Autogenous bone graft: donor sites and techniques

Impact of Age and Duration of Symptoms on Surgical Outcome of Single-Level Microscopic Anterior Cervical Discectomy and Fusion in the Patients with Cervical Spondylotic Radiculopathy

We aim to evaluate the impact of age and duration of symptoms on surgical outcome of the patients with cervical spondylotic radiculopathy (CSR) who had been treated by single-level microscopic anterior cervical discectomy and fusion (ACDF). We retrospectively evaluated 68 patients (48 female and 20 male) with a mean age of 41.2 ± 4.3 (ranged from 24 to 72 years old) in our Orthopedic Department, Imam Reza Hospital. They were followed up for 31.25 ± 4.1 months (ranged from 25 to 65 months). Pain and disability were assessed by Visual Analogue Scale (VAS) and Neck Disability Index (NDI) questionnaires in preoperative and last follow-up visits. Functional outcome was eventually evaluated by Odom's criteria. Surgery could significantly improve pain and disability from preoperative 6.2 ± 1.4 and 22.2 ± 6.2 to 3.5 ± 2.0 and 8.7 ± 5.2 (1–21) at the last follow-up visit, respectively. Satisfactory outcomes were observed in 89.7%. Symptom duration of more and less than six months had no effect on surgical outcome, but the results showed a statistically significant difference in NDI improvement in favor of the patients aged more than 45 years (P = 0.032), although pain improvement was similar in the two groups.

Fresh-frozen allografts combined with bovine bone mineral enhance bone formation in sinus augmentation

We evaluated histologically, histomorphometrically, and tomographically the effects of the association of fresh-frozen bone allograft (FFB) with bovine bone mineral (BBM) in maxillary sinus floor augmentation. In total, 34 maxillary sinuses from 29 patients, with a mean age of 51.32 (±6.44) years, underwent sinus augmentation. Patients were divided into control and test groups (17 sinuses each). The controls were grafted with allograft bone, and the test group received a combination of FFB and BBM at a 2:1 ratio. After 6 months, bone samples were collected for histological and histomorphometric examinations. The implant survival rates were 93.02% (control group) and 100% (test group) at 6 months after functional loading. Median volumetric reductions of 28.32% (17.05-44.05) and 12.62% (5.65-16.87) were observed for the control and test groups, respectively. Statistically significant histomorphometric differences were found between the control and test groups regarding newly formed bone 12.54% (10.50-13.33) vs. 24.42% (17.62-35.92), p < 0.001, total bone 48.34% (39.03-54.42) vs. 61.32% (50.61-64.96), p = 0.007, and connective tissue 51.66% (45.57-60.97) vs. 39.30% (35.03-49.37), p = 0.007. The addition of BBM to allograft bone in maxillary sinus augmentation resulted in higher percentages of new bone formation and total bone, and permitted implant placement with a low rate of osseointegration failure at the 6-month follow-up.

Short-term adverse events, length of stay, and readmission after iliac crest bone graft for spinal fusion

STUDY DESIGN

Retrospective cohort study of 13,927 patients, 820 of whom received iliac crest bone graft (ICBG).

OBJECTIVE

To compare adverse events, length of stay (LOS), and readmission for patients receiving ICBG with those who did not using multivariate analysis to control for potentially confounding factors.

SUMMARY OF BACKGROUND DATA

The use of ICBG in spinal fusion has been associated with increased surgical time, LOS, and donor site morbidity. Development of expensive bone graft substitutes has been predicated on these issues. Data on the effect of bone graft harvest on LOS and readmission rate are sparse, and multivariate analysis has not been used to control for confounding factors.

METHODS

Prospectively collected data from the American College of Surgeons National Surgical Quality Improvement Project 2010-2012 database were retrospectively reviewed. This includes demographics, comorbidities, surgical data, and hospital and 30-day follow-up outcomes data including adverse events, LOS, and readmission.

RESULTS

Only 5.9% of spinal fusions use ICBG. Bivariate logistic regression (used for categorical variables) found the ICBG cohort was more likely to have a postoperative blood transfusion (11.6% vs. 5.5%, P < 0.001). Bivariate linear regression (used for continuous variables) found the ICBG cohort to have an extended operative time (+36.0 min, P < 0.001) and extended LOS (+0.6 d, P < 0.001).Multivariate analyses controlling for comorbidities, demographics, and approach-determined postoperative blood transfusion (odds ratio, 1.5), extended operative time (+22.0 min, P < 0.001), and LOS (+0.2 d, P = 0.037) to be significantly associated with ICBG use.No other adverse event was significantly associated with ICBG use. Readmission rates were not significantly different.

CONCLUSION

This study used a large national database cohort and identified increased postoperative blood transfusion, extended operative time, and increased LOS as short-term outcomes associated with ICBG on multivariate analysis. Other short-term morbidities were not significantly associated with ICBG. Readmission rates were not affected.

LEVEL OF EVIDENCE

4.

Trends in bone graft use in the United States

Bone graft and bone graft substitutes are used to provide structural support and enhance bone healing. Autogenous, allogeneic, and artificial bone grafts each have advantages and drawbacks. The development of allografts, synthetic bone grafts, and new operative techniques may have influenced the use of bone grafts in recent years. The goal of this study was to analyze the use of bone grafts and bone graft substitutes in the United States during a 16-year period. Using data from the National Hospital Discharge Survey, the authors analyzed the use of autogenous and artificial bone grafts in almost 2 million patients in the United States between 1992 and 2007 using International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes in 4 periods (1992-1995, 1996-1999, 2000-2003, and 2004-2007). Among an estimated almost 2 million bone graft procedures (83% autogenous, 17% artificial), the use of both types of grafts decreased. The main diagnoses for which bone grafts were used did not change; however, cervical spine diseases and lower-limb fractures decreased more remarkably. Although sex (52% male in the early 1990s to 47% in 2000-2003) and discharge status (more discharges to a short-term or long-term-care facility) significantly changed, age increased from 47 to 53 years and inpatient days decreased significantly from 6 to 5 days during the study period. The use of bone grafts and bone graft substitutes is decreasing in the United States, with a slight shift from autogenous to substitute grafts.

Efficacy of prevascularization for segmental bone defect repair using β-tricalcium phosphate scaffold in rhesus monkey

Although small animal model (rabbit) showed successful bone defect repair using prevascularized tissue-engineered bone grafts (TEBG), large animal (rhesus monkey) studies are still needed to extrapolate the findings from animal data to humans. In current study, we investigated the efficacy of prevascularized TEBG for segmental bone defect repair in rhesus monkey. The segmental diaphyseal defects were created in both tibias. In group A, the defect was filled with prevascularized MSCs/scaffold prepared by inserting saphenous vascular bundle into the side groove and a fascia flap coverage; In group B, the defect was filled with MSCs/scaffold with a fascia flap coverage; In group C, the defect was filled with MSCs/scaffold; In group D, the defect was filled with only scaffold. The angiogenesis and new bone formation were compared among groups at 4, 8, and 12 weeks postoperatively. The results showed the prevascularized TEBG in group A could augment new bone formation and capillary vessel in-growth. It had significantly higher values of vascularization and radiographic grading score compared with other groups. In conclusion, the in vivo experiment data of prevascularized TEBG was further enriched from small to large animal model. It implies that prevascularized TEBG has great potentials in clinical applications.

Human bone chips release of sclerostin and FGF-23 into the culture medium: an in vitro pilot study

OBJECTIVE

Signaling molecules derived from osteocytes have been proposed as a mechanism by which autografts contribute to bone regeneration. However, there have been no studies that determined the role of osteocytes in bone grafts.

MATERIAL AND METHOD

Herein, it was examined whether bone chips and demineralized bone matrix release sclerostin and FGF-23, both of which are highly expressed by osteocytes.

RESULTS

Bone grafts from seven donors were placed in culture medium. Immunoassay showed that bone chips released sclerostin (median 1.0 ng/ml) and FGF-23 (median 9.8 relative units/ml) within the first day, with declining levels overtime. Demineralized bone matrix also released detectable amounts of sclerostin into culture medium, while FGF-23 remained close to the detection limit. In vitro expanded isolated bone cells failed to release detectable amounts of sclerostin and FGF-23.

CONCLUSION

These results suggest that autografts but also demineralized bone matrix can release signaling molecules that are characteristically produced by osteocytes.

Effect of rhBMP-2 upon maxillary sinus augmentation: a comprehensive review

PURPOSE

The purpose of this review was to summarize the recent in vitro and in vivo research findings in areas where rhBMP-2 was used as a grafting material for sinus augmentation.

MATERIALS AND METHODS

An electronic literature search for relevant articles published in English was conducted in the PubMed database from February 1996 to August 2012. Randomized clinical trials or prospective human clinical and animal trials were included with the primary objective to compare and evaluate the effectiveness of rhBMP-2 for sinus augmentation.

RESULTS

A total of 3 human studies and 4 animal trials qualified the selection criteria that were included in this review. In humans, the selected studies indicated that rhBMP-2 induces new bone formation with comparable bone quality or amount of newly formed bone to that induced by autogenous bone graft. Furthermore, no differences have been reported between new bone induced by rhBMP-2 and native bone. Animal model studies also demonstrated regular bone formation induced by rhBMP-2, followed by normal maturation of new bone.

CONCLUSION

All these studies demonstrate the osteoinductive and osteogenic capacity of rhBMP-2 and support it as an alternative for autogenous bone in sinus floor augmentation.

Bupivacaine for pain reduction after iliac crest bone graft harvest

Iliac crest bone graft remains the gold standard in achieving spinal arthrodesis, but chronic pain from graft harvest occurs in up to 39% of patients. Studies have shown that a single administration of local anesthetic reduces short-term pain, but they have not adequately investigated possible longer-term benefits. The goal of this study was to determine whether local administration of bupivacaine after iliac crest bone graft harvesting reduces pain and improves patient-reported outcomes. In this prospective, randomized, controlled, and blinded clinical study, 40 patients were identified who underwent posterior spine fusion with iliac crest bone graft and were randomized to receive either bupivacaine (treatment group, n=20) or saline (control group, n=20) at the iliac crest bone graft site. Pain at the harvest site was determined by a series of 12 visual and numeric pain scale assessments. Short Form-12 mental and physical component scores, EuroQol-5D, and Oswestry Disability Index assessments were made, along with determination of patient satisfaction and self-reported outcome of surgery. Baseline pain and outcome assessments were statistically similar (P>.05). Average pain scores were lower for all 12 assessments in the treatment group at mean follow-up of 5 weeks (significant differences in 6 assessments) and 20 weeks (significant differences in 2 assessments). No significant differences were found in Short Form-12 and EuroQol-5D scores. For patients who underwent lumbar fusion, the treatment group had significantly improved Oswestry Disability Index scores (mean±SD=10.8±7.1 vs 18.7±5.9, P=.012). Significantly more patients in the treatment group reported that surgery met all expectations (90% vs 50%, P=.016). This study is the 1st to show that a single administration of bupivacaine at the iliac crest bone graft harvest site during posterior spine fusion surgery can result in improved outcomes and reduced pain far beyond the anesthetic duration of activity.

CERAMENT treatment of fracture defects (CERTiFy): protocol for a prospective, multicenter, randomized study investigating the use of CERAMENT™ BONE VOID FILLER in tibial plateau fractures

BACKGROUND

Bone graft substitutes are widely used for reconstruction of posttraumatic bone defects. However, their clinical significance in comparison to autologous bone grafting, the gold-standard in reconstruction of larger bone defects, still remains under debate. This prospective, randomized, controlled clinical study investigates the differences in pain, quality of life, and cost of care in the treatment of tibia plateau fractures-associated bone defects using either autologous bone grafting or bioresorbable hydroxyapatite/calcium sulphate cement (CERAMENT™|BONE VOID FILLER (CBVF)).

METHODS/DESIGN

CERTiFy (CERament™ Treatment of Fracture defects) is a prospective, multicenter, controlled, randomized trial. We plan to enroll 136 patients with fresh traumatic depression fractures of the proximal tibia (types AO 41-B2 and AO 41-B3) in 13 participating centers in Germany. Patients will be randomized to receive either autologous iliac crest bone graft or CBVF after reduction and osteosynthesis of the fracture to reconstruct the subchondral bone defect and prevent the subsidence of the articular surface. The primary outcome is the SF-12 Physical Component Summary at week 26. The co-primary endpoint is the pain level 26 weeks after surgery measured by a visual analog scale. The SF-12 Mental Component Summary after 26 weeks and costs of care will serve as key secondary endpoints. The study is designed to show non-inferiority of the CBVF treatment to the autologous iliac crest bone graft with respect to the physical component of quality of life. The pain level at 26 weeks after surgery is expected to be lower in the CERAMENT bone void filler treatment group.

DISCUSSION

CERTiFy is the first randomized multicenter clinical trial designed to compare quality of life, pain, and cost of care in the use of the CBVF and the autologous iliac crest bone graft in the treatment of tibia plateau fractures. The results are expected to influence future treatment recommendations.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT01828905.

[Technical note: iliac crest bone graft harvesting in children]

Harvesting iliac crest bone in children is special because of the presence of a thick cartilage. Constant pressure on the internal iliac fossa, ascends the skin, and moves the abdominal muscles away from the iliac crest. A single incision is then used for cutaneous and subcutaneous dissection. An internal piece of cartilage is then removed and the iliac muscle retracted in order to harvest cortical and spongy bone from the internal side of the iliac crest. That pièce of cartilage is then sutured at its initial place. During the harvesting, the surgeon needs to be careful to preserve the lateral femoral cutaneous nerve.

Short-segment posterior instrumentation combined with anterior spondylodesis using an autologous rib graft in thoracolumbar burst fractures

BACKGROUND AND PURPOSE

There are very few data concerning the outcome after short-segment posterior stabilization and anterior spondylodesis with rib grafts in patients suffering from unstable thoracolumbar burst fractures. We have therefore investigated the clinical and radiographic outcome after posterior bisegmental instrumentation and monosegmental anterior spondylodesis using an autologous rib graft for unstable thoracolumbar burst fractures.

PATIENTS AND METHODS

This was a retrospective analysis of 32 consecutive patients at a single center. The monosegmental Cobb angle was measured preoperatively, postoperatively, then 6 and 12 months postoperatively, and also after implant removal. Anterior vertebral fusion was graded on conventional radiographs according to the criteria proposed by Molinari.

RESULTS

Segmental kyphosis at the fracture site was corrected from a median of -20° (95% CI: -21.2 to -18.8) to -1.0° (95% CI: -2.7 to 0.7) postoperatively. 1 year after surgery, the segmental angle had decreased by a median of 2.0° (95% CI: 0.2 to 2.8). The spondylodesis fused in all patients, which was evident from incorporation and remodeling of the rib grafts. The median correction loss after implant removal was 0.0° (95% CI: -0.5 to 0.5). 26 of the 32 patients reported having no back complaints at the last follow-up (2 years postoperatively). 1 patient suffered from intercostal neuralgia, and 5 patients reported mild to moderate back pain.

INTERPRETATION

Short-segment posterior instrumentation and anterior spondylodesis using an autologous rib graft resulted in sufficient correction of posttraumatic segmental kyphosis. There was no clinically relevant correction loss, and the majority of patients had no back complaints at the 2-year follow-up.

Bone-Conditioned Medium Inhibits Osteogenic and Adipogenic Differentiation of Mesenchymal Cells In Vitro

BACKGROUND AND PURPOSE

Autografts are used for bone reconstruction in regenerative medicine including oral and maxillofacial surgery. Bone grafts release paracrine signals that can reach mesenchymal cells at defect sites. The impact of the paracrine signals on osteogenic, adipogenic, and chondrogenic differentiation of mesenchymal cells has remained unclear.

MATERIAL AND METHODS

Osteogenesis, adipogenesis, and chondrogenesis were studied with murine ST2 osteoblast progenitors, 3T3-L1 preadipocytes, and ATDC5 prechondrogenic cells, respectively. Primary periodontal fibroblasts from the gingiva, from the periodontal ligament, and from bone were also included in the analysis. Cells were exposed to bone-conditioned medium (BCM) that was prepared from porcine cortical bone chips.

RESULTS

BCM inhibited osteogenic and adipogenic differentiation of ST2 and 3T3-L1 cells, respectively, as shown by histological staining and gene expression. No substantial changes in the expression of chondrogenic genes were observed in ATDC5 cells. Primary periodontal fibroblasts also showed a robust decrease in alkaline phosphatase and peroxisome proliferator-activated receptor gamma (PPARγ) expression when exposed to BCM. BCM also increased collagen type 10 expression. Pharmacologic blocking of transforming growth factor (TGF)-β receptor type I kinase with SB431542 and the smad-3 inhibitor SIS3 at least partially reversed the effect of BCM on PPARγ and collagen type 10 expression. In support of BCM having TGF-β activity, the respective target genes were increasingly expressed in periodontal fibroblasts.

CONCLUSIONS

The present work is a pioneer study on the paracrine activity of bone grafts. The findings suggest that cortical bone chips release soluble signals that can modulate differentiation of mesenchymal cells in vitro at least partially involving TGF-β signaling.

Age-old wisdom concerning cell-based therapies with added knowledge in the stem cell era: our perspectives

Among the various strategies providing a cure for illness, cell-based therapies have caught the attention of the world with the advent of the “stem cell” era. Our inherent understanding indicates that stem cells have been in existence since the birth of multicellular organisms. However, the formal discovery of stem cells in the last century, followed by their intricate and extensive analysis, has led to clinical and translational efforts with the aim of using them in the treatment of conditions which don’t have a definitive therapeutic strategy, has fueled our interest and expectations. Technological advances in our ability to study their cellular components in depth, along with surface markers and other finer constituents, that were unknown until last century, have improved our understanding, leading to several novel applications. This has created a need to establish guidelines, and in that process, there are expressed understandings and views which describe cell therapy along lines similar to that of biologic products, drugs, and devices. However, the age-old wisdom of using cells as tools for curing illness should not be misled by recent knowledge, to make cell therapy using highly complex stem cells equal to factory-synthesized and reproducible chemical compounds, drugs, or devices. This article analyses the differences between these two entities from various perspectives.

Applications of the medial femoral condyle free flap for foot and ankle reconstruction

BACKGROUND

Avascular necrosis (AVN) or persistent nonunion occurs in situations of poor vascular supply. Some specific situations that plague the foot and ankle surgeon are talus nonunion, talus AVN, navicular AVN, and failed ankle arthrodesis with bone loss. The medial femoral condyle (MFC) flap has emerged as a popular source of vascularized corticocancelous bone. We present a series of cases demonstrating the versatility of the MFC flap in complex foot and ankle pathology.

METHODS

A retrospective review was completed of all MFC flaps used in the foot and ankle over the past 5 years. Five patients were identified (average age 48). Surgical indications included talar AVN and ankle arthritis, talar nonunion, and navicular AVN. All patients had undergone conventional bone grafting techniques, which failed, prior to being treated with a MFC free flap; this series of patients did not possess significant medical comorbidities. Fixation techniques included compression screw fixation, plate osteosynthesis, or fine wire external fixation. The average follow-up was 20 months (range 8 to 40 months).

RESULTS

There was a 100% flap success rate with no returns to the operating room for thrombosis. The volume of the bone flaps was 5.6 cm(3) (range 1 cm(3) to 12 cm(3)). The average follow-up time was 20 months (range 8 to 40 months). All cases resulted in union, and full weight bearing status was achieved at a mean of 23.8 weeks (range 10 to 52 weeks) postoperatively.

CONCLUSIONS

Vascularized bone transfer in the form of the MFC free flap was a valuable method for foot and ankle reconstruction. The MFC flap provided an alternative for those defects that were smaller then 3 cm in length. In our experience, for small bone defects requiring vascularized bone, the MFC flap is currently the ideal donor location supplanting the iliac crest.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Bone Regeneration Based on Tissue Engineering Conceptions - A 21st Century Perspective

The role of Bone Tissue Engineering in the field of Regenerative Medicine has been the topic of substantial research over the past two decades. Technological advances have improved orthopaedic implants and surgical techniques for bone reconstruction. However, improvements in surgical techniques to reconstruct bone have been limited by the paucity of autologous materials available and donor site morbidity. Recent advances in the development of biomaterials have provided attractive alternatives to bone grafting expanding the surgical options for restoring the form and function of injured bone. Specifically, novel bioactive (second generation) biomaterials have been developed that are characterised by controlled action and reaction to the host tissue environment, whilst exhibiting controlled chemical breakdown and resorption with an ultimate replacement by regenerating tissue. Future generations of biomaterials (third generation) are designed to be not only osteoconductive but also osteoinductive, i.e. to stimulate regeneration of host tissues by combining tissue engineering and in situ tissue regeneration methods with a focus on novel applications. These techniques will lead to novel possibilities for tissue regeneration and repair. At present, tissue engineered constructs that may find future use as bone grafts for complex skeletal defects, whether from post-traumatic, degenerative, neoplastic or congenital/developmental "origin" require osseous reconstruction to ensure structural and functional integrity. Engineering functional bone using combinations of cells, scaffolds and bioactive factors is a promising strategy and a particular feature for future development in the area of hybrid materials which are able to exhibit suitable biomimetic and mechanical properties. This review will discuss the state of the art in this field and what we can expect from future generations of bone regeneration concepts.

Short Term Culture of Human Mesenchymal Stem Cells with Commercial Osteoconductive Carriers Provides Unique Insights into Biocompatibility

For spinal fusions and the treatment of non-union fractures, biological substrates, scaffolds, or carriers often are applied as a graft to support regeneration of bone. The selection of an appropriate material critically influences cellular function and, ultimately, patient outcomes. Human bone marrow mesenchymal stem cells (BMSCs) are regarded as a critical component of bone healing. However, the interactions of BMSCs and commercial bone matrices are poorly reported. BMSCs were cultured with several commercially available bone substrates (allograft, demineralized bone matrix (DBM), collagen, and various forms of calcium phosphates) for 48 h to understand their response to graft materials during surgical preparation and the first days following implantation (cell retention, gene expression, pH). At 30 and 60 min, bone chips and inorganic substrates supported significantly more cell retention than other materials, while collagen-containing materials became soluble and lost their structure. At 48 h, cells bound to β-tricalcium phosphate-hydroxyapatite (βTCP-HA) and porous hydroxyapatite (HA) granules exhibited osteogenic gene expression statistically similar to bone chips. Through 24 h, the DBM strip and βTCP-collagen became mildly acidic (pH 7.1–7.3), while the DBM poloxamer-putties demonstrated acidity (pH < 5) and the bioglass-containing carrier became basic (pH > 10). The dissolution of DBM and collagen led to a loss of cells, while excessive pH changes potentially diminish cell viability and metabolism. Extracts from DBM-poloxamers induced osteogenic gene expression at 48 h. This study highlights the role that biochemical and structural properties of biomaterials play in cellular function, potentially enhancing or diminishing the efficacy of the overall therapy.

Corrective osteotomy of the distal radius following failed internal fixation

INTRODUCTION

The purpose of this study was to quantify the clinical and radiographic outcomes after corrective osteotomy for malunions of the distal radius following failed internal fixation.

MATERIALS AND METHODS

Results of 18 patients (8 women, 10 men; mean age 41 years) are presented an average of 7 years after osteotomy of a malunited distal radius fracture. We assessed active range of motion, grip strength, radiographic alignment, pain and disability. Subjective and objective data were summarized using the modified Mayo Wrist Score and the point-score system of Fernandez.

RESULTS

Wrist motion, pain and deformity improved with the operation in all cases. The modified Mayo Wrist Score averaged 79 points. The scale of Fernandez indicated ten good, two fair and six poor results.

CONCLUSIONS

The results of this study suggest that the operative correction of a distal radius malunion following an unsuccessful internal fixation can be achieved with outcomes comparable to those reported after initial nonoperative treatment.

Biological extremity reconstruction after sarcoma resection: past, present, and future

In sarcoma surgery besides a wide local resection, limb salvage became more and more important. Reconstruction of bone and soft tissue defects after sarcoma resection poses a major challenge for surgeons. Nowadays a broad range of reconstructive methods exist to deal with bony defects. Among these are prostheses, bone autografts, or bone allografts. Furthermore a variety of plastic reconstructive techniques exist that allow soft tissue reconstruction or coverage after sarcoma resection. Here we discuss the historical highlights, the present role, and possible future options for biological reconstruction.

Bone loss in the hand

Traumatic bone loss in hand surgery is challenging for the patient as well as the doctor. Whereas the patient is threatened with a possible amputation or severe disability, the hand surgeon focuses on reconstruction, restoration of the function, bony union, and appearance of the injured hand. Both are confronted with a long-standing and staged treatment coupled with a high risk of complications. This review encompasses the classifications and treatment options of bone loss in hands. The optimal treatment is still prevention of the trauma itself.

Enhanced in vivo osteogenesis by nanocarrier-fused bone morphogenetic protein-4

Purpose

Bone defects and nonunions are major clinical skeletal problems. Growth factors are commonly used to promote bone regeneration; however, the clinical impact is limited because the factors do not last long at a given site. The introduction of tissue engineering aimed to deter the diffusion of these factors is a promising therapeutic strategy. The purpose of the present study was to evaluate the in vivo osteogenic capability of an engineered bone morphogenetic protein-4 (BMP4) fusion protein.

Methods

BMP4 was fused with a nanosized carrier, collagen-binding domain (CBD), derived from fibronectin. The stability of the CBD-BMP4 fusion protein was examined in vitro and in vivo. Osteogenic effects of CBD-BMP4 were evaluated by computer tomography after intramedullary injection without a collagen–sponge scaffold. Recombinant BMP-4, CBD, or vehicle were used as controls. Expressions of bone-related genes and growth factors were compared among the groups. Osteogenesis induced by CBD-BMP4, BMP4, and CBD was also assessed in a bone-defect model.

Results

In vitro, CBD-BMP4 was retained in a collagen gel for at least 7 days while BMP4 alone was released within 3 hours. In vivo, CBD-BMP4 remained at the given site for at least 2 weeks, both with or without a collagen–sponge scaffold, while BMP4 disappeared from the site within 3 days after injection. CBD-BMP4 induced better bone formation than BMP4 did alone, CBD alone, and vehicle after the intramedullary injection into the mouse femur. Bone-related genes and growth factors were expressed at higher levels in CBD-BMP4-treated mice than in all other groups, including BMP4-treated mice. Finally, CBD-BMP4 potentiated more bone formation than did controls, including BMP4 alone, when applied to cranial bone defects without a collagen scaffold.

Conclusion

Altogether, nanocarrier-CBD enhanced the retention of BMP4 in the bone, thereby promoting augmented osteogenic responses in the absence of a scaffold. These results suggest that CBD-BMP4 may be clinically useful in facilitating bone formation.

Nonviral gene transfer strategies to promote bone regeneration

Despite the inherent ability of bone to regenerate itself, there are a number of clinical situations in which complete bone regeneration fails to occur. In view of shortcomings of conventional treatment, gene therapy may have a place in cases of critical-size bone loss that cannot be properly treated with current medical or surgical treatment. The purpose of this review is to provide an overview of gene therapy in general, nonviral techniques of gene transfer including physical and chemical methods, RNA-based therapy, therapeutic genes to be transferred for bone regeneration, route of application including ex vivo application, and direct gene therapy approaches to regenerate bone.

Can platelet-rich plasma (PRP) improve bone healing? A comparison between the theory and experimental outcomes

The increased concentration of platelets within platelet-rich plasma (PRP) provides a vehicle to deliver supra-physiologic concentrations of growth factors to an injury site, possibly accelerating or otherwise improving connective tissue regeneration. This potential benefit has led to the application of PRP in several applications; however, inconsistent results have limited widespread adoption in bone healing. This review provides a core understanding of the bone healing mechanisms, and corresponds this to the factors present in PRP. In addition, the current state of the art of PRP preparation, the key aspects that may influence its effectiveness, and treatment outcomes as they relate specifically to bone defect healing are presented. Although PRP does have a sound scientific basis, its use for bone healing appears only beneficial when used in combination with osteoconductive scaffolds; however, neither allograft nor autograft appear to be appropriate carriers. Aggressive processing techniques and very high concentrations of PRP may not improve healing outcomes. Moreover, many other variables exist in PRP preparation and use that influence its efficacy; the effect of these variables should be understood when considering PRP use. This review includes the essentials of what has been established, what is currently missing in the literature, and recommendations for future directions.

Complex distal radius fractures

Complex distal radius fractures are high-energy injuries of the wrist with articular disruption, ligamentous instability, significant comminution, soft tissue injury, and/or neurovascular impairment. The management of these injuries requires a thorough understanding of wrist functional anatomy and familiarity with a wide selection of approach and fixation options. This article reviews an approach that involves structured evaluation, aggressive soft tissue management, early reduction and skeletal stabilization, and a columnar approach to definitive care. Outcome is determined by multiple factors and depends greatly on the soft tissue injury, patient factors, and management and the adequacy of restoration of osseous and ligamentous relationships.

The pore size of PLGA bone implants determines the de novo formation of bone tissue in tibial head defects in rats

PURPOSE

The influence of the pore size of biodegradable poly(lactic-co-glycolic acid) scaffolds on bone regeneration was investigated.

METHODS

Cylindrical poly(lactic-co-glycolic acid) scaffolds were implanted into a defect in the tibial head of rats. Pore sizes of 100-300, 300-500, and 500-710 μm were tested and compared to untreated defects as control. Two and four weeks after implantation, the specimens were explanted and defect regeneration and de novo extracellular matrix generation were investigated by MRI, quantitative solid-state NMR, and mass spectrometry.

RESULTS

The pore size of the scaffolds had a pronounced influence on the quantity of the extracellular matrix synthesized in the graft; most collagen was synthesized within the first 2 weeks of implantation, while the amount of hydroxyapatite increased in the second 2 weeks. After 4 weeks, the scaffolds contained large quantities of newly formed lamellar bone while the control defects were filled by inhomogenous woven bone. Best results were obtained for scaffolds of a pore size of 300-500 μm.

CONCLUSION

Our analysis showed that the structure and dynamics of the regenerated extracellular matrix was very similar to that of the native bone, suggesting that biomineralization was significantly enhanced by the choice of the most appropriate implant material.

Building bridges: leveraging interdisciplinary collaborations in the development of biomaterials to meet clinical needs

Our laboratory at Rice University has forged numerous collaborations with clinicians and basic scientists over the years to advance the development of novel biomaterials and the modification of existing materials to meet clinical needs. This review highlights collaborative advances in biomaterials research from our laboratory in the areas of scaffold development, drug delivery, and gene therapy, especially as related to applications in bone and cartilage tissue engineering.

Scaphocapitolunate arthrodesis and radial styloidectomy for posttraumatic degenerative wrist disease

Long-standing scaphoid nonunion, scaphoid malunion, and chronic scapholunate dissociation result in malalignment of the carpal bones, progressive carpal collapse, instability, and osteoarthritis of the wrist. The most commonly used procedures to treat scaphoid nonunion advanced collapse (SNAC) and scapholunate advanced collapse (SLAC) wrists are the four-corner fusion (4CF) and the proximal row carpectomy (PRC). The purpose of this study was to evaluate the clinical outcome of a different treatment modality: radial styloidectomy and scaphocapitolunate (SCL) arthrodesis. This treatment option is chosen in an effort to maintain the joint contact surface and load transmission across the radiocarpal joint. We conducted a retrospective review of 20 patients (average age 62 years, range: 27 to 75 years) treated from 1994 to 2010. Seven patients were treated for SNAC, 12 patients for SLAC wrists, and 1 for degenerative joint disease following a transscapho-transcapitate perilunar dislocation. Sixteen patients had Herbert screw fixation, and four had Spider plate fixation. All patients had autologous bone graft used for the arthrodesis. The mean follow-up was 4.6 years (range: 2 to 9.6 years). Patients were evaluated clinically and radiographically. Nineteen of 20 arthrodeses healed on an average of 9.6 weeks. One patient was reoperated 8 months after the initial operation with salvage of the SCL arthrodesis with a spider plate with an adequate result. The mean active flexion-extension arc was 70 degrees and the radioulnar deviation arc was 23 degrees. Pain decreased in all patients, 13 of whom were pain free postoperatively. The average postoperative disabilities of arm, shoulder, and hand score was 24. Radiographically, neither radiolunate nor radioscaphoid arthritis was noted on follow-up. SCL arthrodesis with radial styloidectomy resulted in an adequate residual range of motion and pain relief. This method preserves the normal ulnar sided joints of the carpus and maintains a more physiologic joint surface for radiocarpal load sharing.

Biomimetic three-dimensional nanocrystalline hydroxyapatite and magnetically synthesized single-walled carbon nanotube chitosan nanocomposite for bone regeneration

Background

Many shortcomings exist in the traditional methods of treating bone defects, such as donor tissue shortages for autografts and disease transmission for allografts. The objective of this study was to design a novel three-dimensional nanostructured bone substitute based on magnetically synthesized single-walled carbon nanotubes (SWCNT), biomimetic hydrothermally treated nanocrystalline hydroxyapatite, and a biocompatible hydrogel (chitosan). Both nanocrystalline hydroxyapatite and SWCNT have a biomimetic nanostructure, excellent osteoconductivity, and high potential to improve the load-bearing capacity of hydrogels.

Methods

Specifically, three-dimensional porous chitosan scaffolds with different concentrations of nanocrystalline hydroxyapatite and SWCNT were created to support the growth of human osteoblasts (bone-forming cells) using a lyophilization procedure. Two types of SWCNT were synthesized in an arc discharge with a magnetic field (B-SWCNT) and without a magnetic field (N-SWCNT) for improving bone regeneration.

Results

Nanocomposites containing magnetically synthesized B-SWCNT had superior cytocompatibility properties when compared with nonmagnetically synthesized N-SWCNT. B-SWCNT have much smaller diameters and are twice as long as their nonmagnetically prepared counterparts, indicating that the dimensions of carbon nanotubes can have a substantial effect on osteoblast attachment.

Conclusion

This study demonstrated that a chitosan nanocomposite with both B-SWCNT and 20% nanocrystalline hydroxyapatite could achieve a higher osteoblast density when compared with the other experimental groups, thus making this nanocomposite promising for further exploration for bone regeneration.