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PubMed2001

[Unstable fracture of the distal radius and its treatment: comparison of three techniques: external fixation, intramedullary pinning and AO plates].

This retrospective study compares 94 distal radius fractures. Sixty one women (median age 66) and 33 men (median age 42) were reviewed clinically and radiologically by a surgeon not involved in treatment. Fractures were classified into three AO groups. Standard X-rays were used for radiological evaluation. Fractures of the distal ulna were evaluated separately. Chi-square tests, Wilcoxon, Mann-Whitney and Fisher's tests were used for statistical evaluation. Women presented mainly "A" type fractures. They were treated by intramedullary pinning. Forty two fractures were grafted, using autogenous bone for young patients and bone substitute for the elderly. Twelve scapholunate dissociations were recorded, all but one were detected in women, 50 years of age or more. Four were painfree, two presented climatic pain and six claimed pain during effort; none had snapping. Radio-ulnar laxity was similar with or without styloid fractures. External fixator and autogenous grafts appeared the most efficient technique for maintaining radial length. Ulnar head fractures were related to a significant higher incidence of sympathetic dystrophy with reduced prono-supination, a correlation not previously noted to your knowledge. This suggests that radius and ulnar head fracture should be classified independently. The amount of pain was not related to classification, internal fixation or gender.

Adolescent↗
PubMed2001

Replacement therapy and the immediate post-extraction dental implant.

Immediate postextraction implant placement often deals with two major problems: maintaining the initial stability of the implant(s) and preventing soft tissue ingrowth during the healing period. Both problems may lead to the loss of the implant(s). The objective of this clinical study was to evaluate the effectiveness, reliability, and placement of single-stage implants in extraction sockets in combination with a synthetic bone substitute. Hopeless teeth were extracted and one-stage cylindrical screw implants, hollow and solid, were inserted together with a composite polymer without using a membrane. Rehabilitation was performed three to six months postoperatively by placement of different types of prostheses. Excellent initial results were confirmed by the follow-up of 7 to 10 years. The hollow screw-type showed a higher failure rate when compared with the solid screw-type. One-stage implant osseointegration in extraction sockets is enhanced if used with this synthetic graft material, and the simplicity of the method does not jeopardize outcome and predictability. It provides the patient with the benefits of implant-supported restorations in a simple, quick, cost-effective, and secure manner.

Adult↗
PubMed1998

[Interbody arthrodesis of the lumbar vertebrae using retroperitoneal videoendoscopy. A preliminary study of 38 cases].

AIM OF THE STUDY: To report a series of 38 patients presenting retroperitoneoscopic inter-body fusion of the lumbar spine from L2 to L5, performed between 1995 and 1998. PATIENTS AND METHODS: This series included 25 women and 13 men aged from 16 to 74 years (mean age: 48.5 years). Surgery was performed in 32 patients for primary degenerative or post-operative instability of the lumbar spine, in five patients for painful sequels of burst fracture, and in one patient for sequels of disc infection. The main complaint was lumbar pain but a real sciatic pain was present in nine patients and was not a contraindication for this surgery. Standard X-rays were performed for each patient, and MRI performed in 30 patients confirmed the diagnosis and was also useful in determining vascular abnormalities. A cast immobilisation of the lumbar spine was done as a preoperative test in every patient. RESULTS: Forty-two levels were fused: 31 with a cage filled with cancellus bone and screwed between the end plates, and 11 with cancellus bone alone or in association with bone substitute, such as beta TCP. Post-operative complications included only a transient paresthesia of the thigh in two cases and a chyloretroperitoneum spontaneously resolutive. After 2.3 months of plaster immobilisation with a follow-up of 11.4 months, patient satisfaction rate was 84.5%, with 68.5% reporting no further back pain. The improvement was estimated by Prolo score. Fusion was considered effective by X-ray examination in all patients with an increase in the intervertebral space of 35% and a recovery of the local lordosis of 15%. CONCLUSION: Retroperitoneoscopic surgery is an elegant and secure method for lumbar interbody fusion of L2 to L5 with very few postoperative complications.

Adult↗
PubMed1993

Treatment of experimental osteomyelitis with antibiotic-impregnated bone graft substitute.

The model of Norden was used to induce osteomyelitis in the left tibia of New Zealand White rabbits. Twenty-one days following inoculation, the animals had primary debridement and then were randomized into one of three treatment groups. Group I received no additional treatment; in Group II, plain hydroxyapatite beads were packed into the defect; and in Group III, gentamicin crobefat-loaded hydroxyapatite beads were packed into the defect. The animals were observed for 40 days after the primary debridement and then were killed. The intensity of infection was determined by swab cultures and quantitative bacterial cultures of the debrided material. At primary debridement, all of the animals in each group were equally infected. At the time of secondary debridement, only the animals in Group III had a statistically significant reduction in infection (p < 0.001). In this study, we demonstrated that an antibiotic-loaded osteoinductive ceramic bead can effectively eliminate bacteria from an osteomyelitic cavity.

Animals↗
PubMed2004

Implantology and the severely resorbed edentulous mandible.

Patients with a severely resorbed edentulous mandible often suffer from problems with the lower denture. These problems include: insufficient retention of the lower denture, intolerance to loading by the mucosa, pain, difficulties with eating and speech, loss of soft-tissue support, and altered facial appearance. These problems are a challenge for the prosthodontist and surgeon. Dental implants have been shown to provide a reliable basis for fixed and removable prostheses. This has resulted in a drastic change in the treatment concepts for management of the severely resorbed edentulous mandible. Reconstructive, pre-prosthetic surgery has changed from surgery aimed to provide a sufficient osseous and mucosal support for a conventional denture into surgery aimed to provide a sufficient bone volume enabling implants to be placed at the most optimal positions from a prosthetic point of view. The aim of this paper is to review critically the literature on procedures related to the severely resorbed edentulous mandible and dental implant treatment. The study includes the transmandibular implant, (short) endosseous implants, and reconstructive procedures such as distraction osteogenesis, augmentation of the mandibular ridge with autogenous bone, and bone substitutes followed by the placement of implants. The number of patients participating in a study, the follow-up period, the design of the study, the degree of mandibular resorption, and the survival rate of the dental implants all are considered evaluation parameters. Although numerous studies have described the outcome results of dental implants in the edentulous mandible, there have been few prospective studies designed as randomized clinical trials that compare different treatment modalities to restore the severely resorbed mandible. Therefore, it is not yet possible to select an evidence-based treatment modality. Future research has to be focused on long-term, detailed follow-up clinical trials before scientifically based decisions in treating these patients can be made. This will contribute to a higher level of care in this field.

Alveolar Bone Loss↗
PubMed2004

In vitro cytocompatibility assessment of beta-tricalcium phosphate/carboxymethyl-chitin composite.

A novel bioabsorbable bone substitute composed of a beta-tricalcium phosphate (beta-TCP) and a carboxymethyl-chitin (CM-chitin) sodium has been developed. Rabbit tibia defects (4 mm in diameter) were repaired after 4 weeks more effectively by the composite compared with a sham-operation group. To further investigate the biological safety of the components, genotoxicity and carcinogenicity of an extract prepared from the composite were determined using four different in vitro assays. The main extract component was identified as CM-chitin sodium [average molecular weight (Mw) approximately 230 kDa] as determined by Fourier transform infrared spectroscopy and gel permeation chromatography analysis. The concentrations of P and Ca possibly derived from beta-TCP were 17.7 and 37.1 microg/g, respectively, as determined by inductively coupled plasma mass spectroscopy. Both the metabolic activation and nonactivation (-S9) systems of the rat microsome S9 fraction were used to perform a genotoxicity evaluation using the Ames test and chromosome aberration assay on Chinese hamster lung fibroblast cells treated with the extract. In these assays, no genotoxicity was detected with doses < or =5 mg/mL (maximum concentration). The cell transformation assay using BALB/c 3T3 cells and the metabolic cooperation assay with V79 cells both showed negative results for any tumor-promoting activity caused by the extract (approximately 5 mg/mL). These results indicate that the bioabsorbable beta-TCP/CM-chitin composite is a highly biocompatible bone substitute.

3T3 Cells↗
PubMed1994

Post-menopausal vertebral osteoporosis: can dual energy X-ray absorptiometry forearm bone density substitute for axial measurements?

This study compared measurements of BMD using dual energy X-ray absorptiometry (DXA) at three sites in the nondominant forearm (ultradistal, distal one-third and a mid-region between these two), the lumbar spine (L1-L4) and the proximal femur (femoral neck, trochanter and Ward's triangle) for the evaluation of vertebral osteoporosis. Studies were performed on 100 normal women aged 29-69 yr (average 52 yr) and 63 osteoporotic women age 48-75 yr (average 66 yr) using the Hologic QDR-1000. Precision values of < 1% were obtained in both normal and osteoporotic women at both forearm and axial sites. Z-scores for the osteoporotics [Z = (mean BMD normal--mean abnormal)/S.D.] were--2.02 lumbar spine, -1.96 femoral neck, -1.79 ultradistal forearm, -1.73 mid region and -1.66 distal one-third forearm. Receiver operating characteristic curves showed that the lumbar spine and femoral neck equally discriminated between normals and osteoporotics with a 95% area under each curve, significantly greater values than those for the forearm which were 87% ultradistal, 89% mid forearm and 86% distal one-third forearm. Fracture thresholds, defined as the 90th centile of BMD for osteoporotic patients, were 1 S.D. below the normal mean for lumbar spine and femoral neck but equal to the mean for ultradistal, 0.6 S.D. below mean for mid region and 0.3 S.D. below mean for distal one-third region. We conclude that for the discrimination of normals and osteoporotic women the three forearm sites are comparable. However, both lumbar spine and proximal femur BMD are superior to all forearm sites.

Absorptiometry, Photon↗
PubMed2002

Effect of perforations in burr hole covers on cranial bone regeneration in rabbits.

The reconstruction of bone defects is a significant problem in cranio-maxillofacial surgery. In an effort to avoid the known disadvantages of autogenous bone grafting, alternatives have been investigated. Bone substitute materials, degradable or nondegradable, aim at facilitating bone regeneration, while they take over load-bearing functions for a period of time. In this study, the healing of cranial defects in rabbits was assessed using polylactide guiding covers with and without perforations. Bilateral circular cranial defects were produced in 16 New Zealand white rabbits. The defects were covered with extruded and laser cut polylactide burr hole covers, each animal receiving a perforated burr hole cover on one side and a nonperforated one on the contralateral side. Bone seeking fluorochromes were administered at regular intervals. After an observation period of 8 weeks the amount of bone regeneration in the area of the defects was quantified from contact radiographs, and the dynamics of bone formation were assessed by fluorescence microscopy. Stained sections were used to analyze morphologic differences. No signs of adverse tissue reactions or osteolysis were observed. A bone-guiding function was observed for both covers with or without perforations. Intracranial tissue herniation into the defect hindered the regeneration process. Wide intraindividual and interindividual variation became apparent and average defect filling was only 40% within the 8-week observation period. In this model the perforated covers offered no advantage over nonperforated covers. It can be concluded from this study, that the use of external burr hole covers alone does not guarantee a full thickness regeneration of the cranial defect, but it provides a guiding function for promotion of structured bone regeneration.

Absorbable Implants↗
PubMed2004

[Long-term effects of 7-year growth hormone substitution on bone metabolism, bone density, and bone quality in growth hormone-deficient adults].

BACKGROUND AND PURPOSE: Subnormal bone mineral density (BMD) and increased fracture risk are described in patients with growth hormone deficiency (GHD). Growth hormone (GH) has been reported to have beneficial effects on bone in GHD. The aim of this study was to investigate the long-term effects of GH replacement therapy on bone metabolism, BMD, and bone quality in patients with GHD. PATIENTS AND METHODS: 20 adult patients with GHD (eleven male, nine female, mean age 42.5 years) were included in the study and randomized to either GH or placebo in a dose of 0.25 U/kg body weight/week. After 6 months all patients received GH. After a 1-year double-blind, placebo-controlled study the patients were followed for another 72 months in an open study. The patients were compared to 20 age- und sex-matched healthy controls. Bone turnover was determined by ICTP (type I collagen carboxyterminal cross-linked telopeptide) as parameter of bone resorption and PICP (carboxyterminal propeptide of type I procollagen) as marker of bone formation. BMD was measured at the lumbar spine by dual-photon absorptiometry (DPA) and at the forearm by single-photon absorptiometry (SPA). Apparent phalangeal ultrasound transmission velocity (APU) was assessed as parameter of bone quality independent of BMD. RESULTS: At the beginning of the study BMD at both measuring sites was lower in patients with GHD than in healthy controls. During the 1st year of GH replacement therapy BMD decreased, followed by a continuous increase in BMD (about 12%) up to 60 months which remained unchanged thereafter, building up a plateau. After 72 months no significant difference between the patients and the healthy controls could be detected. Concerning parameters of bone turnover, first ICTP as marker of bone resorption showed a significant increase, later on the marker of bone formation increased as well. APU decreased during the first 6 months of treatment, but had returned to its baseline value after 24 months and remained unchanged throughout the rest of the study. CONCLUSION: BMD is subnormal in adults with GHD. GH replacement therapy stimulates bone turnover in patients with GHD and in the long term such stimulation results in an increased BMD. Thereby, GH shows a triphasic action on BMD: an initial decrease in BMD during the 1st year, followed by a continuous increase in BMD with buildup of a stable plateau after 60 months. The newly formed bone seems to have normal bone elasticity.

Absorptiometry, Photon↗
PubMed1987

Functional alveolar reconstruction in a patient with total mandibular replacement.

Alveolar reconstruction in a case of total mandibular replacement is presented. The placement of hydroxylapatite bone substitute and the staple bone plate into a previously grafted area demonstrates that the properties of transplanted bone are similar to natural bone. Furthermore, the safety and effectiveness of the utilization of these biomaterials in areas of previous osseous reconstruction is documented. An awareness of biologic tissue response may have also contributed to successful functional restoration. In addition, a major question about the functions of the muscles of mastication arises.

Adult↗
PubMed2004

Combination of porous hydroxyapatite and cationic liposomes as a vector for BMP-2 gene therapy.

The clinical significance of hydroxyapatite (HAP) as a bone substitute has become apparent in recent years and bone morphogenetic protein (BMP) a substance which induces bone has attracted much attention. In this study, a 1.2 cm diameter bone defects created on rabbit cranium were treated with the BMP-2 gene (cDNA plasmid) introduced with porous HAP after completion of hemostasis and the resultant bone formation was analyzed histopathologically. The amounts of bone formation was compared BMP-2 cDNA plasmids were not combined with cationic liposomes as a vector. Four groups of rabbits were compared. In the HAP group the cranial bone defect was treated with HAP containing 40 microg of liposomes and a dummy gene (PU). The BMP gene HAP group was treated with HAP soaked in liposomes and 10 microg of the BMP-2 gene. In addition, a group was treated with the gene without implanting HAP. Bone formation on the cranial defects was evaluated 3, 6 and 9 weeks after the operation, by X-ray and histopathological examinations. Three weeks after the operation there was vigorous bone formation in the cranial defect in the group which received the BMP-2 gene without HAP, and complete ossification was observed at 9 weeks. In the group which received HAP containing the BMP-2 gene, although new bone formation was evident surrounding the scaffold 3 weeks post-operation, the induced bone tissue did not fill all the pores of the scaffold even at 9 weeks post-operation. These results confirm the clinical usefulness of gene therapy for bone formation, using the BMP-2 gene combined with cationic liposomes as a vector. It is possible that the effects of administering the BMP-2 gene will be improved by specializing the microstructure of scaffold for gene therapy.

Animals↗
PubMedDate not supplied

[Clinical experience with the implantation of collagen-apatite for local bone regeneration].

After a short review of the problematic of bone substitution the possibility of bone regeneration induced by implantation of synthetic Apatite and reaffined heterogenic Collagen is displayed especially with an industrial manufactured mixed preparation called "Collapat". Firstly it is referred especially to the comparing animal experience and histological results by Nizard. According to this research fine dispersed Apatite powder has obviously a remarkable osteoinductive effect, which is inhenced by the Collagen component, used especially as a distribution medium. The tract mainly concerns the clinical experiences in human patients with Collagen-Apatite-implantation since October 1979 with the indication of larger bone defects. In 85 patients with totally 94 Collagen-Apatite-implantations in different age groups no incompatibility was seen. In X-ray controls a rapid reestablishment of natural bone structures was observed. The Collagen-Apatite product seems particularly to be apt for the reconstruction of defect cavities as well as for an additive to autologous bone transplantation which by this method can be limited as well in number as in quantity.

Adolescent↗
PubMed2006

Platelet-rich plasma improves expansion of human mesenchymal stem cells and retains differentiation capacity and in vivo bone formation in calcium phosphate ceramics.

INTRODUCTION: Mesenchymal stem cells (MSC) applied to bone substitution materials can improve bone healing. Bone formation in biocomposites is highly dependent on the kind of biomaterial, its pre-treatment and the applied cells. Potentially immunogenic or infectious supplements such as fetal calf serum (FCS) should be avoided in cell expansion media. Therefore, we developed an expansion protocol free of xenogenic supplements. Cells expanded with two different media were tested on distinct biomaterials for their bone formation capacity after ectopic implantation in vivo, as well as for their growth rate and differentiation capacity in vitro. METHODS: MSC of six donors were expanded with cell expansion medium containing FCS (2%) or platelet-rich plasma (PRP, 3%). Their growth rate and osteogenic, adipogenic and chondrogenic differentiation capacity were compared in vitro. For the in vivo bone formation assay, expanded cells (2 x 105 or 2 x 106) were seeded on calcium-deficient hydroxyapatite (CDHA; n = 12) and on beta-tricalcium phosphate (beta-TCP; n = 12) blocks, which had been coated with either fibronectin or human serum. They were then implanted subcutaneously in severe combined immunodeficient mice (SCID), harvested after 8 weeks and analysed by histology. Bone formation was assessed by a semi-quantitative bone score, after toluidine blue and alizarin red staining. Human cells were detected by an in situ hybridisation for human-specific alu sequences. RESULTS: PRP-supplemented expansion medium yielded two-fold higher cell numbers compared to medium with FCS (P = 0.046) after 3 weeks (four passages) and retained a similar capacity to differentiate towards the osteogenic, chondrogenic and adipogenic lineage. In vivo bone formation was equal for cells expanded with PRP and FCS and depended on the specific surface area of the carrier. CDHA (specific surface area (SSA) 48 m2/g) showed a significantly better bone formation in deep layers (P = 0.005) than beta-TCP (SSA 0.5 m2/g). Fibronectin-coating of the ceramics was slightly superior to coating with human serum (P = 0.045). CONCLUSIONS: The replacement of FCS by PRP eliminated risks connected with the use of xenogeneic supplements. It improved expansion of MSC and retained their differentiation and in vivo bone formation capacity in a setting adaptable to autogenous use.

Animals↗
PubMed1979

Experimental evaluation of ceramic calcium phosphate as a substitute for bone grafts.

Tricalcium phosphate (Synthos) is a bioceramic material which can be carved with a scalpel and wired into place as a bone graft would be. The process of bone replacement of the prosthesis begins with an ingrowth of cellular loose connective tissue, which is replaced later by dense connective tissue. Around the periphery of this dense fibrous connective tissue, osteoid tissue becomes evident and on later specimens this mixture seems to be converted to bone--which at first is in the form of spicules but later takes on the characteristics of lamellar bone (with tricalcium phosphate particles seen within its lacunae). The progressive replacement occurs in a circumferential pattern, but most heavily at the bone-prosthesis interface. Although the periosteum is beneficial, we do not feel that the major source of bone formation is as the soft tissue or subperiosteal area. The replacement of the tricalcium phosphate prosthesis is slower than we originally thought, or than reported by others. We have noted pockets of tricalcium phosphate, incompletely replaced, in dogs up to 18 months after implantation. We believe this may be related to the larger sized prostheses we used (2 x 2 cm blocks) with, therefore, longer distances that the ingrowth and calcification had to traverse.

Animals↗
PubMed1999

Properties of coralline hydroxyapatite and expanded polytetrafluoroethylene membrane in the immature craniofacial skeleton.

Although extensive research regarding the treatment of calvarial defects has been done in adult models, little is known about the response in the maturing skeleton. The role of coralline hydroxyapatite and expanded polytetrafluoroethylene membrane in augmenting bone growth and repair of calvarial defects in a neonatal model is explored. Utilizing a 3-week-old neonatal swine model, bone growth into 28 calvarial defects was measured. After exposure of the calvaria in seven animals, four defects of 10 mm in diameter were created. In each animal, one defect was treated with a 10-mm disc of porous hydroxyapatite alone (Interpore 500, Interpore International), and a second defect was covered with an expanded polytetrafluoroethylene membrane (Gore-Tex OV-6) secured by four 3-mm microscrews (Luhr Microsystem, Howe-Medica Inc.). The third defect combined an implanted hydroxyapatite disc covered by an expanded polytetrafluoroethylene membrane, whereas the fourth defect served as an untreated control. Histology and histomorphometry were performed on undecalcified specimens harvested at 6 weeks after surgery. In both hydroxyapatite groups, the bone growth into the inorganic matrix provided complete osseous union in all specimens, and the amount of fibrosis was significantly lower (p < 0.02) in comparison with the control. Unexpectedly, there was significant osteoclastic resorption of the hydroxyapatite matrix (35.1 percent decrease) with simultaneous bone deposition and remodeling. The addition of an expanded polytetrafluoroethylene membrane covering the hydroxyapatite implant provided an insignificant advantage in bone growth (27.3 percent versus 28.3 percent, respectively). Finally, the expanded polytetrafluoroethylene membrane alone afforded no qualitative advantage secondary to intrusion of brain and dura into the defect as well as displacement of the membrane inward during appositional growth, leading to incomplete healing of the defect with thinning of the surrounding cranial bone. Unique in this maturing model was morphologic evidence of complete union at the calvaria-hydroxyapatite interface in all specimens as well as active remodeling of the hydroxyapatite matrix. The results of this study suggest that porous hydroxyapatite may be a suitable bone substitute in maturing calvarial bone defects, achieving superior osseous integration and volumetric bone gain while undergoing concurrent resorption and remodeling.

Animals↗
PubMedDate not supplied

Aptamer-based capture molecules as a novel coating strategy to promote cell adhesion.

The improvement of the cytocompatibility of medical implants is a major goal in biomaterials research. During the last years many researchers worked on the fascinating approach to seed the respective cell types on various artificial substrates before implantation. For instance, cell-seeded implants are supposed to be better candidates for transplantable bone substitutes than conventional artificial bone grafts. To improve cell seeding efficiency and cytocompatibility, we designed a new coating material for medical implants. We used aptamers, highly specific cell binding nucleic acids generated by combinatorial chemistry with an in vitro selection called systematic evolution of exponential enrichment (SELEX). Aptamers do have high binding affinity and selectivity to their target. In our study, human osteoblasts from osteosarcoma tissue were used as a target to create the aptamer. Single aptamer mediated cell sorting assays showed the binding affinity with osteoblasts. Additionally, the aptamers immobilized on tissue culture plates could capture osteoblasts directly and rapidly from the cell solution. This model proves that aptamer coated artificial surfaces can greatly enhance cell adhesion. We assume that this strategy is capable to improve the clinical application of tissue engineered implants.

Base Sequence↗
PubMed2001

[Manufacture and study of porous poly(l-lactic acid) (PLLA)/beta-tricalcium phosphate (beta-TCP) composite].

A promising alternative to supply bone substitutes is to develop living tissue substitutes based on biodegradable materials, which is called bone tissue engineering. One of the research high-lights of bone tissue engineering is to design and manufacture scaffolds for cell attaching, migrating, and proliferating. A process which consists of a solvent casting stage, a compression molding stage and a leaching stage has been used to fabricate macroporous composites of poly(l-lactic acid) (PLLA) and beta-tricalcium phosphate (beta-TCP). The effects of the weight fraction of porogen--NaCl, of the weight ratio of PLLA to beta-TCP and of the diameters of beta-TCP on the porosities, the average pore diameters and the compressive yield strength and compressive modulus have been studied. The results showed that the porosities and the average pore diameters increased and the compressive yield strength and modulus decreased when the weight fraction went from 50% to 90%. The compressive yield strength and compressive modulus could be improved by changing the weight ratio of PLLA to beta-TCP and the diameters of beta-TCP in low-porosity composites (lower than 70%). But high-porosity composites (90%) were not reinforced by changing the weight ratio.

Biocompatible Materials↗