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Biomedical subjects

E M Lunceford

Publications and source records attributed to E M Lunceford.

9 recordsLinked to original sources

Cefazolin versus cefamandole for prophylaxis during total joint arthroplasty.

A prospective, randomized, double-blind comparison of cefazolin versus cefamandole was carried out to evaluate safety and efficacy and to determine bone and serum antibiotic concentrations in patients undergoing total joint arthroplasty. Dosages were 1 g of cefazolin before surgery followed by 500 mg every eight hours for six doses, versus 2 g of cefamandole before surgery followed by 1 g every eight hours for six doses. Intraoperative doses were given during prolonged procedures. No significant adverse drug reactions were clearly attributable to either drug. Among 48 patients receiving cefazolin there was one postoperative wound infection and one distant site infection. Among 49 patients receiving cefamandole, there were two postoperative wound infections and two distant site infections. No deep wound infections occurred in either group during at least 48 months of follow-up study. In hip specimens removed at surgery, the mean antibiotic concentrations were 1.6 +/- 1.4 micrograms/g for cefazolin recipients, compared with 5.7 +/- 5.9 micrograms/g for cefamandole recipients (p less than .001). In knee specimens, the mean antibiotic concentrations were 0.64 +/- 0.57 microgram/g for cefazolin recipients compared to 3.8 +/- 3.4 micrograms/g for cefamandole recipients (p = .004). Cefazolin given at one-half the dose of cefamandole appeared to be equally safe and effective but resulted in lower bone concentrations of antibiotic.

Aged

Porous polysulfone coatings for fixation of femoral stems by bony ingrowth.

Sixteen porous polysulfone-coated canine femoral stems were inserted into 14 dogs. Coatings were approximately 40% porous, with an average pore size of 125 or 250 microns. Bone was formed within at least about 30% of the surface pores of the implants. The tissue ingrowths filling the pores included marrow and fibrous tissue. Correlated roentgenographic and histologic observations revealed a trabecular "lamina dura" at the coating-bone interface and relatively dense trabeculae distal to the stem tip. These observations support the concept of coating femoral prostheses with porous material for cement-free stabilization.

Animals

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

The effect of high pressure insertion and antibiotic inclusions upon the mechanical properties of polymethylmethacrylate.

The properties of self-curing polymethylmethacrylate as affected by the admixing of an antibiotic to the powder-liquid mixture and as affected by insertion technique demonstrated that the antibiotic agent may leach from the surface of the acrylic, but not necessarily from the interior. The compressive and tensile strength, determined on two different commercial formulations, suggests that the antibiotic additive is not detrimental to the mechanical properties. A high pressure insertion technique produces a significant improvement in the mechanical properties of the self-curing acrylic material.

Acrylic Resins