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Biomedical subjects

M Postel

Publications and source records attributed to M Postel.

At least 19 recordsLinked to original sources
PubMed1992

[One stage revision of infected total hip replacements with replacement of bone loss by allografts. Study of 90 cases of which 46 used bone allografts].

We usually manage infected total hip replacements by a one stage revision. We have reviewed 90 cases operated on before 1988. Notable bone loss was frequently encountered and reconstructed using allografts. In all cases complete surgical debridement was performed and a cemented total hip replacement implanted. Bone allografts were used in 46 cases. Systemic antibiotics and antibiotic loaded cement were utilised. There were 17 failures (19%); one patient died soon after operation, there were 8 obvious infections (9%), 1 hip was thought to be infected although the prosthesis was not loose, and 7 femoral prostheses became loose of which 3 were due to mechanical failure and the remainder had no obvious explanation. Infection with staphylococcus aureus and pseudomonas had a statistical correlation with failure, but other factors including the preoperative status and the use of allografts did not appear to influence the result. Allograft femoral heads from the bone bank were found to be reliable for reconstruction of the acetabulum and small femoral defects. With major femoral bone loss we preferred massive irradiated cortical allografts. The quality of the bone reconstruction was probably the most important factor in the good functional results observed in 79% of cases. Effective surgical debridement and an appropriate antibiotic regime will allow a successful one stage revision procedure. The use of allografts gave a reliable reconstruction of the bone loss and was not associated with an increased rate of failure.

Acetabulum↗
PubMed1992

Stability and stabilization of fluorocarbon emulsions destined for injection.

The factors that have an impact on the stability, and the mechanisms of degradation of fluorocarbon emulsions suited for intravascular use, are briefly reviewed. Various ways of prolonging shelf stability are discussed. The effectiveness of perfluoroalkylated surfactants and/or co-surfactants as stabilizers is demonstrated. New means of stabilizing fluorocarbon-in-water emulsions using molecular dowels are presented.

Blood Substitutes↗
PubMed1992

Drop size stability assessment of fluorocarbon emulsions.

The aging of fluorocarbon emulsions prepared with natural egg yolk phospholipids (EYP) has been studied and a linear variation (r2 greater than 0.95) of the mean average volume of the droplets with time has been observed. The slope of the experimental lines, called "Stability Parameter, S" can thus be taken as a representation of the rate of aging of the emulsions. Examples are given of use of parameter S to assess the effect of formulation and processing parameters on the stability of diverse fluorocarbon emulsions. S is a useful tool to compare emulsions and ascertain any factors of stabilization/destabilization.

Blood Substitutes↗
PubMed1991

Fluorocarbon/lecithin emulsions: identification of EYP-coated fluorocarbon droplets and fluorocarbon-empty vesicles by freeze-fracture electron microscopy.

Freeze-fracture has been used to examine perfluorodecalin/egg yolk phospholipid emulsions (70:8, w/v%) destined to be used as injectable oxygen carriers. The fluorocarbon displays a specific granular aspect upon freeze-fracture which makes it readily recognizable and allows the distinction between two populations of objects on the micrographs: fluorocarbon droplets and water-filled lipid vesicles.

Egg Yolk↗
PubMed1991

Prevention of deep vein thrombosis after hip replacement: randomised comparison between unfractionated heparin and low molecular weight heparin.

OBJECTIVE: To evaluate the efficacy and safety of two subcutaneous prophylactic regimens for postoperative deep vein thrombosis after total hip replacement. DESIGN: Prospective open randomised multicentre trial. SETTING: 28 European departments of orthopaedic surgery. INTERVENTION: All patients had bilateral phlebography 10 days after surgery. 31 patients receiving low molecular weight heparin and 29 receiving unfractionated heparin were excluded from the efficacy analysis for various reasons. PATIENTS: 349 patients undergoing total hip replacement between September 1988 and May 1989. 174 patients received subcutaneously a low molecular weight heparin (Fraxiparine) with anti-factor Xa activity of 41 IU/kg/day for three days, then 62 IU/kg/day from day 4 to day 10. 175 patients received subcutaneous unfractionated heparin at intervals of eight hours; doses were adjusted to maintain the activated thromboplastin time at two to five seconds above control values. MAIN OUTCOME MEASURE: Total incidence of deep vein thrombosis and incidence of proximal deep vein thrombosis on bilateral phlebography. RESULTS: The total incidence of deep vein thrombosis was 16% in patients receiving unfractionated heparin and 12.6% in patients receiving low molecular weight heparin (p = 0.45), and the incidence of thrombosis of the proximal veins was 13.1% and 2.9% respectively (p less than 0.001). Four patients receiving unfractionated heparin and one receiving low molecular weight heparin developed pulmonary embolism. The incidence of bleeding complications was low and comparable in the two groups. CONCLUSION: Low molecular weight heparin is at least as effective as unfractionated heparin in preventing deep vein thrombosis and is more effective at preventing thrombosis of the proximal veins in patients undergoing hip replacement. Low molecular weight heparin is not more likely to cause bleeding complications and is simpler to give than unfractionated heparin.

Blood Coagulation↗
PubMed1991

Histological patterns of bone and articular tissues after orthopaedic reconstructive surgery (artificial joint implants).

Revision surgery after failures of joint replacements leads to histological studies on joint and bone tissues close to the implanted material. Aspectic loosening is the main complication. The surgical pathologist has to identify wear debris (metal, polyethylene, polymethylmethacrylate, chiefly) which promotes a histiocytic granuloma. Some surgical procedures such as cup or resurfacing arthroplasties create a new articular surface and a bone remodeling or necrosis. Cemented joint prostheses show various membrane structures between bone and the cement mantle while there is an association of bone resorption and formation. Non-cemented, porous-coated joint prostheses induce little bone ingrowth, even in satisfactory clinical results. Mechanical factors are predominant in massive limb prostheses. For silicone elastomer implants or artificial ligaments, wear of material promotes many tissular reactions. Often used bone grafts show little creeping substitution process in case of homografts, even well-incorporated on X-rays. More retrieval specimen studies are necessary to delineate precise topographical histological lesions, including non-loosened joint implants.

Bone and Bones↗
PubMed1991

[A new trochanteric osteotomy method for a postero-lateral approach of the hip (330 operations with posterior transosseus and paramuscular curved approach].

The authors studied a series of 330 Total hip replacements with 6 months to 4 years follow-up, in order to define a new trans-trochanteric approach. The procedure, with a two slope trochanterotomy, is a curved posterolateral approach. The shell bone, with attachment of Mm gluteus, M. vastus lateralis and M. piriformis is pushed forward. The other pelvic-trochanteric muscles stay with the femoral shaft. Two revisions (0.6 per cent) had to be performed because a faulty accomplishment of the trochanteric osteotomy. The trochanteric fusion was always achieved. One third of the hips was stable at one month post-op and 95 per cent at 6 months. This approach is a variable of the conventional transtrochanteric approach and it seems to decrease markedly its disadvantages.

Femur Neck↗
PubMed1990

[Efficacy and tolerance of low molecular weight heparin in the prevention of deep venous thrombosis during non-emergent total hip arthroplasty. A prospective, multicenter trial].

A multicenter prospective trial was conducted on 149 patients to test the efficacy and tolerance of low molecular weight heparin (LMWH) in the preventive treatment of deep venous thrombosis consecutive to total hip arthroplastic surgery. An original dose-adjusted protocol was tested, whereby the patients were injected a single dose of LMWH daily, determined on a weight and operation date basis; the prophylactic efficacy of this protocol was assessed by bilateral phlebography performed systematically on the 10th postoperative day. Only 12.9% of patients developed deep venous thrombosis of the lower extremities, and the thrombus formation site was proximal in 3.6% of cases. These rates are low compared with published data and considering the diagnostic criterion used. The low incidence of premature treatment withdrawal and hemorrhagic complication (2%) cases is indicative of the good tolerance of this preventive treatment.

Adult↗
PubMed1990

Bone allografts sterilised by irradiation. Biological properties, procurement and results of 150 massive allografts.

Massive bone allografts from cadavers have been sterilised by gamma-radiation from radioactive cobalt at a dose of 25,000 gray (Gy). The biological effects of radiation are discussed. Human cortical bone showed an acceptable 20% decrease in strength on bending tests after 27,000 Gy irradiation, but higher doses are more damaging and should be avoided. The procurement protocol used at the Cochin Hospital is described, and the importance of dosimetry and record-keeping emphasised. The clinical results of 150 massive bone allografts are reported. The infection rate was low. The evolution of the graft in each type of reconstruction is analysed and appears to be comparable to nonirradiated allografts. Very few complications occurred after composite reconstructions in the lower limb. Pelvic reconstructions had the highest complication rate, but most were not related to the use of the allograft.

Bone Transplantation↗
PubMed1990

[The use of coral in bone surgery. Results following 4 years of utilization].

The authors have used Porites coral as a bone substitute in more than 200 patients since 1985, initially for reconstruction after craniotomy or removal of graft from the iliac crest. Encouraging results have prompted wider use. No complications have occurred. The biological properties of coral are described. It is easily available and appears to be a promising bone substitute.

Calcium Carbonate↗
PubMed1989

[Replacement of prostheses of the hip].

In view of the widespread insertion of total hip prostheses, in recent years loosening of such prostheses requiring operative revision has become increasingly frequent. Simultaneous bone resorption defects in the acetabulum and the femur pose a particular problem. Attrition of the polyethylene obviously plays an important part in this process, its effects becoming apparent after 15-20 years. When a total prosthesis is replaced every effort should be made to reproduce the normal anatomical situation as nearly as possible. In particular, the bone defects should not be filled up with massive implants or with bone cement, but should be reconstructed with bone transplants. Mechanical protection in the form of internal fixation is necessary for the larger bone transplants; if this is not provided they may not take properly. When there are defects in the acetabulum corticospongious bone chips taken from femoral heads are used in the vast majority of cases. For larger defects in the femur, large allogeneic transplants of cortical bone taken from cadavers and applied to the defects in the form of a cuff following sterilization with gamma irradiation have given very positive results in recent years.

Bone Transplantation↗
PubMed1979

Clear-cell chondrosarcoma: a report of five cases including ultrastructural study.

Five cases of clear-cell variant of chondrosarcoma (Unni et al.) are reported. The tumors occurred in the epiphyseal region of long bones; three in the femoral head. Roentgenographically, the lesion was usually a well-defined and benign appearing one, either purely lytic (3 cases) or with central radiodensity (2 cases). Histologically, all five cases had areas of conventional chondrosarcoma; however, the greater portion of the tumor was made up of sheets of clear-cells intermixed with nonneoplastic bone trabeculae but devoid of chondroid matrix. Electron microscopic studies showed that these clear-cells possess cytoplasmic microvilli, abundant glycogen particles and prominent golgi complexes, like normal or tumorous chondroid cells usually have. In our experience, the best treatment seemed to be en bloc resection with joint replacement; indeed, despite the fact that they are true chondrosarcomas, these tumors usually have a very slow rate of growth.

Adolescent↗
PubMed1978

[Surgical treatment of osteoarthritis of the hip (author's transl)].

Surgery can improve function for one or more decades for patients with osteoarthritis of the hip, even though the operations may not be very invasive. The indications must be made by surgeons in collaboration with rheumatologists. There is no patent recipe, no 'common' intervention which gives a reliable result in all cases. The patient must be studied in all stages of development of his disease: his joint structure in the radiogram, the morphology of the bones, the functional requirements and his general state of health influence the decision regarding the possibility and modality of a surgical intervention. The patient's return to an active life which would not have been possible for him under medicinal treatment supports the importance of surgical treatment.

Adult↗