Surgical harvesting of bone graft from the ilium: point of view

Clinical and radiological outcomes of n-HA/PA66 cages in anterior spine reconstruction following total en bloc spondylectomy for tumors

Objective

This retrospective monocentric study was conducted to evaluate the clinical and radiological outcomes of the nano-hydroxyapatite/polyamide66 (n-HA/PA66) cage in reconstructing the anterior column of the spine following total en bloc spondylectomy (TES).

Methods

A cohort of 24 patients, 20 diagnosed with primary malignant tumors and 4 with metastatic malignancies, was selected based on specific inclusion criteria. All were subjected to TES and anterior column reconstruction with the n-HA/PA66 cage from January 2013 to July 2023 at a single institution. Pre-operative embolization was performed on all patients. Documented factors included operation duration, intraoperative blood loss, length of hospital stay, treatment history, and involved level. Mechanical complications and radiological parameters such as the local kyphotic angle (LKA), anterior vertebral height (AVH), posterior vertebral height (PVH), cage subsidence, and bone fusion time were evaluated. Quality of life and neurological function were gauged using tools like the Visual Analog Scale (VAS), Eastern Cooperative Oncology Group (ECOG) performance score, Karnofsky Performance Score (KPS) scale, and American Spinal Injury Association (ASIA) grading.

Results

All patients were followed up for 12-127 months, with an average period of 39.71 months. An average operation time of approximately 8.57 h and a blood loss volume of about 1,384 ml were recorded. No instances of tumor recurrence or multiple organ metastases were reported, though recurrence was detected in 2 living patients. Solid fusion was achieved in all patients at a mean time of 6.76 ± 0.69 months. Cage breakage or migration was not observed. Subsidence into the adjacent vertebral bodies was identified in 3 patients but was deemed clinically irrelevant. Significant improvements in VAS, ECOG performance score, KPS scale, and ASIA scores were noted from pre- to post-surgery (P < 0.05). A marked enhancement in the AVH was observed from before surgery to immediately after (P < 0.05). LKA, AVH, and PVH values between postoperative and final follow-up showed no significant variance (P > 0.05).

Conclusion

The integration of TES and the n-HA/PA66 cage was found to yield promising clinical and radiological outcomes in anterior column spine reconstruction. The use of this material did not hinder oncological care, including the provision of adjuvant treatments (chemo/radiotherapy), ultimately contributing to the enhanced long-term quality of life for spinal tumor patients.

Comparative Evaluation of Mineralized Bone Allografts for Spinal Fusion Surgery

The primary objective of this review is to evaluate whether the degree of processing and the clinical utility of commercially available mineralized bone allografts for spine surgery meet the 2020 US Food and Drug Administration's (FDA) guideline definitions for minimal manipulation and homologous use, respectively. We also assessed the consistency of performance of these products by examining the comparative postoperative radiographic fusion rates following spine surgery. Based on the FDA's criteria for determining whether a structural allograft averts regulatory oversight and classification as a drug/device/biologic, mineralized bone allografts were judged to meet the Agency's definitional descriptions for minimal manipulation and homologous use when complying with the American Association of Tissue Banks' (AATB) accredited guidelines for bone allograft harvesting, processing, storing and transplanting. Thus, these products do not require FDA medical device clearance. Radiographic fusion rates achieved with mineralized bone allografts were uniformly high (>85%) across three published systematic reviews. Little variation was found in the fusion rates irrespective of anatomical location, allograft geometry, dimensions or indication, and in most cases, the rates were similar to those for autologous bone alone. Continued utilization of mineralized bone allografts should be encouraged across all spine surgery applications where supplemental grafts and/or segmental stability are required to support mechanically solid arthrodeses.

Management of talar lesions with cement augmentation and autologous bone graft

BACKGROUND

Treatment of bone lesions involved with the articular cartilage at the talus is challenging. We report the management of talus lesions, particularly tumors and avascular necrosis (AVN), at the articular surface through treatment with cement augmentation and autologous bone graft.

METHODS

Eight benign bone tumors and three cases of AVN were reviewed retrospectively at a mean follow-up of 56 months (range, 12-162). The mean age of all patients was 36.1 years old (range, 15-73) when assessed between February 2005 and November 2021. Curettage of tumorous and necrotic lesions resulted in significant bone defects filled with bone cement augmentation. Cartilage defects of the talar dome were supported with autologous cancellous bone graft. Tolerable weight-bearing ambulation was permitted immediately after surgery. Radiological and functional evaluations were recorded.

RESULTS

We observed an increase in the average The American Orthopaedic Foot and Ankle Score (AOFAS) (p = .003) and a decrease in the average Visual Analogue Scale pain score (p = .003). There was no statistically significant decrease in ROM before or after surgery (p = .114). Additionally, no talus collapse of the ankle joint occurred. Talar dome status did not aggravate before or after surgery, except for one patient. Despite no radiographic osteoarthritis exacerbation before or after surgery in six patients, five patients had osteoarthritic change.

CONCLUSION

Cement implantation and autologous bone graft performed simultaneously for benign bone tumors with joint cartilage damage and AVN are technically simple, have good outcomes, and may be a suitable alternative to standard treatments.

Fusion Revision Surgery With Reamer-Irrigator-Aspirator to Harvest Autograft After Spinal Pseudarthrosis

Background and purpose

Spinal pseudarthrosis (SPA) is a common complication after attempted cervical or lumbosacral spinal fusion surgery. Revision surgeries usually necessitate bone graft implementation as an adjunct to hardware revision. Iliac crest bone graft is the gold standard but availability can be limited and usage often leads to persistent postoperative pain at the donor site. There is scant literature regarding the use of reamer-irrigator-aspirator (RIA)-harvested bone graft in lumbar spinal fusion. This is a collaborative study between orthopedic surgery and neurosurgery departments to utilize femur intramedullary autograft harvested using the RIA system as an adjunct graft in SPA revision surgeries.

Materials and methods

A retrospective review was conducted at a single center between August 2014 and December 2017 of patients aged ≥ 18 years and diagnosed with cervical, thoracic, or lumbar SPA who underwent revision fusion surgery using femur intramedullary autograft harvested using the RIA system. Plain radiographs and CT scans were utilized to confirm successful fusion.

Results

Eleven patients underwent 12 SPA revision surgeries using the RIA system as a source for bone graft in addition to bone morphogenetic protein 2 (BMP-2) and allograft. The mean amount of graft harvested was 51.3 mL (range: 20-70 mL). Nine patients achieved successful fusion (81.8%). The average time to fusion was 9.1 months. Four patients (36.4%) had postoperative knee pain. Regarding patient position and approach for harvesting, 66.7% (n = 8) of cases were positioned prone and a retrograde approach was utilized in 91.7% (n = 11) of cases.

Interpretation

This is the first case series in known literature to report the RIA system as a reliably considerable source of autologous bone graft for SPA revision surgeries. It provides a useful adjunct to the known types of bone grafts. Patient positioning and the approach choice for graft harvesting can be adjusted according to the fusion approach and the surgeon’s preference.

Characterization of porous fluorohydroxyapatite bone-scaffolds fabricated using freeze casting

With the increasing demand for orthopedic and dental reconstruction surgeries, there comes a shortage of viable bone substitutes. This study was therefore designed to assess the efficacy of porous fluorohydroxyapatite (FHA) as a potential bone substitute. For this, porous FHA scaffolds were fabricated using the freeze casting technique. They were then sintered at 1250, 1350 and, 1450 °C, and microstructural, mechanical, and in vitro properties were analyzed. The microstructure analyses revealed the porosity remained constant within the temperature range. However, the pore size decreased with increasing sintering temperature. The greatest compressive strength and elastic modulus were obtained at 1450 °C, which were 13.5 ± 4.0 MPa and 379 ± 182 MPa, respectively. These are comparable values to human trabecular bone and other porous scaffolds made using hydroxyapatite. This analysis has thus helped to attain an understanding of the mechanical and material properties of freeze-cast FHA scaffolds that have not been presented before. In vitro studies revealed an increasing rate of human osteoblast cell proliferation on freeze-cast FHA scaffolds with increasing sintering temperature, suggesting improved osteogenic properties. Additionally, osteoblasts cells were also shown to proliferate into the interior pores of all freeze-cast FHA scaffolds. These results indicate the potential of porous FHA scaffolds fabricated using the freeze-casting technique to be utilized clinically as bone substitutes.

The Impact of Osteobiologic Subtype Selection on Perioperative Complications and Hospital-Reported Charges in Single- and Multi-Level Lumbar Spinal Fusion

BACKGROUND

Over the last several decades, various osteobiologics including allograft, synthetics, and growth factors have been used for lumbar spinal fusion surgery. However, the data on these osteobiologic products remain controversial with conflicting evidence in the literature. This study evaluates the influence of osteobiologic type selection on perioperative complications and hospital-reported charges in single-level and multilevel lumbar fusion.

METHODS

Using the 2016 and 2017 Nationwide Readmission Database, we conducted a retrospective cohort analysis of 125,143 patients who received lumbar fusion with either autologous tissue substitute, nonautologous tissue substitute, or synthetic substitute. This cohort was split into single-level and multilevel fusion procedures, and one-to-one age and sex propensity score matching was implemented. This resulted in cohorts each consisting of 1967 patients for single-level fusion, and cohorts each consisting of 1657 patients for multilevel fusion. Statistical analysis included one-way analysis of variance and Tukey multiple comparisons of means.

RESULTS

Autologous single-level fusion resulted in significantly more postoperative pain at 30-, 90-, and 180-day follow-up compared to fusion with nonautologous graft (P < .05). Multilevel fusion with autologous graft had higher rates of acute postsurgical anemia compared with synthetic (P = .021) and nonautologous (P = .016) alternatives, and less postsurgical infection when compared with nonautologous fusion (P = .0020). In addition, procedures using autologous osteobiologics were associated with significantly more neurological complications at 30 days (P = .049) and 90 days (P = .048) for multi-level fusion and at 30 days (P = .044) for single-level fusion compared with the nonautologous group. Lastly, for both cohorts, the total accrued inpatient hospital charges during admission for patients receiving nonautologous grafts were the most expensive and those for patients receiving autologous grafts were the least expensive.

CONCLUSION

Significant differences were found between the groups with respect to rates of complications, including infection, postoperative pain, and neurologic injury. Furthermore, the hospital-reported charges of each procedure varied significantly. As the field of biologics continues to expand, it is important to continually evaluate the safety, efficacy, and cost-effectiveness of these novel materials and techniques.

LEVEL OF EVIDENCE

3 CLINICAL RELEVANCE: With increased utilization of osteobiologics and spinal fusion being a common procedure, longitudinal data on readmissions, and post-operative complications are critical in guiding evidence-based practice.

Effect of Particle Size Ratios on the Physical and Chemical Properties of Surgical-Grade Calcium Sulfate Hemihydrate

Objectives

To analyze the optimum particle size or formula ratio of surgical‐grade calcium sulfate (CS) for appropriate compressive strength, setting time, and vitro degradation rate.

Methods

Three types of calcium sulfate hemihydrate (CSH) particles with diameters of 0–37.5 μm, 37.5–75 μm, and >75 μm were screened. Based on formulation ratio of different particles, this topic is divided into 10 groups by the unconstrained third‐order simplex lattice mixing design scheme in formula design experiment. The optimum formulation ratio of particle diameter for compressive strength, solidification time, and degradation rate in vitro was analyzed.

Results

When the percentage of the particle diameter of CS with 0–37.5 μm, 37.5–75 μm and >75 μm are 55.0%, 17.4%, and 27.6% respectively, the compressive strength of the test sample is the highest, which is 14.16 MPa. When the percentage of the particle diameter of CS with 0–37.5 μm, 37.5–75 μm, and >75 μm are 0.00%, 0.00%, and 100.00% respectively, the initial setting time of the sample is the longest, which is 410.0 s. When the percentage of the particle diameter of CS with 0–37.5 μm, 37.5–75 μm, and >75 μm are 0.00%, 0.00%, and 100.00% respectively, the final setting time of the sample is the largest, and the final setting time of the sample is 460.00 s. When the percentage of the particle diameter of CS with 0–37.5 μm, 37.5–75 μm, and >75 μm are 0.00%, 0.00%, and 100.00% respectively, the degradation rate of the sample in vitro is the slowest, which is 18.8%.

Conclusion

The morphological structure of surgical‐grade CS can affect compressive strength, setting time, and in vitro degradation rate. Surgical CS should be prepared based on different uses.

Demineralized Bone Matrix Carriers and their Clinical Applications: An Overview

Reconstruction of massive bone defects is challenging for orthopaedic clinicians, especially in cases of severe trauma and resection of tumors in various locales. Autologous iliac crest bone graft (ICBG) is the “gold standard” for bone grafting. However, the limited availability and complications at donor sites resulted in seeking other options like allografts and bone graft substitutes. Demineralized bone matrix (DBM) is a form of allograft using acidic solution to remove mineral components, while leaving much of the proteinaceous components native to bone, with small amounts of calcium‐based solids, inorganic phosphates, and some trace cell debris. It is an osteoconductive and osteoinductive biomaterial and is approved as a medical device for use in bone defects and spinal fusion. To pack consistently into the defect sites and stay firmly in the filling parts, DBM products have various forms combined with biocompatible viscous carriers, including sponges, strips, injectable putty, paste, and paste infused with chips. The present review aims to summarize the properties of various kind of viscous carriers and their clinical use combined with DBM in commercially available products. Given DBM'mercially available products. Given DBM;s long clinical track record and commercial accessibility in standard forms, opportunities to further develop and validate DBM as a versatile bone biomaterial in orthopaedic repair and regenerative medicine contexts are attractive.

Hyper-Crosslinked Carbohydrate Polymer for Repair of Critical-Sized Bone Defects

This study evaluated the safety and efficacy of a novel hyper-crosslinked carbohydrate polymer (HCCP) for the repair of critical-sized bone defects in comparison to two alternative treatments: autologous bone and poly(lactide-co-glycolide) with hyaluronic acid (PLGA/HA). Bilateral critical-sized defects were created in the lateral femoral condyles of skeletally mature New Zealand White rabbits, and they were subsequently implanted with HCCP, PLGA/HA, or autologous bone in a randomized manner. Clinical and behavioral observations were made daily, and radiological and histopathological evaluations were performed at 4, 10, and 16 weeks postimplantation. Defects implanted with HCCP showed progressive bone regeneration and bridging of the defect without adverse histological events. No signs of infection or inflammation associated with the implant material were observed in all animals that received HCCP implantation. A radiographic assessment performed at 16 weeks post-implantation showed significantly higher bone density and volume in defects implanted with HCCP compared to PLGA/HA. No statistically significant difference was observed in bone density and volume between HCCP and autologous bone. These findings demonstrate that HCCP is biocompatible, osteoconductive, and capable of promoting bone regeneration in vivo; therefore, it is suitable for both tissue engineering and the repair of critical-sized bone defects.

Autologous bone marrow clot as an alternative to autograft for bone defect healing

Objectives

Long bone defects often require surgical intervention for functional restoration. The ‘gold standard’ treatment is autologous bone graft (ABG), usually from the patient’s iliac crest. However, autograft is plagued by complications including limited supply, donor site morbidity, and the need for an additional surgery. Thus, alternative therapies are being actively investigated. Autologous bone marrow (BM) is considered as a candidate due to the presence of both endogenous reparative cells and growth factors. We aimed to compare the therapeutic potentials of autologous bone marrow aspirate (BMA) and ABG, which has not previously been done.

Methods

We compared the efficacy of coagulated autologous BMA and ABG for the repair of ulnar defects in New Zealand White rabbits. Segmental defects (14 mm) were filled with autologous clotted BM or morcellized autograft, and healing was assessed four and 12 weeks postoperatively. Harvested ulnas were subjected to radiological, micro-CT, histological, and mechanical analyses.

Results

Comparable results were obtained with autologous BMA clot and ABG, except for the quantification of new bone by micro-CT. Significantly more bone was found in the ABG-treated ulnar defects than in those treated with autologous BMA clot. This is possibly due to the remnants of necrotic autograft fragments that persisted within the healing defects at week 12 post-surgery.

Conclusion

As similar treatment outcomes were achieved by the two strategies, the preferred treatment would be one that is associated with a lower risk of complications. Hence, these results demonstrate that coagulated BMA can be considered as an alternative autogenous therapy for long bone healing.

Cite this article: Z. X. H. Lim, B. Rai, T. C. Tan, A. K. Ramruttun, J. H. Hui, V. Nurcombe, S. H. Teoh, S. M. Cool. Autologous bone marrow clot as an alternative to autograft for bone defect healing. Bone Joint Res 2019;8:107–117. DOI: 10.1302/2046-3758.83.BJR-2018-0096.R1.

Complications Associated With Anterior Iliac Bone Grafting for the Reconstruction of Dentoalveolar Defects

The aim of this study is to evaluate donor- and recipient-site complications of iliac bone grafting for the reconstruction of atrophic jaws.Our study includes 86 consecutive patients with atrophic jaws who underwent iliac bone grafting surgery. At the donor site, hematoma, infection, paresthesia, chronic pain, prolonged gait disturbance, fracture of the ilium, and esthetic concerns; at the recipient site, hematoma, infection, prolonged pain, graft exposure, graft loss, and loss of the implants were evaluated.Grafting was successfully performed in all patients. The mean follow-up period was 35 months. Prolonged gait disturbance (20.9%) and paresthesia (9.3%) were the most frequently observed donor-site complications. At the recipient site, hematoma (8.1%), infection (12.8%), prolonged pain (11.6%), partial graft exposure (33.7%), total graft exposure (7%), partial graft loss (17.4%), and total graft loss (5.8%) were observed.Reconstruction of atrophic jaws can be achieved successfully with iliac bone grafting. However, there are possible donor- and recipient-site complications that have to be taken into consideration.

Differentiated adipose-derived stem cell cocultures for bone regeneration in RADA16-I in vitro

Craniofacial defects can cause morbidness. Adipose-derived stem cells (ADSCs) have shown great promise for osteogeneration and vascularization; therefore cocultures of differentiated ADSCs are explored to increase bone and vessel formation. In this study, ADSCs were induced into osteogenic ADSCs (os-ADSCs) and endothelial ADSCs (endo-ADSCs) cells, which were then cocultured in variable proportions (os-ADSCs/endo-ADSCs = 2:1, 1:1, 1:2). The os-ADSCs in a ratio of 1:1 expressed more ALP, RUNX2 and COL-I, whereas VEGF, vWF and CD31 were upregulated in the endo-ADSCs of this group. Next generation RNA sequencing (RNA-seq) was performed to evaluate the molecular mechanisms of cocultured ADSCs. The os-ADSCs and endo-ADSCs interacted with each other during osteogenic and angiogenic differentiation, especially at the ratio of 1:1, and were regulated by vascular-related genes, cell-mediated genes, bone-related genes and the transforming growth factor β signaling pathway (TGF-β), mitogen-activated protein kinase signaling pathway (MAPK) and wnt signaling pathway (Wnt). Angptl4, apoe, mmp3, bmp6, mmp13 and fgf18 were detected to be up-regulated, and cxcl12 and wnt5a were down-regulated. The results showed that the gene expression levels were consistent with that in RNA-seq. The cells were then seeded into self-assembling peptide RADA16-I scaffolds as cocultures (1:1) and monocultures (ADSCs, os-ADSCs, endo-ADSCs). The results showed that the cells of all groups grew and proliferated well on the scaffolds, and the cocultured group exhibited better osteogeneration and vascularization. In conclusion, cocultured os-ADSCs and endo-ADSCs at the ratio of 1:1 showed strong osteogenic and angiogenic differentiation. There is a great potential for osteogenesis and vascularization by 3D culturing cells in a 1:1 ratio in self-assembling peptide RADA16-I scaffolds, which requires evaluation for bone regeneration in vivo.

Reconstruct the proximal radius with iliac graft and elastic intramedullary nail fixation after tumor resection

Background

This study aims to introduce a novel technique in treating benign bone tumors of the proximal radius by elastic intramedullary nail fixation and iliac graft after tumor resection.

Method

In this retrospective case series, the treatment outcomes of 17 patients with benign bone tumor involving the proximal radius were reported from January 2010 to August 2014. All the patients received reconstruction surgery with iliac graft and elastic intramedullary nail fixation after tumor resection. Pain scoring was assessed using the 0 to 10 numerical rating scale. The quality of life scoring was assessed using the SF-30 scoring system. In addition, functional outcome was assessed with the Musculoskeletal Tumor Society score and the Disabilities of the Arm, Shoulder, and Hand score.

Results

The mean follow-up was 16 months (range, 10–22). The average bone consolidate time was 19.2 weeks (range, 16–24 weeks). The pre- and postoperative pain scores were 5.47 ± 1.58 and 1.18 ± 0.39, respectively. The pain symptom was significantly ameliorated after the operation (t = 13.50, p < 0.01). The pre- and postoperative and the quality of life scores were 48.29 ± 6.58 and 77.47 ± 5.89, respectively; the quality of life score was dramatically improved (t = −20.11, p < 0.01). The mean Musculoskeletal Tumor Society score was 83.41 % (range, 63–93 %) and the mean Disabilities of the Arm, Shoulder, and Hand score was 14.1 (range, 5.8–38.3).

Conclusion

Taken together, the application of iliac graft and elastic intramedullary nail fixation after excision of lesions might be associated to a significant reduction of the pain and improvement of QOL (quality of life) and limb function of patients with benign bone tumors of proximal radius.

Donor Site Morbidity After Anterior Iliac Bone Graft Harvesting

OBJECTIVES

The objective of this study was to evaluate donor site morbidity associated with anterior iliac crest bone graft harvesting for orthopaedic trauma reconstructions.

DESIGN

Retrospective case series.

SETTING

Level 1 trauma center.

PATIENTS

Forty-Six consecutive patients who had undergone anterior iliac crest bone graft harvesting more than a 7-year period were reviewed.

INTERVENTION

Grafts were taken by removing the inner table of the ilium from 2 cm posterior to the Anterior Superior Iliac Spine. The abductor insertion was left intact and the external contour of the ilium remained unaffected.

MAIN OUTCOME MEASURE

Visual analog scale and modified Questionnaires.

RESULTS

Thirty-seven of the 46 patients were evaluated at average follow-up of 4.5 years after anterior iliac bone graft harvesting for nonunion or fusion for posttraumatic arthrosis. No patient complained of pain at final follow-up with all patients having a visual analog scale pain of 0 at final follow-up. Three patients reported some scar numbness, however, none complained of thigh numbness. Three patients, if they needed grafting in the future would seek alternative sources based on their remembrance of significant postoperative pain.

CONCLUSIONS

Anterior inner table bone graft harvesting resulted in minimal morbidity and neither pain nor functional limitations at an average of 4.5 years. This technique has lower donor-site morbidity than previous reports of posterior graft sites.

LEVEL OF EVIDENCE

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

Differentiated adipose-derived stem cell cocultures for bone regeneration in polymer scaffolds in vivo

Critical-sized bone defects can lead to significant morbidity, and interventions are limited by the availability and donor-site morbidity of bone grafts. Polymer scaffolds seeded with cells have been explored to replace bone grafts. Adipose-derived stem cells have shown great promise for vascularization and osteogenesis of these constructs, and cocultures of differentiated stem cells are being explored to augment vessel and bone formation. Adipose-derived stem cells were differentiated into endothelial cells and osteoblasts, and in vitro studies showed increased proliferation of cocultured cells compared with undifferentiated adipose-derived stem cells and monocultures of endothelial cells and osteoblasts. The cells were seeded into polylactic acid gas-plasma-treated scaffolds as cocultures and monocultures and then implanted into critical-sized rat calvarial defects. The cocultures were in a 1:1 osteoblast to endothelial cell ratio. The increase in proliferation seen by the cocultured cells in vitro did not translate to increased vascularization and osteogenesis in vivo. In vivo, there were trends of increased vascularization in the endothelial cell group and increased osteogenesis in the osteoblast and endothelial monoculture groups, but no increase was seen in the coculture group compared with the undifferentiated adipose-derived stem cells. Endothelial cells enhance vascularization and osteoblast and endothelial cell monocultures enhance bone formation in the polymer scaffold. Predifferentiation of adipose-derived stem cells is promising for improving vascularization and osteogenesis in polymer scaffolds but requires future evaluation of coculture ratios to fully characterize this response.

Bone graft substitutes for spine fusion: A brief review

Bone graft substitutes are widely used in the field of orthopedics and are extensively used to promote vertebral fusion. Fusion is the most common technique in spine surgery and is used to treat morbidities and relieve discomfort. Allograft and autograft bone substitutes are currently the most commonly used bone grafts to promote fusion. These approaches pose limitations and present complications to the patient. Numerous alternative bone graft substitutes are on the market or have been developed and proposed for application. These options have attempted to promote spine fusion by enhancing osteogenic properties. In this review, we reviewed biology of spine fusion and the current advances in biomedical materials and biological strategies for application in surgical spine fusion. Our findings illustrate that, while many bone graft substitutes perform well as bone graft extenders, only osteoinductive proteins (recombinant bone morphogenetic proteins-2 and osteogenic protein-1) provide evidence for use as both bone enhancers and bone substitutes for specific types of spinal fusion. Tissue engineered hydrogels, synthetic polymer composites and viral based gene therapy also holds the potential to be used for spine fusion in future, though warrants further investigation to be used in clinical practice.

Hybrid Biosynthetic Autograft Extender for Use in Posterior Lumbar Interbody Fusion: Safety and Clinical Effectiveness

Autologous iliac crest bone graft is the preferred option for spinal fusion, but the morbidity associated with bone harvest and the need for graft augmentation in more demanding cases necessitates combining local bone with bone substitutes. The purpose of this study was to document the clinical effectiveness and safety of a novel hybrid biosynthetic scaffold material consisting of poly(D,L-lactide-co-glycolide) (PLGA, 75:25) combined by lyophilization with unmodified high molecular weight hyaluronic acid (10-12% wt:wt) as an extender for a broad range of spinal fusion procedures. We retrospectively evaluated all patients undergoing single- and multi-level posterior lumbar interbody fusion at an academic medical center over a 3-year period. A total of 108 patients underwent 109 procedures (245 individual vertebral levels). Patient-related outcomes included pain measured on a Visual Analog Scale. Radiographic outcomes were assessed at 6 weeks, 3-6 months, and 1 year postoperatively. Radiographic fusion or progression of fusion was documented in 221 of 236 index levels (93.6%) at a mean (±SD) time to fusion of 10.2+4.1 months. Single and multi-level fusions were not associated with significantly different success rates. Mean pain scores (+SD) for all patients improved from 6.8+2.5 at baseline to 3.6+2.9 at approximately 12 months. Improvements in VAS were greatest in patients undergoing one- or two-level fusion, with patients undergoing multi-level fusion demonstrating lesser but still statistically significant improvements. Overall, stable fusion was observed in 64.8% of vertebral levels; partial fusion was demonstrated in 28.8% of vertebral levels. Only 15 of 236 levels (6.4%) were non-fused at final follow-up

Is DBM beneficial for the enhancement of bony consolidation in distraction osteogenesis? A randomized controlled trial

The aim of the present study was to compare the radiographic and clinical outcomes of DBM injection and conventional treatment during tibial lengthening over an intramedullary nail in adult patients with short stature. Twenty-nine patients were randomized to receive DBM injection (n = 14) or conventional treatment without any injection (n = 15) and evaluated. The outcome was measured on the basis of the pixel value ratio (PVR) in the digital radiographs during the consolidation period; healing index; clinical assessment; and the rate of complications. In the DBM group, the mean PVR of 1 (mineral density of the callus is comparable to the adjacent bone) was reached by 40 weeks in anterior and medial cortices which was significantly different than that in the control group (P = 0.03 for anterior cortex; P = 0.04 for medial cortex). The average healing index in the DBM group was 39.8 ± 5.3 days/cm compared to 44.3 ± 5.8 days/cm in the control group (P = 0.05). There were no significant differences in clinical outcomes (P = 0.23) and functional status (P = 0.47) including complications (P = 0.72) between two groups. In this randomized clinical trial, injection of DBM at the time of initial operation enhanced consolidation of regenerate callus without interfering with clinical outcomes compared to that with conventional treatment.

Midline Splitting Cervical Laminoplasty Using Allogeneic Bone Spacers: Comparison of Fusion Rates between Cervical Spondylotic Myelopathy and Ossification of Posterior Longitudinal Ligament

OBJECTIVE

To analyze factors associated with fusion using allogeneic bone spacers for midline splitting cervical laminoplasty (MSCL).

METHODS

During April 2012 and September 2013, seventeen patients with cervical spondylotic myelopathy (CSM) or ossification of posterior longitudinal ligament (OPLL) underwent MSCL with allogeneic bone spacers by a single surgeon. Mean follow up periods was 11.3 months (range, 6-19 months). Clinical outcomes were evaluated by the Japanese Orthopedic Association (JOA) scores at preoperative and postoperative 6 months. Simple cervical X-rays were taken preoperatively, immediate postoperatively, 3, and 6 months after operation. Computed tomography (CT) scans were performed preoperatively, immediate postoperatively and 6 months postoperatively. The differences between two diseases were analyzed on cervical lordosis, canal dimension, anteroposterior (AP) distance, fusion between lamina and allogeneic bone spacer and affecting factors of fusion.

RESULTS

All surgeries were performed on 59 levels. There were no significant differences on the changes of lordosis (p=0.602), canal dimension (p=0.554), and AP distance (p=0.924) as well as JOA scores (p=0.257) between CSM and OPLL groups. Overall fusion rate was 51%. Multivariate analysis on the factor for the fusion rates between lamina and spacers showed that the immediate postoperative contact status between lamina and spacers in CT as significant factor of fusion (p=0.024).

CONCLUSION

The present study suggests that CSM and OPLL did not show difference of surgical outcome in MSCL using allogeneic bone spacer. In addition, we should consider the contact status between lamina and bone spacer for the better fusion rates for this surgery.

Allograft alone versus allograft with bone marrow concentrate for the healing of the instrumented posterolateral lumbar fusion

BACKGROUND CONTEXT

Spondylodesis in the operative management of lumbar spine diseases has been the subject of numerous studies over several decades. The posterolateral fusion (PLF) with pedicle screw fixation is a commonly used procedure.

PURPOSE

To determine whether the addition of bone marrow concentrate (BMC) to allograft bone increases fusion rate after instrumented posterior lumbar fusion.

STUDY DESIGN

The study was prospective, randomized, controlled, and blinded.

METHODS

Eighty patients with degenerative disease of the lumbar spine underwent instrumented lumbar or lumbosacral PLF (22 men, 58 women; body mass index less than 35 for a good visualization of the PLF in the X-rays). In 40 cases, the PLF was done with spongious allograft chips alone (Group I, age 62.7 years in average, range 47-77 years, level of fusion 1-2). In another 40 cases, spongious allograft chips were mixed with BMC (Group II, age 58.5 years in average, range 42-80, level of fusion 1-3), including the mesenchymal stem cells (MSCs). Patients were scheduled for anteroposterior and lateral radiographs 12 and 24 months after the surgery and for computed tomography scanning 24 months after the surgery. Fusion status and the degree of mineralization of the fusion mass were evaluated separately by two radiologists blinded to patient group affiliation. The bony mass was judged as fused if there was uninterrupted bridging of well-mineralized bone between the transverse processes or sacrum, with trabeculation indicating bone maturation on least at one side of the spines.

RESULTS

In Group I at 12 months, the bone graft mass was assessed in X-rays as fused in no cases (0%) and at 24 months in four cases (10%). In Group II, 6 cases (15%) achieved fusion at 12 months and 14 cases (35%) at 24 months. The statistically significant difference between both groups was proven for complete fusion at both 12 (p=.041) and 24 months (p=.011). Computed tomography scans showed that 16 cases (40%) in Group I and 32 cases (80%) in Group II had evidence of at least unilateral continuous bridging bone between neighboring vertebrae at 24 months (p<.05).

CONCLUSIONS

We have confirmed the hypothesis that the autologous BMC together with the allograft is a better alternative for PLF than the allograft alone. The use of autologous MSCs in form of BMC in combination with allograft is an effective option to enhance the PLF healing.

Evaluation of Amniotic-Derived Membrane Biomaterial as an Adjunct for Repair of Critical Sized Bone Defects

Introduction. Autogenous bone graft is the gold standard in reconstruction of bone defects. The use of autogenous bone graft is problematic because of limited bone as well as donor site morbidity. This study evaluates a novel biomaterial as an alternative to autogenous bone graft. The biomaterial is amniotic membrane, rich in growth factors. Methods. Twenty-one adult male Sprague-Dawley rats were implanted with biomaterial using the rat critical size femoral gap model. After creation of the critical size femoral gap animals were randomized to one of the following groups: Group 1 (control): gap left empty and received no treatment; Group 2 (experimental): the gap was filled with commercially available bone graft; Group 3 (experimental): the gap was filled with bone graft plus NuCel amniotic tissue preparation. Results. The experimental groups demonstrated new bone formation compared to controls. The results were evident on radiographs and histology. Histology showed Group 1 controls to have 11.1% new bone formation, 37.8% for Group 2, and 49.2% for Group 3. These results were statistically significant. Conclusions. The study demonstrates that amniotic membrane products have potential to provide bridging of bone defects. Filling bone defects without harvesting autogenous bone would provide a significant improvement in patient care.

The outcome of scapulothoracic arthrodesis using cerclage wires, plates, and allograft for facioscapulohumeral dystrophy

BACKGROUND

Scapulothoracic arthrodesis is a recognized treatment for impaired shoulder function in patients with facioscapulohumeral dystrophy (FSHD) and is traditionally performed with autograft. The purpose of the study was to report our experience with scapulothoracic arthrodesis in patients with FSHD using allograft, rather than autograft, with particular respect to the effect of fusion on preoperative and postoperative Disabilities of the Arm, Shoulder and Hand (DASH) scores; forced vital capacity (FVC); and complications.

MATERIALS AND METHODS

The early results of 14 consecutive scapulothoracic arthrodeses in FSHD patients with cerclage wires, plates, and allograft (fresh-frozen femoral heads) are reported. DASH scores were recorded preoperatively and 6 months postoperatively. Preoperative and 6-month FVCs were compared. The surgical technique is described.

RESULTS

Eleven patients underwent 14 fusions. The mean follow-up period was 29 months (range, 6-50 months). Forward flexion improved from 70° to 115° (P = .001) and abduction from 68° to 109° (P = .007). The DASH score improved from 48 points to 34 points (P = .005). FVC decreased from 98% to 92% of predicted (P = .021), although this was not clinically significant. One patient required revision for nonunion, and metalwork was removed in 5 scapulae. A postoperative chest infection developed in 1 patient and a pleural effusion in another. One brachial plexus palsy occurred, which had almost completely resolved by 27 months postoperatively.

CONCLUSION

Scapulothoracic arthrodesis can be performed successfully with allograft. The nonunion and complication rates are similar to those in the existing literature. A small decrease in FVC does occur but not to a clinically significant level.

Histological remodelling of demineralised bone matrix allograft in posterolateral fusion of the spine--an ex vivo study

Background

Demineralised bone matrix (DBM) has shown to be effective in enhancing posterior fusion of the spine. Several animal studies and clinical investigations in humans showed its successful remodelling. The use of allogenic matrix may decrease the need of autologous bone graft and therefore helps prevent corresponding donor site morbidity. Since DBM products are very expensive, the question arises, whether it is completely remodelled into new bone, and therefore truly is comparable to autologous cancellous bone graft. To our knowledge there is no report of a consecutive series of patients where ex vivo histological analysis after postero-lateral fusion of the spine was performed.

Methods

Osseous biopsies of nine consecutive patients who underwent postero-lateral fusion of the spine for trauma were obtained at the time of elective removal of the hardware. Histological samples were then analyzed on ground and thin sections stained with toluidine blue and von Kossa stainings.

Results

Time span between index operation and removal of the metal ranged between 6 and 18 month. Histological analysis showed good incorporation and overall remodelling of DBM into new bone in all patients. No foreign body reaction was visible and new bone formation progressed time dependently with DBM in situ. Four out of nine patients showed more than 50% new bone formation after one year.

Conclusion

DBM shows good overall remodelling properties in histological analysis and therefore seems to be an effective adjunct in postero-lateral fusion of the spine. Furthermore, DBM substitution increases over time.

A review of demineralized bone matrices for spinal fusion: the evidence for efficacy

BACKGROUND AND PURPOSE

Autologous Iliac Crest Bone Grafting (ICBG) is considered the gold-standard graft choice for spinal arthrodesis; however, it is associated with donor site morbidity and a limited graft supply. Bone graft alternatives to replace autograft and augment arthrodesis are a topic of ongoing research. This article will review properties of Demineralized Bone Matrix (DBM) and review the evidence for its use, including animal models and human clinical trials.

METHODS

A systematic and critical review of the English-language literature was conducted on Pubmed, Cochrane, CINAHL, and Google Scholar using search key terms such as 'Demineralized Bone Matrix', 'Spine' and 'Fusion'. Papers that were included were original research articles in peer-reviewed journals that investigated fusion outcomes. Scientific validity of articles was appraised using the PRISMA methodology. Articles were critically examined and compared according to study design, DBM type, outcomes, and results. Primary outcome of interest was fusion rate. Secondary outcomes included Oswestry Disability Index; Short Form-36 survey; Odom's criteria; Visual Analog Scale neurologic pain score; Japanese Orthopedic Association myelopathy score; Neck Disability and Ishihara Curvature Indices; and pseudarthrosis and surgical failure rates.

RESULTS

Demineralized Bone Matrix has been evaluated in animal models and human clinical trials of spine fusion. Results of animal studies indicate variation in performance within and among DBM products. The majority of human clinical trials report high fusion rates when DBM is employed as a graft extender or a graft enhancer. Few prospective randomized controlled trials have been performed comparing DBM to autologous iliac crest bone graft in spine fusion.

CONCLUSIONS

Although many animal and human studies demonstrate comparable efficacy of DBM when combined with autograft or compared to autograft alone, additional high level of evidence studies are required to clearly define the indications for its use in spine fusion surgeries and the appropriate patient population that will benefit from DBM.

Acceleration of segmental bone regeneration in a rabbit model by strontium-doped calcium polyphosphate scaffold through stimulating VEGF and bFGF secretion from osteoblasts

The development of suitable bioactive three-dimensional scaffold for the promotion of bone regeneration is critical in bone tissue engineering. The purpose of this study was to investigate in vivo osteogenesis of the porous strontium-doped calcium polyphosphate (SCPP) scaffolds for bone repair, as well as the relationship between osteogenic properties of SCPP scaffolds and the secretion of bFGF and VEGF from osteoblasts stimulated by SCPP. Besides, the advantages of scaffolds seeded with mesenchymal stem cells (MSCs) for bone repair were also studied. Firstly, the bone repair evaluation of scaffolds was performed on a rabbit segmental bony defects model over a period of 16 weeks by histology combined with X-ray microradiography. And then, in order to avoid the influence from the other factors such as hypoxia which emerge in vivo study and affect the secretion of VEGF and bFGF from host cells, human osteoblast-like cells (MG63) were seeded to SCPP, CPP and HA scaffolds in vitro to determine the ability of these scaffolds to stimulate the secretion of angiogenic growth factors (VEGF and bFGF) from MG63 and further explore the reason for the better osteogenic properties of SCPP scaffolds. The histological and X-ray microradiographic results showed that the SCPP scaffolds presented better osteogenic potential than CPP and HA scaffolds, when combined with MSCs, the SCPP scaffolds could further accelerate the bone repair. And the amounts of VEGF measured by ELISA assay in SCPP, CPP and HA groups after cultured for 7 days were about 364.989 pg/mL, 244.035 pg/mL and 232.785 pg/mL, respectively. Accordingly, the amounts of bFGF were about 27.085 pg/mL, 15.727 pg/mL and 8.326 pg/mL. The results revealed that the SCPP scaffolds significantly enhanced the bFGF and VEGF secretion compared with other scaffolds. The results presented in vivo and in vitro study demonstrated that the SCPP could accelerate bone formation through stimulating the secretion of VEGF and bFGF from osteoblasts, making it attractive for bone regeneration.

The use of bone grafts and bone graft substitutes in pediatric orthopaedics: an overview

Bone graft substitutes have become progressively more widely used, and are currently heavily marketed. To make intelligent decisions, a complete knowledge of autograaft and allograft bone healing is essential, including the definition of "sterile". Differences in donor selection and tissue processing may confound the user not familiar with the implications of these different approaches. Specific products include demineralized bone matrix (DBM), specific growth factors (recombinant BMP's), ceramic grafts, and platelet-rich plasma (PRP). There are a number of useful applications of bone graft substitues for pediatric orthopaedists, but the data base is evolving. This paper describes the current status of these products.

An evaluation of the processing conditions, structure, and properties (biaxial flexural strength and antibacterial efficacy) of sintered strontium–zinc–silicate glass ceramics

The use of artificial bone grafts has increased in order to satisfy a growing demand for bone replacement materials. Initial mechanical stability of synthetic bone grafts is very advantageous for certain clinical applications. Coupled with the advantage of mechanical strength, a material with inherent antibacterial properties would be very beneficial. A series of strontium-doped zinc silicate (Ca–Sr–Na–Zn–Si) glass ceramics have been characterized in terms of their crystalline structure, biaxial flexural strength and antibacterial efficacy based on the identification of optimum sintering conditions. All three glass ceramics, namely, BT110, BT111, and BT112 were found to be fully crystalline, with BT111 and BT112 comprising of biocompatible crystalline phases. The biaxial flexural strengths of the three glass ceramics ranged from 70 to 149 MPa and were shown to be superior to those of clinically established ceramics in dry conditions and following incubation in simulated physiological conditions. The bacteriostatic effect for each glass ceramic was also established, where BT112 showed an inhibitory effect against three of the most common bacteria found at implantation sites, namely, Enterococcus faecalis, methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa. The results of the evaluation suggest that the materials studied offer advantages over current clinical materials and indicate the potential suitability of the glass ceramics as therapeutic bone grafts.

Safety and effectiveness of bone allografts in anterior cervical discectomy and fusion surgery

STUDY DESIGN

Systematic review.

OBJECTIVE

The primary aim of this review was to evaluate clinical and radiographic outcomes in studies of anterior cervical discectomy and fusion (ACDF) using allograft versus ACDF with autograft, ACDF with cage devices, and cervical disc arthroplasty for the treatment of symptomatic cervical disc disease.

SUMMARY OF BACKGROUND DATA

ACDF remains the standard of care for patients with cervical radiculopathy who are unresponsive to conservative medical care. However, no known study has compared patient outcomes after ACDF with allograft, ACDF with autograft, ACDF with cage, and disc arthroplasty.

METHODS

After applying strict inclusion criteria, 21 comparisons from 20 studies formed the basis for this review. Patient outcomes included neck and arm pain, neck disability index (NDI), physical component summary (PCS), and mental component summary (MCS) scores from the SF-36, radiographic fusion rate, and select adverse events (e.g., wound infection, dysphagia, and adjacent segment degeneration).

RESULTS

The four treatment groups included ACDF with allograft (allograft, n = 1341), ACDF with autograft (autograft, n = 568), ACDF with cage (cage, n = 87), and cervical disc arthroplasty (arthroplasty, n = 603). Neck pain was reduced similarly by 63% to 69% in all groups. Comparable improvements were realized in arm pain after ACDF with allograft (75%) or arthroplasty (73%) that were greater than other treatment groups (62-68%). There was notable improvement in neck disability (61-65%) with allograft and arthroplasty after treatment. PCS scores improved with allograft (42%) and arthroplasty (44%). MCS scores improved modestly (16-21%) with allograft and arthroplasty. Fusion rates were 91% for allograft and autograft and 97% for cage. Adverse events were uncommon in all groups.

CONCLUSION

ACDF with allograft, ACDF with autograft, ACDF with cage, and cervical disc arthroplasty show similar improvements in pain, function, and quality of life with correspondingly low adverse event rates. All ACDF procedures result in high fusion rates.

Preliminary evaluation of therapeutic ion release from Sr-doped zinc-silicate glass ceramics

Bioactive and degradable porous bioceramics play an important role in many clinical situations. Porosity is essential to the performance of a material that is proposed to be used as an implantable osseous scaffold. Scaffolds provide a three dimensional support and template to osseous integration and vascularization. Combining the porosity of a scaffold with the ability of the scaffold material to deliver therapeutic ions to the site of implantation goes some way towards developing an ideal bone graft. A series of strontium-doped zinc silicate (Ca-Sr-Na-Zn-Si) glass ceramics scaffoldswere developed, whose porosity was measured to be between 93% and 96%, which is advantageous in terms of osseous integration and vascularization. The levels of Zn2+ and Sr2+ detected as a result of degradation of the crystalline phases were found to be 1.4–600 parts per million (ppm) and 0–583 ppm, respectively. The levels detected correlate well with the levels of Sr2+ and Zn2+ions typically associated with clinical benefits, including antibacterial efficacy, osteoblastic differentiation and impaired osteoclastic resorption.

Fracture of anterior iliac crest following bone graft harvest in an anorexic patient: case report and review of the literature

In the treatment of jaw bone atrophies, autologus bone is still considered the gold standard because of its excellent osteoconductive, osteoinductive, and osteogenetic proprieties and lack of immunogenicity, which allow better graft integration and stability. Although various donor sites are available, the iliac crest represents the best source of corticocancellous bone, and literature suggests that it has low morbidity. However, this case report emphasizes that patients with systemic diseases such as anorexia should be carefully evaluated before such an operation, because unfavorable bone conditions may jeopardize the outcome. A 47-year-old woman needing rehabilitation of the upper arch was considered for iliac crest harvesting. She stated that she had suffered from anorexia for 30 years. A corticocancellous block was harvested by a bone saw using an anterolateral approach to the outer table of the right anterior iliac crest. The postoperative course was uneventful, but 13 days later, she complained of a sudden pain in the operated area, and X rays revealed a fracture of the anterior iliac crest. So far, the literature has mentioned 50 cases of iliac crest fractures after bone harvesting, and 28 cases among these are due to harvesting in the anterior part of the iliac crest. Several factors seem to be responsible for this complication, including the area of harvesting, residual bone thickness, technique used, and age and gender of the patient. To our knowledge, our case is the first of hip fracture after bone harvesting in a patient suffering from anorexia. Both low weight and osteoporosis are probably responsible for this complication. In our opinion, patients suffering from anorexia should be considered at risk for bone harvesting, and an appropriate mini-invasive surgical technique should be carried out instead.

Biodegradable poly(alpha-hydroxy acid) polymer scaffolds for bone tissue engineering

Synthetic graft materials are emerging as a viable alternative to autogenous bone graft and bone allograft for the treatment of critical-sized bone defects. These materials can be osteoconductive but are rarely intrinsically osteogenic, although this can be greatly enhanced by the application of bone morphogenetic proteins (BMPs). This review will discuss the versatility of biodegradable poly(alpha-hydroxy acids) for the delivery of BMPs for bone tissue engineering. Poly(alpha-hydroxy acids) have a considerable potential for customization and adaptability via modification of design parameters, including scaffold architecture, composition, and biodegradability. Different fabrication techniques will also be discussed.

Efficacy of minimally invasive techniques for enhancement of fracture healing: evidence today

The successful treatment of nonunions represents a major challenge for orthopaedic surgeons. Lately, ongoing advances made in the field of molecular medicine and molecular biology have increased our understanding of the pathways and involvement of mediators surrounding the bone healing process. As a result, the surgeon's armamentarium has been increased in terms of options for intervention. This article aims to provide an overview of minimally invasive techniques applicable in the treatment of nonunions of fractures.

Bone regeneration potential of a soybean-based filler: experimental study in a rabbit cancellous bone defects

Autologous and allogenic bone grafts are considered as materials of choice for bone reconstructive surgery, but limited availability, risks of transmittable diseases and inconsistent clinical performances have prompted the development of alternative biomaterials. The present work compares the bone regeneration potential of a soybean based bone filler (SB bone filler) in comparison to a commercial 50:50 poly(D: ,L: lactide-glycolide)-based bone graft (Fisiograft((R)) gel) when implanted into a critical size defect (6-mm diameter, 10-mm length) in rabbit distal femurs. The histomorphometric and microhardness analyses of femoral condyles 4, 8, 16 and 24 weeks after surgery showed that no significant difference was found in the percentage of both bone repair and bone in-growth in the external, medium and inner defect areas. The SB filler-treated defects showed significantly higher outer bone formation and microhardness results at 24 weeks than Fisiograft((R)) gel (P < 0.05). Soybean-based biomaterials clearly promoted bone repair through a mechanism of action that is likely to involve both the scaffolding role of the biomaterial for osteoblasts and the induction of their differentiation.

Autologous bone graft versus demineralized bone matrix in internal fixation of ununited long bones

Background

Non-unions are severe complications in orthopaedic trauma care and occur in 10% of all fractures. The golden standard for the treatment of ununited fractures includes open reduction and internal fixation (ORIF) as well as augmentation with autologous-bone-grafting. However, there is morbidity associated with the bone-graft donor site and some patients offer limited quantity or quality of autologous-bone graft material. Since allogene bone-grafts are introduced on the market, this comparative study aims to evaluate healing characteristics of ununited bones treated with ORIF combined with either iliac-crest-autologous-bone-grafting (ICABG) or demineralized-bone-matrix (DBM).

Methods and results

From 2000 to 2006 out of sixty-two consecutive patients with non-unions presenting at our Level I Trauma Center, twenty patients had ununited diaphyseal fractures of long bones and were treated by ORIF combined either by ICABG- (n = 10) or DBM-augmentation (n = 10). At the time of index-operation, patients of the DBM-group had a higher level of comorbidity (ASA-value: p = 0.014). Mean duration of follow-up was 56.6 months (ICABG-group) and 41.2 months (DBM-group). All patients were clinically and radiographically assessed and adverse effects related to bone grafting were documented. The results showed that two non-unions augmented with ICABG failed osseous healing (20%) whereas all non-unions grafted by DBM showed successful consolidation during the first year after the index operation (p = 0.146). No early complications were documented in both groups but two patients of the ICABG-group suffered long-term problems at the donor site (20%) (p = 0.146). Pain intensity were comparable in both groups (p = 0.326). However, patients treated with DBM were more satisfied with the surgical procedure (p = 0.031).

Conclusion

With the use of DBM, the costs for augmentation of the non-union-site are more expensive compared to ICABG (calculated difference: 160 €/case). Nevertheless, this study demonstrated that the application of DBM compared to ICABG led to an advanced outcome in the treatment of non-unions and simultaneously to a decreased quantity of adverse effects. Therefore we conclude that DBM should be offered as an alternative to ICABG, in particular to patients with elevated comorbidity and those with limited availability or reduced quality of autologous-bone graft material.

The effect of a single dose of bupivacaine on donor site pain after anterior iliac crest bone harvesting

Transplants from the anterior iliac crest are used for most reconstructive procedures in cranio-maxillofacial surgery. The advantages are easy accessibility, the ability to work in two teams and the amount of corticocancellous bone available; disadvantages are postoperative pain and gait disturbances. To reduce donor-site pain, the effect of a single dose of bupivacaine (10 cc of 2.5mg/cc with 1:80.000 epinephrine) was studied. 200 consecutive patients, who underwent anterior iliac crest bone harvesting for reconstructive procedures, were randomly divided into those receiving bupivacaine and those not. They completed a standardized questionnaire. Patients scored the intensity of the pain and difficulties walking at different times with a visual analogue scale. They recorded analgesics used. 98 questionnaires were eligible for analysis. No differences between the bupivacaine and the control group were detected for postoperative pain and gait disturbance. There is no support for administration of a single dose of bupivacaine to reduce pain in the first postoperative days. The surface area of the removed bone had a significant influence on pain and walking; pain is related to the local osseous damage or periosteal stripping rather than to the length of incision or the operation time.

Calcium phosphate cement enhances primary stability of open-wedge high-tibial osteotomies

We investigated if injectable calcium phosphate cement improves primary stability in open-wedge high-tibial osteotomy. A 10 mm open-wedge osteotomy was performed on eight pairs of preserved cadaver tibiae and seven pairs of composite (Sawbone) left tibiae. Osteosynthesis was performed with the Dynafix plate system. The gap resulting from surgery either was filled with 15 g injectable calcium phosphate cement in half the bones or was left untreated. The composite tibiae were loaded at a ramp speed of 20 mm/min up to 20 kN. The cadaver tibiae were exposed to 100 cycles with a maximum compressive force of 2,250 N. After 100 cycles of loading with 2,250 N, the final loaded displacement was 1.2 mm for the cadaver tibiae treated with injectable calcium phosphate cement as compared with 3.6 mm for the empty defects (P = 0.028). All the seven empty defect composite specimens failed prior to 20 kN (median 2.8 kN) as compared with five of the injectable calcium phosphate cement specimens (median 17 kN) (P = 0.005). The injection of injectable calcium phosphate cement following open-wedge osteotomy of the proximal tibia increases the initial stability of the bone as measured by load-to-failure and displacement after cyclic loading. Clinical studies are ongoing to investigate whether injectable calcium phosphate cement also has clinical advantage on wedge healing and stability.

The effect of composition on ion release from Ca-Sr-Na-Zn-Si glass bone grafts

Controlled delivery of active ions from biomaterials has become critical in bone regeneration. Some silica-based materials, in particular bioactive glasses, have received much attention due to the ability of their dissolution products to promote cell proliferation, cell differentiation and activate gene expression. However, many of these materials offer little therapeutic potential for diseased tissue. Incorporating trace elements, such as zinc and strontium, known to have beneficial and therapeutic effects on bone may provide a more viable bone graft option for those suffering from metabolic bone diseases such as osteoporosis. Rational compositional design may also allow for controlled release of these active ions at desirable dose levels in order to enhance therapeutic efficacy. In this study, six differing compositions of calcium-strontium-sodium-zinc-silicate (Ca-Sr-Na-Zn-Si) glass bone grafts were immersed in pH 7.4 and pH 3 solutions to study the effect of glass composition on zinc and strontium release in a normal and extreme physiological environment. The zinc release levels over 30 days for all zinc-containing glasses in the pH 7.4 solution were 3.0-7.65 ppm. In the more acidic pH 3 environment, the zinc levels were higher (89-750 ppm) than those reported to be beneficial and may produce cytotoxic or negative effects on bone tissue. Strontium levels released from all examined glasses in both pH environments similarly fell within apparent beneficial ranges--7.5-3500 ppm. Glass compositions with identical SrO content but lower ZnO:Na(2)O ratios, showed higher levels of Sr(2+) release. Whereas, zinc release from zinc-containing glasses appeared related to ZnO compositional content. Sustainable strontium and zinc release was seen in the pH 7.4 environment up to day 7. These results indicate that the examined Ca-Sr-Na-Zn-Si glass compositions show good potential as therapeutic bone grafts, and that the graft composition can be tailored to allow therapeutic levels of ions to be released.

Transplanted xenogenic bone marrow stem cells survive and generate new bone formation in the posterolateral lumbar spine of non-immunosuppressed rabbits

Bone marrow stem cells (BMSCs) are pluripotent cells that have been used to facilitate bone repair because of their capability of differentiating into osteoblasts. However, it is well known that the number of BMSCs with osteogenic potential decreases in patients with old age, osteoporosis, and metabolic diseases. In such conditions, xenogenic BMSCs may provide an alternative to autologous BMSCs. In the current study, we investigated the potential of transplanted xenogenic BMSCs to survive and generate new bone formation in the posterolateral lumbar spine of non-immunosuppressed rabbits. The BMSCs were obtained from bilateral femurs of four male rats, cultured and expanded in medium with osteoinduction supplement. The BMSCs (1,000,000 cells) of male rats loaded onto 5 cc compression resistant matrix (CRM; Medtronic Sofamor Danek, USA) were implanted bilaterally onto the L4-5 intertransverse processes of 16 female rabbits (xenogenic BMSCs + CRM group). The 16 female rabbits that received 5 cc CRM alone were used as controls (CRM alone group). To exclude the possibility of migration of BMSCs from the transverse processes of the recipient rabbits, we did not decorticate the transverse processes. No rabbits received any immunosuppressive medications during the experiment. Four rabbits each in both of the experimental and control groups were killed at 1, 2, 4, and 6 months postimplantation, and the lumbar spine underwent radiological and histological analyses for evaluation of new bone formation. The polymerase chain reaction (PCR) for Sry gene (Y-chromosome-specific marker) was used to evaluate the survival of transplanted xenogenic BMSCs. The expression of Sry gene was clearly identified in the lumbar spines of all the 16 rabbits in the xenogenic BMSCs + CRM group at 1-6 months postimplantation. Serial plain radiographs showed gradual resorption of CRM; however, it was difficult to clearly identify the presence of new bone formation due to the radiopacity of the remaining CRM. Histologically, mature lamellar and woven bone with osteoblasts and osteocytes were identified in all eight rabbits in the xenogenic BMSCs + CRM group at 4 and 6 months postimplantation, but in none of the eight rabbits at 1 and 2 months postimplantation. None of CRM alone group showed new bone formation at 1-6 months postimplantation. Mild-to-moderate infiltration of inflammatory cells was identified around the CRM carriers in both the groups. No post-operative wound infection was found in either group. Our results indicate that xenogenic BMSCs loaded onto CRM survive and generate new bone formation when placed into the posterolateral lumbar spine of rabbits without immunosuppression. To determine if a solid fusion can be achieved with such techniques, further studies are needed to investigate the appropriate dose of xenogenic BMSCs, amounts of CRM, and the requisite incubation time.

Orthogonal cutting of cancellous bone with application to the harvesting of bone autograft

Autogenous bone graft harvesting results in cell death within the graft and trauma at the donor site. The latter can be mitigated by using minimally invasive tools and techniques, while cell morbidity may be reduced by improving cutter design and cutting parameters. We have performed orthogonal cutting experiments on bovine cancellous bone samples, to gain a basic understanding of the cutting mechanism and to determine design guidelines for tooling. Measurements were performed at cutting speeds from 11.2 to 5000 mm/min, with tool rake angles of 23 degrees, 45 degrees and 60 degrees, and depths of cut in the range of 0.1-3.0 mm. Horizontal and vertical cutting forces were measured, and the chip formation process video recorded. Continuous chip formation was observed for rake angles of 45 degrees and 60 degrees , and depths of cut greater than 0.8 mm. Chip formation for depths of cut greater than 1.0 mm was accompanied by bone marrow extruding out of the free surfaces and away from the rake face. Specific cutting energies decreased with increasing rake angle, increasing depth of cut and increasing cutting speed. Our orthogonal cutting experiments showed that a rake angle of 60 degrees and a depth of cut of 1mm, will avoid excessive fragmentation, keep specific cutting energy low and promote bone marrow extrusion, which may be beneficial for cell survival. We demonstrate how drill bit clearance angle and feed rate can be calculated facilitating a 1mm depth of cut.

Safety and efficacy of commercially available demineralised bone matrix preparations: a critical review of clinical studies

Demineralised bone matrix (DBM), a form of allograft, possesses the properties of osteoinductivity and osteoconductivity. A large body of data obtained from extensive preclinical studies have clearly supported the utility of DBM in human clinical settings. However, it is now recognized that various DBM configurations may differ considerably with regard to their bone inductive activity. Several factors could account for such variability, including the biologic properties of the graft, the host environment, and the methods of allograft preparation. The differing efficacy of DBM products may also depend on differences in particle size and shape, donor selection criteria, protocols for collection and storage, as well as DBM carrier materials. Several comparative studies have confirmed the differences in the osteoinductive potential of various DBM preparations. The purpose of the present review is to provide a critical overview of the current applications of DBM in a clinical setting.

Efficacy of mesenchymal stem cell enriched grafts in an ovine posterolateral lumbar spine model

STUDY DESIGN

Four groups of 6 animals underwent single-level noninstrumented posterolateral lumbar fusion (PLF) with one of the following grafts: 1) autograft, 2) cell-enriched beta-tricalcium phosphate (TCP), 3) TCP with whole bone marrow, and 4) TCP alone. Plain radiographs were taken after surgery and at death, 6 months after surgery. Explanted spine segments were analyzed by manual palpation, micro-CT, and histology.

OBJECTIVE

A sheep spine fusion study was undertaken to evaluate the healing performance of a TCP graft enriched with osteoprogenitor cells using Selective Cell Retention technology (SCR), compared with autograft, TCP with whole bone marrow, and TCP alone.

SUMMARY OF BACKGROUND DATA

Improved bone healing with previously demonstrated using grafts enriched in osteoprogenitor cells.

METHODS

Cell-enriched grafts were obtained by processing 30 mL of bone marrow through 10 mL of TCP. TCP was also used either saturated with bone marrow or alone.

RESULTS

At 6 months, 33% of the SCR-enriched TCP and 25% of the autograft sites were fused, compared with 8% of the TCP plus whole bone marrow and 0% of the TCP alone. Histology of fused samples showed denser bone formation in the SCR-enriched TCP grafts than in the autograft sites.

CONCLUSIONS

The use of SCR-enriched TCP and autograft resulted in similar fusion rates in an ovine posterolateral noninstrumented lumbar spine fusion model.

Initial results of anterior interbody fusion achieved with a less invasive bone harvesting technique

STUDY DESIGN

A retrospective review.

OBJECTIVE

To review the initial experience using a trephine bone harvesting system from the local lumbar spine for use in anterior interbody fusions, analyzing fusion rates and complications.

SUMMARY OF BACKGROUND DATA

Historically, autogenous bone for lumbar spine fusions has been procured from the iliac crest. No data exist regarding the use of a trephine bone harvesting system for obtaining cancellous bone locally from the lumbar spine for use in anterior interbody fusions. In this technique, the donor site is replaced with a corticocancellous humeral dowel.

METHODS

A total of 36 patients who underwent anterior lumbar interbody fusion were retrospectively reviewed. There were 56 interbody fusions performed using 36 trephine donor sites. Twenty individuals had the bone divided between 2 fusion levels, placed within allograft femoral rings, and 16 had the bone applied to 1 fusion level. Radiographs were analyzed for complications associated with the fibular dowel and time to interbody fusion.

RESULTS

By 6 months, 35 of 36 (97%) of the corticocancellous fibular dowels had incorporated. Two dowels migrated 3 mm, each without sequelae. Of 56 of interbody spaces, 50 (89%) were fused. Two eventually fused at 9 and 11 months, and 4 (7%) failed to unite by 15 months.

CONCLUSION

Harvesting cancellous autograft anteriorly from the lumbar spine using a trephine technique appears to be safe and reliable, with satisfactory fusion rates. Iliac crest graft harvesting with its attendant morbidity is avoided.

Demineralized bone matrix and spinal arthrodesis

Spinal fusion is a gold-standard treatment for many disorders of the spine with autogenous bone graft as the gold-standard source for augmenting fusion. However, the morbidity and limitations of autogenous bone grafting has motivated the search for bone graft alternatives. One such alternative is demineralized bone matrix (DBM). The purpose of this paper is to describe and characterize the properties of DBM in addition to reviewing the results of its use in animal and human studies of spinal fusion. A thorough and critical review of the English-language literature was conducted. DBM is both osteoconductive and osteoinductive. Studies have produced variable results with respect to spinal fusion rates. Various studies have demonstrated inferior, equal, or enhanced fusion rates. Some of the differences in these studies include the animal models used, the manner in which DBM was prepared, and the carrier with which DBM was combined. These differences may account for the dissimilar results. DBM is able to function as a graft extender in the human species.

Efficacy and safety of a novel moldable, resorbable, and degradable sealant of bone surfaces for hemostasis after bone graft harvesting from the iliac crest

STUDY DESIGN

A prospective, controlled, open, randomized multicenter study.

OBJECTIVE

The study's objective was to demonstrate equivalence of a novel, moldable, resorbable, and degradable synthetic polymer (Bone Seal) compared with a collagen fleece (Lyostypt) in efficacy and safety for topical hemostasis after iliac crest bone graft harvesting.

SUMMARY OF BACKGROUND DATA

Harvesting cortico-cancellous bone from the iliac crest is a well established procedure in orthopedic and particularly in spine surgery. It is associated with significant morbidity at the donor site where hematoma formation may cause impaired wound healing and infections in up to 10% of cases.

METHODS

A total of 112 patients were included in the safety analysis. Safety was determined by a compound wound healing score and the incidence of adverse clinical effects. One hundred and eight patients were studied for equivalence in efficacy using a compound bleeding score. The handling properties and the application to the bone surface of either device were measured with two additional compound scores.

RESULTS

The mean bleeding scores in the final analysis was 4.5 +/- 1.3 for the Bone Seal group and 4.2 +/- 1.3 for the collagen fleece group. Bone Seal was better applicable to the bleeding bone surfaces than the collagen fleece, even though its handling was more complicated. Wound healing and the incidences of adverse clinical events were comparable in either study group.

CONCLUSIONS

Bone Seal is an effective and safe hemostatic material for sealing bleeding bone surfaces after iliac crest bone graft harvesting. By virtue of its hemostatic efficacy, Bone Seal is preventive for wound healing disorders.

Osteoblastic Phenotype Expression of MC3T3-E1 Cells Cultured on Polymer Surfaces

BACKGROUND

Current efforts in bone tissue engineering have as one focus the search for a scaffold material that will support osteoblast proliferation, matrix mineralization, and, ultimately, bone formation. The goal is to develop a bone substitute that is functionally equivalent to autograft bone. Previously published reports have shown that osteoblasts exhibit varying rates and degrees of proliferation and mineralization when grown on different surfaces.

METHODS

This study presents a histologic and biomolecular analysis of MC3T3-E1 murine preosteoblast cells grown on poly(lactide-co-glycolide) (PLGA) versus poly(-caprolactone) (PCL), two commonly studied scaffold polymers. MC3T3-E1 cells were cultured on slides coated with either PLGA or PCL, and on uncoated glass slides as control, with six slides in each group. After 6 weeks in culture, the cells were stained for osteocalcin, alkaline phosphatase activity, and matrix mineralization. In addition, to assess the effects of the surface material on phenotypic expression at the molecular level, MC3T3-E1 cells were cultured on polymer-coated 24-well plates for 4 days, and analyzed by reverse transcription polymerase chain reaction for the expression of osteocalcin and alkaline phosphatase.

RESULTS

The results showed that three groups of slides stained positively for osteocalcin at 6 weeks. However, markedly less alkaline phosphatase activity and mineralization were observed on the cells grown on PCL. Real-time polymerase chain reaction assays subsequently revealed decreased expression of both markers by cells cultured on PCL compared with PLGA.

CONCLUSIONS

These results suggest that PCL does not support the full expression of an osteoblastic phenotype by MC3T3-E1 cells. PCL, therefore, is less desirable as a scaffold polymer in bone tissue engineering in so far as supporting bone formation is concerned. However, because PCL has favorable handling characteristics and strength, modifications of PCL may prompt further investigation.