Biomedical subjects

R W McGraw

Publications and source records attributed to R W McGraw.

10 recordsLinked to original sources

PubMed1995

Position of the knee joint after total joint arthroplasty.

A method for assessing knee joint position after surgery using the preoperative long-leg radiograph and the postoperative knee radiograph is described. Assessment of the formula has shown a near perfect correlation between the calculated position on the long-leg radiograph compared with the measured position for 44 knees. Three hundred eighteen knees after total joint arthroplasty were retrospectively reviewed and the postoperative position was determined. The preoperative position of the mechanical axis was 14.5 +/- 37.3 mm medial to the knee joint center. Using the standing knee radiograph the postoperative position of the mechanical axis was 3.07 +/- 9.2 mm lateral to the knee joint center, while the portable radiograph placed the mechanical axis 4.5 +/- 12.4 mm medial to the knee joint center. There was a highly significant difference in the position of the knee joint center depending on the radiograph used for calculation (standing or portable). The difference between the two means was not due to opening of the knee joint, but likely due to change in the rotation of the knee in the presence of knee flexion. This series of the knee arthroplasties has a low projected rate of aseptic failure.

Femur↗

PubMed1992

Perineural pressures under the pneumatic tourniquet in the upper extremity.

The literature indicates that tourniquet-induced neurological injuries are relatively common and frequently occur at a subclinical level. In order to evaluate the pressure transmitted to the major peripheral nerves of the arm by an externally applied pneumatic tourniquet, a fully implantable biomedical pressure transducer was placed adjacent the radial, median and ulnar nerves in six cadaver upper extremities of average dimensions. This sensor allowed accurate, reproducible measurements of perineural pressures without requiring significant disruption of the normal anatomical structures of the test limb for its installation. At levels of tourniquet cuff inflation which are commonly used in clinical practice, there was little or no decrease in the pressure detected in the perineural regions over that applied to the surface of the limb. In addition, there was a steep gradient of perineural pressure between locations beneath the edge of the cuff and those under its midpoint. This was most marked at the highest levels of tourniquet inflation. At presently accepted levels of inflation, pneumatic tourniquet cuffs transmit high pressures to the peripheral nerves without any significant attenuation by the intervening soft tissues. The distribution of these forces is one which may subject the underlying nerves to deleterious shear forces, especially at higher levels of inflation.

Arm↗

PubMed1991

Massive intrapelvic synovial cyst as a complication of total hip replacement arthroplasty: a case report.

The authors report a case of massive intrapelvic synovial cyst complicating total hip arthroplasty in a 35-year-old woman with rheumatoid arthritis. The clinical presentation raised the possibility of a coincidental soft-tissue malignant tumour. This was ruled out by ultrasonography, computed tomography, fine-needle aspiration with examination of cells and culture and, ultimately, by image intensification in the operating room during aspiration of the cyst and injection of the adjacent hip joint with Hypaque. The authors conclude that perforation of the acetabular floor at total hip arthroplasty was likely the precipitating event. After 1 year there was no indication for surgical excision of the cyst.

Adult↗

PubMed1988

New finger cuffs for use with digital tourniquets.

The advent of tourniquets employing digital technology has led to significant improvements in the safety and accuracy of surgical procedures performed with an occlusive cuff applied proximally on a limb. This article describes the evaluation of new cuffs used on fingers that may permit significantly lower pressures to be more safely and consistently employed. Our experimental studies would suggest that finger occlusion pressure is a function of cuff design, cuff width, finger circumference, and systolic blood pressure.

Adult↗

PubMed1987