Biomedical subjects

James W Pritchett

Publications and source records attributed to James W Pritchett.

3 recordsLinked to original sources

PubMed2006

Heat generated by knee prostheses.

Temperature sensors were placed in 50 knees in 25 patients who had one or both joints replaced. Temperature recordings were made before walking, after walking, and after cycling. The heat generated in healthy, arthritic, and replaced knees was measured. The knee replacements were done using eight different prostheses. A rotating hinge knee prosthesis generated a temperature increase of 7 degrees C in 20 minutes and 9 degrees C in 40 minutes. An unconstrained ceramic femoral prosthesis articulating with a polyethylene tibial prosthesis generated a temperature increase of 4 degrees C compared with a healthy resting knee. The other designs using a cobalt-chrome alloy and high-density polyethylene had temperature increases of 5 degrees-7 degrees C with exercise. Frictional heat generated in a prosthetic knee is not immediately dissipated and may result in wear, creep, and other degenerative processes in the high-density polyethylene. Extended periods of elevated temperature in joints may inhibit cell growth and perhaps contribute to adverse performance via bone resorption or component loosening. Prosthetic knees generate more heat with activity than healthy or arthritic knees. More-constrained knee prostheses generate more heat than less-constrained prostheses. A knee with a ceramic femoral component generates less heat than a knee with the same design using a cobalt-chromium alloy.

Aged↗

PubMed2004

Nerve injury and limb lengthening after hip replacement: treatment by shortening.

Nineteen patients had a severe neurologic deficit and persistent dysesthetic pain after total hip replacement. During surgery their limbs had been lengthened by 1.3 to 4.1 cm. Patients with other reasons for nerve injury such as hematoma, dislocation, or direct operative trauma were excluded. Also excluded were patients whose lengthening was part of the operative plan to address previous shortening. None of the patients had neurologic deficits or dysesthetic pain preoperatively. Patients were offered revision hip surgery to shorten the limb. Seventeen patients proceeded to surgery. Two acetabular revisions, five modular femoral head exchanges, and 10 femoral component revisions were done. The average shortening was 1.5 cm (range, 0.5-3.6 cm). The trochanter was advanced in four patients and a constrained acetabular liner was used in four patients. Nine hips were stable without additional measures. There were no complications and nine patients had an excellent result. This was defined as elimination of their dysesthetic pain. Two patients had partial improvement and six patients had no improvement. Seven of 11 patients with motor deficits had improvement in strength with three making a full recovery. When painful neurologic symptoms accompany limb lengthening after total hip replacement, revision surgery may be helpful, although patients should be informed the rate of success is far from uniform.

Adult↗

PubMed2004

Horizontal platform supported hip replacement.

The cementless horizontal platform supported femoral component for hip replacement was designed to provide physiologic stress loading of the proximal femur after hip replacement. The goal is to extend pain-free implant survival by reducing periprosthetic bone resorption and to provide improved hip function and many years of relief from hip pain. A total hip replacement using this prosthesis was done in 334 consecutive nonselective hips in 322 patients. The mean age of the patients at the time of total hip replacement was 69 years (range, 29-89 years). Thirty-two patients (34 hips) were lost to followup and 81 patients (83 hips) died less than 10 years postoperatively. The remaining 209 patients (217 hips) were followed up for a minimum of 10 years (maximum, 14 years). There were six revisions of the femoral prosthesis. Three (1.8%) were revised for loosening, two were revised for femoral fracture, and one was revised for unexplained pain. The rate of stem survival was 0.97 +/- 0.02 (mean and standard error). There were 209 (96%) hips with excellent or good results. Seven (3%) patients had osteolytic changes develop. Radiographic evidence of diminished bone density in the proximal femur was seen in 34 hips (16%). The clinical results are comparable with other reported results for cementless hip replacements at 10 years.

Adult↗