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Biomedical subjects

M Donkerwolcke

Publications and source records attributed to M Donkerwolcke.

At least 19 recordsLinked to original sources
PubMed2002

[The orthopedics-traumatology department].

The Department is involved in clinical and research activities. We pioneered the clinical application of "smart of Orthopaedic implants". The monitoring concept, bringing a high added value, helps in assessing fracture healing or implant fixation. The technique, featuring the 21st century, also requires advanced knowledge in biomaterials. Such implants have been used during the ESA Parabolic Flight Campaigns. These measurements are a prerequisite to establish prevention programs of the bone demineralisation during space flights but also in disuse osteoporosis. The Department is deeply involved in external fixation. In vitro studies of the mechanical insertion and holding parameters of external fixation pins have been performed to produce new implants, which efficiency has been proved by a clinical study. We defined original clinical principles of external fixation as its use in upper limb indications, to maintain microsurgery transplant, preserving devascularization and providing adequate fixation. Our biomechanical approach of the upper limb, now confirmed by others research groups, questioned old clinical concepts. The isokinetic evaluation assesses the dynamic function of articulations, i.e. after arthroplasty, and is also used for medico-legal evaluation. The clinical research touches orthopaedic (or systemic) diseases as algodystrophy, Kienböck disease, Kashing Beck. We conducted a multidisciplinary research on the effect of electromagnetic fields (EMF) on cells differentiation. In addition to possible healing properties, it helps as an objective support to analyse the exposure to the environmental EMF.

Belgium↗
PubMed2000

Concept, design and fabrication of smart orthopedic implants.

Extensive clinical experience has been built up using orthopaedic implants instrumented with strain gauges connected to a Wheatstone bridge by means of percutaneous leads. This research showed the medical relevance of the monitoring of the deformation of implants as a powerful tool to evaluate nursing and rehabilitation exercises, for tracing dangerous overloads and anticipating implant failure and also to observe the healing process. The IMPACT 3500 project focuses on the instrumentation of femoral implants with on board sensors: regular Benoist-Girard implants have been modified, to contain a 'sensing cell', and thoroughly tested in vitro and in vivo. The implant deformations are measured with resistive strain gauges, and the signal is transferred to a personal computer for processing and display, via a hard wired connection, or via a telemetry system. Two fully implantable wireless designs, called Linkstrain and Sealstrain, are powered from the outside by magnetic induction. As Sealstrain contains the whole telemetric system in its cavity, the highest miniaturization was required; this seriously deteriorates the efficiency of the inductive power link.

Biocompatible Materials↗
PubMed1998

Tissues and bone adhesives--historical aspects.

Glues and adhesives attach to a surface principally involving molecular attraction, whereas cements mostly work through mechanical interlocking. The adhesive and its degradation products must be biocompatible: chemical, clinical, legal, physical aspects are considered; the toxicity of even minor components must be extremely reduced. The idea of bone bonding using biological materials has been proposed by Gluck, in Berlin, more than a century ago. Cements and adhesives have been used for the fixation of fractures, the repair of defects and the fixation of prostheses. The cements are initially liquid or plastic and conform with the irregularities in the substratum, producing better bonding on rough surfaces. Developed during the early 1950s, cyanocrylate adhesives attracted the medical community by their bonding strength and ability to bond in wet environments but reports of displacement of the fracture ends were followed by reports of high infection rates, nonunion, and severe local reactions. Polymethylmethacrylate does not form a chemical bond with bone but a mechanical bond, a weak bone-polymer joint. Charnley used self-curing acrylic cement to bond a femoral head prosthesis into a femur. When adhesives are used to bond tissues, the polymer acts as a barrier between the growing edges and delay healing; the adhesive tends to be rapidly isolated from the bone by a fibrotic, non-adhesive capsule. No proof exists concerning the osteogenic potential of fibrin sealing (FS); its beneficial effect on bone formation has been questioned even if there is some evidence that FS should influence the early phases of bone repair and may help to solve the problem of reattachment of small osteocartilagenous fragments following joint trauma.

Animals↗
PubMed1994

Osteosynthesis of the proximal femur anchorage of a cervical nail.

One of the factors determining the stability of osteosynthesis is the mechanical strength of the bone fragments required for the anchorage of the implant. The aim is to study the driving of a Thornton nail in the proximal epiphysis of a human femur as a way to measure the strength of the trabecular bone and to predict the stability of the implanted system.

Aged↗
PubMed1994

[Surgical treatment of chronic hematogenous osteomyelitis. A series of 42 cases].

INTRODUCTION: Chronic hematogenous osteomyelitis (C.H.O.) is still a scourge of the non-industrialized countries. The authors operated on 420 cases of C.H.O. in Algeria between 1968 and 1987. A computerized analysis of the results of the surgical treatment of these 420 cases was made in Brussels, Belgium, by two of the authors. The results of this computerized study are exposed. MATERIAL AND METHODS: 67.1 per cent of the patients were male and 37.9 female. 68 per cent were operated before 16 y. of age. 381 lesions involved tubular bones: femur, tibia and humerus were the most frequent locations. Only 4 per cent of the cases had never presented a suppuration. Cultures of Staphylococcus were positive in 82 per cent of the cases. Surgical procedure was classical--bone window opening, sequestrectomy and saucerisation--in 359 cases. Operation was limited to soft tissues in 22 cases and bone resection was performed in 39 cases. Post-operative antibiotherapy was administered for a period of 10 to 60 days according to the patients. RESULTS: After the first operation with the classical procedure, results were satisfactory in 72 per cent of the cases but "healing" was achieved in 95 per cent of the cases after 2, 3, 4 and up to 6 operations. After bone resection, the rate of permanent healing was of 100 per cent. Follow-up was of more of 1 year (up to 22 y.) in 80 per cent of the cases. DISCUSSION: As far as classical procedure is concerned, a computerized analysis made according to 34 variables, led to the conclusions that the following variables could have a positive influence upon the prognosis: surgical team's experience, young age of the patient at the time of operation, subacute onset of the disease, location on the humerus, diaphysis of long bones, membranous and short bones, small number of sinuses, sclero-geodic radiologic appearance of the lesions, thin perifocal radiologic condensation, periosteal reaction, post-operative administration of two antibiotics. Excellent results of bone resection are pointed out but attention is drawn on the dangers of extending the indications for resection to the tubular bones. CONCLUSION: The authors conclude that improvement in the results of the surgical treatment of C.H.O. may only take place after improvement of the quality and duration of chemotherapy: that is confirmed by the results of a clinical trial they organized on the role of post-operative administration of Amoxicilline + Clavulanic Acid for a period of 60 days after surgery: 44 patients, 2 lost to follow-up, 4 failures and 38 "healings" (90.5 per cent) at 2 years and more.

Adolescent↗
PubMed1991

External minifixation for treatment of closed fractures of the metacarpal bones.

External minifixators were used in the treatment of 63 closed diaphyseal metacarpal bone fractures. A simple half-frame configuration was applied in all the cases. Open reduction was performed in 26%. The mean duration of external fixation was 30 days. There were no cases of nonunion. Anatomical reduction was obtained in 86.6% of the cases. There were no cases of reflex sympathetic dystrophy. The general functional results were very good or good in 96.6%. Open reduction did not significantly alter the final results. External minifixation is usually accepted as a treatment of open metacarpal fractures. Because of the excellent results obtained in our series, we believe that the indications of external minifixation could be enlarged to closed metacarpal bone fractures.

Adolescent↗
PubMed1989

[Osteosynthesis of the clavicle using an external fixator].

Twenty-four fractures or nonunions of the clavicle were treated by a Hoffmann external fixator, for selected indications. No vascular or pleural complications were observed. All clavicles healed, after a mean duration of 52 days.

Adolescent↗
PubMed1988

External fixation of the clavicle for fracture or non-union in adults.

A technique of osteosynthesis of the clavicle with Hoffmann external fixation was used to treat twenty patients for selected indications, including an open fracture, inability of a patient to tolerate prolonged conservative treatment, or a painful non-union. No vascular or pleural complication was observed. The average time that the external fixator was retained was fifty-one days. All of the clavicles united well. Mobility of the shoulder returned to normal in all patients.

Clavicle↗
PubMed1987

External fixation pin: an in vitro general investigation.

Surgical drilling and pin insertion can lead to mechanical and thermic damage of the bone. A methodology giving reproducible in vitro records of insertion and holding parameters of threaded implants is presented. Both drilling and tapping are related to the cutting technology. To understand the basic principles of the cutting technology some important parameters of drilling and tapping of an external fixation pin are defined. A bone model was selected based on specific mechanical and thermal properties of the bone tissue. In addition, a specific instrumentation was designed in order to compare the insertion characteristics and the anchorage of different pins. Electronic scanning microscopy of the samples was systematically performed to evaluate the quality of the bone thread. The in vitro measurements of the shearing torque and the pull-out force are representative of the immediate holding power of a pin. The different holding parameters were then correlated. Temperature measurements were performed during drilling, smooth part penetration (transfixing pins), tapping, and screwing. The final objective of the study was to develop new threaded implants with better biomechanical characteristics.

Biomechanical Phenomena↗
PubMed1985

[Complications following talus trauma].

The injuries of the talus are rare. In this retrospective study, complications of 359 talar lesions are studied. Secondary displacement occurred in 8%. Bone infection remained low in spite of frequent primary skin injury (20%). Bone fusion was slow but no case of non-union could be found. Avascular necrosis of the body or of the trochlea occurred in 33% but could be partially prevented by accurate reduction of the fractured bone. Osteoarthritis occurred in 33%.

Adult↗
PubMed1981

In vivo bone strain measurements: clinical results, animal experiments, and a proposal for a study of bone demineralization in weightlessness.

An extensive review of the literature of the aetiology of bone demineralization in weightlessness underline the prevalent effect of mechanical stimulations on bone structure and metabolism. The accurate determination of the mechanical environment of bone can be realized using strain gauges. The results of more than 10 years of clinical application of bone strain measurements demonstrate the interest of this technic. We designed an implantable bone strain transducer composed of a strain gauge embedded in epoxy resin and surrounded by a porous shell. The fixation of the transducer is by bone ingrowth. Results on animals and an acute experimentation on man are presented. The objective of our study in space is to compare the mechanical response of bones of an animal or of a human submitted to normal 1-G gravity and to weightlessness. The average amount of bone strains and their variations during specific movements can be compared.

Aerospace Medicine↗
PubMed1979

Cardiovascular effects of methyl methacrylate monomer.

Although cardiorespiratory human sensitivity to circulating methyl methacrylate monomer remains unknown, it is clear that the blood levels responsible for cardiocirculatory alterations in intact dogs are not obtained after insertion of acrylic cement in long bones in clinical practice. Circulating monomer considered as the sole causal factor for the hemodynamic changes described during orthopedic method is highly questionable.

Animals↗