Autogenous bone graft: donor sites and techniques

Can stem cells enhance bone formation in the human edentulous alveolar ridge? A systematic review and meta-analysis

Several non-biological materials are currently being used to increase the alveolar bone volume to support dental implants. Recently, stem cell therapy has emerged as a promising biological substitute or adjuvant to enhance bone healing. In order to determine if stem cell therapy has enough clinical evidence to bone ridge augmentation in humans, a systematic review and meta-analysis were conducted. Two independent investigators searched the Entrez PubMed, SCOPUS and Web of Science databases for eligible randomized clinical trials that describe stem cell therapies for alveolar bone formation. The included studies were evaluated for risk of bias. A random-effects meta-analysis model was used to evaluate the percentage of bone formation in the selected studies. Heterogeneity was evaluated using the Cochrane Chi ² and I ². Nine eligible trials were included. These studies presented an overall unclear risk of bias. A comparison between the lower heterogeneity studies and the long term observational outcomes showed a slight tendency to enhance bone formation. High heterogeneity between the included studies was observed. The lack of outcome standardization made a wide-ranging comparison difficult. The application of stem cells in oral surgery and implantology appears to be promising although more standardized study designs, increased samples and long-term observations are needed to strength the clinical evidence that stem cell therapy is effective for alveolar bone formation.

Exogenous PTHrP Repairs the Damaged Fracture Healing of PTHrP+/- Mice and Accelerates Fracture Healing of Wild Mice

Bone fracture healing is a complicated physiological regenerative process initiated in response to injury and is similar to bone development. To demonstrate whether an exogenous supply of parathyroid hormone–related protein (PTHrP) helps in bone fracture healing, closed mid-diaphyseal femur fractures were created and stabilized with intramedullary pins in eight-week-old wild-type (WT) PTHrP+/+ and PTHrP+/− mice. After administering PTHrP for two weeks, callus tissue properties were analyzed at one, two, and four weeks post-fracture (PF) by various methods. Bone formation–related genes and protein expression levels were evaluated by real-time reverse transcriptase–polymerase chain reaction and Western blots. At two weeks PF, mineral density of callus, bony callus areas, mRNA levels of alkaline phosphatase (ALP), type I collagen, Runt-related transcription factor 2 (Runx-2), and protein levels of Runx-2 and insulin-like growth factor-1 decreased in PTHrP+/− mice compared with WT mice. At four weeks PF, total collagen-positive bony callus areas, osteoblast number, ALP-positive areas, and type I collagen-positive areas all decreased in PTHrP+/− mice. At both two and four weeks PF, tartrate-resistant acid phosphatase–positive osteoclast number and surface decreased a little in PTHrP+/− mice. The study indicates that exogenous PTHrP provided by subcutaneous injection could redress impaired bone fracture healing, leading to mutation of activated PTHrP by influencing callus areas, endochondral bone formation, osteoblastic bone formation, and bone turnover.

Non-structural cancellous bone graft and headless compression screw fixation for treatment of scaphoid waist non-union

PURPOSE

Scaphoid fracture commonly occurs around the mid-third of the scaphoid, and non-union of this fracture has several treatment options. The authors performed autologous cancellous bone graft from the iliac crest and headless compression screw fixation for the treatment of Mack-Lichtman type II scaphoid waist non-union. The purpose of this study was to determine whether this procedure was effective in achieving bony union and restoration of alignment.

METHODS

Medical records and radiographs of 30 patients who underwent cancellous bone graft and headless compression screw fixation for non-union of scaphoid waist fracture were retrospectively reviewed. There were 28 men and 2 women, with a mean age of 32.8 years (range: 21-63). The mean time to surgery was 10 months (range: 3-25) and mean follow-up was 37.5 months (range: 15-52). The authors analyzed bony union, lateral intrascaphoid angle, scapholunate angle, radiolunate angle and scaphoid length on radiographs and evaluated the Modified Mayo wrist score (MMWS) as a functional outcome.

RESULTS

Bony union was achieved in all cases. The lateral intrascaphoid angle improved from 40° to 32° (P<0.001). The scapholunate angle also improved from 61° to 56° (P=0.009). The radiolunate angle decreased from 8° to 4° (P=0.048) and scaphoid length increased from 22mm to 26mm (P<0.001) postoperatively. Wrist motion and MMWS improved significantly at last follow-up. However, there were no significant differences between scaphoid deformity correction angle and pre- to post-operative difference in MMWS.

CONCLUSIONS

Non-structural autologous cancellous bone graft from the iliac crest and headless screw fixation provided reliable results and can be one of the effective treatment options for patients with symptomatic Mack-Lichtman type II non-union in the mid-third of the scaphoid.

LEVEL OF EVIDENCE

Level III.

Infected nonunion of tibia

Infected nonunions of tibia pose many challenges to the treating surgeon and the patient. Challenges include recalcitrant infection, complex deformities, sclerotic bone ends, large bone gaps, shortening, and joint stiffness. They are easy to diagnose and difficult to treat. The ASAMI classification helps decide treatment. The nonunion severity score proposed by Calori measures many parameters to give a prognosis. The infection severity score uses simple clinical signs to grade severity of infection. This determines number of surgeries and allows choice of hardware, either external or internal for definitive treatment. Co-morbid factors such as smoking, diabetes, nonsteroidal anti-inflammatory drug use, and hypovitaminosis D influence the choice and duration of treatment. Thorough debridement is the mainstay of treatment. Removal of all necrotic bone and soft tissue is needed. Care is exercised in shaping bone ends. Internal fixation can help achieve union if infection was mild. Severe infections need external fixation use in a second stage. Compression at nonunion site achieves union. It can be combined with a corticotomy lengthening at a distant site for equalization. Soft tissue deficit has to be covered by flaps, either local or microvascular. Bone gaps are best filled with the reliable technique of bone transport. Regenerate bone may be formed proximally, distally, or at both sites. Acute compression can fill bone gaps and may need a fibular resection. Gradual reduction of bone gap happens with bone transport, without need for fibulectomy. When bone ends dock, union may be achieved by vertical or horizontal compression. Biological stimulus from iliac crest bone grafts, bone marrow aspirate injections, and platelet concentrates hasten union. Bone graft substitutes add volume to graft and help fill defects. Addition of rh-BMP-7 may help in healing albeit at a much higher cost. Regeneration may need stimulation and augmentation. Induced membrane technique is an alternative to bone transport to fill gaps. It needs large amounts of bone graft from iliac crest or femoral canal. This is an expensive method physiologically and economically. Infection can resorb the graft and cause failure of treatment. It can be done in select cases after thorough eradication of infection. Patience and perseverance are needed for successful resolution of infection and achieving union.

First report on treating spontaneous infectious spondylodiscitis of lumbar spine with posterior debridement, posterior instrumentation and an injectable calcium sulfate/hydroxyapatite composite eluting gentamicin: a case report

Background

Spontaneous infectious spondylodiscitis is a rare, but serious disease with the risk of progressive neurological impairment. The surgical approach to spontaneous infectious spondylodiscitis is in most cases an anterior debridement and fusion, often in staged surgeries. Here we report a case of single-stage posterior debridement and posterior instrumented fusion in combination with an injectable calcium sulfate/hydroxyapatite composite eluting gentamicin.

Case presentation

A 59-year-old Caucasian man presented with a 6-week history of lumbar pain without sensory or motor disorders of his lower extremities. A magnetic resonance imaging scan of his lumbar spine in T2-weighted sequences showed a high signal of the intervertebral disc L4/L5 and in T1-weighted sequences an epidural abscess at the posterior wall of L4. Additional computed tomography imaging revealed osteolytic destruction of the base plate of L4 and the upper plate of L5. Antibiotic therapy was started with intravenous ciprofloxacin and clindamycin. We performed a posterior debridement via a minimally invasive approach, a posterior percutaneous stabilization using transpedicular screw-rod instrumentation and filled the intervertebral space with an injectable calcium sulfate/hydroxyapatite composite which elutes a high concentration of gentamicin. The patient’s lower back pain improved quickly after surgery and no recurrence of infection has been noticed during the 1-year follow-up. Computed tomography at 11 months shows complete bony fusion of L4 and L5.

Conclusions

An injectable calcium sulfate/hydroxyapatite composite releasing a high level of gentamicin can support the surgical treatment of spondylodiscitis in combination with posterior debridement and transpedicular screw-rod instrumentation.

Distraction First Metatarsophalangeal Arthrodesis With Tricortical Calcaneus Autograft: Technique Tips

First metatarsophalangeal joint arthritis can stem from a biomechanical imbalance as in hallux abducto valgus, metabolic arthritidies such as rheumatoid or gout, and even in posttraumatic cases. Advanced arthritis in the foot and ankle can often become debilitating. Surgical intervention is often necessary. Revision of failed first metatarsophalangeal joint arthroplasty is often in the setting of bony erosion and lysis, cystic changes, and loss of bone stock. In this article, we describe first metatarsophalangeal distraction arthrodesis technique using tricortical calcaneus autograft with the aim of simplifying donor site graft harvesting and decreasing donor site morbidity while attaining successful osseous union.

LEVELS OF EVIDENCE

Level V.

Autologous Bone Graft in Foot and Ankle Surgery

Bone graft is a common adjunct procedure in orthopedic surgery used for fusions, fracture repair, and the reconstruction of skeletal defects in the foot and ankle. Autologous graft, or autograft, involves the transport of bone from a donor site to another location in the same patient. It is considered by many to be the gold standard of bone grafting, as it is provides all biologic factors required for functional graft. Further, autograft is 100% histocompatible with no risk of disease transmission.

Calcium Concentration in Culture Medium as a Nondestructive and Rapid Marker of Osteogenesis

Artificial bones made of β-tricalcium phosphate (β-TCP) combined with bone marrow-derived mesenchymal stromal cells (BM-MSCs) are used for effective reconstruction of bone defects caused by genetic defects, traumatic injury, or surgical resection of bone tumors. However, the selection of constructs with high osteogenic potential before implantation is challenging. The purpose of this study was to determine whether the calcium concentration in BM-MSC culture medium can be used as a nondestructive and simple osteogenic marker for selecting tissue-engineered grafts constructed using β-TCP and BM-MSCs. We prepared three cell passages of BM-MSCs derived from three 7-week-old, male Fischer 344 rats; the cells were cultured in osteoinductive medium in the presence of β-TCP for 15 days. The medium was replaced with fresh medium on day 1 in culture and subsequently changed every 48 h; it was collected for measurement of osteocalcin secretion and calcium concentration by enzyme-linked immunosorbent assay and X-ray fluorescence spectrometry, respectively. After cultivation, the constructs were implanted subcutaneously into the backs of recipient rats. Four weeks after implantation, the alkaline phosphatase (ALP) activity and osteocalcin content of the constructs were measured. A strong inverse correlation was observed between the calcium concentration in the medium and the ALP activity and osteocalcin content of the constructs, with Pearson's correlation coefficients of 0.92 and 0.90, respectively. These results indicate that tissue-engineered bone with high osteogenic ability can be selected before implantation based on low calcium content of the culture medium, resulting in successful bone formation after implantation. This nondestructive, simple method shows great promise for assessing the osteogenic ability of tissue-engineered bone.

Autologous bone graft in the treatment of post-traumatic bone defects: a systematic review and meta-analysis

Background

This meta-analysis aimed to determine the bone union rate of bone defects treated with the different autologous bone graft techniques.

Methods

The PubMed and the Cochrane Library databases were searched using the terms: ‘fracture’ AND (‘bone loss’ OR ‘defect’ OR ‘defects’) AND ‘bone graft’, restricted to English language, to human species, and to a publication period from January 1999 to November 2014. Data were extracted by one of the reviewers and then checked by the second. A quality of evidence score and a methodology score were used. Heterogeneity was assessed. A random effects model approach was used to combine estimates.

Results

Out of 376 selected studies only 34 met the inclusion criteria. The summary pooled union rate was 91 % (95 % CI: 87–95 %) while union rate after additional procedures raised to 98 % (95 % CI 96–99 %). No association between union rate and bone defect size was found. (Univariable regression model: vascularized: P = 0.677; non-vascularized: 0.202. Multivariable regression model: vascularized: P = 0.381; non-vascularized: P = 0.226). Vascularized graft was associated with a lower risk of infection after surgery when compared to non-vascularized graft (95 % CI 0.03 to 0.23, p < 0.001).

Conclusion

The results of this meta-analysis demonstrate the effectiveness of autologous graft for bone defects. Furthermore, from the available clinical evidence bone defect size does not seem to have an impact on bone union when treated with autologous bone graft techniques.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1312-4) contains supplementary material, which is available to authorized users.

A biomechanical study of proximal tibia bone grafting through the lateral approach

BACKGROUND

Autologous bone graft remains the gold standard source of bone graft. Iliac crest has traditionally been the most popular source for autologous bone graft. However, iliac crest bone graft harvesting is associated with high donor site morbidity. Bone graft harvesting from the proximal tibia has shown great potential with reported low complication rates. However, there is a paucity of biomechanical studies concerning the safety as well as yield of proximal bone graft harvesting.

PURPOSE

This biomechanical study was designed to investigate (1) the stability of the harvested proximal tibial during physiological loading, and (2) the maximum size of the cortical window that can be safely created and (3) volume of accessible bone graft.

METHODS

Bone grafts were harvested from eleven cadaveric tibiae using a circular cortical window along the lateral proximal tibia. These harvested proximal tibiae were then loaded under physiological conditions (mean 2320N, range 1650-3120N) using a customized test fixture. Strain rosettes were mounted at 7 locations in the harvested proximal tibia to record the changes in strain at the harvested proximal tibia. The change in strain with increasing cortical window size (10-25mm diameter) was also studied. Bone principal strains as well as volume of bone harvested were recorded.

RESULTS

A repeated measures ANOVA was used to analyze the change in bone strains with the cortical window size. Statistically significant (p<0.05) increases in bone strains at the anterior and medial aspects of the tibia were observed with increasing size of osteotomies (-328.85με, SD=232.21 to -964.78με, SD=535.89 and 361.64με, SD=229.90 to -486.08με, SD=270.40 respectively), and marginally significant changes in strain at the lateral and posterior aspects. None of the tibiae failed under normal walking loads even with increasing osteotomies size of 10-25 mm diameter. A smaller osteotomy of 10mm diameter yielded an average volume of 7.15ml of compressed bone graft, while a larger osteotomy of 25mm diameter yielded on average an additional 3.64ml of bone graft. Bone grafting of the proximal tibia through the lateral approach with a circular osteotomy is a feasible option even with osteotomies of 25mm diameter. Even though increased bone strains were observed, the strains did not exceed the yield strain of cortical bone when loaded under normal walking conditions. The quantity of bone harvested from the proximal tibia is comparable to that harvested from the iliac crest.

CONCLUSIONS

This biomechanical study demonstrated the stability of the harvested proximal tibia under conditions of full weight bearing ambulation. It has also refined the technique of proximal bone graft harvesting by determining the maximum size of the cortical window. The findings of this study add to the overall understanding of proximal tibial bone graft harvesting, providing objective data regarding stability as well as yield. This information would be useful during selection of source of autologous bone graft.

Bone healing in 2016

Delayed fracture healing and nonunion occurs in up to 5-10% of all fractures, and can present a challenging clinical scenario for the treating physician. Methods for the enhancement of skeletal repair may benefit patients that are at risk of, or have experienced, delayed healing or nonunion. These methods can be categorized into either physical stimulation therapies or biological therapies. Physical stimulation therapies include electrical stimulation, low-intensity pulsed ultrasonography, or extracorporeal shock wave therapy. Biological therapies can be further classified into local or systemic therapy based on the method of delivery. Local methods include autologous bone marrow, autologous bone graft, fibroblast growth factor-2, platelet-rich plasma, platelet-derived growth factor, and bone morphogenetic proteins. Systemic therapies include parathyroid hormone and bisphosphonates. This article reviews the current applications and supporting evidence for the use of these therapies in the enhancement of fracture healing.

Implantation of Stromal Vascular Fraction Progenitors at Bone Fracture Sites: From a Rat Model to a First-in-Man Study

Stromal Vascular Fraction (SVF) cells freshly isolated from adipose tissue include osteogenic- and vascular-progenitors, yet their relevance in bone fracture healing is currently unknown. Here, we investigated whether human SVF cells directly contribute to the repair of experimental fractures in nude rats, and explored the feasibility/safety of their clinical use for augmentation of upper arm fractures in elderly individuals. Human SVF cells were loaded onto ceramic granules within fibrin gel and implanted in critical nude rat femoral fractures after locking-plate osteosynthesis, with cell-free grafts as control. After 8 weeks, only SVF-treated fractures did not fail mechanically and displayed formation of ossicles at the repair site, with vascular and bone structures formed by human cells. The same materials combined with autologous SVF cells were then used to treat low-energy proximal humeral fractures in 8 patients (64-84 years old) along with standard open reduction and internal fixation. Graft manufacturing and implantation were compatible with intraoperative settings and led to no adverse reactions, thereby verifying feasibility/safety. Biopsies of the repair tissue after up to 12 months, upon plate revision or removal, demonstrated formation of bone ossicles, structurally disconnected and morphologically distinct from osteoconducted bone, suggesting the osteogenic nature of implanted SVF cells. We demonstrate that SVF cells, without expansion or exogenous priming, can spontaneously form bone tissue and vessel structures within a fracture-microenvironment. The gained clinical insights into the biological functionality of the grafts, combined with their facile, intra-operative manufacturing modality, warrant further tests of effectiveness in larger, controlled trials. Stem Cells 2016;34:2956-2966.

Distal Radius Bone Graft From the Second Extensor Compartment: A Safe and Effective Technique

We describe a technique for harvesting cancellous bone graft from the floor of the second extensor compartment that is both easy and effective. It confines surgery to a single operative field under the same regional anesthesia and tourniquet as the primary hand surgical procedure while at the same time allowing wide visualization for harvesting bone graft. It provides cancellous bone of sufficient quality and quantity for use in most hand surgical cases. The technique has so far been used in 80 patients and has proven to be very safe.

The Importance of Sufficient Graft Material in Achieving Foot or Ankle Fusion

BACKGROUND

Nonunion, an important complication following foot and ankle arthrodesis, causes substantial morbidity and disability. In patients undergoing hindfoot and ankle arthrodesis, autogenous bone graft (autograft) or a suitable alternative is often used to promote osseous fusion across the joint. This study assessed the importance of adequate graft material in the fusion space to achieve joint fusion during ankle and hindfoot arthrodesis.

METHODS

This study used data from a previously published clinical trial of grafting material (recombinant human platelet-derived growth factor-BB with beta-tricalcium phosphate [rhPDGF-BB/β-TCP] or autograft) for healing in hindfoot and ankle arthrodesis to correlate the amount of graft fill at 9 weeks with ultimate healing. Patients who received supplemental graft material for ankle or hindfoot arthrodesis for end-stage ankle or hindfoot arthritis were stratified according to nonunion risk factors and surgical fusion site. Patients underwent arthrodesis using standard rigid internal fixation. Graft fill was defined as "adequate" if the material occupied ≥50% of the cross-sectional area of the fusion space on a computed tomography (CT) scan made at 9 weeks. Fusion was defined as osseous bridging of ≥50% of each articulation on a CT scan made at 24 weeks. Three hundred and seventy-nine patients with 573 joints (383 managed with rhPDGF-BB/β-TCP and 190 managed with autograft) that underwent arthrodesis had complete follow-up with 9-week and 24-week CT scans available.

RESULTS

Overall, 472 (82%) of 573 joints had adequate graft fill; of those, 383 (81%) were successfully fused at 24 weeks compared with 21 (21%) of 101 joints without adequate graft fill (p < 0.0001). Absolute fusion rate differences (joints with adequate fill minus those without adequate fill) were consistent across joints (61% to 63%) and for graft materials. The overall odds ratio (OR) of successful fusion in joints with adequate graft fill compared with those without adequate graft fill was 16.4 (95% confidence interval, 9.6 to 27.9).

CONCLUSIONS

This study demonstrates an association between the amount of graft material and successful hindfoot and ankle arthrodesis. Graft material filling of ≥50% of the fusion space at 9 weeks, regardless of type or origin, was associated with significantly higher fusion rates at 24 weeks.

LEVEL OF EVIDENCE

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

Bone Marrow Mesenchymal Stem Cells Expressing Baculovirus-Engineered Bone Morphogenetic Protein-7 Enhance Rabbit Posterolateral Fusion

Previous studies have suggested that bone marrow-derived mesenchymal stem cells (BMDMSCs) genetically modified with baculoviral bone morphogenetic protein-2 (Bac-BMP-2) vectors could achieve successful fusion in a femur defect model or in a spinal fusion model. In this study, BMDMSCs expressing BMP-7 (Bac-BMP-7-BMDMSCs) were generated. We hypothesized that Bac-BMP-7-BMDMSCs could secrete more BMP-7 than untransduced BMDMSCs in vitro and achieve spinal posterolateral fusion in a rabbit model. Eighteen rabbits underwent posterolateral fusion at L4-5. Group I (n = 6) was implanted with collagen-β-tricalcium phosphate (TCP)-hydroxyapatite (HA), Group II (n = 6) was implanted with collagen-β-TCP-HA plus BMDMSCs, and Group III (n = 6) was implanted with collagen-β-TCP-HA plus Bac-BMP-7-BMDMSCs. In vitro production of BMP-7 was quantified with an enzyme-linked immunosorbent assay (ELISA). Spinal fusion was examined using computed tomography (CT), manual palpation, and histological analysis. ELISA demonstrated that Bac-BMP-7-BMDMSCs produced four-fold to five-fold more BMP-7 than did BMDMSCs. In the CT results, 6 fused segments were observed in Group I (50%, 6/12), 8 in Group II (67%, 8/12), and 12 in Group III (100%, 12/12). The fusion rate, determined by manual palpation, was 0% (0/6) in Group I, 0% (0/6) in Group II, and 83% (5/6) in Group III. Histology showed that Group III had more new bone and matured marrow formation. In conclusion, BMDMSCs genetically transduced with the Bac-BMP-7 vector could express more BMP-7 than untransduced BMDMSCs. These Bac-BMP-7-BMDMSCs on collagen-β-TCP-HA scaffolds were able to induce successful spinal fusion in rabbits.

Effect of collagen sponge and fibrin glue on bone repair

The ability of hemostatic agents to promote bone repair has been investigated using in vitro and in vivo models but, up to now, the results are inconclusive.

Efficacy and safety of porous hydroxyapatite/type 1 collagen composite implantation for bone regeneration: A randomized controlled study

BACKGROUND

Porous hydroxyapatite/collagen composite (HAp/Col) is a bioresorbable bone substitute composed of nano-scale HAp and porcine type 1 collagen. In this study, the efficacy and safety were assessed in comparison to commercially available porous β-tricalcium phosphate (β-TCP).

METHODS

Patients with bone defects caused by benign bone tumors, fractures, or harvesting of autografts were randomly allocated for implantation of porous HAp/Col (n = 63) or porous β-TCP (n = 63). X-ray images were scored and used to evaluate the efficacy of the implantation until 24 weeks after surgery. Blood tests and observation of the surgical site were also performed to evaluate the safety of the implants. In total, 59 and 60 cases were analyzed in the porous HAp/Col and β-TCP groups, respectively.

RESULTS

At 18 and 24 weeks after surgery, the highest grade of bone regeneration was more frequent in the porous HAp/Col group than in the porous β-TCP group (p = 0.0004 and 0.0254 respectively). Wilcoxon's rank sum test confirmed the superiority of porous HAp/Col from early time points onward (p = 0.0084, 4 w; p = 0.0037, 8 w; p = 0.0030, 12 w; p < 0.0001, 18 w; and p = 0.0316, 24 w). The incidence of adverse effects was higher in the porous HAp/Col group than in the β-TCP group. However, no serious adverse events were reported and no cases needed to drop out of the clinical trial.

CONCLUSIONS

The superiority of porous HAp/Col for bone regeneration in comparison to an established porous β-TCP was confirmed. Although the incidence of side effects associated with the porous HAp/Col implant was higher than that in the β-TCP group, no serious adverse events occurred that resulted in rejection of the implants.

Efficacy of Postoperative Pain Management Using Continuous Local Anesthetic Infusion at the Iliac Crest Bone Graft Site in Patients with Adolescent Idiopathic Scoliosis: A Parallel, Double-Blinded, Randomized Controlled Pilot Trial

Study Design Randomized controlled trial. Objective Adolescent idiopathic scoliosis (AIS) is a common spinal deformity that affects every population. In severe deformity, surgical intervention is performed. Autogenous iliac crest bone graft (ICBG) harvesting remains a common procedure worldwide for scoliosis surgery. Postoperative pain at the ICBG donor site is a major concern in patients undergoing spine surgery that affects postoperative functional outcome and consumes health care resources. Previous studies have noted a decrease in pain and postoperative analgesic use with the application of continuous infusion of anesthetic at the ICBG site in comparison with placebo. However, there is lack of evidence addressing the efficacy of continuous anesthetic infusion at the ICBG site in young patients and in particular those with spinal deformity, such as AIS. As such, this parallel, double-blinded, randomized controlled trial addressed the pain management efficacy of continuous anesthetic infusion versus saline at the ICBG site in patients with AIS during the immediate postoperative period. Methods Participants were randomized into two groups. Group A (control subjects) received 3 mL per hour of saline locally at the ICBG site, and group B (treatment subjects) received a constant rate of infusion of 3 mL per hour of 0.25% levobupivacaine. Both groups received their postoperative intervention for 47 hours. All subjects and outcome assessors were blinded to the type of intervention. Utilizing the visual analog pain scale, pain was assessed at the primary spine surgical site, ICBG site, and contralateral ICBG site. Overall physical pain was assessed by the McGill Pain Questionnaire. The degree of analgesic use and complications were also evaluated. All outcomes were assessed up until the fourth day of the patients' hospitalization following surgery. Results Twelve subjects were recruited (five in group A; seven in group B). No difference was noted at baseline regarding age, weight, height, arm span, sex, curve type, instrumented and fused levels, length of hospitalization, and pain scores between groups. Postoperatively, no difference was noted in surgical site pain between groups (p > 0.05). However, decreased ICBG and contralateral ICBG pain decreased twofold in group B patients in comparison with group A. Similarly, group B subjects had notably decreased postoperative overall pain scores (group A, mean 15.3; group B, mean 3.8). No significant differences were noted for the pain scores due to the small sample size. Conclusions This study is the first with a robust level I study design to assess the efficacy of continuous infusion of analgesia into the ICBG site in young patients with AIS. This pilot study noted a trend that continuous anesthetic infusion reduces pain at the ICBG site and may further decrease overall physical bodily pain. This study further established a sample size calculation to facilitate large-scale studies addressing these parameters. This study provides further support of postoperative pain management options for children with spinal deformities.

Evaluation of the osteogenic potential of growth factor-rich demineralized bone matrix in vivo

BACKGROUND

The study evaluates the osteogenic properties and biocompatibility of growth factor-rich demineralized bone matrix (GDBM) by comparing with cancellous mineralized bone matrix (CMBM) and anorganic bovine bone matrix (ABBM).

METHODS

Thirty-six Sprague-Dawley rats were used (n = 6/group/time point). To assess biocompatibility and osteoinductivity, the respective bone matrices were randomly placed in subcutaneous pouches for 7 and 28 days and evaluated by histology and osteopontin expression. Osteoconductivity was assessed by randomly implanting respective bone matrices in osteotomies on femurs for 14 and 28 days and evaluated by microcomputed tomography and histology.

RESULTS

Neither acute inflammation nor mineralized tissue was noted in any of the subcutaneous specimens, whereas expression of osteopontin was more prominent in the GDBM group. Among the femoral specimens, the greatest relative bone volume (bone volume [BV] divided by trabecular volume [TV]) and trabecular thickness was noted in the ABBM group at both time points, whereas less BV/TV was noted in GDBM group at day 14. Residual matrix particles were noted in all examined groups at both time points, without significant differences regarding defect fill between groups. The GDBM group presented similar levels of newly formed bone compartment and marrow space to those of the ABBM group.

CONCLUSIONS

GDBM demonstrated acceptable biocompatibility and osteogenic potential comparable to ABBM in vivo. Further investigations in a more clinically relevant model are warranted.

Bone Defect Regeneration by a Combination of a β-Tricalcium Phosphate Scaffold and Bone Marrow Stromal Cells in a Non-Human Primate Model

Background:

Reconstruction of large bone defects is a great challenge in orthopedic research. In the present study, we prepared composites of bone marrow-derived stromal cells (BMSCs) and β-tricalcium phosphate (β-TCP) with three novel aspects: proliferation of BMSCs with continuous dexamethasone treatment, cell loading under low pressure, and use of autologous plasma as the cell loading medium. The effectiveness of the resulting composite for large bone-defect reconstruction was tested in a non-human primate model, and the bone union capability of the regenerated bones was examined.

Materials and Methods:

Primary surgery: Bone defects (5 cm long) were created in the left femurs of nine cynomolgus monkeys with resection of the periosteum (five cases) or without resection (four cases), and porous β-TCP blocks were transplanted into the defects. Secondary surgery: Bone marrow aspirates harvested from seven of the nine monkeys were cultured with dexamethasone, and BMSCs were obtained. BMSCs were suspended in autologous plasma and introduced into a porous β-TCP block under low-pressure conditions. The BMSC/β-TCP composites were transplanted into bone defects created at the same sites as the primary surgery. Bone union evaluation: Five regenerated femurs were shortened by osteotomy surgery 8 to 15 months after transplantation of the β-TCP/BMSC composites, and bone union was evaluated radiographically.

Results:

After the primary surgery and treatment with β-TCP alone, one of the five periosteum-resected monkeys and two of the four periosteum-preserved monkeys exhibited successful bone reconstruction. In contrast, five of the seven cases treated with the β-TCP/MSC composite showed successful bone regeneration. In four of the five osteotomy cases, bone union was confirmed.

Conclusion:

We validated the effectiveness of a novel β-TCP/BMSC composite for large bone defect regeneration and confirmed the bone union capability of the regenerated bone.

Small Players Ruling the Hard Game: siRNA in Bone Regeneration

Silencing gene expression through a sequence-specific manner can be achieved by small interfering RNAs (siRNAs). The discovery of this process has opened the doors to the development of siRNA therapeutics. Although several preclinical and clinical studies have shown great promise in the treatment of neurological disorders, cancers, dominant disorders, and viral infections with siRNA, siRNA therapy is still gaining ground in musculoskeletal tissue repair and bone regeneration. Here we present a comprehensive review of the literature to summarize different siRNA delivery strategies utilized to enhance bone regeneration. With advancement in understanding the targetable biological pathways involved in bone regeneration and also the rapid progress in siRNA technologies, application of siRNA for bone regeneration has great therapeutic potential. High rates of musculoskeletal injuries and diseases, and their inevitable consequences, impose a huge financial burden on individuals and healthcare systems worldwide.

Biomaterial-Stabilized Soft Tissue Healing for Healing of Critical-Sized Bone Defects: the Masquelet Technique

Critical-sized bone defects present a significant burden to the medical community due to their challenging treatment. However, a successful limb-salvaging technique, the Masquelet Technique (MT), has significantly improved the prognosis of many segmental bone defects in helping to restore form and function. Although the Masquelet Technique has proven to be clinically effective, the physiology of the healing it induces is not well understood. Multiple modifiable factors have been implicated by various surgical and research teams, but no single factor has been proven to be critical to the success of the Masquelet Technique. In this review the most recent clinical and experimental evidence that supports and helps to decipher the traditional Masquelet, as well as the modifiable factors and their effect on the success of the technique are discussed. In addition, future developments for the integration of the traditional Masquelet Technique with the use of alternative biomaterials to increase the effectiveness and expand the clinical applicability of the Masquelet Technique are reviewed.

The Evaluation of Donor Site Pain After Harvest of Tricortical Anterior Iliac Crest Bone Graft for Spinal Surgery: A Prospective Study

STUDY DESIGN

A prospective cohort.

OBJECTIVE

The aim of this study was to prospectively observe donor site pain, health-related quality-of-life outcomes, and complications following harvest of tricortical anterior iliac crest bone graft (AICBG) for anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

Persistent donor site pain from the anterior iliac crest has been reported to range between 2% and 40%. This morbidity has led surgeons to consider interbody alternatives for ACDF, which carry additional costs.

METHODS

We prospectively enrolled 50 patients from 2 tertiary care centers over the course of 1 year observing complications and patient-reported outcomes. Patients filled out SF-12 and numeric rating scale (NRS) for pain in the arm, neck, and donor site pre-operatively and at 1 week, 2 weeks, 6 weeks, 3 to 6 months, and 1 year postoperatively. Outcomes were compared with a control group undergoing ACDF with allograft or Polyether ether ketone cages at 1 year.

RESULTS

The mean ± SD donor site pain at 1 week was 5.6 ± 2.8 but decreased to 2.2 ± 2.4 at 6 weeks and 1.1 ± 1.8 at 1 year (P < 0.001). Including the 3 patients who were lost to follow-up, 10% of patients may have experienced persistent moderate or worse pain at 1 year. Linear regression analysis demonstrated that preoperative opioid use was an independent risk factor for increased donor site pain at 1 and 2 weeks (P < 0.05). There were no differences in outcomes at 1 year compared with the nonautograft group. There were 2 (4%) minor wound complications, both treated successfully with oral antibiotics.

CONCLUSION

Tricortical AICBG for ACDF is not associated with major complications and only 4% of patients (potentially, maximum of 10%) experienced moderate, persistent donor site pain at 1 year. There is no difference in health-related outcomes between patients who have autograft with those who did not at 1 year. Preoperative opioid use is associated with increased donor site pain within the first 2 weeks postoperatively but not in the long term. At 6 weeks postoperatively, patients can expect the majority of their donor site pain to be resolved.

LEVEL OF EVIDENCE

2.

Comparing Morbidities of Bone Graft Harvesting from the Olecranon Process and the Distal Radius

The aim of this study is to compare donor-site morbidities between patients who underwent bone graft harvesting from either the olecranon process (OP) or the distal radius (DR).

METHODS

We evaluated 44 patients who underwent bone graft harvesting from the OP (25 cases) or the DR (19 cases) for various procedures in the ipsilateral upper extremity. Follow-up averaged 14 (OP group) and 19 months (DR group). Outcome measures included visual analog scales (VAS) for graft harvest-site pain and scar appearance, joint motion, and x-rays of the graft harvest and recipient sites. The VAS scores ranged from 0 to 10 with a low score reflecting no pain and excellent satisfaction and a high score reflecting severe pain and poor satisfaction.

RESULTS

The VAS scores for pain averaged 0.4 (OP) and 0.5 (DR), and the VAS scores for scar appearance averaged 0.3 (OP) and 0.7 (DR). These differences were not significant. Within each group, there were no significant differences between the operative and nonoperative limbs for elbow or wrist motion. Early graft harvest-site complications involved 1 superficial wound infection (OP) and 1 wound dehiscence (DR). A graft harvest-site defect was detected by x-ray in 84% of OP cases and in 67% of DR cases. Bone healing at the graft recipient sites was observed in more than 87% of cases in both groups.

CONCLUSIONS

Bone graft harvesting from either the OP or the DR led to comparable patient- and evaluator-determined outcomes with low risks of complications. Surgeons can safely use either option.

Non-unions treated with bone morphogenic protein 7: introducing the quantitative measurement of human serum cytokine levels as promising tool in evaluation of adjunct non-union therapy

BACKGROUND

In this study we sought to determine if application of bone morphogenic protein 7 (BMP-7) promotes physiological bone healing of non-unions and to investigate if serum cytokine analysis may serve as a promising tool in the analysis of adjunct non-union therapy. Therefore we analyzed the influence of BMP-7 application on the serum cytokine expression patterns on patients with impaired bone healing compared to patients that showed proper bone healing.

METHODS

Our study involved analyzing blood samples from 208 patients with long bone fractures together with patients that subsequently developed non-unions. From this large pool, 15 patients with atrophic non-union were matched to 15 patients with atrophic non-union treated with local application of BMP-7 as well as normal bone healing. Changes in the cytokine expression patterns were monitored during the 1st, 2nd, 4th, 8th, 12th and 52nd week. The patients were followed both clinically and radiologically for the entire duration of the study. Serum cytokine expression levels of transforming growth factor beta (TGF-β), platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) were analyzed and compared.

RESULTS

Serum expression of TGF-β were nearly parallel in all three groups, however serum concentrations were significantly higher in patients with proper bone healing and those treated with BMP-7 than in patients with non-unions (p < 0.05). bFGF serum concentrations increased initially in patients with proper bone healing and in those treated with BMP-7. Afterwards, values decreased; bFGF serum concentrations in the BMP-7 group were significantly higher than in the other groups (p < 0.05). PDGF serum concentration levels were nearly parallel in all groups, serum concentrations were significantly higher in patients with proper bone healing and those treated with BMP-7 than in patients with non-unions (p < 0.05).

CONCLUSION

Treatment with BMP-7 in patients with former non-unions led to similar cytokine expression patterns after treatment as those found in patients with proper bone healing. Our results suggest that treatment with BMP-7 promote healing of non-unions. Furthermore, quantitative measurement of serum cytokine expression is a promising tool for evaluating the effectiveness of additional non-union therapies such as adjunct application of growth factors.

Treatment of compound tibia fracture with microvascular latissimus dorsi flap and the Ilizarov technique: A cross-sectional study of long-term outcomes

BACKGROUND

Extensive compound tibial fractures present reconstructive challenges. The present study aimed to assess the outcomes of microvascular latissimus dorsi (LD) flap combined with the Ilizarov technique for extensive compound tibial fractures with bone loss and bone healing complications.

METHODS

Patient records were reviewed retrospectively. The Lower Extremity Functional Scale (LEFS), the Disabilities of the Arm, Hand and Shoulder (DASH), and the 15D health-related quality of life (HRQoL) instrument were applied.

RESULTS

Between 1989 and 2014, 16 patients underwent reconstruction with a microvascular LD flap and bone transport (11/16) or late bone lengthening (5/16). The mean clinical follow-up time was 6.6 (standard deviation (SD): 6.5) years. Three patients had minor complications requiring reoperation. Partial necrosis of one flap required late flap reconstruction in one case. Late bone grafting was used to enhance union in eight of 16 cases. The mean new bone gain was 3.8 cm (SD: 2.5). Overall, 11 patients completed the questionnaires in a mean of 22.3 years (SD: 2.4) after surgery. The main findings revealed a relatively good function of the reconstructed limb and good shoulder function. The mean HRQoL was comparable to that of an age-standardized sample of the general population.

CONCLUSION

Segmental tibia transport and lengthening to correct limb length discrepancy do not compromise the microvascular muscle flap. Combined microvascular LD flap reconstruction and the Ilizarov technique can be used in treating acute compound tibial defects, pseudoarthrosis, and osteitis, all associated with significant amputation risk. Fair long-term functional outcomes and HRQoL are achieved when these combined techniques are used.

Development of biomimetic nanocomposites as bone extracellular matrix for human osteoblastic cells

Here, we have developed biomimetic nanocomposites containing chitosan, poly(vinyl alcohol) and nano-hydroxyapatite-zinc oxide as bone extracellular matrix for human osteoblastic cells and characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction. Scanning electron microscopy images revealed interconnected macroporous structures. Moreover, in this study, the problem related to fabricating a porous composite with good mechanical strength has been resolved by incorporating 5wt% of nano-hydroxyapatite-zinc oxide into chitosan-poly(vinyl alcohol) matrix; the present composite showed high tensile strength (20.25MPa) while maintaining appreciable porosity (65.25%). These values are similar to human cancellous bone. These nanocomposites also showed superior water uptake, antimicrobial and biodegradable properties than the previously reported results. Compatibility with human blood and pH was observed, indicating nontoxicity of these materials to the human body. Moreover, proliferation of osteoblastic MG-63 cells onto the nanocomposites was also observed without having any negative effect.

Treatment of malreduced pilon fracture: A case report and the result in the long-term follow-up

•

Tibial plafond fractures carry a high risk for post-traumatic osteoarthritis.

•

Tricortical iliac crest autologous bone grafting (TCG) avoided need for arthrodesis.

•

TCG with internal fixation restored joint stability, congruency and alignment.

•

TCG should be considered for whom biological restoration is feasible.

Introduction

The risk for post-traumatic osteoarthritis (POA) following tibial plafond joint trauma has been reported to be as high as 70–75%. In the treatment of more severe joint pathologies, with incongruity and intra-articular defects, internal or external fixations techniques may be required.

Presentation of case

We report the orthopedic management of a pilon fracture in a 30-year-old male with malunion and implant failure after initial mal-reduction of the fracture 9-months earlier. Tricortical iliac crest autologous bone grafting (TCG) was used in combination with internal fixation to restore distal tibial articular. The procedure resulted in a pain free ankle, sufficient range of motion for function and patient satisfaction.

Discussion

Early surgical intervention and anatomical reduction with appropriate fixation are recommended for intra-articular tibial pilon fractures. Autogenous bone grafting is a reliable treatment option to augment structural stability, bone defects and bone-healing. Indications for bone grafting include delayed union or nonunion, malunion, arthrodesis, limb salvage, and reconstruction of bone voids or defects. The application of TCG in the management of a malreduced tibial plafond fracture has not been described before.

Conclusion

We performed TCG with internal fixation in order to restore stability, congruency and alignment in a young patient in whom a biological restoration was feasible due to good bone quality. In suitable cases, TCG might provide an alternative to arthrodesis or arthroplasty.

Olecranon tip osteoarticular autograft transfer for irreparable coronoid process fracture: a biomechanical study

BACKGROUND

We hypothesized that transfer of the olecranon tip for simulated type III coronoid fracture would restore posterior ulnohumeral translation to a level not different from that in the intact state.

METHODS

The collateral ligaments were left intact in 12 fresh-frozen cadaveric elbows, and all other soft tissues were removed. The entire coronoid process was osteotomized flush with the ventral aspect of the ulna and was reconstructed using the tip of the olecranon process. Specimens were tested with an axial load of 100 N at 0.25 mm/s in 15° increments from 15 to 120° of flexion. Intact, osteotomized, and reconstructed posterior ulnohumeral displacement was measured.

RESULTS

The bony reconstruction did not obstruct range of motion of the elbow. Intact translation (mean ± SD) ranged from 0.3 ± 0.1 to 1.1 ± 0.6 mm, and translation in the osteotomized state ranged from 1.3 ± 1.0 to 2.0 ± 1.0 mm. Resection of the coronoid resulted in a significant increase in posterior ulnar translation compared with intact at all flexion angles (p < 0.05) except at 75°. Reconstruction decreased translation versus the osteotomized state at all flexion angles, significantly at 60 and 120°. No significant difference in translation was found between reconstructed and intact states at five of eight positions tested.

CONCLUSIONS

In this biomechanical study of irreparable coronoid fracture, autograft olecranon tip transfer restored posterior elbow stability to a level not significantly different from the intact elbow in five of eight elbow positions tested.

Optimal internal fixation of anatomically shaped synthetic bone grafts for massive segmental defects of long bones

BACKGROUND

Large segmental bone defects following tumor resection, high-energy civilian trauma, and military blast injuries present significant clinical challenges. Tissue engineering strategies using scaffolds are being considered as a treatment, but there is little research into optimal fixation of such scaffolds.

METHODS

Twelve fresh-frozen paired cadaveric legs were utilized to simulate a critical sized intercalary defect in the tibia. Poly-ε-caprolactone and hydroxyapatite composite scaffolds 5 cm in length with a geometry representative of the mid-diaphysis of an adult human tibia were fabricated, inserted into a tibial mid-diaphyseal intercalary defect, and fixed with a 14-hole large fragment plate. Optimal screw fixation comparing non-locking and locking screws was tested in axial compression, bending, and torsion in a non-destructive manner. A cyclic torsional test to failure under torque control was then performed.

FINDINGS

Biomechanical testing showed no significant difference for bending or axial stiffness with non-locking vs. locking fixation. Torsional stiffness was significantly higher (P=0.002) with the scaffold present for both non-locking and locking compared to the scaffold absent. In testing to failure, angular rotation was greater for the non-locking compared to locking constructs at each torque level up to 40 N-m (P<0.05). The locking constructs survived a significantly higher number of loading cycles before reaching clinical failure at 30 degrees of angular rotation (P<0.02).

INTERPRETATION

The presence of the scaffold increased the torsional stiffness of the construct. Locking fixation resulted in a stronger construct with increased cycles to failure compared to non-locking fixation.

Anatomical Variations of the Lateral Femoral Cutaneous Nerve and Iatrogenic Injury After Autologous Bone Grafting From the Iliac Crest

OBJECTIVE

We describe 2 patients with surgical injury to the lateral femoral cutaneous nerve (LFCN) after bone harvesting from the iliac crest for autologous bone grafting.

DESIGN

A case-series of 2 patients and literature study of all anatomical variants of the LFCN in relation to the anterior superior iliac spine and inguinal ligament.

SETTING

A teaching hospital in The Hague, the Netherlands.

PATIENTS

Two patients with surgical injury to the LFCN after bone harvesting from the iliac crest for autologous bone grafting.

RESULTS

All 9 known anatomical variations of the LFCN in the literature are reviewed, and the importance of these anatomical variations for surgeons and anesthetists is stressed.

CONCLUSIONS

For every trauma, orthopedic, plastic, and cranio-maxillofacial surgeon and anesthesiologist it is important to know the anatomy of the LFCN and its known variations. To prevent injury of the LFCN during bone harvesting, the bone should be harvested 4-5 cm posterior to the anterior superior iliac spine and the incision should be parallel to the iliac crest.

LEVEL OF EVIDENCE

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

Complete twelve month bone remodeling with a bi-phasic injectable bone substitute in benign bone tumors: a prospective pilot study

Background

Benign primary bone tumors are commonly treated by surgery involving bone grafts or synthetic bone void fillers. Although synthetic bone grafts may provide early mechanical support while minimizing the risk of donor-site morbidity and disease transmission, difficult handling properties and less than optimal transformation to bone have limited their use.

Methods

In a prospective series, patients with benign bone tumors were treated by minimal invasive intervention with a bi-phasic and injectable ceramic bone substitute (CERAMENT™ BONE VOID FILLER, BoneSupport, Sweden) with the hypothesis that open surgery with bone grafting might be avoided. The defects were treated by either mini-invasive surgery (solid tumors) or percutaneous injection (cysts) and followed clinically and radiologically for 12 months. CT scan was performed after 12 months to confirm bone remodeling of the bone substitute. All patients were allowed full weight bearing immediately after surgery.

Results

Fourteen patients with a median age of 13 years (range 7–75) were consecutively recruited during 11 months. Eleven lesions were bone cysts (eight unicameral and three post-traumatic) and three were solid benign tumors. The median size of the lesions was 40 mL (range 1–152). The most common location was humerus (n = 10). After 12 months the defects completely or partially filled with median 18 mL (range 5–28) of bone substitute demonstrated full resolution (Neer Classification grade I) in 11 patients, partial resolution (Neer II) in 2 patients and in 1 patient the cyst persisted (Neer III).

No lesions required recurrent surgery during the observation period. No post-operative fracture or infection was recorded.

Conclusions

Minimal invasive treatment with a bi-phasic and injectable ceramic bone substitute might offer an alternative to regular bone grafting due to convenient handling properties and rapid bone remodeling.

Trial Registration

ClinicalTrials NCT02567084 Release Date 10/01/2015

Enhanced osteogenic potential of mesenchymal stem cells from cortical bone: a comparative analysis

Introduction

Mesenchymal stem cells (MSCs) hold great promise for regenerative therapies in the musculoskeletal system. Although MSCs from bone marrow (BM-MSCs) and adipose tissue (AD-MSCs) have been extensively characterized, there is still debate as to the ideal source of MSCs for tissue-engineering applications in bone repair.

Methods

MSCs were isolated from cortical bone fragments (CBF-MSCs) obtained from patients undergoing laminectomy, selected by fluorescence-activated cell sorting analysis, and tested for their potential to undergo mesodermic differentiation. CBF-MSCs were then compared with BM-MSCs and AD-MSCs for their colony-forming unit capability and osteogenic potential in both normoxia and hypoxia. After 2 and 4 weeks in inducing media, differentiation was assessed qualitatively and quantitatively by the evaluation of alkaline phosphatase (ALP) expression and mineral deposition (Von Kossa staining). Transcriptional activity of osteoblastogenesis-associated genes (Alp, RUNX2, Spp1, and Bglap) was also analyzed.

Results

The cortical fraction of the bone contains a subset of cells positive for MSC-associated markers and capable of tri-lineage differentiation. The hypoxic conditions were generally more effective in inducing osteogenesis for the three cell lines. However, at 2 and 4 weeks, greater calcium deposition and ALP expression were observed in both hypoxic and normoxic conditions in CBF-MSCs compared with AD- and BM-MSCs. These functional observations were further corroborated by gene expression analysis, which showed a significant upregulation of Bglap, Alp, and Spp1, with a 22.50 (±4.55)-, 46.56 (±7.4)-, 71.46 (±4.16)-fold increase compared with their uninduced counterparts.

Conclusions

This novel population of MSCs retains a greater biosynthetic activity in vitro, which was found increased in hypoxic conditions. The present study demonstrates that quantitative differences between MSCs retrieved from bone marrow, adipose, and the cortical portion of the bone with respect to their osteogenic potential exist and suggests the cortical bone as suitable candidate to use for orthopedic tissue engineering and regenerative medicine.

Bone Regeneration from PLGA Micro-Nanoparticles

Poly-lactic-co-glycolic acid (PLGA) is one of the most widely used synthetic polymers for development of delivery systems for drugs and therapeutic biomolecules and as component of tissue engineering applications. Its properties and versatility allow it to be a reference polymer in manufacturing of nano- and microparticles to encapsulate and deliver a wide variety of hydrophobic and hydrophilic molecules. It additionally facilitates and extends its use to encapsulate biomolecules such as proteins or nucleic acids that can be released in a controlled way. This review focuses on the use of nano/microparticles of PLGA as a delivery system of one of the most commonly used growth factors in bone tissue engineering, the bone morphogenetic protein 2 (BMP2). Thus, all the needed requirements to reach a controlled delivery of BMP2 using PLGA particles as a main component have been examined. The problems and solutions for the adequate development of this system with a great potential in cell differentiation and proliferation processes under a bone regenerative point of view are discussed.

Elastomeric and mechanically stiff nanocomposites from poly(glycerol sebacate) and bioactive nanosilicates

Poly(glycerol sebacate) (PGS) has been proposed for tissue engineering applications owing to its tough elastomeric mechanical properties, biocompatibility and controllable degradation. However, PGS shows limited bioactivity and thus constraining its utilization for musculoskeletal tissue engineering. To address this issue, we developed bioactive, highly elastomeric, and mechanically stiff nanocomposites by covalently reinforcing PGS network with two-dimensional (2D) nanosilicates. Nanosilicates are ultrathin nanomaterials and can induce osteogenic differentiation of human stem cells in the absence of any osteogenic factors such as dexamethasone or bone morphogenetic proteins-2 (BMP2). The addition of nanosilicate to PGS matrix significantly enhances the mechanical stiffness without affecting the elastomeric properties. Moreover, nanocomposites with higher amount of nanosilicates have higher in vitro stability as determined by degradation kinetics. The increase in mechanical stiffness and in vitro stability is mainly attributed to enhanced interactions between nanosilicates and PGS. We evaluated the in vitro bioactivity of nanocomposite using preosteoblast cells. The addition of nanosilicates significantly enhances the cell adhesion, support cell proliferation, upregulate alkaline phosphates and mineralized matrix production. Overall, the combination of high mechanically stiffness and elastomericity, tailorable degradation profile, and the ability to promote osteogenic differentiation of PGS-nanosilicate can be used for regeneration of bone.

Does autogenous bone graft work? A logistic regression analysis of data from 159 papers in the foot and ankle literature

BACKGROUND

While autogenous cancellous iliac crest bone graft is the gold standard for foot and ankle surgery, it lacks Level I evidence. Although one third of all graft cases performed in the United States today rely on allograft, some surgeons believe no graft is necessary. We hypothesized that a systematic review of the foot and ankle literature would reveal that (1) autogenous bone graft during foot and ankle arthrodesis would demonstrate healing rates that were superior to the use of either using allograft or no bone graft at all, and (2) these differences would be even more dramatic in patients having risk factors that impair bone healing. To our knowledge, neither of these assessments to date has ever been performed with this body of literature. The goal of this study was to review the use and union rates of bone graft during foot and ankle arthrodesis and determine if autogenous bone graft was superior.

METHODS

A literature search was performed to include articles between 1959 and 2012 using autograft, allograft, and/or no bone graft for foot and/or ankle arthrodesis. Case reports involving fewer than four patients, investigations failing to incorporate outcome data, those involving orthobiologic augmentation, and those including vascularized graft, xenograft, or pediatric patients were excluded. Recorded search results included patient demographics, comorbidities, pre-operative diagnosis, surgical procedure, bone graft type and indication, union rate, method of fixation, patient satisfaction, all outcome scores, definition of healing/success, and any listed complications including revision. Final data were stratified based upon the type of graft material.

RESULTS

This search generated 953 related articles, of which 159 studies (5327 patients) met inclusion criteria. The majority (153/159) were retrospective case series. Systematic review demonstrated a trend toward higher union rates for cancellous autograft (OR 1.39, p=0.11), structural autograft (OR 1.52, p=0.09), and cancellous allograft (OR 1.31, p=0.52) relative to no graft material, but none reached statistical significance. Compared to no graft, structural allograft trended toward worse performance (OR 0.62, p=0.17). The overall probability of union was 93.7% for cancellous autograft, 94.2% for structural autograft, 93.3% for cancellous allograft, 91.4% for no graft, and 86.9% for structural allograft. When only comparing the 19 papers that included a no graft arm (91.9% union rate), data revealed the highest union using cancellous autograft (95.1%, OR 1.73, p=0.09) and structural autograft (96.3%, OR 2.33, p=0.06) while only 76% for structural allograft. No significant statistical association existed between union rates and other recorded variables.

CONCLUSION

Systematic analysis of bone graft use in foot and ankle fusions favors the use of autograft and cancellous allograft for optimized healing rates, although no differences were statistically significant. If we assume that graft material been chosen for more complex procedures having lower anticipated union rates, then these data lend further support to the use of autograft and cancellous allograft.

LEVEL OF EVIDENCE

Level IV.

The regeneration and augmentation of bone with injectable osteogenic cell sheet in a rat critical fracture healing model

Limitations in the current treatment strategies make cases with compromised bone healing challenging clinical problems. Osteogenic cell sheets (OCSs), fabricated from rat bone marrow stromal cells (BMSCs), contain enriched osteoblasts and extracellular matrix. Here, we evaluated whether the minimally invasive percutaneous injection of OCSs without a scaffold could be used as a treatment to increase bone regeneration in a critical fracture healing model. Critical fracture healing model was created in the femora of 60 male Fischer 344 inbred rats using marrow ablation and periosteal removal. The rats were then randomly divided into two groups. Six hours after fracture, one group received an injection of OCSs (OCS group), while the second group was injected with phosphate-buffered saline (PBS) (control group). Fracture healing was evaluated using radiological, histological, micro-computed tomography (CT) and biomechanical analyses. The radiological and histological evaluations demonstrated enhanced bone regeneration in the OCS group compared with that in the control group. By 12 weeks, the hard callus had been remodelled via recorticalization in the OCS group. By contrast, no fracture union was found in the rats in the control group. Biomechanical testing revealed a significantly higher maximum bending load in the OCS group compared with that in the control group. The results of the present study demonstrate that the injection of entire OCSs can enhance bone regeneration and lead to bony union in a critical fracture healing model. Therefore, this procedure offers a minimally invasive technique to promote hard tissue reconstruction and, in particular, bone repair strategies for cases with compromised bone healing.

Prospective Randomized Controlled Trial of Hindfoot and Ankle Fusions Treated With rhPDGF-BB in Combination With a β-TCP-Collagen Matrix

BACKGROUND

Ankle and hindfoot arthrodesis is often supplemented with autograft to promote bony union. Autograft harvest can lead to increased perioperative morbidity. Purified recombinant human platelet-derived growth factor BB homodimer (rhPDGF-BB) has stimulated bone formation in mandibular defects and hindfoot fusion. This randomized controlled trial evaluated the efficacy and safety of rhPDGF-BB combined with an injectable, osteoconductive beta-tricalcium phosphate (β-TCP)-collagen matrix versus autograft in ankle and hindfoot fusions.

METHODS

Seventy-five patients requiring ankle or hindfoot fusion were randomized 5:1 for rhPDGF-BB/β-TCP-collagen (treatment, n = 63) or autograft (control, n = 12). Prospective analysis included 142 autograft control subjects from another clinical trial with identical study protocols. Standardized operative and postoperative protocols were used. Patients underwent standard internal fixation augmented with autograft or 0.3 mg/mL rhPDGF-BB/β-TCP-collagen. Radiologic, clinical, and quality-of-life outcomes were assessed over 52 weeks. Primary outcome was joint fusion (50% or more osseous bridging on computed tomography) at 24 weeks. Secondary outcomes included radiographs, clinical healing status, visual analog scale pain score, American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Scale score, Foot Function Index score, and Short Form-12 score. Noninferiority P values were calculated.

RESULTS

Complete fusion of all involved joints at 24 weeks as indicated by computed tomography was achieved in 53 of 63 (84%) rhPDGF-BB/β-TCP-collagen-treated patients and 100 of 154 (65%) autograft-treated patients (P < .001). Mean time to fusion was 14.3 ± 8.9 weeks for rhPDGF-BB/β-TCP-collagen patients versus 19.7 ± 11.5 weeks for autograft patients (P < .01). Clinical success at 52 weeks was achieved in 57 of 63 (91%) rhPDGF-BB/β-TCP-collagen patients and 120 of 154 (78%) autograft patients (P < .001). Safety-related outcomes were equivalent. Autograft controls had 2 bone graft harvest infections.

CONCLUSIONS

Application of rhPDGF-BB/β-TCP-collagen was a safe, effective alternative to autograft for ankle and hindfoot fusions, eliminating the pain and morbidity associated with autograft harvesting.

LEVEL OF EVIDENCE

Level I, prospective randomized study.

Bone Engineering of Maxillary Sinus Bone Deficiencies Using Enriched CD90+ Stem Cell Therapy: A Randomized Clinical Trial

Bone engineering of localized craniofacial osseous defects or deficiencies by stem cell therapy offers strong prospects to improve treatment predictability for patient care. The aim of this phase 1/2 randomized, controlled clinical trial was to evaluate reconstruction of bone deficiencies of the maxillary sinus with transplantation of autologous cells enriched with CD90+ stem cells and CD14+ monocytes. Thirty human participants requiring bone augmentation of the maxillary sinus were enrolled. Patients presenting with 50% to 80% bone deficiencies of the maxillary sinus were randomized to receive either stem cells delivered onto a β-tricalcium phosphate scaffold or scaffold alone. Four months after treatment, clinical, radiographic, and histologic analyses were performed to evaluate de novo engineered bone. At the time of alveolar bone core harvest, oral implants were installed in the engineered bone and later functionally restored with dental tooth prostheses. Radiographic analyses showed no difference in the total bone volume gained between treatment groups; however, density of the engineered bone was higher in patients receiving stem cells. Bone core biopsies showed that stem cell therapy provided the greatest benefit in the most severe deficiencies, yielding better bone quality than control patients, as evidenced by higher bone volume fraction (BVF; 0.5 versus 0.4; p = 0.04). Assessment of the relation between degree of CD90+ stem cell enrichment and BVF showed that the higher the CD90 composition of transplanted cells, the greater the BVF of regenerated bone (r = 0.56; p = 0.05). Oral implants were placed and restored with functionally loaded dental restorations in all patients and no treatment-related adverse events were reported at the 1-year follow-up. These results provide evidence that cell-based therapy using enriched CD90+ stem cell populations is safe for maxillary sinus floor reconstruction and offers potential to accelerate and enhance tissue engineered bone quality in other craniofacial bone defects and deficiencies (Clinicaltrials.gov NCT00980278).

Comparison of structural allograft and traditional autograft technique in occipitocervical fusion: radiological and clinical outcomes from a single institution

OBJECT The authors' objectives were to compare the rate of fusion after occipitoatlantoaxial arthrodesis using structural allograft with the fusion rate from using autograft, to evaluate correction of radiographic parameters, and to describe symptom relief with each graft technique. METHODS The authors assessed radiological fusion at 6 and 12 months after surgery and obtained radiographic measurements of C1-2 and C2-7 lordotic angles, C2-7 sagittal vertical alignments, and posterior occipitocervical angles at preoperative, postoperative, and final follow-up examinations. Demographic data, intraoperative details, adverse events, and functional outcomes were collected from hospitalization records. Radiological fusion was defined as the presence of bone trabeculation and no movement between the graft and the occiput or C-2 on routine flexion-extension cervical radiographs. Radiographic measurements were obtained from lateral standing radiographs with patients in the neutral position. RESULTS At the University of Utah, 28 adult patients underwent occipitoatlantoaxial arthrodesis between 2003 and 2010 using bicortical allograft, and 11 patients were treated using iliac crest autograft. Mean follow-up for all patients was 20 months (range 1-108 months). Of the 27 patients with a minimum of 12 months of follow-up, 18 (95%) of 19 in the allograft group and 8 (100%) of 8 in the autograft group demonstrated evidence of bony fusion shown by imaging. Patients in both groups demonstrated minimal deterioration of sagittal vertical alignment at final follow-up. Operative times were comparable, but patients undergoing occipitocervical fusion with autograft demonstrated greater blood loss (316 ml vs 195 ml). One (9%) of 11 patients suffered a significant complication related to autograft harvesting. CONCLUSIONS The use of allograft in occipitocervical fusion allows a high rate of successful arthrodesis yet avoids the potentially significant morbidity and pain associated with autograft harvesting. The safety and effectiveness profile is comparable with previously published rates for posterior C1-2 fusion using allograft.

Micro-structured Beta-Tricalcium Phosphate for Repair of the Alveolar Cleft in Cleft Lip and Palate Patients: A Pilot Study

Objectives

Can a synthetic bone substitute be used to repair the alveolar cleft to bypass donor site morbidity as well as to shorten the operating time? In earlier experimental studies, micro-structured beta-tricalcium phosphate (β-TCP) provided similar bone healing when compared with grafting with iliac crest bone. This justifies the clinical evaluation of this bone substitute in the human alveolar cleft situation.

Design

Prospective clinical study.

Setting

University clinic.

Participants

Seven patients, all with unilateral alveolar cleft, were randomly included for alveolar cleft repair with β-TCP in 2010 and 2011.

Main Outcome Measures

In all patients, the alveolar cleft was repaired by micro-structured β-TCP grafting. Our assessments were distilled from cone beam computed tomography scans taken preoperatively, 1 week postoperatively, and 6 months postoperatively. A volumetric outcome could be realized.

Results

Six months after the operative grafting of micro-structured β-TCP into the alveolar cleft, the bone volume thus acquired was satisfactory. We found an average bone volume percentage of 73% ± 6% compared with the original cleft volume.

Conclusions

Previous experimental and clinical studies and the initial findings of this pilot study now elucidate a path toward the clinical use of micro-structured β-TCP bone substitute for repair of the alveolar cleft.

Hydroxyapatite reinforced collagen scaffolds with improved architecture and mechanical properties

Hydroxyapatite (HA) reinforced collagen scaffolds have shown promise for synthetic bone graft substitutes and tissue engineering scaffolds. Freeze-dried HA-collagen scaffolds are readily fabricated and have exhibited osteogenicity in vivo, but are limited by an inherent scaffold architecture that results in a relatively small pore size and weak mechanical properties. In order to overcome these limitations, HA-collagen scaffolds were prepared by compression molding HA reinforcements and paraffin microspheres within a suspension of concentrated collagen fibrils (∼ 180 mg/mL), cross-linking the collagen matrix, and leaching the paraffin porogen. HA-collagen scaffolds exhibited an architecture with high porosity (85-90%), interconnected pores ∼ 300-400 μm in size, and struts ∼ 3-100 μm in thickness containing 0-80 vol% HA whisker or powder reinforcements. HA reinforcement enabled a compressive modulus of up to ∼ 1 MPa, which was an order of magnitude greater than unreinforced collagen scaffolds. The compressive modulus was also at least one order of magnitude greater than comparable freeze-dried HA-collagen scaffolds and two orders of magnitude greater than absorbable collagen sponges used clinically. Moreover, scaffolds reinforced with up to 60 vol% HA exhibited fully recoverable elastic deformation upon loading to 50% compressive strain for at least 100,000 cycles. Thus, the scaffold mechanical properties were well-suited for surgical handling, fixation, and bearing osteogenic loads during bone regeneration. The scaffold architecture, permeability, and composition were shown to be conducive to the infiltration and differentiation of adipose-derive stromal cells in vitro. Acellular scaffolds were demonstrated to induce angiogenesis and osteogenesis after subcutaneous ectopic implantation by recruiting endogenous cell populations, suggesting that the scaffolds were osteoinductive.