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

Comparison of Fusion Rates among Various Demineralized Bone Matrices in Posterior Lumbar Interbody Fusion

Background and Objectives: Posterior lumbar interbody fusion (PLIF) plays a crucial role in addressing various spinal disorders. The success of PLIF is contingent upon achieving bone fusion, as failure can lead to adverse clinical outcomes. Demineralized bone matrix (DBM) has emerged as a promising solution for promoting fusion due to its unique combination of osteoinductive and osteoconductive properties. This study aims to compare the effectiveness of three distinct DBMs (Exfuse®, Bongener®, and Bonfuse®) in achieving fusion rates in PLIF surgery. Materials and Methods: A retrospective review was conducted on 236 consecutive patients undergoing PLIF between September 2016 and February 2019. Patients over 50 years old with degenerative lumbar disease, receiving DBM, and following up for more than 12 months after surgery were included. Fusion was evaluated using the Bridwell grading system. Bridwell grades 1 and 2 were defined as 'fusion', while grades 3 and 4 were considered 'non-fusion.' Clinical outcomes were assessed using visual analog scale (VAS) scores for pain, the Oswestry disability index (ODI), and the European quality of life-5 (EQ-5D). Results: Fusion rates were 88.3% for Exfuse, 94.3% for Bongener, and 87.7% for Bonfuse, with no significant differences. All groups exhibited significant improvement in clinical outcomes at 12 months after surgery, but no significant differences were observed among the three groups. Conclusions: There were no significant differences in fusion rates and clinical outcomes among Exfuse, Bongener, and Bonfuse in PLIF surgery.

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.

Construction of three-dimensional, homogeneous regenerative cartilage tissue based on the ECG-DBM complex

Introduction: The feasibility of using a steel decalcified bone matrix (DBM)-reinforced concrete engineered cartilage gel (ECG) model concept for in vivo cartilage regeneration has been demonstrated in preliminary experiments. However, the regenerated cartilage tissue contained an immature part in the center. The present study aimed to achieve more homogeneous regenerated cartilage based on the same model concept. Methods: For this, we optimized the culture conditions for the engineered cartilage gel-decalcified bone matrix (ECG-DBM) complex based on the previous model and systematically compared the in vitro chondrogenic abilities of ECG in the cartilage slice and ECG-DBM complex states. We then compared the in vivo cartilage regeneration effects of the ECG-DBM complex with those of an equivalent volume of ECG and an equivalent ECG content. Results and discussion: Significant increases in the DNA content and cartilage-specific matrix content were observed for the ECG-DBM complex compared with the ECG cartilage slice, suggesting that the DBM scaffold significantly improved the quality of ECG-derived cartilage regeneration in vitro. In the in vivo experiments, high-quality cartilage tissue was regenerated in all groups at 8 weeks, and the regenerated cartilage exhibited typical cartilage lacunae and cartilage-specific extracellular matrix deposition. Quantitative analysis revealed a higher chondrogenic efficiency in the ECG-DBM group. Specifically, the ECG-DBM complex achieved more homogeneous and stable regenerated cartilage than an equivalent volume of ECG and more mature regenerated cartilage than an equivalent ECG content. Compared with ECG overall, ECG-DBM had a more controllable shape, good morphology retention, moderate mechanical strength, and high cartilage regeneration efficiency. Further evaluation of the ECG-DBM complex after in vitro culture for 7 and 14 days confirmed that an extended in vitro preculture facilitated more homogeneous cartilage regeneration.

Lumbar Interbody Fusion and Osteobiologics for Lumbar Fusion

Lumbar interbody fusion (LIF) is an excellent treatment option for a number of lumbar diseases. LIF can be performed through posterior, transforaminal, anterior, and lateral or oblique approaches. Each technique has its own pearls and pitfalls. Through LIF, segmental stabilization, neural decompression, and deformity correction can be achieved. Minimally invasive surgery has recently gained popularity and each LIF procedure can be performed using minimally invasive techniques to reduce surgery-related complications and improve early postoperative recovery. Despite advances in surgical technology, surgery-related complications after LIF, such as pseudoarthrosis, have not yet been overcome. Although autogenous iliac crest bone graft is the gold standard for spinal fusion, other bone substitutes are available to enhance fusion rate and reduce complications associated with bone harvest. This article reviews the surgical procedures and characteristics of each LIF and the osteobiologics utilized in LIF based on the available evidence.

Clinical and radiological outcomes in patients who underwent posterior lumbar interbody fusion: comparisons between unilateral and bilateral cage insertion

BACKGROUND

Although the original technique involves inserting two cages bilaterally, there could be situations that only allow for insertion of one cage unilaterally. However, only a few studies have compared the outcomes between unilateral and bilateral cage insertion. The purpose of this study was to compare the clinical and radiological outcomes in patients who underwent posterior lumbar interbody fusion (PLIF) between unilaterally and bilaterally inserted cages.

METHODS

Among 206 eligible patients who underwent 1- or 2-level PLIF, 78 patients were 1:3 cohort-matched by age, sex, and operation level (group U, 19 patients with unilateral cages; and group B, 57 patients with bilateral cages). Fusion status was evaluated by computed tomography (CT) scans at postoperative 1 year. Clinical outcomes were measured by visual analog scale (VAS), Oswestry Disability Index (ODI), and EQ-5D. Radiological and clinical parameters were compared between the two groups. Risk factors for pseudarthrosis were also analyzed by multivariate analysis.

RESULTS

The demographic data were not significantly different between the two groups. However, previous laminectomy, asymmetric disc collapse, and fusion at L5-S1 level were more frequently found in group U (P = 0.003, P = 0.014, and P = 0.014, respectively). Furthermore, pseudarthrosis was more frequently observed in group U (36.8%) than in group B (7.0%) (P = 0.004). Back pain VAS was higher in group U at postoperative 1 year (P = 0.033). Lower general activity function of EQ-5D was observed in group U at postoperative 1 year (P = 0.035). Older age (P = 0.028), unilateral cage (P = 0.007), and higher bone mineral density (P = 0.033) were positively correlated with pseudarthrosis.

CONCLUSIONS

Unilaterally inserted cage might be a possible risk factor for pseudarthrosis when performing PLIF, which could be related with the difficult working conditions such as scars due to previous laminectomy or asymmetric disc collapse. Furthermore, suboptimal clinical outcomes are expected following PLIF with unilateral cage insertion at postoperative 1 year regardless of similar clinical outcomes at postoperative 2 year. Therefore, caution is advised when inserting cages unilaterally, especially under above-mentioned conditions in terms of its possible relationship with symptomatic pseudarthrosis.

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.

Understanding the Future Prospects of Synergizing Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery with Ceramics and Regenerative Cellular Therapies

Transforaminal lumber interbody fusion (TLIF) is the last resort to address the lumber degenerative disorders such as spondylolisthesis, causing lower back pain. The current surgical intervention for these abnormalities includes open TLIF. However, in recent years, minimally invasive TLIF (MIS-TLIF) has gained a high momentum, as it could minimize the risk of infection, blood loss, and post-operative complications pertaining to fusion surgery. Further advancement in visualizing and guiding techniques along with grafting cage and materials are continuously improving the safety and efficacy of MIS-TLIF. These assistive techniques are also playing a crucial role to increase and improve the learning curve of surgeons. However, achieving an appropriate output through TLIF still remains a challenge, which might be synergized through 3D-printing and tissue engineering-based regenerative therapy. Owing to their differentiation potential, biomaterials such as stem/progenitor cells may contribute to restructuring lost or damaged tissues during MIS-TLIF, and this therapeutic efficacy could be further supplemented by platelet-derived biomaterials, leading to improved clinical outcomes. Thus, based on the above-mentioned strategies, we have comprehensively summarized recent developments in MIS-TLIF and its possible combinatorial regenerative therapies for rapid and long-term relief.

Surgical outcomes of two kinds of demineralized bone matrix putties/local autograft composites in instrumented posterolateral lumbar fusion

Background

This study aimed to assess the surgical outcomes of two kinds of demineralized bone matrix (DBM) putties/local autograft composites in instrumented posterolateral lumbar fusion (PLF).

Methods

Twenty-seven fusion segments of 19 patients, who underwent decompression and instrumented PLF for lumbar spinal stenosis or degenerative spondylolisthesis less than grade 1, were included in this study. The PLF mass consisted of different two kinds of DBMs (Grafton® and DBX®) and local autograft. Next, 7.5 cc of Grafton® DBM/local autograft composite was implanted on the left side, and the same amount of DBX® DBM/local autograft composite was implanted on the right side in the same patient. The PLF masses of 54 total sides (27 Grafton® sides and 27 DBX® sides) were assessed for fusion based on both flexion/extension lateral radiographs and computed tomography images at 12 and 24 months postoperatively. Clinical symptoms were also evaluated.

Results

At 12 months postoperatively, the fusion rates for the Grafton® and DBX® sides were 59.5 and 51.9%, respectively; the difference was not statistically significant (P = 0.425). At 24 months postoperatively, the fusion rates for the Grafton® and DBX® sides increased to 70.4 and 66.7%, respectively, but the difference was still not statistically significant (P = 0.574). Diabetes mellitus, smoking, and obesity (body mass index ≥25) negatively affected the fusion rate of both the Grafton® and DBX® sides. Visual analog scores for lower back pain and leg pain and Oswestry Disability Index were significantly improved after surgery (both, P < 0.01). No deep or superficial infections occurred postoperatively. No patients underwent revision surgery due to nonunion during follow-up.

Conclusions

Our results suggest that two kinds of DBMs/local autograft composites might be considered as useful bone graft substitute in instrumented posterolateral fusion for lumbar spinal stenosis or degenerative spondylolisthesis less than grade 1.

In vitro performance of 3D printed PCL-TCP degradable spinal fusion cage

Spinal fusion cages are commonly used to treat spinal diseases caused by degenerative changes, deformities, and trauma. At present, most of the main clinical spinal fusion cage products are non-degradable and still cause some undesirable side effects, such as the stress shielding phenomenon, interference with postoperative medical imaging, and obvious foreign body sensation in patients. Degradable spinal fusion cages have promising potential with extensive perspectives. The purpose of this study was to fabricate a degradable spinal fusion cage from both polycaprolactone (PCL) and high-proportion beta-tricalcium phosphate (β-TCP), using the highly personalised, accurate, and rapid fused deposition modelling 3 D printing technology. PCL and β-TCP were mixed in three different ratios (60:40, 55:45, and 50:50). Both in vitro degradation and cell experiments proved that all cages with the different PCL:β-TCP ratios met the mechanical properties of human cancellous bone while maintaining their structural integrity. The biological activity of the cages improved with higher amounts of the β-TCP content. This study also showed that a spinal fusion cage with high β-TCP content and suitable mechanical properties can be manufactured using extruding rods and appropriate models, providing a new solution for the design of degradable spinal fusion cages.

Spinal fusion procedures in the adult and young population: a systematic review on allogenic bone and synthetic grafts when compared to autologous bone

This systematic review aims to compare clinical evidences related to autologous iliac crest bone graft (ICBG) and non-ICBG (local bone) with allografts and synthetic grafts for spinal fusion procedures in adult and young patients. A systematic search was carried out in three databases (PubMed, Scopus, Web of Science, Cochrane Central Register of Controlled Trials) to identify clinical studies in the last 10 years. The initial search retrieved 1085 studies, of which 24 were recognized eligible for the review. Twelve studies (4 RCTs, 5 prospective, 3 retrospective) were focused on lumbar spine, 9 (2 RCTs, 2 prospective, 4 retrospective, 1 case-series) on cervical spine and 3 (1 RCT, 2 retrospective) on spinal fusion procedures in young patients. Calcium phosphate ceramics, allografts, bioglasses, composites and polymers have been clinically investigated as substitutes of autologous bone in spinal fusion procedures. Of the 24 studies included in this review, only 1 RCT on cervical spine was classified with high level of evidence (Class I) and showed low risk of bias. This RCT demonstrated the safety and efficacy of the proposed treatment, a composite bone substitute, that results in similar and on some metrics superior outcomes compared with local autograft bone. Almost all other studies showed moderately or, more often, high incidence of bias (Class III), thus preventing ultimate conclusion on the hypothesized beneficial effects of allografts and synthetic grafts. This review suggests that users of allografts and synthetic grafting should carefully consider the scientific evidence concerning efficacy and safety of these bone substitutes, in order to select the best option for patient undergoing spinal fusion procedures.

Effect of Trabecular Microstructure of Spinous Process on Spinal Fusion and Clinical Outcomes After Posterior Lumbar Interbody Fusion: Bone Surface/Total Volume as Independent Favorable Indicator for Fusion Success

OBJECTIVE

We assessed the trabecular microarchitecture of the spinous process as an autograft and investigated its correlations with fusion success and clinical outcomes for patients undergoing posterior lumbar interbody fusion.

METHODS

Micro-computed tomography reconstruction techniques were used to scan cancellous bone specimens from spinous processes. We then measured the microarchitectural parameters for 105 subjects.

RESULTS

The patient cohort included 44 older men and 61 postmenopausal women with a minimum of 2-year follow-up data available. The complete fusion rate was 87.6% (92 of 105) at the last follow-up. When stratified by fusion status, the union group had significantly greater bone surface/total volume (BS/TV) and trabecular number but significantly lower trabecular separation than the nonunion group. No statistically significant differences were observed between the 2 groups in the clinical variables, except for the bone mineral density at the femoral neck (P = 0.028). On binomial logistic regression analysis, BS/TV was identified as an independent predictor for fusion success (odds ratio, 8.532; P = 0.032). The receiver operating characteristic curve showed that BS/TV had excellent performance in predicting successful fusion (area under the curve, 0.807). Using a cutoff value for BS/TV of 3.145, a greater BS/TV was significantly associated with visual analog scale scores for lower back pain 6 months postoperatively and lower Oswestry disability index scores at 12 and 24 months postoperatively but not with visual analog scale scores for leg pain.

CONCLUSIONS

Our data suggest that microstructural deterioration of the spinal process as an autograft has detrimental effects on spinal fusion and clinical outcomes for patients undergoing instrumented posterior lumbar interbody fusion. Specifically, the microstructural parameter BS/TV has good potential for assessing lumbar bone quality and predicting fusion success.

Graft Materials and Biologics for Spinal Interbody Fusion

Spinal fusion is the most widely performed procedure in spine surgery. It is the preferred treatment for a wide variety of pathologies including degenerative disc disease, spondylolisthesis, segmental instability, and deformity. Surgeons have the choice of fusing vertebrae by utilizing cages containing autografts, allografts, demineralized bone matrices (DBMs), or graft substitutes such as ceramic scaffolds. Autografts from the iliac spine are the most commonly used as they offer osteogenic, osteoinductive, and osteoconductive capabilities, all while avoiding immune system rejection. Allografts obtained from cadavers and living donors can also be advantageous as they lack the need for graft extraction from the patient. DBMs are acid-extracted organic allografts with osteoinductive properties. Ceramic grafts containing hydroxyapatite can be readily manufactured and are able to provide osteoinductive support while having a long shelf life. Further, bone-morphogenetic proteins (BMPs), mesenchymal stem cells (MSCs), synthetic peptides, and autologous growth factors are currently being optimized to assist in improving vertebral fusion. Genetic therapies utilizing viral transduction are also currently being devised. This review provides an overview of the advantages, disadvantages, and future directions of currently available graft materials. The current literature on growth factors, stem cells, and genetic therapy is also discussed.

Ketogenic diet delays spinal fusion and decreases bone mass in posterolateral lumbar spinal fusion: an in vivo rat model

BACKGROUND

Ketogenic diet (KD), a low-carbohydrate-and-high-fat diet, causes a metabolic state of ketogenesis and has been used to treat drug-resistance epilepsy. Our recent studies showed KD neuroprotective after spinal cord injury and causing bone loss. Effects of KD on spinal fusion were still unknown. This study was aimed to evaluate effects of KD on spinal fusion in rats.

METHODS

Thirty-two Sprague-Dawley rats were randomly divided into KD and standard diet (SD) groups. The KD group was fed with food of 1:4 carbohydrates to fat. All rats were subjected to L4/5 posterolateral lumbar spinal fusion. The blood ketone, and serum calcium, phosphorus, and insulin-like growth factor-1 (IGF-1) were measured, as well as the fusion rates, bone mass (BV), and bone mineral contents (BMC) of fusion sites were estimated at 4 and 8 weeks.

RESULTS

There was no significant difference in serum calcium or phosphorus levels between groups at 4 or 8 weeks. However, there was a significant increase of blood ketone (1.02 mmol/L vs 0.38 mmol/L at 4 weeks; 0.83 mmol/L vs 0.32 mmol/L, at 8 weeks) and decrease of serum IGF-1 (339.4 ng/mL vs 630.6 ng/mL at 4 weeks; 418.8 ng/mL vs 628.6 ng/mL, at 8 weeks) in the KD group compared with the SD group. The spinal fusion occurred less in the KD group (1/16 vs 6/16 at 4 weeks; 7/16 vs 10/16, at 8 weeks), particularly at 4 weeks after surgery. The BV and BMC were lower in the KD group than that in the SD group at 4 weeks, but not different between groups at 8 weeks.

CONCLUSIONS

This study demonstrated that KD delayed spinal fusion and decreased bone mass in posterolateral lumbar spinal fusion in rats.

Results of lumbar spondylodeses using different bone grafting materials after transforaminal lumbar interbody fusion (TLIF)

PURPOSE

Can a mixture of hydroxyapatite (HA) and autologous bone from decompression sites produce similar results when used for transforaminal lumbar interbody fusion (TLIF)? In the current literature, autologous iliac crest bone grafts (ICBGs) have been reported the gold standard for this procedure. Indeed, to date, no clinical data have confirmed that a mixture of equal volumes of HA and local autologous bone produce similar results in term of fusion as the same volume of autologous ICBG alone.

METHODS

Study design/setting This study was approved by the local ethics committee and completed in a prospective, randomized, single-blinded manner. The results of lumbar fusion using TLIF and different bone grafting materials were compared. Patient sample The patient sample included patients with spinal lumbar degenerative disease. Outcome measures The clinical outcome was determined using the Oswestry Low Back Pain Disability Questionnaire (ODI) and Visual Analog Scale (VAS). The radiological outcomes and fusion rates were determined with radiographs evaluated using the McAfee criteria and computed tomography (CT) data evaluated by the Williams criteria. Three blinded investigators (one radiologist and two orthopedic surgeons) assessed the data. The secondary variables included donor site morbidity. Methods The patients were admitted to our department for orthopedic surgery with degenerative lumbar pathologies (L2-S1) that required stabilization in one or two segments using a TLIF procedure. The patients were 18-80 years old. Only those patients who had degenerative lumbar pathologies and agreed to be educated about the study were included. The patients were divided into the following two randomized groups: group A: TLIF procedure using autologous ICBGs alone; and group B: TLIF procedure using local bone from decompression site mixed with hydroxyapatite. Each group received equal graft volumes. The mixture in group B consisted of equal volumes of local autograft (5 cc) and synthetic bone (5 cc). A graft volume of 10 cc was used at each fusion level. The patients were followed up at three appointments at 1.5, 6 and 12 months postoperatively. Every patient received detailed education about the course of the study.

RESULTS

Forty-eight patients finished the study (2 patients dropped out). The radiographic fusion rate did not significantly differ between the two groups. Based on the CT criteria, 83.3% of the patients showed fusion in both groups after 12 months. Furthermore, 95.3% of the patients in group A and 91.7% of the patients in group B showed bony spondylodeses according to the radiographic criteria at the 12-month follow-up. The donor site morbidity consisted of one patient with a wound infection and one with a hematoma in group A and two patients with persistent pain in group B. Group A also included one patient with cage subsidence of 4 mm and archived fusion after 12 months. In group B, one patient had a pedicle screw breakage and achieved fusion after 6 months. The clinical outcomes were similar between the two groups. In both groups, the VAS and ODI data improved during the follow-up period (p < 0.05). No patients required additional surgeries.

CONCLUSIONS

Both groups demonstrated equivalent clinical outcomes. HA and autologous bone from decompression sites can achieve similar fusion rates to those achieved with identical volumes of the gold standard autologous graft. The graft mixture can be used for one- or two-level lumbar spondylodeses to avoid donor site morbidity.

Demineralized Bone Matrix (DBM) as a Bone Void Filler in Lumbar Interbody Fusion: A Prospective Pilot Study of Simultaneous DBM and Autologous Bone Grafts

Objective

Solid bone fusion is an essential process in spinal stabilization surgery. Recently, as several minimally invasive spinal surgeries have developed, a need of artificial bone substitutes such as demineralized bone matrix (DBM), has arisen. We investigated the in vivo bone growth rate of DBM as a bone void filler compared to a local autologous bone grafts.

Methods

From April 2014 to August 2015, 20 patients with a one or two-level spinal stenosis were included. A posterior lumbar interbody fusion using two cages and pedicle screw fixation was performed for every patient, and each cage was packed with autologous local bone and DBM. Clinical outcomes were assessed using the Numeric Rating Scale (NRS) of leg pain and back pain and the Korean Oswestry Disability Index (K-ODI). Clinical outcome parameters and range of motion (ROM) of the operated level were collected preoperatively and at 3 months, 6 months, and 1 year postoperatively. Computed tomography was performed 1 year after fusion surgery and bone growth of the autologous bone grafts and DBM were analyzed by ImageJ software.

Results

Eighteen patients completed 1 year of follow-up, including 10 men and 8 women, and the mean age was 56.4 (32–71). The operated level ranged from L3/4 to L5/S1. Eleven patients had single level and 7 patients had two-level repairs. The mean back pain NRS improved from 4.61 to 2.78 (p=0.003) and the leg pain NRS improved from 6.89 to 2.39 (p<0.001). The mean K-ODI score also improved from 27.33 to 13.83 (p<0.001). The ROM decreased below 2.0 degrees at the 3-month assessment, and remained less than 2 degrees through the 1 year postoperative assessment. Every local autologous bone graft and DBM packed cage showed bone bridge formation. On the quantitative analysis of bone growth, the autologous bone grafts showed significantly higher bone growth compared to DBM on both coronal and sagittal images (p<0.001 and p=0.028, respectively). Osteoporotic patients showed less bone growth on sagittal images.

Conclusion

Though DBM alone can induce favorable bone bridging in lumbar interbody fusion, it is still inferior to autologous bone grafts. Therefore, DBM is recommended as a bone graft extender rather than bone void filler, particularly in patients with osteoporosis.