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Biomedical subjects

M B Coventry

Publications and source records attributed to M B Coventry.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

Sequential blood volume changes in patients undergoing total hip arthroplasty.

Adequacy of transfusion based exclusively on clinical observations of hemodynamic changes and quantities of blood lost during total hip arthroplasty (THA) in 15 adults was tested by serial measurements of 51-Cr red-cell volume (RCV), 125-I RISA plasma volume (PV), and peripheral hematocrit (Hv) determined immediately before and 2 and 48 hours after operation. Blood transfusion and intravenous-fluid therapy were based on clinical observations and designed to restore blood volume (BV) to within 10 percent of its preoperative level prior to the isotopic determination 2 hours postoperatively. (When that determination showed a BV less than 90 percent, transfusions were given to restore it to between 90 and 100 percent). Isotopic data 2 hours after operation showed that the BV reduction--thought clinically to be less than 10 percent in every case--averaged 21.6 percent (range: 6 to 39 percent) and was shared by RCV and PV. Isotopic measurements 48 hours after operation showed that patients whose BV at 2 hours was within 10 percent of the preoperative BV were able to compensate for an average continuing RCV reduction of 23.9 percent by expansion of PV, resulting in an average BV reduction of 11.4 percent. Hv was a valuable guide for transfusion therapy at 48 hours, but not 2 hours after operation. In view of inadequacy of blood replacement based on clinical observations and the magnitude and variability of the 2 hour postoperative isotopically measured BV reductions in our patients, we recommend obtaining a derived BV by measuring PV and Hv preoperatively and 2 hours postoperatively as a further guide to transfusion therapy for each patient under-going THA. This is simpler and more practical than the two-isotope technique and is more sensitive than clinical observation alone. If clinical observation had been supplemented with a derived BV in our 15 cases, 80 percent instead of 30 percent would have had their BV restored to within 10 percent of the preoperative BV.

Adult↗
PubMedDate not supplied

Two-part total knee arthroplasty: evolution and present status.

The inception of a 2-part total knee arthroplasty consisting of a Vitallium femoral component and a polyethylene tibial component occurred in 1970. It was termed "geometric," because it was not anatomic in design. This geometric design was altered during the ensuing years to allow better fixation of the tibial unit, because loosening of this unit became apparent in an appreciable percentage of patients. As biomechanical research and clinical evidence progressed, less need for the constraint built into the geometric prosthesis became evident. So a less constrained, more anatomic total knee, called the "anametric" total knee arthroplasty, was developed. There was duplication of the normal anatomic configuration of the femoral component for both left and right sides, a femoral flange so that the patella could be surfaced with polyethylene, and a flatter surface for the tibial unit. The tibial unit was first anchored with the geomatric triflanged system, but eventually comprised a medullary stem and a metal T-tray to contain the polyethylene. At this time, we believe that sufficient constraint necessary in the usual total knee arthroplasty is realized with the anametric design. The anametric design has proved itself and is now our prosthesis of choice.

Biomechanical Phenomena↗
PubMedDate not supplied

Anametric total knee arthroplasty.

The early experience with the anametric knee prosthesis shows it to be effective in achieving the aims desired in total knee arthroplasty. Decreased pain and improved function have been noted in most patients, with relatively few complications. In osteoarthritics, patellar replacement increases the level of improvement. This prosthetic system has been improved by the addition of further sizes and additional tibial fixation options. Detailed long-term follow-up evaluation of these patients will be necessary to judge the effectiveness of the newly introduced design modifications.

Adult↗