Standardizing compression testing for measuring the stiffness of human bone.

OBJECTIVES: The ability to determine human bone stiffness is of clinical relevance in many fields, including bone quality assessment and orthopaedic prosthesis design. Stiffness can be measured using compression testing, an experimental technique commonly used to test bone specimens in vitro. This systematic review aims to determine how best to perform compression testing of human bone. METHODS: A keyword search of all English language articles up until December 2017 of compression testing of bone was undertaken in Medline, Embase, PubMed, and Scopus databases. Studies using bulk tissue, animal tissue, whole bone, or testing techniques other than compression testing were excluded. RESULTS: A total of 4712 abstracts were retrieved, with 177 papers included in the analysis; 20 studies directly analyzed the compression testing technique to improve the accuracy of testing. Several influencing factors should be considered when testing bone samples in compression. These include the method of data analysis, specimen storage, specimen preparation, testing configuration, and loading protocol. CONCLUSION: Compression testing is a widely used technique for measuring the stiffness of bone but there is a great deal of inter-study variation in experimental techniques across the literature. Based on best evidence from the literature, suggestions for bone compression testing are made in this review, although further studies are needed to establish standardized bone testing techniques in order to increase the comparability and reliability of bone stiffness studies.Cite this article: S. Zhao, M. Arnold, S. Ma, R. L. Abel, J. P. Cobb, U. Hansen, O. Boughton. Standardizing compression testing for measuring the stiffness of human bone. Bone Joint Res 2018;7:524-538. DOI: 10.1302/2046-3758.78.BJR-2018-0025.R1.

Microindentation - a tool for measuring cortical bone stiffness? A systematic review.

OBJECTIVES: Microindentation has the potential to measure the stiffness of an individual patient's bone. Bone stiffness plays a crucial role in the press-fit stability of orthopaedic implants. Arming surgeons with accurate bone stiffness information may reduce surgical complications including periprosthetic fractures. The question addressed with this systematic review is whether microindentation can accurately measure cortical bone stiffness. METHODS: A systematic review of all English language articles using a keyword search was undertaken using Medline, Embase, PubMed, Scopus and Cochrane databases. Studies that only used nanoindentation, cancellous bone or animal tissue were excluded. RESULTS: A total of 1094 abstracts were retrieved and 32 papers were included in the analysis, 20 of which used reference point indentation, and 12 of which used traditional depth-sensing indentation. There are several factors that must be considered when using microindentation, such as tip size, depth and method of analysis. Only two studies validated microindentation against traditional mechanical testing techniques. Both studies used reference point indentation (RPI), with one showing that RPI parameters correlate well with mechanical testing, but the other suggested that they do not. CONCLUSION: Microindentation has been used in various studies to assess bone stiffness, but only two studies with conflicting results compared microindentation with traditional mechanical testing techniques. Further research, including more studies comparing microindentation with other mechanical testing methods, is needed before microindentation can be used reliably to calculate cortical bone stiffness.Cite this article: M. Arnold, S. Zhao, S. Ma, F. Giuliani, U. Hansen, J. P. Cobb, R. L. Abel, O. Boughton. Microindentation - a tool for measuring cortical bone stiffness? A systematic review. Bone Joint Res 2017;6:542-549. DOI: 10.1302/2046-3758.69.BJR-2016-0317.R2.

Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone.

A bright µm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 µm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications.

An examination of hyperconjugative and electrostatic effects in the hydride reductions of 2-substituted-4-tert-butylcyclohexanones.

To better understand electronic effects on the diastereoselectivity of nucleophilic additions to the carbonyl group, a series of 2-X-4-tert-butylcyclohexanones (X = H, CH(3), OCH(3), F, Cl, Br) were reacted with LiAlH(4). Reduction of ketones with equatorial substituents yields increasing amounts of axial alcohol in the series for X [H < CH(3) < Br < Cl < F << OCH(3)]. These data cannot be explained by steric or chelation effects or by the theories of Felkin-Anh or Cieplak. Instead, an electrostatic argument is introduced: due to repulsion between the nucleophile and the X group, axial approach becomes energetically less favorable with an increase in the component of the dipole moment anti to the hydride approach trajectory. The ab initio calculated diastereoselectivities were close to the experimental values but did not reproduce the relative selectivity ordering among substituents. For reduction of ketones with axial substituents, increasing amounts of axial alcohol are seen in the series for X [Cl < Br < CH(3) < OCH(3) < H < F]. After some minor adjustments are made, this ordering is consistent with both the electrostatic model and Felkin-Anh theory. Cieplak theory cannot account for these data regardless of adjustments. Ab initio calculated diastereoselectivities were reasonably accurate for the nonpolar substituents but were poor for the polar substituents.

Data used to improve quality of health care.

Many factors are involved in improving the quality of health care. Using data to measure performance is an essential element. Whether the objective is to improve outcomes (e.g., reducing mortality among patients hospitalized with acute myocardial infarction) or to improve a process of care (e.g., increasing the rate of beta blocker administration at discharge in patients with acute myocardial infarction), data are central to assessing the quality of health care. Data help determine where opportunities for improvement exist and document the impact that system change interventions have made on the outcomes or processes of care for a clinical condition or topic. Measuring performance is critical to learning how your practice compares with best practices. If you haven't measured, you do not know. This article will focus specifically on the role and use of data to improve processes of health care for Medicare beneficiaries. Examples of projects and results are cited from the work of the Texas Medical Foundation, which is the Medicare peer review organization under the Health Care Financing Administration's Health Care Quality Improvement Program.

A ribonuclease A variant with low catalytic activity but high cytotoxicity.

Onconase, a homolog of ribonuclease A (RNase A) with low ribonucleolytic activity, is cytotoxic and has efficacy as a cancer chemotherapeutic. Here variants of RNase A were used to probe the interplay between ribonucleolytic activity and evasion of the cytosolic ribonuclease inhibitor protein (RI) in the cytotoxicity of ribonucleases. K41R/G88R RNase A is a less active catalyst than G88R RNase A but, surprisingly, is more cytotoxic. Like Onconase, the K41R/G88R variant has a low affinity for RI, which apparently compensates for its low ribonucleolytic activity. In contrast, K41A/G88R RNase A, which has the same affinity for RI as does the K41R/G88R variant, is not cytotoxic. The nontoxic K41A/G88R variant is a much less active catalyst than is the toxic K41R/G88R variant. These data indicate that maintaining sufficient ribonucleolytic activity in the presence of RI is a requirement for a homolog or variant of RNase A to be cytotoxic. This principle can guide the design of new chemotherapeutics based on homologs and variants of RNase A.

Aspirin administration for cardiac-related acute chest pain/angina: increased use in Medicare patients.

BACKGROUND: Coronary heart disease (CHD), the leading cause of death in the United States, accounted for approximately 490,000 deaths in 1993. Angina pectoris, a manifestation of CHD, accounted for 13,586 Medicare discharges in 1993 in Texas. A pilot project showed aspirin prophylaxis that reduces cardiovascular morbidity and mortality in individuals with acute angina is underused. Texas Medical Foundation collaborated with 10 acute-care facilities to improve aspirin prophylaxis. METHODS: Collaborators assessed processes of care and implemented clinical pathways to improve aspirin administration. Data were abstracted from medical records before and after pathway implementation to evaluate impact. RESULTS: Aspirin administration during hospital stay increased 10.8%, aspirin administration on discharge increased 11.7%, and average time from arrival to aspirin administration decreased 2.9 hours. CONCLUSIONS: Results suggest collaborator-implemented clinical pathways significantly improved care received by Medicare patients admitted for cardiac-related acute chest pain/angina. Data suggest room for further improvement.

Methodology of quality improvement projects for the Texas Medicare population.

The Texas Medical Foundation, the quality improvement organization for the state of Texas, develops local quality improvement projects for the Medicare population. These projects are developed as part of the Health Care Quality Improvement Program undertaken by the Health Care Financing Administration. The goal of a local quality improvement project is to collaborate with providers to identify and reduce the incidence of unintentional variations in the delivery of care that negatively impact outcomes. Two factors are critical to the success of a quality improvement project. First, as opposed to peer review that is based on implicit criteria, quality improvement must be based on explicit criteria. These criteria represent key steps in the delivery of care that have been shown to improve outcomes for a specific disease. Second, quality improvement must be performed in partnership with the health care community. As such, the health care community must play an integral role in the design and evaluation of a quality improvement project and in the design and implementation of the resulting quality improvement plan. Specifically, this article provides a historical perspective for the transition from peer review to quality improvement. It discusses key steps used in developing and implementing local quality improvement projects including topic selection, quality indicator development, collaborator recruitment, and measurement of performance/improvement. Two Texas Medical Foundation projects are described to highlight the current methodology and to illustrate the impact of quality improvement projects.

Implementing a clinical pathway for the treatment of Medicare patients with cardiac chest pain.

BACKGROUND: A small urban hospital identified angina pectoris (DRG 140) as a high-cost and low-reimbursement DRG. Variation in the process of care for patients with cardiac chest pain was related to the timing of decisions on stress tests and whether inpatient GI workups were performed. Underutilization of aspirin was identified as a quality of care issue. In collaboration with Texas Medical Foundation (TMF), the Quality Improvement Organization (QIO) for Texas, this became the initial Health Care Quality Improvement Program (HCQIP) project and the first effort by the hospital at pathway development. INTERVENTION: A team effort lead by physicians, including other healthcare groups at the hospital, identified elements considered essential to providing ideal care for patients with cardiac chest pain, formulating these elements into a clinical pathway. RESULTS: Emergency room physicians, an essential stakeholder group, had not been included in the initial pathway development, which proved to be a critical factor to effective implementation. Pathway implementation was associated with increased administration of aspirin by 45.7% (p < 0.001), reduced length of stay by 1.0 days (p = 0.064), and reduced total charges by an average of $1710.20 (p = 0.039). DISCUSSION: These results suggest that process of care improvement, i.e., clinical pathway implementation, in collaboration with a QIO, contributed to reduced variation in the process of care. Participation by all stakeholders from the beginning in process of care improvement is essential.

Medical necessity for right heart catheterization.

Because there are no definitive guidelines for performing right heart catheterizations or controlled clinical trials demonstrating medical benefit, the value and necessity of performing routine right heart catheterizations for coronary artery disease have been questioned. This Texas Medical Foundation Health Care Quality Improvement Program project was designed to ensure medical necessity and proper documentation of right heart catheterization when performed as part of a bilateral procedure. Medicare claims data were used to identify Texas facilities where rates of bilateral catheterizations suggested that right heart catheterizations were being performed routinely. Five facilities were found to have rates of bilateral procedures exceeding 70%. Suggested guidelines for performing right heart catheterizations were prepared by the Texas Medical Association Committee on Cardiovascular Diseases. These guidelines, together with the facility's data on its rate of right heart catheterizations, were presented by the Texas Medical Foundation to the staff of each facility. They were asked to examine their individual facility's procedures for ensuring medical necessity and to develop and implement process improvement plans. Medicare claims data were analyzed to determine the rates of bilateral catheterizations before and after the plans were instituted. The statewide rate of bilateral procedures decreased from 27.2% to 21.3% (p < 0.005). Rate reductions for 4 facilities implementing improvement plans were statistically significant (p < 0.001): at the 1st facility, the rate decreased from 74.3% to 25.0%; at the 2nd, from 85.0% to 21.0%; at the 3rd, from 76.7% to 17.7%; and at the 4th facility, from 85.4% to 42.9%. The rate for the facility not implementing an improvement plan increased from 86.4% to 89.1%. Reductions in rates of bilateral procedures at the 4 facilities suggest that many procedures previously performed were routine and not medically indicated. Presentation of data and practice guidelines to facilities may have contributed to their ability to improve processes.