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Biomedical subjects

P Hardouin

Publications and source records attributed to P Hardouin.

At least 19 recordsLinked to original sources
PubMed1997

In vitro growth of human adult bone-derived cells on hydroxyapatite plasma-sprayed coatings.

The growth of adult human bone-derived cells on hydroxyapatite (HA) plasma-sprayed coatings was investigated. Such cells were difficult to grow on original plasma-sprayed coatings, even following rinsing and rubbing down. We obtained cell growth only on samples previously immersed 15 or 22 days in complete culture medium. We describe a dissolution/precipitation phenomenon on the HA coating surface assessed by modifications of Ca and P concentrations in the culture medium, by the transformation of the HA coating into carbonated HA (X-ray diffraction and infrared spectrometry and by the presence demonstrated by scanning electron microscopy of spherocrystallites on the HA after 15 days of immersion. Our results show that adult human bone-derived cells are apparently particularly sensitive to the changes in the coating surface induced by liquid immersion. We raise the question of the limits of in vitro investigations on bioactive ceramics such as HA plasma-sprayed coatings susceptible to modification by simple immersion in aqueous solutions such as cell culture medium or physiologic saline.

Adult↗
PubMed1996

[Bone cements and their uses in orthopedics and rheumatology. GRIBOI. Groupe de Recherche interdisciplinaire sur les Biomatériaux ostéo-articulaires injectables].

Acrylic cement has been used for total hip arthroplasty fixation for several years. Use of new cements for bony injections or for treatment of fractures is often misunderstood, in spite (or because?) of numerous paper in non-medical magazines. Acrylic cement continues to be the reference for bony cements. Most hip arthroplasties are still cemented, with good results in most cases, even after ten years. Other applications of acrylic cement are reported here, especially for percutaneous injection in metastatic vertebral lesions. New kind of cements are now available, especially pastes of carbonated apatite, and beta tricalcium phosphate-monocalcium phosphate monohydrate water mixtures. With this new family of injectable biomaterials we can hope the development of mini-invasive therapies for bone lesions, and first results appear to be very attractive. However continuous improvements of these materials and rigorous clinical evaluations are need.

Bone Cements↗
PubMed1996

Resorption of, and bone formation from, new beta-tricalcium phosphate-monocalcium phosphate cements: an in vivo study.

Hard cylinders (4.7 x 10 mm) of two kinds of beta-tricalcium phosphate-monocalcium phosphate monohydrate-calcium sulfate hemihydrate (beta-TCP-MCPM-CSH) cements with and without beta-TCP granules (500-1000 microns) were implanted into holes drilled in rabbit femoral condyles for up to 16 weeks. Empty cavities were used as control. Cement resorption and new bone formation in the cylinders were evaluated with contact microradiography and quantified through an automatic image analysis system. At 4 weeks, both kinds of cement cylinders were surrounded by new bone. At 8 weeks, except for beta-TCP granules, both cement cylinders were almost completely resorbed and replaced by bone tissue. At 16 weeks the bone in the cavities of both cements recovered a trabecular pattern, but only the bone trabeculae in the initial cavity of the cement with beta-TCP granules became thick and mature. However, the cavities of the empty control were still empty and large. These results show that the beta-TCP-MCPM-CSH cements stimulate bone formation and are rapidly replaced by bone tissue. When added with nonresorbable beta-TCP granules, this cement maintains bone formation for a longer time.

Animals↗
PubMed1996

[Fatigue rupture of a Harris-Galante shell in contact with an autograft of the femur head. Analysis of bone, mechanical and metallurgical factors].

We observed, after 38 months of follow-up, the rupture of the metallic shell of a Harris-Galante cup implanted in a dysplastic acetabulum augmented with a femoral head autograft. Bone ingrowth was extended to 53% of the porous surface, but only in the areas in contact with the true acetabulum. No bone ingrowth was identified in the fiber mesh in contact with the autograft. The graft was necrotic on histologic examination and showed collapse radiographically. These last conditions were responsible for shear stress in the part of the cup that was in contact with the graft-acetabulum junction. These stresses were involved in the fatigue rupture mechanism identified on microscopic examination of rupture surfaces. We observed metallic structure anomalies in the failed cup by comparing with another Harris-Galante cup considered as a reference: larger alpha elements, reduction of the titanium equiaxial structure. These defects could be related to uncontrolled temperature during the sintering process utilized for fiber mesh fixation. These structural anomalies, by reducing the metallic fatigue strength, potentiated the deleterious effect of partial bone ingrowth and graft collapse.

Acetabulum↗
PubMed1996

[Cell culture and orthopedic surgery. 1. Principles, methods, fundamental applications].

Many reasons, in 1996, may incite orthopaedic surgeons to take an interest in cell culture. Firstly, cell culture bring informations on bone cell physiology, and the physiological properties of the skeletal cells are involved in the success of the orthopaedic surgeon's act. Secondly, in orthopaedics field's literature, more and more articles using cell culture techniques are published and surgeons need some basic knowledges to understand these results. Then, in the first part of this work, we detail the essential rudiments; vocabulary, cell culture methods, and cell physiology notions. In the second part of this work, we resume the progress realized these last years with cells cultured from the skeleton. Using these informations, surgeons will be able to appreciate the potential uses of cell cultures for diagnosis, biomaterial evaluation and for the development of new therapies.

Bone Neoplasms↗
PubMed1996

[Cell culture and orthopedic surgery. II. Medical applications. Diagnosis, biomaterials evaluation, therapy].

Currently, cell cultures are used for 3 kinds of applications in orthopaedics: diagnosis: they can help to diagnose hereditary diseases like Marfan syndrome, osteogenesis imperfecta, or some osteochondrodysplasia. biomaterial evaluation: cell cultures bring information to ensure safety and efficacy of medical devices following the European Community's directive concerning medical devices. Results of in vitro biomaterial evaluation must be related to cell types (osteoblasts or fibroblasts), cell species (human or rat) and methods used (primary cell line or immortalised cell line). therapy: first clinical applications of cell cultures have been published recently. They concern cultured autologous chondrocytes reimplantation. Bone cells cultured on biomaterials have been tested in animal reimplantation experiments. Animal cells mediated gene therapy experiments are now developed on muscle cells. Cell cultures allow also to determine the best therapeutic way to cure bone tumors. For the moment, these applications are still limited but in the next years, they could develop considerably. Therefore, orthopaedic surgeons must keep interest in this new field.

Animals↗
PubMed1994

Experimental model of posterolateral spinal arthrodesis in sheep. Part 1. Experimental procedures and results with autologous bone graft.

OBJECTIVES: The authors evaluated the reliability in obtaining a posterolateral spinal arthrodesis (PSA) with autologous bone graft. SUMMARY OF BACKGROUND DATA: Posterolateral spinal arthrodesis using autogenous cancellous bone graft is the most simple and efficient technique to get a spinal graft. No extensive biomechanical study of PSA is available. Thus, an experimental model of PSA is needed. METHODS: Eleven sheep underwent lumbar autologous bone grafts and Cotrel-Dubousset instrumentations, and four sheep were used as controls. Sacrifice and biomechanical evaluation of the lumbar spines were performed after 1 year. RESULTS: All grafts appeared continuous. A large decrease of flexibility (in rotation and in translation) was found in grafted spines in every direction. Failure in extension occurred at a mean value of 35.26 +/- 3.71 Nm. CONCLUSION: A constant and homogenous PSA appears to be obtained in sheep under conditions close to the human surgery.

Animals↗
PubMed1994

Experimental model of posterolateral spinal arthrodesis in sheep. Part 2. Application of the model: evaluation of vertebral fusion obtained with coral (Porites) or with a biphasic ceramic (Triosite).

OBJECTIVES: The authors evaluated two bone substitutes in a posterolateral spinal arthrodesis (PSA) model in sheep: coral porites (99% calcium carbonate, Biocoral, Inoteb, France) and a biphasic ceramic (BCP) (65% hydroxyapatite and 35% B tricalcium phosphate, Triosite, Zimmer International). SUMMARY OF BACKGROUND DATA: Bone substitutes would be of great interest for PSA. Previous trials began with two kinds of biomaterials: natural coralline calcium carbonate, and phosphate calcium ceramic. METHODS: A lumbar PSA was performed in 11 sheep (coral group) and in 9 sheep (BCP group). Sacrifice and biomechanical tests were performed after 1 year. RESULTS: A large decrease of flexibility in all directions was obtained with both coral PSA and BCP PSA similarly to autologous graft. No nonfusion case was observed. CONCLUSION: In conditions close to the human surgery, a PSA can be obtained using either coral porites or BCP as bone substitutes.

Animals↗
PubMed1994

Effects of glucocorticoids on skeletal growth in rabbits evaluated by dual-photon absorptiometry, microscopic connectivity and vertebral compressive strength.

The effects of corticosteroid on bone were examined in female growing rabbits treated with 0.7 mg/kg per day prednisolone for 5 months. The evolution of whole-body total bone mineral measured by dual-photon absorptiometry showed a significant difference between the prednisolone-treated group and the control group from the first to the fifth month. The histomorphometric profile of corticosteroid-induced osteoporosis was observed, in particular the lower bone volume and thinner and fewer trabecular plates. Mechanical tests are possible on rabbit vertebrae and showed a very significant difference in bone strength between the prednisolone-treated and control groups, and a good correlation between mechanical tests and histomorphometric or densitometric results. This bone corticosteroid model shows that vertebral compression tests are possible on rabbit lumbar vertebrae. It may contribute to a better evaluation of corticosteroid treatments.

Absorptiometry, Photon↗
PubMed1993

Effects of the calcium channel blocker nifedipine on epiphyseal growth plate and bone turnover: a study in rabbit.

The potential effects of a calcium channel blocker (nifedipine) on epiphyseal growth plate and bone remodeling have been investigated in growing rabbits. The treated group received 6 mg/kg/day nifedipine twice daily by gavage for 10 weeks. An untreated group was used as control; with this dose, neither toxic effects nor decrease in the body weight have been observed. No modifications of blood phosphocalcic parameters have been found. In the treated group there is a significant lower cancellous bone volume, lower osteogenesis, shorter labeled perimeters, and lower mineral apposition rate than in the control group. Epiphyseal growth plate thickness is lower than in the untreated animals and considerable morphological changes are observed in the growth zone compared with the control group. A decrease in the growth of humerus length was found. In conclusion, nifedipine affects bone physiology, especially with consequences on bone growth. These effects appear to be quantitatively important, and there is the possibility of bone side effects on therapeutic use in humans, especially in young subjects.

Animals↗
PubMed1993

Relationship between bone fluoride content and histological evidence of calcification defects in osteoporotic women treated long term with sodium fluoride.

Fluoride treatment is used to increase bone formation and cancellous bone mass in patients suffering from postmenopausal osteoporosis with vertebral fractures. Patients submitted to similar therapeutic protocols have shown various histological responses to the treatment, some developing calcification defects and others not. In fact, the bone histological response to fluoride salts depends on the cumulative uptake of fluoride by bone. To clarify the relationship between the presence of calcification defects (identified by the presence of mottled bone and linear formation defects) and the bone fluoride content, a retrospective study was performed on 29 women with type 1 osteoporosis and treated for several months (11-24) with sodium fluoride (50 mg/day), calcium and vitamin D. Bone fluoride content always significantly increased after treatment, but it was significantly higher in patients showing calcification defects than in those having no defects. These differences between the two groups of patients were not due to differences in clinical details (no significant differences concerning age, duration of treatment, total amount of fluoride ingested, renal function) or in their bone remodelling activity. Thus, it may be hypothesized that the high bone fluoride uptake is due to different individual responses from one patient to another concerning the bioavailability of the same dose of fluoride. This is difficult to predict, except by testing the individual bioavailability of the compound to be used in each patient before starting long-term treatment.

Aged↗
PubMed1993

Fate of bioresorbable poly(lactic acid) microbeads implanted in artificial bone defects for cortical bone augmentation in dog mandible.

The fate was examined of poly(lactic acid) microbeads implanted in large artificial defects created in cortical bone of dog mandibles. Two poly(lactic acid) polymers--poly(L-lactic acid) (PLA 100) and poly(DL-lactic acid) (PLA 50)--were used to make microbeads by solvent evaporation with poly(vinyl alcohol) as surfactant. Histological observation of non-decalcified mandibular bone showed that no real bone regeneration existed in the experimental bone defects 18 months after PLA 100 microbeads implantation. The same observation was made 6 months after implantation of PLA 50 microbeads. PLA 100 and PLA 50 microbeads appeared unable to induce regeneration of cortical bone defects of dog mandible, in contrast to previous observations in man for PLA 50 large implants. The failure is tentatively assigned to the presence of poly(vinyl alcohol) at the surface of microbeads.

Animals↗
PubMed1993

[Neurologic paraosteoarthropathy of the hand. Apropos of 2 cases].

The frequency of heterotopic ossification in neurological conditions averages 20-25% with variations according to the type of neurological disease and presence or absence of coma. The most common sites are the hips, knees, shoulders, and elbows. Involvement of the hands is an exceedingly rare event of which two instances are reported herein. In both patients evidence of inflammation developed four months after a deep, prolonged coma. Swanneck deformity of the fingers occurred in one case. Juxta-articular ossifications were seen on roentgenograms two months after the onset of symptoms. Both patients had heterotopic ossifications around the shoulders. Erythrocyte sedimentation rate and serum alkaline levels were elevated. Local injections effectively relieved pain in one patient.

Adult↗
PubMed1992

[Microradiography in the study of trabecular parameters].

The intermethod variation in measurement of trabecular bone volume (VTO) and the indirect estimation of its microstructure according to Parfitt MTPT (microns), MTPD (/mm) and MTPS (microns) were evaluated in seven undecalcified bone biopsies by analyzing the microradiograph of a 100-microns-thick section with an automatic method (IBAS II Zeiss, Munich) in addition to reference methods (manual and semiautomatic) described in the literature and performed on 7-microns-thick stained sections. Three consecutive 7-microns-stained sections and one 100-mu-thick microradiographed section were taken in each specimen. The 100 microns-thick section was also superficially stained. Trabecular bone volume was measured with both a manual integrating eyepiece and an automatic method. The automatic method on the microradiograph underestimated the VTO by 24.42%. There was a correlation (r = 0.75; p < 0.02) between the manual and computerized methods. Mean trabecular plate thickness (microns), mean trabecular plate density (/mm) and mean trabecular separation (microns) were measured with both semiautomatic and automatic methods. The automatic method on the microradiograph underestimated the MTPT (microns) by 18.98% and the MTPD (/mm) by 14.14% and overestimated the MTPS (microns) by 23.17%. For the MTPT (microns) there was a correlation (r = 0.88; p < 0.02), between both methods, and the correlation was good for MTPD (/mm) (r = 0.97; p < 0.001), and MTPS (r = 0.86; p < 0.002).

Biometry↗
PubMed1992

[Mastocytosis and bone manifestations. Results of the survey of the bone and phosphorus-calcium metabolism section of the French Society of Rheumatology].

Thirty two cases of the association of mastocytosis and bone lesions were collected in a multicentre study. Five cases involved osteocondensation forms. However, most often (27 cases), there was osteoporosis (OP). The diagnosis was made in the absence of obvious risk factors, and thus often in men (2/3 of patients), when there was the association of pigmented urticaria and an excess of mast cells in bone biopsies. Laboratory, radiological and isotope scan findings are often non-specific, being identical to those encountered in common OP. The histomorphometric profile involves an association of decreased cancellous bone volume, increased area of resorption and decreased bone formation parameters. Progression to malignant mastocytosis occurs essentially in diffuse osteocondensation forms and is rare in OP types. Emphasis must be placed on the importance of qualitative study of bone marrow, using specific stains, since the diagnosis may be missed in the absence of typical skin lesions. Conversely, since a simple increase in mast cell count is possible during common OP, a search for mast cell nodules is important in order to establish the diagnosis with certitude.

Adult↗