PubMed Health⌕ Search

Biomedical subjects

C A Collinge

Publications and source records attributed to C A Collinge.

5 recordsLinked to original sources
PubMed2000

Mechanical properties of small fragment screws.

For many years, stainless steel small fragment screws have been produced by one manufacturer. Recently, other implant makers have begun offering similar stainless steel screws. In addition, screw geometry and material composition have been modified in an attempt to produce screws for a wide range of clinical situations. This study compared the mechanical properties of several commonly used small fragment screws. Seven sets of screws were tested mechanically, including three brands of geometrically identical standard stainless steel cortical screws and one brand each of cannulated stainless steel cortical screws, titanium cortical screws, stainless steel cancellous screws, and bioabsorbable polylactic acid screws. Screws from each group were tested for pullout strength, torque to failure, and three-point bending to failure. There were no differences in the mechanical properties of the identical 3.5-mm standard stainless steel cortical screws. No difference in pullout strength was found between the five sets of cortical screws. However, the cancellous screws had 4% to 24% less pullout strength. Torsion tests showed that cannulated stainless steel cortical, titanium cortical screws, stainless steel cancellous screws, and polylactic acid screws failed at significantly less torque than did standard stainless steel cortical screws. Standard stainless steel cortical screws had the highest mean yield point and maximal load at failure of all screws in three-point bending. Other metal screws had lower yield strength and maximal load at failure than did the standard stainless steel cortical screws, and polylactic acid screws had the least bending strength.

Biomechanical Phenomena↗
PubMed1994

Pin tract infections: silver vs uncoated pins.

To test the hypothesis that coating external fixation pins with a silver-containing compound (Spi-Argent, Spire Corp, Bedford, Mass) will reduce bacterial colonization and/or pin tract infection, 36 silver-coated and 12 conventional stainless steel pins were placed in the iliac crest of six sheep and inoculated with Staphylococcus aureus. After 2 1/2 weeks the pin sites were examined for motion and inflammation, and the pin tips were quantitatively cultured and examined with scanning electron microscopy (SEM). We found that 84% of the uncoated pins were infected, while 62% of the silver-coated pins were infected. Silver-coated pins were less frequently infected than uncoated pins (confidence interval [CI] > 85%). Also, silver-coated pins were loose less frequently than uncoated pins. Pin motion was closely correlated with infection: 28 of 32 infected pins (88%) had motion, while only 9 of 16 uninfected pins (56%) had motion (CI > 80%). SEM study of the pin tips showed a decreased level of glycocalyx-protected colonization on the surface of the silver-coated pins. Clinically, these results suggest that silver-coated pins will result in less infection and motion at the pin site, the most significant problems in external fixation.

Animals↗
PubMedDate not supplied

Percutaneous plating in the lower extremity.

Since the late 1950s, open reduction and internal fixation has been advocated to restore bone anatomy and enable early mobilization. This approach often necessitated extensive dissection and tissue devitalization, creating an environment less favorable for fracture union and more prone to bone infection. As a result, other methods, such as intramedullary nailing, have become the standard treatment for most diaphyseal fractures of the femur and tibia. However, internal fixation with plates and screws remains the treatment of choice for most periarticular fractures and other complex fractures inadequately stabilized by intramedullary nailing. Recently, more "biologic" methods of reduction involving the use of indirect techniques and new plate designs have been developed in an attempt to preserve the blood supply to the injured bone, improve the rate of fracture healing, decrease the need for bone grafting, and lower the incidence of infection and other complications. Percutaneous plating appears to be the next step in the evolution of biologic plating. With these techniques, the fracture is reduced indirectly, and plates are placed into submuscular or subcutaneous tunnels through limited skin incisions. This may result in less surgical trauma to tissues and further improvements in clinical results compared with current methods of plate insertion.

Bone Plates↗