Search PubMed⌕ Search

Biomedical subjects

L Claes

Publications and source records attributed to L Claes.

At least 199 records · Page 11Linked to original sources
PubMed1979

Total "internal" hemipelvectomy.

Several authors have described resections of tumorbearing parts of the pelvis including reconstructive plastic surgery. With extensive tumor growth present mutilating hemipelvectomies often have been the last resort. Even the most sophisticated prostheses hardly ever enabled the patients to walk again. We have therefore performed total "internal" hemipelvectomies in three cases. The necessary substitute consisted of half a pelvis made of polyacetal resin produced from a given model. The model's measures and shape was established by computer tomograms thus resulting in an individually shaped pelvis half. The operative procedure aims at the maintenance of osseous muscular insertions and origins and their reconstruction. Utmost care has to be taken in avoiding damage to nerves and vessels. Fixation of the implant is performed by screws aiming through the sacroiliac joint into ala and corpus of the sacrum and corticocancellous grafts incorporated in the implant. The symphyses are united by means of plate fixation. The hip joint is substituted by a total prosthesis. With the procedure described we have managed three cases of extensive malignant tumors of the pelvis. One patient suffered a nerve lesion and skin necrosis with infection. The two remaining patients are capable of weight-bearing and standing on the inflicted leg alone.

Adolescent↗
PubMed1979

[Plastic replacement of the abdominal wall by uncoated carbon cloth. An animal experiment on the rabbit (author's transl)].

Carbon cloth is a new biomaterial which is suitable for the replacement of ligaments and connective tissues, because of its biological and physical properties. In 30 rabbits a defect was cut into the abdominal wall. In 20 the defect was covered by an implanted carbon cloth. The other 10 animals were used as controls. After implantation wound healing was excellent. No herniation could be observed in the group with the implants. After 3 months histological examinations revealed the ingrowth of collagen fibres into the carbon cloth. It had become a strong and resilient abdominal wall replacement. A physical-strength test showed stability of the newly formed abdominal wall with good anchorage to normal tissue.

Abdominal Muscles↗
PubMed1979

[Studies on the modification of wound healing by a lack of essential fatty acids].

A fat-free diet produces a deficiency of essential fatty acids in Wistar rats. This is associated with disturbances of wound healing in the colon and skin due to an impaired collagen metabolism, since hydroxyproline content in the wound area is decreased. The results are of clinical significance with regard to total parenteral nutrition in surgical patients.

Animals↗
PubMed1979

[Experimental studies on the biomechanics of the lateral ligaments of the knee joint].

Measurements of absolute strain and stress on collateral ligaments of human knees were made with two new measuring cells. The medial collateral ligament was found to have three functional different parts, the most important of which was the ventral. During motion of the knee, tensile forces amounted to about 20 N when the lateral ligament was in extension and the medial ligament in full flexion. Moments of abduction and adduction increased strain and stress manyfold.

Biomechanical Phenomena↗
PubMed1979

[Studies on the intra-osseous fastening of alloplastic ligament substitutes in sheep using carbon fibers].

The alloplastic replacement of the medial collateral ligament of the knee of sheep by carbon fibers gave a strength comparable with the natural ligament. Coating of the fibers, e.g., with epoxy resin, leads to a reduced integration of the implant into the tissues. Physical and histologic results together with the intraosseus anchorage show that pure carbon fibers are a suitable material for alloplastic ligament replacement.

Animals↗
PubMed1978

[Biomechanical efficiency and biocompatibility of lubricating sprays PTFE or graphite (author's transl)].

The screws and plates used in operative treatment of fractures cause moments of friction between the bone screw head and the bone plate hole during the tightening of the screws. This results in hidden damage to the grinding metal surfaces, with the danger of erosion corrosion and in a reduction in the screw force. By covering the screw heads with the lubricating sprays PTFE or graphite friction was significantly reduced, the screw force increased by 40% and extensive damage to the surfaces avoided. Lubricating sprays or their extracts, in fetal calf serum or in dimethylsulfoxide, were added to fibroblast cultures. Toxicity was manifest as changes in the synthesis of DNA, as measured by autoradiography. Sprays or spray extracts in fetal calf serum did not inhibit cell proliferation. In vivo experiments in rats reflected the in vitro results, there being no evidence that toxic substances were released from the sprays by physiological solvents: There was a lack of histopathological changes in the inner organs and a local encapsulation of implants which was essentially like that in a teflon control group.

Aerosols↗
PubMed1978

[Stability after obtaining cancellous bone from the greater trochanter].

To test the endangered stability after obtaining cancellous bone from the greater trochanter, the ultimate breaking force of 40 human femura was measured with a material testing machine (Instron 1115). 1. 10 Femura after removing bone from the greater trochanter as a routine clinical procedure showed a significantly reduced trochanteric stability (p less than 0.05), 4 subtrochanteric and 3 pertrochanteric fractures, compared to 10 intact opposite femura with vertical shear fractures of femural neck and head without damage to the trochanteric region. 2. The number of fractures crossing the window was reduced by half, p less than 0.05 when a round cortical window compared to when a square window of the same area was cut. As the reduced stability caused by the remove of cancellous bone can not be avoided, we can clearly reduce the danger of stress concentration in the notches by cutting a round corticalis window. Cancellous bone from the greater trochanter should only used, if it cannot be taken from the brim or posterior iliac spine of the pelvis.

Biomechanical Phenomena↗
PubMed1978

[Bending and torsion stability of healed metatarsus osteotomy after plate osteosynthesis].

UNLABELLED: 72 transversal osteotomies on metatarsus of sheep were stabilized under contact or gap conditions with three different thicknesses of bone plates. After 16 weeks we measured bending or torsion break loading, moment of inertia of bone by transmission methode and calculated moments of bending and torsion strength. RESULTS: ultimate bending strength on osteotomied bone 100.4 +/- 14.4 N/mm2 under contact, and 77.4 +/- 11.4 N/mm2 under gap condition, torsion bending strength 26.1 +/- 4.9 N/mm2 under contact, and under gap condition 21.5 +/- 4.3 N/mm2. The best results were given by the 2.8 mm plate with the same moment of inertia like the small ASIF plate.

Animals↗
PubMed1977

[Biomechanical studies on the stabilization effect of cortico-spongiosa chips in imperfect osteosynthesis].

Stability and plate strain of internally fixed femoral shaft fractures at different sites were tested under bending and compression loads. Stability of osteosynthesis with compression plate was not acutely affected by stresses encountered when standing on one leg. When fractures with a bone defect were treated by plate fixation stability was improved significantly when lateral support was preserved or when a medial cortico-spongious bone chip was used.

Adult↗
PubMed1977

[The influence of the countersink geometry on the cortical screw force (author's transl)].

In vitro examinations on deformation and relaxation were carried out on cortical countersink of different geometry under a compression load of up to 2000 N through a screw head. Conical countersink showed plastic deformations of an average of 1300 N whereas with spherical countersink they did not occur at the same load. After reaching the load of 2000 N and keeping the deformation constant we saw a significantly stronger reduction of force with the conical countersink then with the spherical type. As far as fracture fixation is concerned a smaller postoperative reduction of screw force can be expected if applying a cortical screw with a spherical head in a spherical countersink.

Aged↗
PubMed1976

[The dependence of the removal torque of a leg screw a screw surface and implantation time (author's transl)].

The experiment was performed on 17 sheep tibiae in vivo. 4.5 mm ASIF leg screws with a constant insertion torque (68.6 Ncm) but different surfaces (smooth or rough) were removed after 3 s, 7, 28, 56 and 112 days after insertion. The screws with a rough surface which were implanted for 28 days and longer exhibited a significantly greater removal torque. For instance rough screws which were implanted for 112 days displayed a removal torque eight times greater than after 3 s.

Animals↗
PubMed1976

[Structure and solidity of new bone in a cortical gliding hole by implanted leg screw (author's transl)].

Leg screws were implanted in 30 tibia diaphysis. 112 days later in the gliding hole there was new lamellar bone round of the screw head, neck of screw and into the both first screw threads. After screw explantation we measured in 8 cases the solidity of the new bone. Under conditions of tension measurement, we use 341 N per millimeter cortical thread surfaces to put out all new bone from the gliding hole. The results of these tension measurements were cylindric fragments. The remodelling into the gliding hole seems to be the results of static stress and dynamic compensation for reaching a defect in living cortical bone.

Animals↗