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Biomedical subjects

E L Thrasher

Publications and source records attributed to E L Thrasher.

7 recordsLinked to original sources
PubMed1990

A reduced-modulus acrylic bone cement: preliminary results.

Excessive local contact stress is implicated as an important factor in the initiation of the loosening process after total joint arthroplasties. A reduced-modulus acrylic bone cement, which decreases the bone-cement interface stresses, was developed to test this hypothesis. The formulation consists of butylmethacrylate beads, having a glass transition temperature of 27 degrees C, in a methylmethacrylate matrix. This cement, polybutylmethylmethacrylate (PBMMA), has an elastic modulus one-eighth that of standard PMMA bone cement, 0.27 vs. 2.1 GPa, at body temperature. In vivo use in a pilot study using the sheep total hip arthroplasty model shows a reduction in the rate of loosening of femoral components when compared both radiographically and mechanically with PMMA controls.

Acrylic Resins↗
PubMed1982

Changes in the bone-cement interface after total hip replacement. An in vivo animal study.

UNLABELLED: In order to study the temporal sequence of radiographic, histological, mechanical, bacteriological, and chemical changes around the femoral component following total hip replacement, a model was created by implanting plastic-on-metal total hip replacements in sheep and walking the animals on a concrete surface beginning six weeks postoperatively. This model demonstrated a decreased torsional rigidity between the prosthesis and the femoral cortex in all sheep. Failure of bonding occurred at the bone-cement interface and appears from our results to be most probably due to alterations in the functional stress of the proximal end of the femur following insertion of the femoral component rather than exothermic polymerization, toxicity of free monomer residue, or infection. CLINICAL RELEVANCE: An understanding of the causes of loosening of cemented metal femoral components in total hip replacement has been thwarted by a lack of specimens at sequential times in the loosening process. Since a patient is not operated on until the prosthetic components are completely loose, such specimens are difficult to obtain clinically. For this reason a model for examining the bone-cement interface, measured by decreased torsional rigidity of the prosthesis relative to the bone, was developed in sheep. Of all the parameters studied, those inherent in the effects (mechanical or vascular, or both) of insertion of the prosthesis itself appeared to be the most likely cause of the change in the mechanical properties of the interface. This suggests that degenerative changes of the bone-cement interface may be inevitable.

Animals↗
PubMed1976

Topical hemostatic agents to reduce bleeding from cancellous bone. A comparison of microcrystalline collagen, thrombin, and thrombin-soaked gelatin foam.

In fifty-three dogs microcrystalline collagen, thrombin-soaked gelatin foam, and thrombin powder were evaluated as hemostatic agents when applied to bleeding cancellous surfaces after osteotomy of the greater trochanter using two quantitative models: one, a single osteotomy; the other, a double osteotomy. All three agents significantly reduced bleeding compared with the controls, the microcrystalline collagen being most effective. At three months there was no evidence that microcrystalline collagen and thrombin-gelatin interfered with bone healing after the greater trochanter was reattached with two wires.

Administration, Topical↗