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We reviewed 19 revision hip arthroplasties in which the new femoral component had been recemented into the old, intact cement mantle. The mean time from the first operation to revision was 64 months and the average follow-up was 59 months. There were 7 excellent, 1 1 good, and one fair result. No femoral component had been revised for loosening and all the stems appeared radiographically stable. Cornplications included intraoperative perforation of the femur on two occasions and one dislocation. The use of the cement-within-cement technique re

Four different single base mutations that cause amino acid substitutions were detected in the steroid 5alpha-reductase type 2 gene of affected individuals. One patient and a normal control had two previously undescribed mutations. Although in the latter individual we cannot exclude the possibility that the base change is a genetic polymorphism, the molecular screening of 100 chromosomes suggests strongly that the change at codon 245 does represent a heterozygous mutation. Further studies, including the recreation of the mutations, will help to reveal the biochemical consequences resulting from these changes.

We reviewed the plain radiographs, bone scans and hip aspiration results of 54 patients with painful hip arthroplasties which had been explored surgically, to compare the results of the investigations with the operative findings. For acetabular loosening, the sensitivity and specificity of bone scanning were 87% and 95%, with an accuracy of 90%: for serial plain radiography sensitivity was 95%, specificity 100% and accuracy 97%. For femoral component loosening, bone scan sensitivity was 85%, specificity 100% and accuracy 89%: the sensitivity of plain radiography was 100%, with specificity 92% and accuracy 98%. Technetium bone scanning did not provide additional information with regard to loosening and is not necessary in the routine investigation of a painful hip arthroplasty. Serial pain radiography is the most effective method of detecting loosening, and bone scanning is useful only when radiography is inconclusive with regard to loosening or infection.

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Recent years have seen the proliferation of numerous standards of quality for the process of providing health care, including total joint replacement. These attempts include the implementation of pay-for-reporting and pay-for-performance programs based on quality measures. These programs have often been implemented with few studies of the validity of the quality measures used and with limited input from the orthopedic community. Our project addresses this relative lack of evidence-based measures by developing a set of quality measures that address the perioperative care of patients undergoing total joint replacement. Our goal is to create a model for improving the quality of care and outcomes of total joint replacement in the United States by facilitating physicians in their efforts to apply the best scientific evidence to their daily practice.

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I AbstractThe purpose of this project is to study the equilibrium particle and energy balance ancl the heating mechanisms in electronegative r.f. discharges. Particular attention is given to the formation of non-Maxwellian electron distributions and their effect on the macroscopic parameters. The research includes theory, pasticle-in-cell simulation, and experimental investigations.The sheath heating theory and the simulation results developed for electropositive plasmas are used to guide the investigations. The investigation was centered on, but is not limited to, the study of oxygen feedstock gas in capacitively and inductively coupled r.f. discharges.