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Biomedical subjects

W R Krause

Publications and source records attributed to W R Krause.

25 records · Page 2Linked to original sources
PubMed1982

The viscosity of acrylic bone cements.

The viscosity of the acrylic bone cement used in total joint arthroplasty is an important material property for determination of the proper handling characteristics and interlock with bone. In this article the rheological properties of the three leading bone cements were determined over a three-decade range of shear rates. In addition, four other cements were tested at a single shear rate. The results indicate that all the acrylic bone cements are non-Newtonian, pseudoplastic materials with significant differences between them. It is shown that the viscosity increases at different rates with respect to increases in time. For the majority of cements there is a steady or increasing rate of viscosity change with time.

Biomechanical Phenomena↗
PubMed1982

Temperature elevations in orthopaedic cutting operations.

Temperature measurements were made in bovine cortical bone using two cutting burst at 20,000 and 100,000 rpm and two reciprocating saw blades at 20,000 strokes per minute. A combination of feed rates and depths of cuts were investigated for the cutting burs. Cortical temperatures decreased as a result of increases in feed rate, but increased as the depth of cut increased. Temperature increase due to an increase in rotational speed was dependent upon the particular bur. The cutting forces were observed to increase with feed rate and depth of cut, but to decrease with increased rotational speed. The effect of saw design and irrigation had a significant effect on the cortical temperature. Without irrigation, the bone temperature exceeded temperatures reported to produce thermal necrosis. Clinical tests during total joint replacement indicated saw temperatures exceeding 200 degrees C when irrigation was not used.

Animals↗
PubMed1982

Strength of the cement-bone interface.

The fixation of total joint components to bone using acrylic bone cement is by the penetration of the cement into the microstructure of cancellous bone to achieve a mechanical interlock. It has been shown that the method of cement application and the preparation of the cancellous surface significantly affects both the tensile and shear strengths of the cement-bone interface. Doughy cement finger-packed on an uncleaned surface resulted in a very low interface strength compared to a low-viscosity cement made to penetrate a cleaned bone surface. Maximum strengths were achieved for cancellous bone cleaned by using either a high-intensity water lavage or a polyethylene brush and by facilitating penetration of the cement for distances of 5 to 10 mm into the bone.

Biomechanical Phenomena↗
PubMed1976

Mechanical changes in the knee after meniscectomy.

A compression testing machine was used to transmit increasing loads at various strain rates across twelve canine and twelve human cadaver knees. The specimens were originally evaluated with both menisci intact and the same tests were repeated with one meniscus removed and then with both menisci removed. This investigation showed that the menisci perform a load-transmitting and energy-absorbing function in the knee joint. The stress acting across the joint increased significantly after meniscectomy. The intact meniscus was deformed during compressive loading rather than being passively pushed away, thus demonstrating the presence of hoop stresses within the meniscus.

Animals↗