Scientific, Clinical, Regulatory, and Economic Aspects of Choosing Bone Graft/Biological Options in Spine Surgery

Exploring an innovative augmentation strategy in spinal fusion: A novel selective prostaglandin EP4 receptor agonist as a potential osteopromotive factor to enhance lumbar posterolateral fusion

BACKGROUND

On-site delivery of bioactive agents facilitates enhancing the effectiveness of spinal fusion. However, the FDA-approved agents currently used in clinical practice are limited by side effects and cost issues, urging exploration of new alternatives.

AIM

This study aimed to investigate the effectiveness of KMN-159, a novel selective prostaglandin EP4 receptor agonist with osteopromotive properties, in spinal posterolateral fusion (PLF) surgery.

METHODS

Various doses of KMN-159 were delivered locally using a mineralized collagen matrix (MCM) scaffold, and its efficacy results were compared with FDA-approved recombinant human bone morphogenetic protein-2 (rhBMP-2) in a rat lumbar PLF model. 192 male Wistar rats, aged 10 weeks, were randomized into 8 groups: 1) SHAM, 2) MCM, 3) MCM +10 μg rhBMP-2 (per scaffold), 4-8) MCM + 0.1, 1, 10, 100 or 1000 μg KMN-159 (per scaffold). PLF surgery was performed at the L4-5 level, and animals were euthanized after 3 and 6 weeks for spinal fusion evaluation.

RESULTS

KMN-159 exhibited dose-dependent osteopromotive effects on osteoblasts, osteoclasts, and vascular ingrowth within MCM carriers, resulting in new bone formation in a dose-dependent manner. The mid- and high-dose KMN-159 (10, 100, and 1000 μg) groups significantly enhanced PLF with biomechanical improvement, while low-dose (0.1 and 1 μg) groups were insufficient to achieve lumbar fusion.

CONCLUSION

KMN-159 emerges as a novel osteopromotive factor, coupled with its functionalized MCM scaffold presents a potential bioactive material for enhancing PLF surgery outcomes.

Comparing Lumbar Spine Cages and Bone Grafts in Spinal Arthrodesis: A Meta-Analysis of Clinical Outcomes

INTRODUCTION AND AIM

The role of interbody cages in lumbar arthrodesis remains debated despite widespread adoption. This meta-analysis aimed to compare clinical and radiological outcomes between synthetic cages and structural bone grafts in lumbar fusion surgery from the latest updated evidence based on subgroup-based analysis and stratification of outcomes.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to conduct a literature search across major databases through December 2024. Studies comparing lumbar interbody fusion outcomes between cage and bone graft cohorts were included in this analysis. Random-effects meta-analyses were performed for fusion rates, radiographic parameters, clinical outcomes, and complications. Subgroup analyses stratified results by surgical approach, cage material, and graft type.

RESULTS

Twenty studies (1,452 patients) met inclusion criteria. Cage utilization demonstrated significantly higher fusion rates (96.3% versus 90.8%, RR=2.74, p=0.03) and greater disc height maintenance (MD=0.73 mm, 95% CI=0.45-1.01). Polyetheretherketone (PEEK) cages showed superior fusion rates compared to titanium (RR=1.00 versus 0.94, p=0.042). Back pain improvement was greater in the cage group (MD=0.65, 95% CI=0.08-1.22), while complication and reoperation rates remained comparable. No significant differences were observed in lordosis restoration or Oswestry Disability Index (ODI) scores.

CONCLUSIONS

Synthetic cage implementation in lumbar arthrodesis is associated with superior fusion rates and disc height maintenance, especially with PEEK devices. These benefits occur without increased complications, supporting cage utilization in appropriate clinical scenarios. Future studies should focus on long-term outcomes and cost-effectiveness analyses.

Comparison of Interbody Fusion Strategies in Anterior Cervical Discectomy and Fusion: A Network Meta-Analysis and Systematic Review

OBJECTIVE

The optimal choice for fusion strategy in Anterior Cervical Discectomy and Fusion (ACDF) remains an unresolved issue. This study aims to perform a network meta-analysis and systematic review of fusion rate and complication rate of various fusion strategies used in ACDF.

METHODS

This study followed Prisma guidelines, and we searched PubMed, Embase, Cochrane Library, and Web of Science from inception to November 11, 2022, for Randomized Controlled trials comparing the efficacy and safety of fusion modalities in ACDF. The primary outcome was the fusion rate and complication rate. The PROSPERO number is CRD42022374440.

RESULTS

This meta-analysis identified 26 Randomized Controlled trial studies with 1789 patients across 15 fusion methods. The cage with autograft + plating showed the highest fusion rate, surpassing other methods like iliac crest bone graft (ICBG) and artificial bone graft (AFG). The stand-alone cage with autograft (SATG) had the second highest fusion rate. Regarding complication rate, the cage with AFG (CAFG) had the highest rate, more than other methods. The ICBG had a higher complication rate compared to ICBG + P, AFG, stand-alone cage with artificial bone graft, SATG, and CALG. The SATG performed well in both fusion and complication rate.

CONCLUSIONS

In this study, we conducted the first network meta-analysis to compare the efficacy and safety of various fusion methods in ACDF. Our findings suggest that SATG, with superior performance in fusion rate and complication rate, may be the optimal choice for ACDF. However, the results should be interpreted cautiously until additional research provides further evidence.

Outcomes of Xenograft with Platelet-rich Fibrin versus Autogenous Bone in Alveolar Cleft Grafting

Background

The use of a suitable graft material helps with sufficient osseointegration. The aim of this study was to compare the clinical and radiographic outcomes of two types of alveolar bone graft materials, xenografts with platelet-rich fibrin (PRF) and autogenous grafts, in patients with alveolar clefts.

Methods

Thirty-six patients with alveolar clefts were enrolled in this study. Those patients were randomly divided into two groups: group A, where the autogenous iliac bone graft was used to fill the alveolar defect, and group B, where the xenograft with PRF was used to fill the alveolar defect. After 6 months of grafting, patients were assessed in terms of pain, duration of hospital stay, and donor site morbidity associated with iliac crest harvesting, while bone formation was evaluated radiographically using cone beam computed tomography.

Results

The results showed no statistical differences as regards baseline and perioperative data. Operative duration was significantly lower among xenograft with PRF patients. Both groups had comparable postoperative success scores, and total failure was reported in a total of three patients (one patient in group A and two patients in group B).

Conclusions

With no potential donor site morbidities, xenograft with PRF is an equivalent bone transplant replacement to the autologous iliac bone graft. Additionally, it is associated with a significant success rate, and a significant decrease in operative time and hospital stay. Many future studies are warranted to draw firm conclusions.

Mycobacterium tuberculosis Infection After Grafting of Infected Bone: A Case Series of Four Patients

Back pain is one of the commonly reported medical symptoms, and the mainstay of treatment is conservative care and rehabilitation, but in severe cases with nerve compression from herniated discs, spondylolisthesis, fractures, or spinal canal stenosis, surgery can be helpful. The use of donor bone grafting is common but associated with some complications, including infection.  We present a case series of four patients who underwent spinal surgery with allograft bone transplantation and developed Mycobacterium tuberculosis (MTB) disease due to infected bone grafts. Each patient required 12 months of therapy for MTB disease and had various complications from the required anti-mycobacterial treatment.  After the first outbreak of MTB infection from donor bone grafting in 2021, the tissue procurement organizations implemented the use of nucleic acid amplification testing for MTB in the bone allografts, but this is not the most sensitive test available. This test did not detect the MTB in the tissue that was implicated in the second outbreak, and cultures for MTB did not become positive until the bone had already been distributed and grafted into 36 patients.  In response to both outbreaks, the American Association of Tissue Banks (AATB) has recently published new guidelines, which include recommended criteria and literature reviews to aid with screening out cases that may have MTB and improving safety measures for recipient patients.

Structural Versus Nonstructural Bone Grafting Via the Posterior Approach in the Treatment of Thoracic and Lumbar Tuberculosis: A Systematic Review and Meta-Analysis

BACKGROUND

Bone grafting is necessary in spinal tuberculosis surgery. Structural bone grafting is considered the gold standard treatment for spinal tuberculosis bone defects; however, nonstructural bone grafting via the posterior approach has recently gained attention. In this meta-analysis, we evaluated the clinical efficacy of structural versus nonstructural bone grafting via the posterior approach in the treatment of thoracic and lumbar tuberculosis.

METHODS

Studies comparing the clinical efficacy of structural and nonstructural bone grafting via the posterior approach in spinal tuberculosis surgery were identified from 8 databases from inception to August 2022. Study selection, data extraction, and evaluation of the risk of bias were performed, and meta-analysis was conducted.

RESULTS

Ten studies including 528 patients with spinal tuberculosis were enrolled. Meta-analysis revealed no between-group differences in fusion rate (P = 0.29), complications (P = 0.21), postoperative Cobb angle (P = 0.7), visual analog scale score (P = 0.66), erythrocyte sedimentation rate (P = 0.74), or C-reactive protein level (P = 0.14) at the final follow-up. Nonstructural bone grafting was associated with less intraoperative blood loss (P < 0.00001), shorter operation time (P < 0.0001), shorter fusion time (P < 0.01), and shorter hospital stay (P < 0.00001), while structural bone grafting was associated with lower Cobb angle loss (P = 0.002).

CONCLUSIONS

Both techniques can achieve a satisfactory bony fusion rate for spinal tuberculosis. Nonstructural bone grafting has the advantages of less operative trauma, shorter fusion time, and shorter hospital stay, making it an attractive option for short-segment spinal tuberculosis. Nevertheless, structural bone grafting is superior for maintaining corrected kyphotic deformities.

Evaluation of interbody fusion efficacy and biocompatibility of a polyetheretherketone/calcium silicate/porous tantalum cage in a goat model

Objective

To evaluate the interbody fusion efficacy and biocompatibility of a graft-free cage made of polyetheretherketone/calcium silicate composite/porous tantalum (PEEK/CS/pTa cage) compared with a PEEK/CS cage with an autogenous bone graft in a goat model.

Methods

PEEK/CS/pTa and PEEK/CS cages were prepared through an injection-moulding method. The PEEK/CS composites and porous tantalum were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) mapping. Then, adult goats were chosen for C2/C3 and C3/C4 discectomy via the anterior cervical approach and randomly implanted with PEEK/CS/pTa and PEEK/CS/cages with autogenous bone grafts. The fusion performance and osseointegration of the cages were evaluated by X-ray imaging, magnetic resonance imaging (MRI) scanning, and bone histomorphometry analysis. Moreover, the concentrations of Ca and Si in urine, serum, tissue around the fusion segments and major organs of the goats were determined by inductively coupled plasma–optical emission spectrometry (ICP–OES). Histological observation of major organs of the goats was used to evaluate the biosafety of PEEK/CS/pTa and PEEK/CS cages.

Results

X-ray and MRI imaging suggested that both PEEK/CS/pTa cages and PEEK/CS cages maintained similar average intervertebral space heights. The tissue volumes in the fusion area were comparable between the two groups of cages at 26 weeks after surgery. Histological morphometric data showed that PEEK/CS/pTa cages and PEEK/CS cages with autogenous bone grafts had similar bone contact and osseointegration at 12 and 26 weeks. Element determination of serum, urine, spinal cord, dura matter, bone and organs showed that the CS/PEEK cages did not cause abnormal systemic metabolism or accumulation of calcium and silicon in local tissues and major organs of goats after implantation. No obvious pathological changes were found in the heart, liver, spleen, liver or kidney tissues.

Conclusion

Overall, these results suggested that the graft-free PEEK/CS/pTa cage showed similar bony fusion performance to the PEEK/CS cages with autogenous bone grafts. The cages releasing calcium and silicon had good biological safety in vivo.

The translational potential of this article: This study provided a new graft-free interbody fusion solution to patients with degenerative disc diseases, which could avert potential donor-site complications. This study also provided a detailed assessment of element excretion and accumulation of Ca and Si in vivo, which validated the biosafety of this new type of bioactive interbody fusion cage.

Bioceramic Scaffold Materials in Joint Movement Rehabilitation of Patients with Osteoarthritis

Arthritis occurs when the bones and joints have focal or degenerative diseases. This can lead to impaired performance and quality of life of the patient. Surgical treatment is used when the bones and joints are worn out or tumors, but often due to incomplete surgery, repeated attacks will occur. Bioceramic scaffold materials can assist in repairing cartilage tissue defects and, at the same time, contribute to arthritis rehabilitation. Therefore, this article will take this as the starting point of the research and use the new porous nanoceramic scaffold material to study its effect on joint repair in patients with osteoarthritis. The research results confirmed that the porous nanoceramic scaffold material has good biocompatibility in the treatment.

A systematic review and meta-analysis of fusion rate enhancements and bone graft options for spine surgery

Our study aimed to evaluate differences in outcomes of patients submitted to spinal fusion using different grafts measuring the effectiveness of spinal fusion rates, pseudarthrosis rates, and adverse events. Applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, this systematic review and meta-analysis identified 64 eligible articles. The main inclusion criteria were adult patients that were submitted to spinal fusion, autologous iliac crest (AIC), allograft (ALG), alloplastic (ALP; hydroxyapatite, rhBMP-2, rhBMP-7, or the association between them), and local bone (LB), whether in addition to metallic implants or not, was applied. We made a comparison among those groups to evaluate the presence of differences in outcomes, such as fusion rate, hospital stay, follow-up extension (6, 12, 24, and 48 months), pseudarthrosis rate, and adverse events. Sixty-four studies were identified. LB presented significantly higher proportions of fusion rates (95.3% CI 89.7–98.7) compared to the AIC (88.6% CI 84.8–91.9), ALG (87.8% CI 80.8–93.4), and ALP (85.8% CI 75.7–93.5) study groups. Pseudarthrosis presented at a significantly lower pooled proportion of ALG studies (4.8% CI 0.1–15.7) compared to AIC (8.6% CI 4.2–14.2), ALP (7.1% CI 0.9–18.2), and LB (10.3% CI 1.8–24.5). ALP and AIC studies described significantly more cases of adverse events (80 events/404 patients and 860 events/2001 patients, respectively) compared to LB (20 events/311 patients) and ALG (73 events/459 patients). Most studies presented high risk-of-bias scores. Based on fusion rates and adverse events proportions, LB showed a superior trend among the graft cases we analyzed. However, our review revealed highly heterogeneous data and a need for more rigorous studies to better address and assist surgeons’ choices of the best spinal grafts.

History of Bone Grafts in Spine Surgery

Bone grafting replaces damaged or missing bone with new bone and is used for surgical arthrodesis. Patients benefit from a huge variety of bone graft techniques and options for spinal fusions. This article reviews the rich history of bone grafts in surgery with particular emphasis on spinal fusion. During the early years of bone grafting in spine surgery, bone grafts were used on tuberculosis patients, and the structural support of the graft was most the important consideration. Between 1960 and 2000, many advances were made, specifically in the use of bone graft substitutes. The field of bone grafts in spine surgery has evolved rapidly since first described.

Investigating the efficacy of allograft cellular bone matrix for spinal fusion: a systematic review of the literature

OBJECTIVE

The use of allograft cellular bone matrices (ACBMs) in spinal fusion has expanded rapidly over the last decade. Despite little objective data on its effectiveness, ACBM use has replaced the use of traditional autograft techniques, namely iliac crest bone graft (ICBG), in many centers.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic review was conducted of the PubMed, Cochrane Library, Scopus, and Web of Science databases of English-language articles over the time period from January 2001 to December 2020 to objectively assess the effectiveness of ACBMs, with an emphasis on the level of industry involvement in the current body of literature.

RESULTS

Limited animal studies (n = 5) demonstrate the efficacy of ACBMs in spinal fusion, with either equivalent or increased rates of fusion compared to autograft. Clinical human studies utilizing ACBMs as bone graft expanders or bone graft substitutes (n = 5 for the cervical spine and n = 8 for the lumbar spine) demonstrate the safety of ACBMs in spinal fusion, but fail to provide conclusive level I, II, or III evidence for its efficacy. Additionally, human studies are plagued with several limiting factors, such as small sample size, lack of prospective design, lack of randomization, absence of standardized assessment of fusion, and presence of industry support/relevant conflict of interest.

CONCLUSIONS

There exist very few objective, unbiased human clinical studies demonstrating ACBM effectiveness or superiority in spinal fusion. Impartial, well-designed prospective studies are needed to offer evidence-based best practices to patients in this domain.

Trends in Spinal Surgery Performed by American Board of Orthopaedic Surgery Part II Candidates (2008 to 2017)

INTRODUCTION

The American Board of Orthopaedic Surgery (ABOS) Part II Oral Examination is typically taken two calendar years after fellowship completion. Despite previous studies using ABOS Part II Oral Examination data in other subspecialties, types of cases performed by spine surgeons in initial independent practice have not been well-studied. Such data may help trainees anticipate case composition observed in early practice and allow spine fellowship programs to understand emerging trends.

METHODS

We retrospectively reviewed surgical cases submitted to the ABOS by candidates taking the Part II Oral Examination between 2008 and 2017 whose designated subspecialty was spine. A hierarchical, restrictive algorithm was used to determine procedures based on candidate-reported International Classification of Diseases 9th/10th Revision and Current Procedural Terminology codes. Adjusted multivariable Poisson regression analyses were used to assess changes in procedure incidence rates over time.

RESULTS

We identified 37,539 cases, averaging 3,754 cases/yr, and an average of 49 cases per candidate per 6-month collection period. The most common procedures were lumbar diskectomy (22% of all procedures), posterolateral spinal fusion (PSF) (19%), and anterior cervical diskectomy and fusion (ACDF) (17%). Rates of ACDF and cervical disk arthroplasty significantly increased over time (incidence rate ratios of 1.41 and 23.3 times higher, respectively, at the end of the study period), whereas rates of cervical foraminotomy, lumbar diskectomy, PSF, and structural autograft use decreased (incidence rate ratios of 0.35, 0.84, 0.55, and 0.30). Rates of anterior lumbar interbody fusion/lateral lumbar interbody fusion and transforaminal lumbar interbody fusion did not significantly change over the study period.

DISCUSSION

Recent spine fellowship graduates are performing more cervical disk arthroplasties and ACDFs while decreasingly using structural autograft as well as performing fewer PSFs and lumbar diskectomies. Techniques such as anterior lumbar interbody fusion/lateral lumbar interbody fusions and transforaminal lumbar interbody fusions have not changed significantly over the last decade.

LEVEL OF EVIDENCE

Level IV (retrospective case series study).

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.

New Strategies in Enhancing Spinal Fusion

The biologic steps involved in creating a bony fusion between adjacent segments of the spine are a complex and highly coordinated series of events. There have been significant advancements in bone grafts and bone graft substitutes in order to augment spinal fusion. While autologous bone grafting remains the gold standard, allograft bone grafting, synthetic bone graft substitutes, and bone graft enhancers are appropriate in certain clinical situations. This article provides an overview of the basic biology of spinal fusion and strategies for enhancing fusion through innovations in bone graft material.

History of Spinal Fusion: Where We Came from and Where We Are Going

Spinal fusion surgery is performed all over the world to help patients with cervical and thoracolumbar pathology. As outcomes continue to improve in patients with spine-related pathology, it is important to understand how we got to modern day spinal fusion surgery. Scientific innovations have ranged from the first spinal fusions performed with basic instrumentation in the late nineteenth century to contemporary tools such as pedicle screws, bone grafts, and interbody devices. This article tracks this technological growth so that surgeons may better serve their patients in treating spine-related pain and disability.