[Preparation of gentamicin-impregnated bone allograft and experimental study on treatment of infective bone defect]

OBJECTIVE

To study and prepare a new kind of bone graft, which has osteogenesis, local anti-infective function and low immunogenicity.

METHODS

Gentamicin-impregnated bone was prepared by means of ultrasonic and vacuum, the release of gentamicin in vivo was measured by inhibition bacteria. Ten healthy male adult sheep were made animal infection models of thigh bone or humerus defect of 6 mm x 6 mm x 20 mm at size, and the defect was inoculated into 1 ml 5 x 10(10) CFU/ml Staphylococcus aureus. The animals were randomly divided into the experimental group (n=5, the bone graft with gentamicin was implanted) and the control group (n=5, the bone graft without gentamicin). Macroscopic, WBC count, radiological, and histological investigations were carried out to evaluate the anti-infective and osteosis capability.

RESULTS

The concentrations of gentamicin were 46.1 microg/ml in bone allograft and 17.3 microg/ml in muscles after 1 day. The concentrations of gentamicin exceeding the minimum inhibitory concentration lasted for 14 days in vivo. WBC in the control group was higher than that in the experimental group. In the control group, 1 case died owing to septicemia 3 weeks after operation. The implanted bones were wrapped in pus 4 and 6 weeks, and the defects were filled with fibre tissue 8 and 10 weeks after operation. In the experimental group, 1 case was infected, the others had a good concrescence. The bone allografts began to integrate with adjacent bone after 4-8 weeks and integrate well after 12 weeks. The X-ray and histological observation showed that new bone formed and took the place of bone allograft.

CONCLUSION

The gentamicin-impregnated bone allograft was of a good sustained release feature in vivo, local anti-infection and osteogenesis. It might be an ideal bone grafting material for bone defects with infection.

Commercially Available Demineralized Bone Matrix Compositions to Regenerate Calvarial Critical-Sized Bone Defects

BACKGROUND

Demineralized bone matrix products are often used by surgeons to regenerate bone. Several different types of carriers have been combined with demineralized bone matrix to improve clinical handling and surgical outcome. The aim of the study was to quantitate bone regeneration in standard-sized calvarial defects (a critical-sized defect) in response to commercially available demineralized bone matrix formulations.

METHODS

The commercial demineralized bone matrix formulations were tested as received in 8-mm-diameter calvarial critical-sized defects in an athymic rat model. The demineralized bone matrix treatment groups included the following: (1) Allomatrix; (2) demineralized bone matrix plus sodium hyaluronate (DBX); (3) DBX with poly(DL-lactide) mesh; 4) Dynagraft; (5) Grafton; (6) Regenafil; and (7) human demineralized bone matrix without a carrier. An eighth treatment was a poly(DL-lactide) mesh. At designated times of 2, 4, and 8 weeks, the critical-sized defects were recovered and processed for undecalcified histology and histomorphometry. Histomorphometric data were subjected to an analysis of variance and Fisher's protected least significant difference multiple comparison test. Significance was established at p <or= 0.05.

RESULTS

Allomatrix, Dynagraft, Regenafil, and poly(DL-lactide) mesh alone had less bone formation than DBX, Grafton, DBX plus mesh, and demineralized bone matrix.

CONCLUSIONS

DBX, DBX plus mesh, demineralized bone matrix, and Grafton produced more bone formation than Allomatrix, Dynagraft, mesh alone, and Regenafil.

Accelerated degradation and improved bone-bonding ability of hydroxyapatite ceramics by the addition of glass

Dense hydroxyapatite (HA) ceramics are useful bone substitutes, but they degrade minimally. One solution is to incorporate degradable materials in the HA. In this study, we manufactured glass-containing HA and investigated whether the degradability and bone-bonding ability of the HA were improved. The glass-containing HA was manufactured from a mixture of HA powder and 1.0 wt% glass powder. The control HA was manufactured from pure HA powder. In vitro degradability was evaluated by soaking in physiological saline, and a rabbit model was used to evaluate in vivo degradability and bone-bonding ability. Detaching tests were performed for all removed samples to quantify bone-bonding ability of each type of HA. The glass-containing HA showed higher degradability than the control HA, both in vitro and in vivo. The detaching failure load of the glass-containing HA was rapidly elevated after implantation and was higher than that of the control HA. Our results suggest that the dissolution of the added glass made the glass-containing HA degradable and that the detaching failure load of the glass-containing HA was elevated by reinforcement of the mechanical locking at the roughened interface. Incorporation of glass additives into HA can be concluded to be a good candidate for producing a bone substitute that can partially degrade and bond to bone firmly and rapidly.

Expression of amino acid transporter LAT1 and 4F2hc in the healing process after the implantation of a tooth ash and plaster of Paris mixture

BACKGROUND

In order to elucidate the expression pattern of L-type amino acid transporter 1 (LAT1) in the bone formation process, the expressions of LAT1 and its subunit 4F2 heavy chain (4F2hc) were investigated in the healing process after the implantation of a tooth ash-plaster of Paris mixture in rats with calvarial osseous defect.

MATERIALS AND METHODS

Circular calvarial defects (8 mm in diameter) were made midparietally. The rats were divided into 2 groups, 1 control group and 1 experimental group. In the control group, the defect was only covered with a soft tissue flap (control group); in the experimental group, it was filled with a mixture of tooth ash and plaster of Paris (2:1 by weight; mixture group). The rats were sacrificed at 1, 2, 4 and 8 weeks after operation and RT-PCR and immunohistochemical analyses were performed.

RESULTS

In the RT-PCR analysis, the expressions of the LAT1 and 4F2hc mRNAs were slightly stronger in the experimental group than in the control group. In the immunohistochemical analysis, at 1 week after operation, the LAT1 protein and its subunit 4F2hc protein were mainly expressed in the osteoblasts, osteocytes and interstitial tissues of the area around the defect and the inner part of newly forming bone in both groups. The expressions of LAT1 and 4F2hc proteins were decreased at 2 and 4 weeks after operation. The LAT1 and 4F2hc proteins were scarcely expressed at 8 weeks after operation in both groups. The expressions of LAT1 and 4F2hc proteins were slightly stronger in the mixture group than in the control group.

CONCLUSION

These results suggest that the LAT1 and its subunit 4F2hc are highly expressed in the early stage of new bone formation and may have an important role in providing cells with neutral amino acids, including several essential amino acids, at that stage.

Closure of Rabbit Calvarial Critical-Sized Defects Using Protective Composite Allogeneic and Alloplastic Bone Substitutes

This study evaluated the repair of critical-sized cranial vault defects in thirty New Zealand white rabbits using various allogeneic and alloplastic bone substitutes designed to provide mechanical protection to the brain as well as osteoinductivity. The strategies employed included demineralized bone matrix (DBM), a putty used in combination with a rigid resorbable plating system as a protective covering and calcium phosphate cement (CPC) combined with native partially purified bone morphogenetic protein (BMP). Bilateral critical-sized defects measuring 15 mm in diameter were created in the parietal bones of 30 adult male New Zealand white rabbits. They were divided into three groups with ten animals in each. Group 1 had one defect left unfilled as a control while autogenous bone was placed in the defect on the other side. In Group 2 a rigid resorbable copolymer membrane, Lactosorb (Lorenz Surgical, Jacksonville, Florida), was placed over both defects to cover them and protect the underlying tissues. The pericranial aspect of one defect was left unfilled while the other defect was filled with DBM putty. Group 3 had a CPC, Mimix (Lorenz Surgical, Jacksonville, Florida), placed into one of the defects while the defect on the other side was filled with the same CPC in combination with BMP in a concentration of 25 mg/mL. Bone healing was assessed clinically, radiographically, and histomorphometrically. All unfilled controlled defects, the defects covered with the resorbable Lactosorb membrane and those filled with calcium phosphate cement alone, healed with a fibrous scar. Defects reconstructed with DBM putty in combination with the resorbable Lactosorb membrane and calcium phosphate in combination with BMP healed with bone bridging the entire defect. This was obvious radiographically where the defects appeared completely filled with a dense radiopaque tissue. Histological analysis demonstrated that specimens where DBM putty was used in combination with the resorbable Lactosorb membrane had 67.7% new bone fill at 6 weeks and 84.0% at 12 weeks. Resorption of DBM particles was evidenced by the presence of osteoclastic activity and by the significant decrease in the size of the demineralized bone particles. In the calcium phosphate groups where BMP was added to the bioimplant there was 45.8% new bone formation at 12 weeks. The utilization of a composite consisting of DBM with resorbable Lactosorb membrane or a composite of calcium phosphate cement composite with BMP promoted complete closure of critical-sized calvarial defects in New Zealand white rabbits with viable new bone at 12 weeks. The complete bone bridging observed with these composites suggests that they could be used to enhance the protection of intracranial contents following craniofacial surgical procedures.

Die Überbrückung von posttraumatischen Knochendefekten

Bony defects as a result of injury or disease can be caused by a variety of conditions such as acute injury, fall fractures in osteoporotic patients or tumours and congenital malformations of the musculoskeletal system which necessitate the resection of affected parts of the bone. This results in a multitude of defects concerning localisation and specificity as well as a number of conditions involving both hard and soft tissue structures and various situations of different patients. A reasonable classification of defects which is relevant for practical purposes includes four basic types: defects of the spine, metaphyseal defects as well as partial and complete diaphyseal defects of long bones. A variety of options exists for the treatment of these conditions. The aim of all efforts is to reinstall the integrity of affected structures long-lastingly and dependably and at the same time guarantee the normal function of joints involved. In addition to classical treatment strategies which involve the use of autogenous and allogenous corticocancellous bone grafts a great number of bone substitute materials can also be used. Further options lie in complex reconstructive methods such as the transport of whole segments or the transplantation of vascularised bone grafts. The field of new regenerative strategies including tissue engineering as well as stem cell and gene therapy holds great promise for the future. The aim of this review is to derive a ranking from the evaluation of biological and mechanical characteristics for the treatment of posttraumatic defects.

Morphology of autogenous bone graft and castor oil polyurethane in the infraorbital rim of rabbits: a comparative study

PURPOSE

Morphological study comparing castor oil polyurethane and autogenous bone graft to repair bone defect in zygomatic bone of rabbits.

METHODS

Twenty-four adult, male New Zealand rabbits were randomly distributed between two groups of twelve. Bone defects of 5mm in diameter were cut through the zygomatic bone and filled with polyurethane discs in the experimental group or autogenous bone harvested from the tibia in the control group. Animals were sacrificed after 30, 60 or 90 days, and the zygomatic bones were macro- and microscopically analyzed. Student's, Fisher's, chi-squared and McNemar's tests were used for statistical analysis.

RESULTS

Both the castor oil polyurethane and the autograft adapted well to the defect, with no need for fixation. Fibrous connective tissue encapsulated the polyurethane, but no inflammation or giant cell reaction was observed. Acidophilic and basophilic areas were observed inside the micropores of the polyurethane, suggesting cell nuclei. After 90 days, bone repair with a lamellar pattern of organization was observed in the control group.

CONCLUSION

The castor oil polyurethane was biocompatible and did not cause inflammation. It may be considered an alternative to fill bone defects.

[Experimental studies on the porous calcium phosphate cement combined with recombinant human bone morphogenetic protein 2 for bone defects repair]

OBJECTIVE

To study in vitro sustained release behaviour of the recombinant human bone morphogenetic protein 2 (rhBMP-2) from the sample which porous calcium phosphate cement (PCPC) was combined with rhBMP-2, and to evaluate the effect of PCPC/rhBMP-2 composite on repairing bone defect in the animal study.

METHODS

rhBMP-2 was absorbed into PCPC by vacuum-adsorption and freeze-dried at -40 degrees C, the PCPC/rhBMP-2 enwrapped with chitosan as the experimental group, the pure PCPC/rhBMP-2 as the control group, then the sustained release of rhBMP-2 from PCPC was determined in simulated body fluid (SBF) by UV-VIS spectrophotometer. At same time, the PCPC/rhBMP-2 composites with chitosan were implanted into the (4.2 mm x 5.0 mm femora defects of rabbits, which were considered as the experimental group, whereas in the control group only PCPC was implanted. The effect of repairing bone defect was evaluated in the 4th and 8th week postoperatively by radiograph and histomorphology.

RESULTS

The PCPC have a high absorption efficiency to rhBMP-2, and the release of rhBMP-2 was sustained release system. The release of rhBMP-2 from PCPC in the experimental group (99% after 350 hours) was slower than that in the control group (100% after 150 hours). In the experimental group, the radiological and histomorphological evaluations showed that the interfaces between the materials and host bones became blurred both at 4th and 8th week. The implanted materials were partially absorbed, and the implanted areas exhibited the formation of new bone. In the control group, a little amount of new bones was observed.

CONCLUSION

The PCPC shows great clinical potential as a carrier for rhBMP-2. The PCPC/rhBMP-2 composite possesses much potentialities of osteoinductivity and the ability of repairing bone defect, so it can be used as a novel bone substitute clinically.

Trigonocephaly: surgical considerations and long term evaluation

Trigonocephaly accounts for approximately 10% of all craniosynostosis. Severe trigonocephaly results in a triangular-shaped forehead, superior-lateral orbital depression, hypotelorism, and compensatory occipital-parietal calvarial changes. Radiographic findings include ovoid orbits with parallel medial borders, thickened keel-shaped frontal bone, small ethmoid sinuses, and a short anterior cranial fossa with pitched sphenoid wings. Our experience with 50 infantile cases of severe nonsyndromic trigonocephaly patients treated from 1987 to 2005 is clinically reviewed to assess long-term growth based on a standardized operative technique. The average age of the patients at surgery was 6 months and the mean follow-up was 12 years. Our complication rate was 2%; the reoperative rate was 12%. The use of resorbable rigid plate fixation combined with alloplastic augmentation has improved the cosmetic outcome in patients treated since 1996 and reduced the reoperative rate.

[A method to avoid the fixator failure by using pedicle screw combined vertebroplasty for spine fractures]

OBJECTIVE

To study a new implant material (carbonated hydroxyapatite, CHA) united pedicle screw to cure spine fracture.

METHODS

Thirty-two cases of spine compressed fracture were used with pedicle screw fixator and vertebroplasty. Before operation, patients' vertebral body were compressed (46 + 21)% (20% approximately 70%) on average. In operation, broken vertebral body was reposition through pedicle screw technique, then used self-made syringe to inject CHA into anterior and central column of broken vertebral body through pedicle. And all of patients were not given any bone-graft.

RESULTS

In 6 - 26 months followed-up, no immunologic rejection was found about hydroxyapatite, and no any broken of the screws and shafts was found, no loosing and other complications either. All the patients could move in 3 - 5 days after operation. The height of the broken vertebral body were reduced 97% compared with pre-operation. And CHA in vertebral body was degraded gradually, and at the same time it was replace by new bone in vertebral body. After operation, VAS score was 61 +/- 32, and there was significant difference compared with pre-operation.

CONCLUSIONS

The pedicle screw fixation united vertebroplasty is an efficient way to prevent the failure of the treatment of spine fracture.

Investigation of a thermoplastic polymeric carrier for bone tissue engineering using allogeneic mesenchymal stem cells in granular scaffolds

PURPOSE

The purpose of this project was to compare alveolar bone repair by allogeneic mesenchymal stem cells using bioglass or synthetic hydroxyapatite (HA)/tricalcium phosphate (TCP) granular scaffolds delivered in a thermoplastic polymeric carrier.

MATERIALS AND METHODS

Canine mesenchymal stem cells were obtained from iliac crest bone marrow of beagle dogs and expanded without differentiation. Cells were resuspended at a final concentration of 5 x 10(6) cells/ml in a thermoplastic polymeric carrier (30% w/v Pluronic F-127) and mixed with an equal volume of synthetic HA/TCP or bioglass scaffold and placed into surgically created 5 mm cylindrical defects in the edentulous premolar region of beagle dogs. After 4 weeks or 7 weeks, tissue healing was evaluated by standard histomorphometric methods (Bioquant Nova, Bioquant Image Analysis Corporation, Nashville, TN) by measurement of bone formation within five random sites from each biopsy.

RESULTS

After 4 weeks, sites treated with or without mesenchymal stem cells contained 58.25 +/-18.43% or 43.35 +/- 17.68% bone area (p= 0.049), respectively. After 7 weeks, sites treated with or without mesenchymal stem cells contained 62.73 +/- 19.10% or 60.39 +/- 21.32% bone area. Bone formation occurred without inflammation in defects treated using Pluronic F-127 carrier with and without mesenchymal stem cells. There was no difference in percent bone area when bioglass or HA/TCP scaffolds were compared at either time point.

CONCLUSIONS

The thermoplastic polymeric carrier did not limit alveolar bone repair in the canine mandible. The combination of a thermoplastic, viscous carrier with a granular scaffold allowed for the delivery of allogeneic mesenchymal stem cells in a clinically manageable form that enhanced bone formation at early stages of alveolar repair.

Synthetic, pure-phase beta-tricalcium phosphate ceramic granules (Cerasorb®) for bone regeneration in the reconstructive surgery of the jaws

The aim of this study was to investigate the long-term effect of the ceramic beta-tricalcium phosphate (beta-TCP) at different sites of alveolar reconstruction and to evaluate its properties. From 1997 to 2002, beta-TCP was implanted as bone substitute in 152 patients using a standardized study protocol. Main indications were the filling of large mandibular cysts (n=52), secondary and tertiary alveolar cleft grafting (n=38), periodontal defects (n=24) and maxillary sinus floor augmentation (n=16). For defects exceeding 2cm in diameter, beta-TCP was combined with autologous bone taken from the retromolar area, the maxillary tuberosity or the chin region. A radiological, clinical and ultrasonographical examination was carried out 4, 12 and 52 weeks postoperative. In 16 cases, biopsies were taken after 12 months indicating complete bony regeneration. While wound-healing disturbances occurred in 9.2% of cases, partial loss of the bone substitute material was found in 5.9%, while total loss occurred in only 2%. Complete radiological replacement of beta-TCP by autologous bone was found after approximately 12 months, indicating its osteoconductive properties. Because of its versatility, low complication rate and good long-term results, synthetic, pure-phase beta-TCP is a suitable material for the filling of bone defects in the alveolar region.

Vertical ridge augmentation around implants using e-PTFE titanium-reinforced membrane and deproteinized bovine bone mineral (bio-oss): A case report

The aim of this case report was to evaluate the ability of Bio-Oss used together with an expanded polytetrafluoroethylene, titanium-reinforced membrane to restore a vertical bone defect. Bio-Oss served as a filler material. After the membrane was removed, screw-type implants were placed. During this phase, cylindric bone samples were retrieved from the augmented area for histologic examination. The biopsy samples were composed of low-density trabecular bone with numerous interspersed graft particles. Clinical and histologic results demonstrated that this surgical technique could be a successful and predictable procedure for rebuilding a resorbed ridge to place implants.

Bone graft substitutes in the upper extremity

The development of effective bone graft substitutes is one of the most important innovations in musculoskeletal surgery. Bone graft substitutes provide an osteoconductive scaffolding similar to those of autogenous bone. They eliminate donor site morbidity,decrease operative time and complexity and treatment costs, and improve patient satisfaction. Osteoinductive and osteogenic elements may be added to further stimulate and enhance healing and incorporation of the scaffolding substance into the adjacent bone. Bone graft substitutes have proven effective in the spine and larger long bones of the extremities. The continuing development of bone graft substitutes, evaluation of their efficacy relative to autogenous bone grafts and to each other, and their use in the hand and wrist are emerging fields.

The bone regenerative effect of platelet-rich plasma in combination with an osteoconductive material in rat cranial defects

The effect of platelet-rich plasma (PRP) on bone regeneration, in combination with an osteoconductive material, was evaluated in a rat model. Cranial defects, 6.2 mm in diameter, were filled with HA/beta-TCP particles, HA/beta-TCP particles combined with PRP and HA/beta-TCP particles combined with PRP gel, where some were left empty as a control. After 4 weeks of implantation histological, histomorphometrical and micro-computed tomography analyses revealed no difference in new bone formation among the groups. Further, no additional effect of PRP gel in comparison with PRP liquid was detected, except for the increased handling capacity of the graft. These findings suggest that PRP had no positive effect on bone formation in addition to an osteoconductive material after an implantation period of 4 weeks. Also, no negative effect was seen, and neither PRP nor HA/beta-TCP hampered bone ingrowth into the defects.

Biomechanical comparison of anatomic trajectory pedicle screw versus injectable calcium sulfate graft-augmented pedicle screw for salvage in cadaveric thoracic bone

Many salvage options for failed thoracic pedicle screws exist including the use of a different trajectory or the augmentation of the screw with polymethylmethacrylate cement. Although polymethylmethacrylate immediately increases the construct stiffness and the pull-out strength, it may cause bone necrosis, toxin relaxation, and/or neural injury. On the other hand, calcium sulfate bone grafts have a high potential for biologic incorporation and no thermal damage effect. In the current study, polyaxial pedicle screws were first inserted with a straightforward approach on both sides in 17 fresh human cadaveric thoracic vertebrae. The maximal insertion torque for each screw was measured and then the pull-out strengths were recorded. Afterward, these pedicle screws were randomly assigned to be replaced either by graft augmentation or by anatomic trajectory technique for salvage. The graft-augmented screws were placed using the previous holes. The maximum insertional torque for each anatomic trajectory screw was measured. Finally, the pull-out strengths of the revision screws were recorded. The mean maximum insertional torque decreased with the anatomic trajectory salvage technique when compared with the straightforward approach, 0.23 versus 0.38 Nm, respectively (P=0.003). The anatomic trajectory revision resulted in decreased pull-out strength when compared with the pull-out strength of the straightforward technique, 297 versus 469 N, respectively (P=0.003). The calcium sulfate graft augmentation increased the pull-out strength when compared with the pull-out strength of the straightforward technique, 680 versus 477 N, respectively (P=0.017). The mean pull-out strength ratio of revised screw to original was 0.71 for anatomic trajectory and 1.8 for graft-augmented screws, a statistically significant difference (P=0.002).

Instrumented fusion of thoracolumbar fracture with type I mineralized collagen matrix combined with autogenous bone marrow as a bone graft substitute: a four-case report

In order to avoid the morbidity from autogenous bone harvesting, bone graft substitutes are being used more frequently in spinal surgery. There is indirect radiological evidence that bone graft substitutes are efficacious in humans. The purpose of this four-case study was to visually, manually, and histologically assess the quality of a fusion mass produced by a collagen hydroxyapatite scaffold impregnated with autologous bone marrow aspirate for posterolateral fusion. Four patients sustained an acute thoracolumbar fracture and were treated by short posterior segment fusion using the AO fixateur interne. Autologous bone marrow (iliac crest) impregnated hydroxyapatite-collagen scaffold was laid on the decorticated posterior elements. Routine implant removal was performed after a mean of 15.3 months (12–20). During this second surgery, fusion mass was assessed visually and manually. A bone biopsy was sent for histological analysis of all four cases. Fusion was confirmed in all four patients intraoperatively and sagittal stress testing confirmed mechanical adequacy of the fusion mass. Three out of the four (cases 2–4) had their implants removed between 12 and 15 months after the index surgery. All their histological cuts showed evidence of newly formed bone and presence of active membranous and/or enchondral ossification foci. The last patient (case 1) underwent implant removal at 20 months and his histological cuts showed mature bone, but no active ossification foci. This four-case report suggests that the fusion mass produced by a mineralized collagen matrix graft soaked in aspirated bone marrow is histologically and mechanically adequate in a thoracolumbar fracture model. A larger patient series and/or randomized controlled studies are warranted to confirm these initial results.

[Perfusion-weighted magnetic resonance imaging for monitoring vascularization in tissue-engineered bone in rhesuses]

OBJECTIVE

To assess the value of perfusion-weighted magnetic resonance (MR) imaging (PWMRI) in monitoring vascularization in tissue-engineered bone graft.

METHODS

Tibial diaphyseal defect of 20 mm was induced in 25 lower limbs of 13 rhesuses and fixed with an AO reconstruction plate with 7 holes. The monkeys were randomized into 5 groups according to the materials used for defect filling: group A, with beta-tricalcium phosphate (beta-TCP), bone marrow stromal cells (BMSCs) and blood vessel bundles; group B, with beta-TCP and blood vessel bundles; group C, with beta-TCP and BMSCs; group D, with beta-TCP, and group E without filling. PWMRI, X-ray, and radionuclide imaging were carried out at weeks 4, 8, 12 postoperatively. The maximum slope rates of the single intensity-time curve (SS(max)) and the baseline values (SI(baseline)) on the same time points were calculated. Transmittances on the X-ray films and isotope counts in the region of interest (ROI) were assessed and calculated.

RESULTS

Compared with other groups, group A showed the highest SS(max) at weeks 4, 8, and 12 postoperatively, and its SS(max) at week 8 was significantly higher than that at week 4 (P=0.003). The SS(max) was positively related to isotope counts in ROI at week 8 after operation (r(s)=0.899, P=0.038), and inversely related to transmittance on X-ray films at week 12 (r(s)=-0.892, P=0.042).

CONCLUSION

The SS(max) of the single intensity-time curve can accurately reflect the vascularization of the tissue-engineered bone graft, and PWMRI allows sensitive, quantitative, noninvasive and radiation-free vascularization monitoring.

The effect of demineralized bone matrix-calcium sulfate with vancomycin on calcaneal fracture healing and infection rates: a prospective study

BACKGROUND

Displaced intra-articular calcaneal fractures may have a central cancellous bone defect area. We hypothesized that human demineralized bone matrix (DBM) calcium sulfate (CaSO(4)) might act as a reasonable alternative to autograft in calcaneal fractures. When combined with antibiotic powder, this bone graft substitute also may act as a local antibiotic delivery device. This is the first clinical study evaluating bone healing and complications associated with DBM-calcium sulfate bone graft substitute in the treatment of displaced intra-articular calcaneal fractures with a central cancellous bone defect.

METHODS

Over a 29-month period, 33 displaced intra-articular calcaneal fractures with central cancellous defects were treated with open reduction and internal fixation (ORIF) and grafting with vancomycin/DBM-calcium sulfate bone graft substitute. Eleven fractures without bone defects were treated with ORIF only. Patient demographics, medical history, and CT fracture classification were recorded. Postoperatively, fractures were monitored every 2 weeks for healing and complications.

RESULTS

The mean time to union was 8.2 weeks in the grafted, while the control group mean time to union was 10.4 weeks (p = 0.0117). Wound problems occurred in five (15%) of the 33 patients with grafting, all in type III fractures with severe soft-tissue swelling, and included two minor wound healing delays, and three serious wound problems. At a mean followup time of 22.4 months, no DBM-calcium sulfate grafted calcaneus demonstrated evidence of osteomyelitis.

CONCLUSIONS

This is the first study examining human DBM-calcium sulfate bone graft substitute to treat displaced intra-articular calcaneal fractures. Based on these initial data, human DBM-calcium sulfate acted as an acceptable and safe autograft alternative in displaced intra-articular calcaneal fractures with moderate (5 cc to 10 cc) central cancellous bone defects.

Regeneration statt Reparation

Autogenous bone transfer is still regarded as the "golden standard" for many indications in oral and cranio-maxillofacial surgery. In this overview, the status of the autogenous bone is re-evaluated under consideration of current research results, clinical long-term studies, risks and safety of the patient as well as the costs. Due to the further development of modern bone substitute materials, which reveal in parts superior long-term results for special indications, the routine use of autogenous bone has to be critically reviewed.

First histological observations on the incorporation of a novel nanocrystalline hydroxyapatite paste OSTIM in human cancellous bone

Background:

A commercially available nanocrystalline hydroxyapatite paste Ostim^® has been reported in few recent studies to surpass other synthetic bone substitutes with respect to the observed clinical results. However, the integration of this implantable material has been histologically evaluated only in animal experimental models up to now. This study aimed to evaluate the tissue incorporation of Ostim^® in human cancellous bone after reconstructive bone surgery for trauma.

Methods:

Biopsy specimens from 6 adult patients with a total of 7 tibial, calcaneal or distal radial fractures were obtained at the time of osteosynthesis removal. The median interval from initial operation to tissue sampling was 13 (range 3–15) months. Samples were stained with Masson-Goldner, von Kossa, and toluidine blue. Osteoid volume, trabecular width and bone volume, and cortical porosity were analyzed. Samples were immunolabeled with antibodies against CD68, CD56 and human prolyl 4-hydroxylase to detect macrophages, osteoblasts, and fibroblasts, respectively. TRAP stainings were used to identify osteoclasts.

Results:

Histomorphometric data indicated good regeneration with normal bone turnover: mean osteoid volume was 1.93% of the trabecular bone mass, trabecular bone volume – 28.4%, trabecular width – 225.12 μm, and porosity index – 2.6%. Cortical and spongious bone tissue were well structured. Neither inflammatory reaction, nor osteofibrosis or osteonecrosis were observed. The implanted material was widely absorbed.

Conclusion:

The studied nanocrystalline hydroxyapatite paste showed good tissue incorporation. It is highly biocompatible and appears to be a suitable bone substitute for juxtaarticular comminuted fractures in combination with a stable screw-plate osteosynthesis.

rhPDGF-BB promotes healing of periodontal defects: 24-month clinical and radiographic observations

A new therapeutic system using purified recombinant human platelet-derived growth factor-BB (rhPDGF-BB) in combination with a biocompatible, osteoconductive, synthetic scaffold beta-tricalcium phosphate (beta-TCP) has recently been shown in a large-scale, prospective, blinded, randomized clinical trial to safely and effectively treat advanced periodontal osseous defects. A significant gain in clinical attachment level was observed 3 months postsurgery for sites treated with 0.3 mg/mL rhPDGF-BB + beta-TCP versus beta-TCP + buffer (active control), with this trend continuing at 6 months postsurgery. Additionally, sites treated with 0.3 mg/mL rhPDGF-BB + beta-TCP also had significantly greater radiographic linear bone gain and percent defect fill at 6 months postsurgery than sites that received bone substitute with buffer. Representative cases from the clinical trial were followed to assess their ability to maintain the initial effect of treatment observed at 6 months. At 18 or 24 months postsurgery, with the same clinical and radiographic measurement techniques used as were performed at the 6-month time point for the clinical trial, these cases demonstrated maintenance of the clinical attachment level for all but one case, with all cases demonstrating substantial increases in linear bone gain and percent bone fill versus measurements obtained at 6 months postsurgery. Substantial radiographic changes in the appearance of the defect fill were observed for both rhPDGF-BB treatment groups, consisting of increased radiopacity and bone trabeculation, indicative of increased mineralization and maturation of the bone observed 6 months postsurgery.

Influence of platelet-rich plasma on a bioglass and autogenous bone in sinus augmentation. An explorative study

Platelet-rich plasma (PRP) has been introduced to the field of oral and maxillofacial surgery for a decade, but its beneficial effects on maxillary sinus augmentation remain unclear. The aim of this study was to evaluate the short- and long-term effects of PRP on osseointegration following single-stage sinus augmentation in a randomized prospective animal study. The maxillary premolars of 24 minipigs were extracted bilaterally and allowed to heal for 2 months. Consecutively all animals underwent bilateral sinus floor elevation using autogenous bone, Biogran as well as a combination of the materials with PRP. Three dental implants (Ankylos, Dentsply Co., Mannheim, Germany) were installed in each sinus simultaneously. Four animals were sacrificed at each period of observation (1, 2, 8 and 12 months). Microradiographic images of the specimens were made for quantitative evaluation of the bone-implant contact (BIC) and light microscopic images were made for qualitative analysis. An increment of the BIC during the observation time could be seen over the observation time in all groups. Autogenous bone exhibited a level of BIC from 25.1 +/- 9.96% at 1 month to 55.1 +/- 13.10% at 12 months; on adding PRP, the BIC ranged from 28.4 +/- 4.64% to 52.5 +/- 17.06%. Biogran with and without PRP led to BIC levels from 16.3 +/- 4.64% to 37.6 +/- 16.40% and 21.7 +/- 4.33% to 46.6 +/- 19.37%, respectively. The results of this study did not show a significantly positive effect of PRP on the BIC following sinus augmentation in both groups.