fusion material for PLF, and could be a notable alternative.

Matched Comparison of Fusion Rates between Hydroxyapatite Demineralized Bone Matrix and Autograft in Lumbar Interbody Fusion

Objective

To compare the fusion rate of a hydroxyapatite demineralized bone matrix (DBM) with post-laminectomy acquired autograft in lumbar interbody fusion surgery and to evaluate the correlation between fusion rate and clinical outcome.

Methods

From January 2013 to April 2014, 98 patients underwent lumbar interbody fusion surgery with hydroxyapatite DBM (HA-DBM group) in our institute. Of those patients, 65 received complete CT scans for 12 months postoperatively in order to evaluate fusion status. For comparison with autograft, we selected another 65 patients who underwent lumbar interbody fusion surgery with post-laminectomy acquired autograft (Autograft group) during the same period. Both fusion material groups were matched in terms of age, sex, body mass index (BMI), and bone mineral density (BMD). To evaluate the clinical outcomes, we analyzed the results of visual analogue scale (VAS), Oswestry Disability Index (ODI), and Short Form Health Survey (SF-36).

Results

We reviewed the CT scans of 149 fusion levels in 130 patients (HA-DBM group, 75 levels/65 patients; Autograft group, 74 levels/65 patients). Age, sex, BMI, and BMD were not significantly different between the groups (p=0.528, p=0.848, p=0.527, and p=0.610, respectively). The HA-DBM group showed 39 of 75 fused levels (52%), and the Autograft group showed 46 of 74 fused levels (62.2%). This difference was not statistically significant (p=0.21). In the HA-DBM group, older age and low BMD were significantly associated with non-fusion (61.24 vs. 66.68, p=0.027; -1.63 vs. -2.29, p=0.015, respectively). VAS and ODI showed significant improvement after surgery when fusion was successfully achieved in both groups (p=0.004, p=0.002, HA-DBM group; p=0.012, p=0.03, Autograft group).

Conclusion

The fusion rates of the hydroxyapatite DBM and Autograft groups were not significantly different. In addition, clinical outcomes were similar between the groups. However, older age and low BMD are risk factors that might induce non-union after surgery with hydroxyapatite DBM.