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Biomedical subjects

W H Harris

Publications and source records attributed to W H Harris.

At least 307 records · Page 17Linked to original sources
PubMed1982

Revision surgery for failed, nonseptic total hip arthroplasty: the femoral side.

The rapidly increasing incidence of femoral failure after total hip arthroplasty has forced the generation of numerous major techniques to treat this complication effectively. Extraction of a femoral component that is not grossly loose is vastly facilitated by a new femoral component extractor. Cement removal has been made much simpler and safer with the use of a medullary canal guide, a fiberoptic headlight, and wide exposure of the proximal femur by release of the iliopsoas, the vastus lateralis, and the intermedius, and more effective using Depuy drills, rigid Kunshcher rods, and an ordinary power source. A new technique developed for removing broken femoral stems uses the Midas Rex to drill a hole in the metal, undercutting the metal and extracting the broken tip through the femoral neck. This technique eliminates the need for a window and the requirement for long-stem prosthesis. Special components are required for specific problems in bone loss, including devices that replace a deficient calcar femorale, as well as more common long-stem and proximal femoral replacement implants. In circumstances of massive bone loss in the proximal part of the femur, techniques for allografting entire femoral segments have been effective. These innovations play a major role in reducing the technical complications with revising a failed femoral component after total hip arthroplasty and obtaining excellent functional restoration.

Bone Cements↗
PubMed1982

Loosening of the femoral component of total hip replacement after plugging the femoral canal.

A roentgen follow-up study was done of 171 total hip replacements at an average of 3.3 years (range 2 to 5 years) after insertion to assess the loosening rate in older adult patients (average age 60 years) in whom the medullary canal was plugged. The cement (Simplex P) was introduced using a cement gun. The femoral components used were CAD and HD-2 in design, made of chrome cobalt alloy. Evaluation was made according to three categories of loosening: definite (requiring evidence of migration of the component or the cement), probable (requiring a continuous radiolucent zone around the cement mantle in one or more radiographic views), or possible (requiring a radiolucent zone that occupied 50% or more of the cement-bone interface in one or more views but was not continuous). One hip was revised for a loose femoral component. Another patient has asymptomatic subsidence of the femoral component. Thus the total incidence of definitely loose femoral components was 1.1%. No hip was classified as probably loose. Seven hips (4%) were rated as possibly loose. Compared to four other reported series of similar groups of patients followed for like duration, this incidence of definitely loose components is statistically significantly less than in nonplugged canals. The other differences among the series compared, such as stem design, type of cement introduction, modulus of elasticity of the metal used, presence or absence of a collar, and dates during which the surgery was done, are also discussed. Plugging the femoral canal; introducing the cement with a cement gun; using a femoral stem that largely fills the medullary canal, has a collar, and has a rounded rectangular cross section with no medial stress risers made of a superalloy with a modulus of elasticity of about 200 GPa--all these factors were associated with a low (1.1%) incidence of femoral component loosening at 3 years.

Adult↗
PubMed1981

Aspirin-induced prolongation of bleeding time and perioperative blood loss.

One hundred twenty-nine patients undergoing total hip replacement were treated with aspirin at a level of either 300 mg four times a day (1.2 g/day) or 900 mg four times a day (3.6 g/day). Baseline bleeding times before aspirin treatment averaged 4.18 +/- 1.44 minutes. Two hours after 300 mg and 900 mg of aspirin, the bleeding times were 5.83 +/- 1.88 and 5.72 +/- 1.57 minutes, respectively. After three to five days of aspirin therapy at 1.2 g/day and 3.6 g/day, the bleeding times were 6.27 +/- 2.27 and 6.43 +/- 2.11 minutes, respectively. The bleeding times for all the aspirin-treated groups were longer than baseline times. No paradoxical shortening of the bleeding time was noted at the 3.6-g/day dose. Perioperative blood loss for those receiving aspirin was not increased in six of eight subsets by operation and anesthesia when compared with historical control subjects. Neither a bleeding time greater than ten minutes nor a prolongation of the bleeding time by aspirin of more than four minutes over baseline bleeding times was associated with increased perioperative blood loss.

Administration, Oral↗
PubMed1981

Placental transfer of indomethacin in the rabbit and sheep.

The placental transfer of indomethacin was studied in the rabbit at 30 days of gestation and in the sheep between 120 and 135 days of gestation. Plasma concentrations of indomethacin reached a maximum of 13.7 +/- 1.6 and 10.9 +/- 1.5 microgram/mL in the doe and fetuses, respectively, at 1 h following a maternal subcutaneous injection of 10.0 mg/kg. The maternal plasma concentration of drug decreased rapidly but the fetal plasma concentration of drug remained elevated and exceeded that of the doe before decreasing. Indomethacin became detectable in the amniotic fluid after 2 h, reached a maximum of 3.2 +/- 0.8 microgram/mL at 4 h, and the gradually decreased. The intravenous infusion of 10.0 mg of indomethacin per kilogram over 30 min into a pregnant ewe resulted in a maximal plasma concentration of 13.5 +/- 0.7 microgram/mL in the ewe and 0.6 +/- 0.1 microgram/mL in the fetus at the termination of the infusion. The concentration of indomethacin in the amniotic fluid increased to a maximum of 3.5 +/- 0.5 microgram/mL 150 min after the infusion stopped. There was an increase in the percentage of drug bound by the fetal plasma proteins as gestation advanced. Thus, there exists the possibility that the fetus would be exposed to increasing amounts of indomethacin as term approached.

Amniotic Fluid↗
PubMed1981

The plated femur: relationships between the changes in bone stresses and bone loss.

Calculations were made of the alterations in the in vivo cyclic bone stresses due to the application of various plates on the canine femoral shaft. The plate configurations analyzed were those used by previous investigators when studying the influence of plating on bone remodeling. The magnitude of the reduction in the loads borne by the bone tissue and the degree of shift in the bone stress neutral axis during the stance phase of gait was influenced by the geometry of the plate, the plate elastic modulus, and the location of plate application. From a correlation of the calculated alterations in bone stresses with the resulting measured changes in bone mass, it appears that bone remodeling is very sensitive to small changes in cyclic bone stresses. Changes in cyclic bone stresses of 1 MPa (less than 1 percent of the ultimate strength) can cause measurable differences in bone remodeling after a period of a few months.

Animals↗
PubMed1981

The calcar replacement femoral component for total hip arthroplasty: design, uses and surgical technique.

A new femoral component for total hip arthroplasty (THA) has been designed for use in patients in whom the calcar region is missing, hence called the calcar replacement device. Experience with its use in 18 hips has indicated that common causes for calcar deficiency requiring this implant are resorption of the calcar region secondary to failure of a prior THA, settling of an endoprosthesis or destruction by tumor. The use of a conventional femoral component in these situations is not recommended because of the lack of adequate bony support. The device is also valuable in restoring leg length in cases of substantial bone loss in the proximal part of the femur. In an entirely different indication, this device may be used to restore hip motion in patients with severely restricted movement secondary to extensive heterotopic ossification. In three of four hips with this condition, excision of the heterotopic bone and use of the calcar replacement device achieved restoration of an arc of 75 degrees or more in the flexion-extension plane.

Adult↗
PubMed1981

Total hip arthroplasty in the treatment of adult hips with current or quiescent sepsis.

Total hip arthroplasty was done in a series of fifty-seven hips with current or prior infection. Active pyrogenic infection existed in eighteen hips at the time of arthroplasty, in five there was probable pyogenic sepsis, and in twenty-seven there was no current pyogenic infection but there was good evidence of prior pyogenic infection. Seven hips had previously been infected with tuberculosis. All but three of the eighteen patients with active infection had a revision of a previous infected arthroplasty. One had had a resection arthroplasty (Girdle-stone) followed six months later by a total hip arthroplasty. The mean length of follow-up was forty-two months. Fourteen of the eighteen reconstructions were successful. The four that were unsuccessful had recurrent infection and included the only two patients with gram-negative organisms. There was no evidence of recurrence of infection in the other three groups (thirty-nine hips).

Adult↗
PubMed1980

The effects of repeated doses of indomethacin on fetal rabbit mortality and on the patency of the ductus arteriosus.

The effects on fetal mortality and on the patency of the ductus arteriosus of several doses of indomethacin administered at different frequencies to pregnant rabbits were studied. The data show that the number of intrauterine deaths was related to both the dose and frequency of indomethacin administration. However, the degree of constriction of the ductus arteriosus of the dead fetuses was approximately the same, regardless of the dose or the frequency of drug administration. Therefore, the smaller doses may have caused constriction of the ductus for a sufficiently short period of time as not to be lethal in all cases whereas the constriction produced by the larger doses would be of greater duration and more likely to cause death. Although both maternal and fetal plasma concentrations of drug were elevated, there were litters in which no fetal deaths occurred. As the Cesarean sections were performed at various times after the last maternal injection of drug, there was no evidence of a relationship between the dose of drug and the plasma concentrations. However, the fetal plasma concentrations of indomethacin were consistently higher than that of the doe, suggesting that the monitoring of only maternal plasma concentrations of some drugs may be a poor index of the amount of drug in the fetal circulation.

Animals↗
PubMed1980

The role of diagnostic and therapeutic angiography in trauma to the pelvis.

Trauma to the pelvis and femora may be associated with vascular injuries. The important role of diagnostic arteriography in such vascular injuries is widely accepted. In addition, transcatheter embolization may be the preferred treatment to control bleeding or occlude traumatic arteriovenous fistulae. The procedure carries a low risk and should be performed early to avoid the complications of excessive blood loss or progressive enlargement of an arteriovenous fistula.

Adolescent↗
PubMed1980

Transcatheter embolization for the control of wound hemorrhage following hip surgery.

Angiography was done on sixteen patients with excessive bleeding from the wound following major hip surgery. In ten patients the bleeding site was so identified and the vessel was embolized with autologous clot or surgical gelatin. In six patients no site of bleeding could be seen. There was one angiographic complication: distal embolization to the popliteal artery. We concluded that angiography often may be helpful in localizing the site of excessive postoperative bleeding from a wound, and transcatheter embolization of the bleeding vessel then can be effective in controlling such bleeding.

Adult↗