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Biomedical subjects

Richard A Brand

Publications and source records attributed to Richard A Brand.

At least 19 recordsLinked to original sources
PubMed2006

The environment of the successful clinician-scientist.

The number of clinician-scientists has declined over the past several decades and evidence suggests this trend also applies to orthopaedic surgery. A previous study identified only 64 principle investigator orthopaedic surgeons with over 100,000 dollars of NIH funding from 1992 to 2001, during which funding declined for orthopaedic surgeons. We surveyed 58 of these 64 surgeons (six were retired) to ascertain aspects of their environment that might lead to success and what obstacles they encountered. The common definition of a clinician-scientist was an individual who obtained external funding for research. With a response rate of 79%, 26 of 40 (65%) began their research careers before residency. Nearly half had additional specialized training in research and most thought at least 6 months training was important. Thirty four of 46 respondents (74%) percent spent less than 20% of their time in research but 43 of 45 (95%) thought at least 30% ideal. Twenty five of 43 (58%) had unshared laboratory space and those without typically share with three or more scientists. Twenty eight of 43 (65%) believed their level of external funding adequate. Twenty of 46 (43%) believed their colleagues resented the time they spent in research. Demands on clinical time continue to be a major impediment to orthopaedic clinician-scientists. The orthopaedic community must develop supportive environments for clinician-scientists.

Attitude of Health Personnel↗
PubMed2005

Joint contact stress: a reasonable surrogate for biological processes?

A joint's normal mechanical history contributes to the maintenance of articular cartilage and underlying bone. Loading facilitates the flow of nutrients into cartilage and waste products away, and additionally provides the mechanical signals essential for normal cell and tissue maintenance. Deleteriously low or high contact stresses have been presumed to result in joint deterioration, and particular aspects of the mechanical environment may facilitate repair of damaged cartilage. For decades, investigators have explored static joint contact stresses (under some more or less arbitrary condition) as a surrogate of the relevant mechanical history. Contact stresses have been estimated in vitro in many joints and in a number of species, although only rarely in vivo. Despite a number of widely varying techniques (and spatial resolutions) to measure these contact stresses, reported ranges of static peak normal stresses are relatively similar from joint to joint across species, and in the range of 0.5 to 5.0 MPa. This suggests vertebrate diarthrodial joints have evolved to achieve similar mechanical design criteria. Available evidence also suggests some disorders of cartilage deterioration are associated with somewhat higher peak pressures ranging from 1-20 MPa, but overlapping the range of normal pressures. Some evidence and considerable logic suggests static contact stresses per se do not predict cartilage responses, but rather temporal aspects of the contact stress history. Static contact stresses may therefore not be a reasonable surrogate for biomechanical studies. Rather, temporal and spatial aspects of the loading history undoubtedly induce beneficial and deleterious biological responses. Finally, since all articular cartilage experiences similar stresses, the concept of a "weight-bearing" versus a "non-weight-bearing" joint seems flawed, and should be abandoned.

Animals↗
PubMed2004

The effects of total contact casting materials on plantar pressures.

The plaster-based total contact cast (TCC) is effective at reducing high plantar pressures associated with foot ulceration in the patient with diabetes. However, the weight and the lengthy drying time which require nonweightbearing create an inconvenience for the patient. Fiberglass has been commonly used as a substitute for plaster due to the quicker drying time, although little is known about the effects of fiberglass on plantar pressures. The purpose of the study was to compare a plaster-based TCC (PB-TCC) and an all-fiberglass TCC (AF-TCC) using selected plantar pressure parameters for commonly ulcerated regions of the foot. Using a repeated measures design, 10 healthy subjects consented to walk, for four consecutive trials, along a 25-m corridor while wearing a running shoe, PB-TCC, and AF-TCC. For each of the footwear conditions, parameters of peak pressure, pressure-time integral, and contact time for the forefoot, lateral midfoot, and heel regions were recorded using the Pedar trade mark system of plantar pressure measurement. Both the PB-TCC and AF-TCC produced similar peak plantar pressures that were significantly lower (p =.001) than the running shoe. Pressure-time integrals were similar for all footwear conditions and contact time was not altered with footwear type. In summary, the AF-TCC appears to be an effective alternative to the PB-TCC for plantar pressure reduction in the management of neuropathic foot ulceration.

Adult↗
PubMed2004

Particulate debris osteolysis simulating malignant tumor.

Osteolysis induced by particulate debris from total joint implants is typically confined to bone and benign in radiographic appearance even when extensive. However, they can extend well beyond bone in which case they can simulate malignancies owing either to mass effects and pressure on adjacent tissues or owing to the radiographic appearance. We report two cases which presented as possible malignancy, and review the literature on extensive osteolysis. Recognition of this possibility may aid in interpretation of the clinical presentation and imaging studies.

Adult↗
PubMed2003

Industrial support of orthopaedic research in the academic setting.

Industry support provides critical resources for researchers in departments of orthopaedic surgery, and affords research that otherwise likely would not be possible. However, in contrast to sponsorship from the federal agencies or most foundations, corporate sponsorship raises ethical, practical, and legal issues for the individual researcher, the department, the academic institution, the scientific community at large, and industry. Most of these issues relate to ownership of intellectual property, confidentiality, disclosure of results, and apparent bias. For the public the issues involve ethical issues, including trust. Academic institutions have evolved approaches for contracts with industry, which minimize, but not eliminate these problems. Given appropriate contracts, corporate sponsorship of research is not only mutually beneficial, but for many departments, critical.

Confidentiality↗
PubMed2003

How do tissues respond and adapt to stresses around a prosthesis? A primer on finite element stress analysis for orthopaedic surgeons.

Joint implant design clearly affects long-term outcome. While many implant designs have been empirically-based, finite element analysis has the potential to identify beneficial and deleterious features prior to clinical trials. Finite element analysis is a powerful analytic tool allowing computation of the stress and strain distribution throughout an implant construct. Whether it is useful depends upon many assumptions and details of the model. Since ultimate failure is related to biological factors in addition to mechanical, and since the mechanical causes of failure are related to load history, rather than a few loading conditions, chief among them is whether the stresses or strains under limited loading conditions relate to outcome. Newer approaches can minimize this and the many other model limitations. If the surgeon is to critically and properly interpret the results in scientific articles and sales literature, he or she must have a fundamental understanding of finite element analysis. We outline here the major capabilities of finite element analysis, as well as the assumptions and limitations.

Arthroplasty, Replacement↗
PubMed2002

Spatial distribution of hip capsule structural and material properties.

Contemporary computational models potentially allow the practical incorporation of the effects of a joint capsule on both motion and the loads transmitted to the other parts of the joint. However, the required material properties have not been available for this purpose. To determine these properties we took both hip joints from five fresh-frozen, nondiseased cadavers. Following dissection and potting of the hemi-pelvis, distraction of the intact joint was conducted to measure the structural tangent stiffness of the joint capsule. Anatomical insertion points of the hip capsule were then recorded, and a complete capsulectomy was performed. Once excised, the capsule was sectioned into eight, approximately even sectors, and initial geometrical measurements were recorded for material property calculations. Material properties (i.e., structural tangent stiffness, failure load, ultimate strength, tangent modulus) were calculated using the load-displacement and geometric data collected for each of the sectors. This specimen-to-specimen thickness variability reveals significantly lower (p<0.01) average tangent structural stiffness values in the posterior-inferior portion of the capsule. Explorations of hip stability using numerical models can now be enhanced by incorporation of these experimental capsule data.

Aged↗
PubMed2002

Cartilage extracellular matrix metabolism differs in serum and synovial fluid.

Most cartilage explant culture studies assume conventional serum-supplemented growth media are biologically equivalent to the natural synovial fluid which baths cartilage in vivo. Few studies have systematically compared the effects of serum versus synovial fluid in culture. To address this assumption we conducted a series of studies to determine if cartilage matrix synthesis is significantly different in serum-based versus synovial fluid-based media. Normal bovine cartilage explants were cultured in DMEM either alone or supplemented with bovine serum or bovine synovial fluid. Matrix synthesis was measured with radiolabeling techniques. We then compared responses to insulin-like growth factor I (IGF-I, a stimulator of matrix synthesis), and interleukin-1beta (IL-1beta, an inhibitor of matrix synthesis). We observed significantly lower matrix synthesis activity in synovial fluid versus serum. Caution shoud be used in extrapolating studies of cartilage grown in media supplemented with serum rather than synovial fluid.

Animals↗