Postoperative pain following posterior iliac crest bone graft harvesting in spine surgery: a prospective, randomized trial

Impact of surgical risk factors for non-union on lumbar spinal fusion outcomes using cellular bone allograft at 24-months follow-up

BACKGROUND

The current report investigates fusion rates and patient-reported outcomes following lumbar spinal surgery using cellular bone allograft (CBA) in patients with risk factors for non-union.

METHODS

A prospective, open label study was conducted in subjects undergoing lumbar spinal fusion with CBA (NCT02969616) to assess fusion success rates and patient-reported outcomes in subjects with risk factors for non-union. Subjects were categorized into low-risk (≤ 1 risk factors) and high-risk (> 1 risk factors) groups. Radiographic fusion status was evaluated by an independent review of dynamic radiographs and CT scans. Patient-reported outcome measures included quality of life (EQ-5D), Oswestry Disability Index (ODI) and Visual Analog Scales (VAS) for back and leg pain. Adverse event reporting was conducted throughout 24-months of follow-up.

RESULTS

A total of 274 subjects were enrolled: 140 subjects (51.1%) were categorized into the high-risk group (> 1 risk factor) and 134 subjects (48.9%) into the low-risk group (≤ 1 risk factors). The overall mean age at screening was 58.8 years (SD 12.5) with a higher distribution of females (63.1%) than males (36.9%). No statistical difference in fusion rates were observed between the low-risk (90.0%) and high-risk (93.9%) groups (p > 0.05). A statistically significant improvement in patient-reported outcomes (EQ-5D, ODI and VAS) was observed at all time points (p < 0.05) in both low and high-risk groups. The low-risk group showed enhanced improvement at multiple timepoints in EQ-5D, ODI, VAS-Back pain and VAS-Leg pain scores compared to the high-risk group (p < 0.05). The number of AEs were similar among risk groups.

CONCLUSIONS

This study demonstrates high fusion rates following lumbar spinal surgery using CBA, regardless of associated risk factors. Patient reported outcomes and fusion rates were not adversely affected by risk factor profiles.

TRIAL REGISTRATION

NCT02969616 (21/11/2016).

Bone Substitute Options for Spine Fusion in Patients With Spine Trauma-Part II: The Role of rhBMP

In Part II, we focus on an important aspect of spine fusion in patients with spine trauma: the pivotal role of recombinant human bone morphogenetic protein-2 (rhBMP-2). Despite the influx of diverse techniques facilitated by technological advancements in spinal surgery, spinal fusion surgery remains widely used globally. The persistent challenge of spinal pseudarthrosis has driven extensive efforts to achieve clinically favorable fusion outcomes, with particular emphasis on the evolution of bone graft substitutes. Part II of this review aims to build upon the foundation laid out in Part I by providing a comprehensive summary of commonly utilized bone graft substitutes for spinal fusion in patients with spinal trauma. Additionally, it will delve into the latest advancements and insights regarding the application of rhBMP-2, offering an updated perspective on its role in enhancing the success of spinal fusion procedures.

Avulsion fracture of the anterior superior iliac crest following autograft for anterior lumbar fusion: case report and literature review

Avulsion fracture of the anterior superior iliac crest (ASIC) following autogenous bone grafting for anterior lumbar fusion (ALF) is an extremely rare complication. We describe a very rare case of avulsion fracture of the ASIC following autograft for ALF in a revision surgery for treating lumbar tuberculosis. A 68-year-old woman with lumbar tuberculosis underwent posterior debridement and posterior iliac crest bone graft fusion; however, her lumbar tuberculosis recurred 9 months after surgery. She then underwent a lumbar revision surgery, including removal of the posterior instrumentation and debridement, followed by anterior L2 corpectomy, debridement, anterior left iliac crest bone graft fusion, and internal fixation. When walking for the first time on postoperative day 3, she experienced a sharp, sudden-onset pain in the anterior iliac crest harvest area. X-ray revealed an avulsion fracture of the ASIC. Considering her failure to respond to conservative treatment for one week and large displacement of the fracture ends, an open reduction and internal fixation surgery was scheduled. Her pain symptoms were significantly relieved after the operation. Although rare, fracture of the ASIC following autograft for ALF should not be ignored. Fracture of the ASIC is usually treated conservatively. Additional surgical treatment is required only when intractable pain fails to respond to conservative treatment or when there is a large displacement of fracture ends that are not expected to heal spontaneously.

Iliac crest bone graft versus cell-based grafts to augment spinal fusion: a systematic review and meta-analysis

INTRODUCTION

Despite successful fusion rates with iliac crest bone graft (ICBG), donor-site morbidity and increased operating time remain a considerable limitation and drive the search for alternatives. In this systematic review, grafts with additional cellular supplementation were compared with ICBG for spinal arthrodesis. We compared safety, efficacy and long-term outcomes, thus providing the current and relevant evidence for orthopaedic surgeons to make informed choices regarding this rapidly developing field.

METHODS

An electronic literature search was conducted according to the PRISMA guidelines by two independent reviewers for articles published up to 1st March 2023 using PubMed, EMBASE and the Cochrane Central Register of Controlled Trial. Cellular allografts were not included. The following data were extracted: Number of patients, type of graft, fusion assessment method, follow-up duration, fusion rates, clinical outcomes and complications. The methodological quality of evidence (MQOE) was assessed using the Risk of Bias 2 (RoB-2) tool and Risk of Bias In Non-Randomised Studies (ROBINS) tool developed by Cochrane for evaluating bias in randomised and non-randomised studies.

RESULTS

Ten studies fulfiled the inclusion criteria, including 465 patients. The mean number of patients per study was 43.8 (std dev. 28.81, range 12-100). Two studies demonstrated cell-based therapy to be significantly more successful in terms of fusion rates compared to ICBG. However, the remaining eight demonstrated equivocal results. No study found that cell-based therapy was inferior. No difference was seen between the two groups in three studies who focused on degenerative cohorts. No difference in functional outcome scores was seen between the groups. A number of different preparation techniques for cell-based grafts were used throughout the studies.

CONCLUSION

Cell-based therapy offers a promising alternative to ICBG in spinal fusion surgery, which could help reduce the associated morbidity to patients. This review found that cell-based therapy is non-inferior to iliac crest bone graft and may offer patients an alternative treatment option with fewer complications and reduced post-operative pain. However, the literature to date is limited by heterogeneity of the cell preparation and grafting process. Future research with a unified approach to the cell preparation process is required to fully delineate the potential advantages of this technology.

Bone Substitute Options for Spine Fusion in Patients With Spine Trauma-Part I: Fusion Biology, Autografts, Allografts, Demineralized Bone Matrix, and Ceramics

Spinal trauma accounts for a large portion of injuries to the spine area, particularly as societies are entering an era of aging populations. Consequently, spine fractures accompanied by osteoporosis are becoming more prevalent. Achieving successful fusion surgery in patients with spine fractures associated with osteoporosis is even more challenging. Pseudarthrosis in the spine does not yield clinically favorable results; however, considerable effort has been made to achieve successful fusion, and the advancement of bone graft substitutes has been particularly crucial in this regard. Autograft bone is considered the best fusion material but is limited in use due to the quantity that can be harvested during surgery and associated complications. Accordingly, various bone graft substitutes are currently being used, although no specific guidelines are available and this mainly depends on the surgeon's choice. Therefore, the purpose of this review, across part I/II, is to summarize bone graft substitutes commonly used in spine surgery for spine fusion in patients with spine trauma and to update the latest knowledge on the role of recombinant human bone morphogenetic protein-2.

Chitosan 3D scaffolds with resolvin D1 for vertebral arthrodesis: a pilot study

PURPOSE

Over the last years, the number of vertebral arthrodesis has been steadily increasing. The use of iliac crest bone autograft remains the "gold standard" for bone graft substitute in these procedures. However, this solution has some side effects, such as the problem of donor site morbidity indicating that there is a real need for adequate alternatives. This pilot study aimed to evaluate the usefulness of chitosan (Ch) porous 3D scaffolds incorporated with resolvin D1 (RvD1) as an alternative implant to iliac bone autograft.

METHODS

We have performed bilateral posterolateral lumbar vertebral arthrodesis in a rat animal model. Three experimental groups were used: (i) non-operated animals; (ii) animals implanted with Ch scaffolds incorporated with RvD1 and (iii) animals implanted with iliac bone autograft.

RESULTS

The collagenous fibrous capsule formed around the Ch scaffolds with RvD1 is less dense when compared with the iliac bone autograft, suggesting an important anti-inflammatory effect of RvD1. Additionally, new bone formation was observed in the Ch scaffolds with RvD1.

CONCLUSION

These results demonstrate the potential of these scaffolds for bone tissue repair applications.

Autologous mesenchymal stem cell transplantation for spinal fusion: 10 years follow-up of a phase I/II clinical trial

Posterolateral spinal fusion is the standard surgical approach for patients with degenerative disc disease. In our previously published article, we reported a 5-years follow-up of a phase I/II clinical trial in patients undergoing spinal fusion with autologous mesenchymal stem cells (MSCs) embedded in tricalcium phosphate. In the current manuscript, we have updated the results with a 10-year follow-up, the longest reported to date in this setting. After clinical and radiological evaluation, safety of the procedure was further confirmed in all 11 treated patients, with no evidence of tumor, infection, inflammatory reaction, or heterotopic ossification related to the administration of MSCs. Regarding clinical efficacy, low back pain and radicular pain (both assessed by the visual analogue scale-VAS), and the Owestry Disability Index remained significantly lower compared to pre-intervention. Radiologic evaluation demonstrated spinal fusion in all cases, improving over time. Finally, quality of life improved significantly also during follow-up. In summary, the use of tricalcium phosphate-embedded autologous MSCs with lumbar posterolateral arthrodesis is safe and potentially provides long-term benefits for 10 years.

Twelve-Month Results from a Prospective Clinical Study Evaluating the Efficacy and Safety of Cellular Bone Allograft in Subjects Undergoing Lumbar Spinal Fusion

BACKGROUND

While autologous bone grafts remain the gold standard for spinal fusion procedures, harvesting autologous bone is associated with significant complications, including donor site infection, hematomas, increased operative time, and prolonged pain. Cellular bone allograft (CBA) presents an alternative to autologous bone harvesting, with a favorable efficacy and safety profile. The current study further investigates CBA as an adjunct to lumbar spinal fusion procedures.

METHODS

A prospective, multicenter, open-label clinical study was conducted in subjects undergoing lumbar spinal fusion with CBA (NCT02969616). Radiographic fusion status was assessed by an independent review of dynamic radiographs and CT scans. Clinical outcome measures included the Oswestry Disability Index (ODI) and visual analogue scale (VAS) for back and leg pain. Adverse-event reporting was conducted throughout 12 months of follow-up. Available subject data at 12 months were analyzed.

RESULTS

A total of 274 subjects were enrolled into the study, with available data from 201 subjects (73.3%) who completed 12 months of postoperative radiographic and clinical evaluation at the time of analysis. Subjects had a mean age of 60.2 ± 11.5 years. A higher number of women (n = 124, 61.7%) than men (n = 77, 38.3%) were enrolled, with a collective mean BMI of 30.6 + 6.5 kg/m² (range 18.0-51.4). At month 12, successful fusion was achieved in 90.5% of subjects. A significant (<i>p</i> &amp;lt; 0.001) improvement in ODI, VAS-back, and VAS-leg clinical outcomes was also observed compared to baseline scores. One adverse event related to CBA (postoperative radiculopathy) was reported, with surgical exploration demonstrating interbody extrusion of graft material. This subject reported successful fusion at month 12.

CONCLUSIONS

CBA represents a viable substitute for harvesting of autograft alone with a high rate of successful fusion and significant improvements in subject-reported outcomes, such as pain and disability. Positive benefit was observed in subjects reporting single and multiple risk factors for pseudoarthrosis.

The impact of misplaced percutaneous iliac dynamic reference frame pins used during navigated spine surgery: incidence and outcomes

OBJECTIVE

Image guidance requires placement of a dynamic reference frame (DRF), often either onto local spinous process or by freehand intraosseous DRF placement into the ilium via the posterior superior iliac spine (PSIS). There is a paucity of studies in the literature that describe the complications of intraosseous DRF placement. The aim of this study was to describe the radiographic location, prevalence and nature of complications, and long-term clinical outcomes of attempted DRF placement into the PSIS.

METHODS

All lumbosacral spine surgical procedures performed between August 2019 and February 2021 at a single institution were queried, and operations in which a DRF was targeted to the PSIS were included. Patient demographic characteristics, indications for surgery, surgical outcomes, and complications were extracted. Intraoperative CT scans were reviewed by 2 independent researchers to determine the accuracy of DRF placement into the PSIS and to assess for DRF malposition.

RESULTS

Of 497 lumbar spine operations performed between August 2019 and February 2021 by 4 surgeons, 85 utilized intraoperative navigation with a PSIS pin. Thirteen operations were excluded due to an inability to visualize the entirety of the pin on intraoperative CT. Of 72 DRFs evaluated, 77.8% had been correctly placed in the PSIS. Of the 22.2% of DRFs not placed into the PSIS, 11 entered the sacrum, 6 crossed the sacroiliac joint, and 2 were deep enough to enter the pelvis. Pain at the pin site was present in 4 patients, of whom 3 had resolution of pain at the last follow-up evaluation. There were no significant complications due to DRF placement: no sacral fractures, significant navigation errors, retroperitoneal hematomas, or neurological deficits. Over a mean ± SD follow-up period of 9 ± 5.2 months, there were no incidences of pin site infection. Interrater reliability between the reviewers was 95.8%.

CONCLUSIONS

This was the first study to examine radiological and clinical outcomes after DRF placement in the PSIS. In this study, a majority of pins were correctly placed within the PSIS, although 22.2% of pins were malpositioned. There were no serious complications, and a majority of those patients with persistent pin site pain had resolution at last follow-up.

Does conflict of interest affect the reported fusion rates of bone graft substitutes and extenders?

Background

Bone graft extenders are being used more in spine surgery as a substitute for iliac crest bone graft. However, potential conflict of interest could impact average fusion rates. The purpose of this study was to evaluate whether fusion rates reported in the literature were different in papers evaluating bone graft substitutes and extenders when there was potential conflict of interest versus no potential conflict of interest.

Methods

Pubmed was searched for studies evaluating fusion rates when bone graft extenders including demineralized bone matrix, hydroxyapatite, and tricalcium sulfate were used. Studies were screened for one or two level fusions and for degenerative spinal conditions. The average fusion rates of subgroups were compared using unpaired Student's t-tests.

Results

1928 studies were evaluated. 86 studies were included in the study. The fusion rates varied from 4 to 100%. There were 24 studies with a potential conflict of interest and 62 studies with no conflict of interest. The average fusion rate of all the studies was 84.63% with standard deviation of 18.33%. The average fusion rates of those studies with conflict of interest was 80.93% versus 86.06% without conflict of interest. This was not statistically significant (p>0.07). The average fusion rate of studies evaluated by CT scan was 79.8% versus 87.9% without CT. The average fusion rate of studies that employed an independent reviewer to evaluate the fusion was 82.61% versus 85.63% for studies with no independent reviewer.

Conclusion

There is a great variability in the reported fusion rates of bone graft extenders. Counter to expectations, average fusion rates were lower in the studies where there was a potential conflict of interest. The use of CT scans and an independent reviewer seem to account for the lower reported fusion rates, and may be a means of negating the potential conflicts of interest in fusion studies.

Level of Evidence

2

Combining Expandable Interbody Cage Technology With a Minimally Invasive Technique to Harvest Iliac Crest Autograft Bone to Optimize Fusion Outcomes in Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery

STUDY DESIGN

This was a retrospective cohort review.

OBJECTIVE

The objective of this study was to determine the rate of fusion associated with an expandable cage and iliac crest bone graft in minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) surgery.

SUMMARY OF BACKGROUND DATA

MI-TLIF is a commonly performed procedure, but challenges inherent in MI-TLIF technique can make achieving an interbody fusion difficult.

METHODS

A retrospective review was performed on consecutive patients treated with an MI-TLIF for degenerative lumbar pathology. Patients that completed patient-reported outcome measures and 1-year computed tomography (CT)-scans for fusion analysis were included. Fusion morphology was analyzed by evaluating CT scans for location of bridging trabecular bone in relation to the cage. Patients with bridging bone were considered fused. Preoperative and postoperative health-related quality of life scores were compared. A Kolmogrov-Smirnoff test was used to determine normality of health-related outcome scores. A Friedman 2-way analysis of variance by ranks with pairwise comparisons to determine statistical significance of differences between the date of a follow-up examination and preoperative examination was done.

RESULTS

Of 75 patients evaluated 23 patients were excluded due to loss to follow-up, adjacent segment degeneration, inability to obtain a CT scan, or reoperation for nonfusion related symptoms. Of 61 disk spaces that were included, 55 had bridging bone through the intervertebral cage, resulting in an overall fusion rate of 90.2%. There was a higher rate of fusion at L5-S1 as compared to L4-L5. There was mean improvement in patient-reported outcome measures for Oswestry Disability Index, Short Form-12 Physical Component Score, Visual Analog Scale Back/Leg pain, and Patient-Reported Outcome Measurement Information System Physical Function. There were no complications associated with iliac crest bone graft harvesting.

CONCLUSION

Combining an expandable cage with iliac crest autograft bone harvested through a minimally invasive technique can allow for improved fusion rates without graft-site complications in MI-TLIF surgery.

Autologous Bone Grafting in Trauma and Orthopaedic Surgery: An Evidence-Based Narrative Review

Autologous bone grafting is common in trauma and orthopaedic surgery. Both the Reamer Irrigator Aspirator (RIA) and Iliac Crest Bone Graft (ICBG) aim to obtain autologous bone graft. Although the process of harvesting a bone graft is considered simple, complications may occur. This study examined morbidity and pain at the donor site, blood loss, and iatrogenic fractures, comparing RIA and ICBG. The source of the autologous bone graft, the alternative graft sites, and the storage modalities of the harvested bone marrow were also evaluated. In May 2021, PubMed, Embase, Scopus, and Google Scholar were accessed, with no time constraints. RIA may produce greater blood loss, but with less morbidity and complications, making it a potential alternative source of bone grafting.

Limited Evidence for Biological Adjuvants in Hindfoot Arthrodesis: A Systematic Review and Meta-Analysis of Clinical Comparative Studies

BACKGROUND

The purpose of the present study was to evaluate the efficacy of biological adjuvants in patients managed with hindfoot arthrodesis.

METHODS

A systematic review of the PubMed and Embase databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines with use of specific search terms and eligibility criteria. Assessment of evidence was threefold: level of evidence by criteria as described in The Journal of Bone & Joint Surgery, quality of evidence according to the Newcastle-Ottawa scale, and conflicts of interest. Meta-analysis was performed with fixed-effects models for studies of low heterogeneity (I2 < 25%) and with random-effects models for studies of moderate to high heterogeneity (I2 ≥ 25%).

RESULTS

A total of 1,579 hindfeet were recruited across all studies, and 1,527 hindfeet were recorded as having completed treatment and follow-up visits. The duration of follow-up ranged from 2.8 to 43 months. Twelve of the 17 included studies comprised patients with comorbidities associated with reduced healing capacity. Based on the random-effects model for nonunion rates for autograft versus allograft, the risk ratio was 0.82 (95% CI, 0.13 to 5.21; I2 = 56%; p = 0.83) in favor of lower nonunion rates for autograft. Based on the random-effects model for rhPDGF/β-TCP versus autograft, the risk ratio was 0.90 (95% CI, 0.74 to 1.10; I2 = 59%; p = 0.30) in favor of lower nonunion rates for rhPDGF/β-TCP.

CONCLUSIONS

There is a lack of data to support the meaningful use of biological adjuvants as compared with autograft/allograft for hindfoot arthrodesis. The meta-analysis favored the use of autograft when compared with allograft but favored rhPDGF/β-TCP when compared with autograft in the short term.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Radiological and mid- to long-term patient-reported outcome after stabilization of traumatic thoraco-lumbar spinal fractures using an expandable vertebral body replacement implant

Background

For the treatment of unstable thoraco-lumbar burst fractures, a combined posterior and anterior stabilization instead of a posterior-only instrumentation is recommend in the current literature due to the instability of the anterior column. Data on restoring the bi-segmental kyphotic endplate angle (BKA) with expandable vertebral body replacements (VBR) and on the mid- to long-term patient-reported outcome measures (PROM) is sparse.

Methods

A retrospective cohort study of patients with traumatic thoraco-lumbar spinal fractures treated with an expandable VBR implant (Obelisc™, Ulrich Medical, Germany) between 2001 and 2015 was conducted. Patient and treatment characteristics were evaluated retrospectively. Radiological data acquisition was completed pre- and postoperatively, 6 months and at least 2 years after the VBR surgery. The BKA was measured and fusion-rates were assessed. The SF-36, EQ-5D and ODI questionnaires were evaluated prospectively.

Results

Ninety-six patients (25 female, 71 male; age: 46.1 ± 12.8 years) were included in the study. An AO Type A4 fracture was seen in 80/96 cases (83.3%). Seventy-three fractures (76.0%) were located at the lumbar spine. Intraoperative reduction of the BKA in n = 96 patients was 10.5 ± 9.4° (p < 0.01). A loss of correction of 1.0 ± 2.8° at the first follow-up (t1) and of 2.4 ± 4.0° at the second follow-up (t2) was measured (each p < 0.05). The bony fusion rate was 97.9%. The total revision rate was 4.2%. Fifty-one patients (53.1% of included patients; age: 48.9 ± 12.4 years) completed the PROM questionnaires after 106.4 ± 44.3 months and therefore were assigned to the respondent group. The mean ODI score was 28.2 ± 18.3%, the mean EQ-5D VAS reached 60.7 ± 4.1 points. Stratified SF-36 results (ISS < and ≥ 16) were lower compared to a reference population.

Conclusion

The treatment of traumatic thoraco-lumbar fractures with an expandable VBR implant lead to a high rate of bony fusion. A significant correction of the BKA could be achieved and no clinically relevant loss of reduction occurred during the follow-up. Even though health related quality of life did not reach the normative population values, overall satisfactory results were reported.

A BMP/Activin A Chimera Induces Posterolateral Spine Fusion in Nonhuman Primates at Lower Concentrations Than BMP-2

BACKGROUND

Supraphysiologic bone morphogenetic protein (BMP)-2 concentrations are required to induce spinal fusion. In this study, a BMP-2/BMP-6/activin A chimera (BV-265), optimized for BMP receptor binding, delivered in a recombinant human collagen:CDHA [calcium-deficient hydroxyapatite] porous composite matrix (CM) or bovine collagen:CDHA granule porous composite matrix (PCM), engineered for optimal BV-265 retention and guided tissue repair, was compared with BMP-2 delivered in a bovine absorbable collagen sponge (ACS) wrapped around a MASTERGRAFT Matrix (MM) ceramic-collagen rod (ACS:MM) in a nonhuman primate noninstrumented posterolateral fusion (PLF) model.

METHODS

In vivo retention of 125I-labeled-BV-265/CM or PCM was compared with 125I-labeled-BMP-2/ACS or BMP-2/buffer in a rat muscle pouch model using scintigraphy. Noninstrumented PLF was performed by implanting CM, BV-265/CM, BV-265/PCM, or BMP-2/ACS:MM across L3-L4 and L5-L6 or L3-L4-L5 decorticated transverse processes in 26 monkeys. Computed tomography (CT) images were acquired at 0, 4, 8, 12, and 24 weeks after surgery, where applicable. Manual palpation, μCT (microcomputed tomography) or nCT (nanocomputed tomography), and histological analysis were performed following euthanasia.

RESULTS

Retention of 125I-labeled-BV-265/CM was greater than BV-265/PCM, followed by BMP-2/ACS and BMP-2/buffer. The CM, 0.43 mg/cm3 BMP-2/ACS:MM, and 0.05 mg/cm3 BV-265/CM failed to generate PLFs. The 0.15-mg/cm3 BV-265/CM or 0.075-mg/cm3 BV-265/PCM combinations were partially effective. The 0.25-mg/cm3 BV-265/CM and 0.15 and 0.3-mg/cm3 BV-265/PCM combinations generated successful 2-level PLFs at 12 and 24 weeks.

CONCLUSIONS

BV-265/CM or PCM can induce fusion in a challenging nonhuman primate noninstrumented PLF model at substantially lower concentrations than BMP-2/ACS:MM.

CLINICAL RELEVANCE

BV-265/CM and PCM represent potential alternatives to induce PLF in humans at substantially lower concentrations than BMP-2/ACS:MM.

Low-frequency electromagnetic fields combined with tissue engineering techniques accelerate intervertebral fusion

Background

Intervertebral fusion is the most common surgery to treat lumbar degenerative disease (LDD). And the graft material used in the operation is derived from the iliac crest to promote fusion. However, autografts possess the fatal disadvantage of lack of source. Therefore, economical and practical bone substitutes are urgently needed to be developed. Sinusoidal electromagnetic fields (EMF) combined with tissue engineering techniques may be an appropriate way to promote intervertebral fusion.

Methods

In this research, porous scaffolds made of polycaprolactone (PCL) and nano-hydroxyapatite (nHA) were used as cell carriers. Then, the scaffolds loaded with bone marrow mesenchymal stem cells (BMSCs) were treated with sinusoidal electromagnetic field and the osteogenic capability of BMSCs was tested later. In addition, an intervertebral disc of the tail vertebra of the rat was removed to construct a spinal intervertebral fusion model with a cell-scaffold implanted. The intervertebral fusion was observed and analyzed by X-ray, micro-CT, and histological methods.

Results

BMSCs stimulated by EMF possess splendid osteogenic capability under an osteogenic medium (OM) in vitro. And the conditioned medium of BMSCs treated with EMF can further promote osteogenic differentiation of the primitive BMSCs. Mechanistically, EMF regulates BMSCs via BMP/Smad and mitogen-activated protein kinase (MAPK)-associated p38 signaling pathways. In vivo experiments revealed that the scaffold loaded with BMSCs stimulated by EMF accelerated intervertebral fusion successfully.

Conclusion

In summary, EMF accelerated intervertebral fusion by improving the osteogenic capacity of BMSCs seeded on scaffolds and might boost the paracrine function of BMSCs to promote osteogenic differentiation of the homing BMSCs at the injured site. EMF combined with tissue engineering techniques may become a new clinical treatment for LDD.

TRANSFORAMINAL INTERSOMATIC LUMBAR ARTHRODESIS: COMPARISON BETWEEN AUTOGRAFT AND CAGE IN PEEK

OBJECTIVE

To compare the postoperative outcomes of transforaminal intersomatic lumbar arthrodesis with structured iliac bone autograft and PEEK device.

METHODS

The total of 93 medical records of patients undergoing transforaminal intersomatic fusion between January 2012 and July 2017 with at least 1 year of postoperative follow-up, with complete medical record, containing clinical file and radiological exams, were reviewed.

RESULTS

From the medical records evaluated, 48 patients underwent the procedure with structured iliac autograft (group 1) and 45 with PEEK device (group 2). There was an improvement in functional capacity in both groups (p < 0.001), however there was no difference when comparing them (p = 0.591).

CONCLUSION

The postoperative clinical and radiological results of lumbar arthrodesis with TLIF technique, using a structured iliac bone autograft compared to a PEEK device, were similar. Level of Evidence II, Retrospective study.

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.

Patient Perceptions of Iliac Crest Bone Grafting in Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

The objective of this study was to determine patients' perception of iliac crest bone graft (ICBG) harvesting and donor site pain following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND DATA

The incidence of donor site pain has been debated in the literature because of the varying techniques associated with its harvest.

METHODS

Patients undergoing primary, single-level MIS TLIF with ICBG were retrospectively identified. ICBG harvesting was performed using a percutaneous technique with a tubular retractor. A survey was administered to assess if patients could accurately describe which side of their iliac crest they believed was harvested, and if they were experiencing any pain perceived to be originating from the donor site. Patient characteristics were compared using χ analysis and independent t test.

RESULTS

In total, 82 patients were included. The majority of patients had the ICBG harvested from the left iliac crest (97.5%). Approximately half of the patients correctly identified the side of harvest (50.6%). 48.1% of patients reported they were not confident or had guessed on their response. Patients that reported pain from the ICBG were more likely to feel confident or somewhat confident in their harvest site identification (57.9% vs. 46.3%) but less likely to be correct (36.8% vs. 63.4%) than patients without pain. 22 patients (27.8%) correctly identified the side of harvest without guessing. Of these, 11 (13.9%) reported pain.

CONCLUSIONS

Approximately half of patients undergoing MIS TLIF with ICBG are able to correctly identify which side of their iliac crest was harvested. However, the majority of patients reporting pain were unable to correctly identify the side of harvest. This suggests that most patients are likely attributing other sources of pain to their ICBG. Therefore, rates of donor site pain may be over-reported in the current literature with contemporary harvesting techniques.

Patients Cannot Reliably Distinguish the Iliac Crest Bone Graft Donor Site From the Contralateral Side After Lumbar Spine Fusion: A Patient-blinded Randomized Controlled Trial

STUDY DESIGN

A multicenter, randomized, intrapatient controlled trial.

OBJECTIVE

This study investigated whether lumbar fusion patients blinded to the harvest site (A) can identify the iliac crest used for bone harvesting and (B) whether this iliac crest is more painful than the contralateral side.

SUMMARY OF BACKGROUND DATA

Spinal fusion with iliac crest autograft is a frequently performed surgical procedure. A widely reported disadvantage of the harvesting procedure is potential donor site morbidity. This has driven the development of many bone graft substitutes. However, more recently the incidence and severity of donor site pain is debated, especially in lumbar fusion surgery.

METHODS

Ninety-two nontraumatic adult patients underwent a posterolateral (thoraco)lumbar fusion. Iliac crest bone graft was harvested unilaterally through the primary midline incision. At 6 weeks, 3 months, 6 months, and 1 year follow-up, patients were asked to identify the donor site and to rate pain in their back, left iliac crest and right iliac crest on a Visual Analogue Scale (VAS).

RESULTS

Ninety patients, 44 males and 46 females with a mean age of 54 years, were analyzed. The left/right distribution of the iliac crest donor site was 50/50 and 89% of the patients underwent a lumbar fusion below L3. Only 24% patients identified the harvest site correctly. Moreover, the VAS pain scores for the donor site and contralateral iliac crest did not differ and were at each timepoint lower than the scores for back pain.

CONCLUSION

This study showed that, during the first year after lumbar fusion surgery via a single midline incision approach, patients could not reliably identify the iliac crest used for bone graft harvesting and this iliac crest was not more painful than the untouched contralateral iliac crest. Therefore, donor site pain should not be the main reason to use bone graft alternatives for lumbar spinal fusion.

LEVEL OF EVIDENCE

2.

Biomechanical analysis of iliac crest loading following cortico-cancellous bone harvesting

BACKGROUND

Iliac crest bone harvesting is a frequently performed surgical procedure widely used to treat bone defects. The objective of this study is to assess the biomechanical quantities related to risk for pelvic fracture after harvesting an autologous bone graft at the anterior iliac crest.

METHODS

Finite element models with a simulated harvest site (sized 15 × 20 mm, 15 × 35 mm, 30 × 20 mm and 30 × 35 mm) in the iliac wing are created. The relevant loading case is when the ipsilateral leg is lifted off the ground. Musculoskeletal analysis is utilized to compute the muscle and joint forces involved in this motion. These forces are used as boundary conditions for the finite element analyses. Bone tissue stress is analyzed.

RESULTS

Critical stress peaks are located between the anterior superior iliac spine (ASIS) and the anterior edge of the harvest site. Irrespective of the graft size, the iliac wing does not show any significant stress peaks with the harvest site being 20 to 25 mm posterior to the ASIS. The harvest area itself inhibits the distribution of the forces applied on the ASIS to extend to the posterior iliac wing. This leads to a lack of stress posterior to the harvest site. A balanced stress distribution with no stress peaks appears when the bone graft is taken below the iliac crest.

CONCLUSION

A harvest site located at least 20 to 25 mm posterior to the ASIS should be preferred to minimize the risk of iliac fatigue fracture.