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Biomedical subjects

D W Howie

Publications and source records attributed to D W Howie.

36 records · Page 2Linked to original sources
PubMed1993

The differences in toxicity and release of bone-resorbing mediators induced by titanium and cobalt-chromium-alloy wear particles.

We investigated the relationship between the toxic effects of metal wear particles and their ability to stimulate the release of inflammatory mediators implicated in bone resorption. In vitro studies were carried out with use of rat peritoneal macrophages, which were exposed to either cobalt-chromium-alloy or titanium-aluminum-vanadium particles, milled from the metal components of hip prostheses. The particles were in the size-range of, and at concentrations similar to, those found in the tissues surrounding failed prostheses in humans. The titanium-aluminum-vanadium particles showed little toxicity even at high concentrations, while the cobalt-chromium particles were very toxic. The titanium-aluminum-vanadium particles induced significantly more release of prostaglandin E2 than did the cobalt-chromium particles, and this was true for a wide range of concentrations. Exposure to titanium-aluminum-vanadium increased the release of prostaglandin E2, interleukin-1, tumor necrosis factor, and interleukin-6. In contrast, exposure to cobalt-chromium particles was associated with a decreased release of prostaglandin E2 and interleukin-6, and it had little effect on the release of interleukin-1 and tumor necrosis factor.

Alloys↗
PubMed1993

The response to particulate debris.

The most common cause of failure of total hip and other arthroplasties is aseptic loosening of the prosthesis. Substantial evidence suggests that the adverse tissue response to prosthesis wear particles is an important contributor to bone loss around implants. The results may be an increased risk of loosening and severe bone loss, which makes revision surgery more difficult. Studies in humans have demonstrated that the appearances of the periprosthetic tissues are related to the type, number, and size of wear particles. The appearance and tissue response around any given prosthesis is related to the balance among the rate of production of wear particles, the ability of the tissues to deal with the particles, and the rate of clearance of the particles from the joint. Prosthesis wear particles may be produced by wear at the articulating surface, particularly if there is three-body wear, by abrasion due to movement at the prosthesis-bone interface of uncemented prostheses, by abrasion at the prosthesis-cement and cement-bone interfaces of cemented prostheses, or at any articulation of the components of modular prostheses. Future in vivo and in vitro studies of the effects of wear particles should focus on quantitative measurement of the effects of particles and on the use of particles of comparable size and in concentrations similar to those found in the tissues surrounding failed prostheses.

Animals↗
PubMed1993

The viability of the femoral head after resurfacing hip arthroplasty in humans.

Histologic examination of 72 femoral heads retrieved at revision of resurfacing arthroplasties was performed to determine the possible role of generalized osteonecrosis caused by avascular necrosis (AVN) in early loosening of the femoral components. The degree of loosening at the femoral bone-cement interface was correlated with the histologic appearance of the femoral heads. None of the ten femoral heads with solid femoral components and only one of the 15 heads with slight loosening showed evidence of generalized osteonecrosis. The one case might have been attributable to AVN after the resurfacing procedure. In the remaining femoral heads with marked loosening of the femoral component, necrosis of bone was uncommon. When present, it was attributed to loosening. Thickening of bone trabeculae, a fibrovascular marrow, and superficial necrosis of bone of the femoral head are not evidence of generalized AVN caused by the resurfacing arthroplasty procedure, but are the result of remodeling changes and subsequent loosening.

Adult↗
PubMed1993

The synovial response to intraarticular injection in rats of polyethylene wear particles.

To study the effect on tissues of wear particles commonly released from the articulating surfaces of joint prostheses, ultra-high-molecular-weight polyethylene particles were prepared in a joint simulator and injected into rat knees. The particles caused synovial proliferation and induced a macrophage and multinucleate giant-cell response in the subsynovium. Of particular interest was the macrophage response to particles ranging from 5 microns in maximum dimension to the limits of resolution of the light microscope; the multinucleate giant-cell response occurred in response to larger particles and aggregates of small particles. These findings emphasize the importance of wear particles in causing an adverse tissue response around joint replacements having a polyethylene component. The difference in cellular response to wear particles of different size suggests that not only the prosthesis material but also the pattern of wear and size of wear particles produced at the articulating surfaces of a prosthesis will determine the type of cellular response.

Animals↗
PubMed1991

Peripheral wear of Wagner resurfacing hip arthroplasty acetabular components.

One hundred nine Wagner resurfacing arthroplasty acetabular components retrieved at revision surgery were examined for type, depth, and extent of wear at the periphery of the components. Ninety-two components were found to have evidence of peripheral wear caused by impingement of the femoral neck on the edge of the component. The thickness of the wall loss due to this impingement wear was found to be less the farther that measurements were taken from the edge of the component. Thus, when those components with any evidence of impingement wear were analyzed, it was found that significantly fewer components had evidence of impingement at depths of 3 mm and 5 mm in from the edge of the component. It is suggested that future designs of resurfacing hip arthroplasty acetabular components should be at least 3 mm and possibly 5 mm less than a hemisphere. This is likely to lead to less impingement on the femoral neck and therefore less cause for mechanical loosening and less production of wear debris.

Acetabulum↗
PubMed1991

Pseudo-abscess of the psoas bursa in failed double-cup arthroplasty of the hip.

Seven psoas bursae filled with purulent fluid and inspissated debris were revealed at revision operations for failed resurfacing hip arthroplasties, an incidence of 5.8% in such revisions. Histological and microbiological investigations demonstrated that the psoas bursa collections resulted from the tissue response to polyethylene wear debris. None was due to infection.

Adult↗
PubMed1990

Tissue response in relation to type of wear particles around failed hip arthroplasties.

To establish the types of wear particles and associated tissue response around human prostheses the periprosthetic tissues around 50 hip arthroplasties revised for aseptic loosening of one or more components were examined by light microscopy, transmission electron microscopy, and energy-dispersing x-ray microanalysis. The tissues around cementless metal-on-bone and ceramic-on-ceramic prostheses contained few or no prosthesis wear particles. The tissues around metal-on-metal prostheses contained large numbers of metal particles and large numbers of macrophages, and occasional multinucleate giant cells. The tissues around cemented metal-on-polyethylene prostheses often contained large numbers of small and large polyethylene particles, variable numbers of cement particles, and occasional metal particles. Large numbers of macrophages and multinucleate giant cells were frequently seen in these tissues. Lymphocytes were occasionally seen in association with metal particles. Ultrastructural studies of the periprosthetic tissues confirmed the phagocytosis of submicroscopic wear particles by macrophages. Varying degrees of degenerative change in macrophages were seen in association with phagocytosis of metal particles. Large numbers of cytolysosomes were seen in cells in association with the accumulation of wear particles.

Adult↗
PubMed1990

Plain film and arthrographic findings in painful total hip arthroplasties with surgical correlation.

The plain films and arthrograms performed on 42 painful cemented hip arthroplasties in 40 patients were reviewed and the radiological findings compared to the surgical assessment of component stability. All radiography, which included Judet views in the plain films, was reviewed without knowledge of the surgical findings and without comparison with previous studies. Criteria for the detection of loosening of cemented femoral and acetabular components were predetermined. The accuracy of plain film assessment of acetabular component stability was increased significantly (p less than 0.05) by including oblique views in the plain film assessment. The accuracy of assessment of acetabular component stability on plain films was 88%, on arthrography 90% and, with both studies combined, was 98%. Femoral component stability was assessed accurately on 90% of plain films and 90% of arthrograms, and this was not improved by combining the studies. The difficulty of detecting low grade infections is discussed with results of pseudocapsule aspiration.

Adult↗
PubMed1990

Resurfacing hip arthroplasty. Classification of loosening and the role of prosthesis wear particles.

Operative grading of loosening and histologic examination of the periprosthetic tissues and the femoral and acetabular bone-cement interfaces were undertaken in 72 revised resurfacing hip arthroplasties. By correlating the degree of macroscopic and microscopic loosening at the bone-cement interface, a classification of the stages of loosening at the bone-cement interface was devised. Examination of the femoral bone-cement interface of solidly fixed prosthesis components has demonstrated the presence of polyethylene wear particles and a macrophage response at the interface prior to loosening. This suggests that wear particles may migrate along bone-cement interfaces that are both macroscopically and microscopically solid, and emphasizes the important role of wear particles in prosthesis loosening.

Adult↗
PubMed1990

Wagner resurfacing hip arthroplasty. The results of one hundred consecutive arthroplasties after eight to ten years.

In a prospective study of 100 consecutive Wagner resurfacing hip arthroplasties in ninety-three patients, the outcomes for all hips were determined for an eight to ten-year follow-up period. By survivorship analysis, the rate of survival of the arthroplasty was calculated to be 70 per cent at five years, but only 40 per cent at eight years. The major cause of failure was aseptic loosening of the acetabular or femoral component, or both. Fracture of the neck of the femur occurred in three hips. Although the medium-term results (at fifty-six to eighty-three months) were better than those in most comparable studies of resurfacing arthroplasty, the poor long-term results (at ninety-one to 118 months) show that meaningful studies of new prosthetic designs must continue for at least eight years, and, if at all possible, must include 100 per cent follow-up. The survival curve for the resurfacing arthroplasties in this study can serve as the basis for comparison of the early, medium, and long-term results of future designs of resurfacing hip prostheses.

Adult↗
PubMed1989

A comparison of plain and fluoroscopically guided radiographs in the assessment of arthroplasty of the knee.

A cadaver model was used to compare the sensitivity of fluoroscopically guided radiographs with that of plain radiographs in revealing lucent lines beneath the tibial component of an uncemented total knee arthroplasty and subsidence of the component. Fluoroscopically guided radiographs allowed accurate measurement of a lucent line that was one millimeter wide. Plain radiographs were inadequate for the detection and measurement of these lucent lines, leading to inaccuracy. Fluoroscopically guided radiographs also allowed measurement of the distance between the tibial component and radiopaque markers in the proximal part of the tibial metaphysis that was reproducible to within one-half millimeter. Plain radiographs did not provide a reproducible measurement of this distance. The relatively simple technique of fluoroscopically guided radiography is recommended to detect the presence and progression of radiolucent lines and the subsidence of uncemented tibial components after total knee arthroplasty.

Aged↗
PubMed1988

Synovial macrophage response to aluminium oxide ceramic and cobalt-chrome alloy wear particles in rats.

The tissue response to intra-articular injection into rat knees of similar concentrations of sterile cobalt-chrome (Co-Cr) alloy and aluminium oxide (AL2O3) ceramic prosthesis wear particles was assessed at 1, 4 and 13 wk. A semiquantitative method of histological assessment showed a correlation between the numbers of particles and macrophage response in the tissues, and a difference in the response to different concentrations of Co-Cr particles. At 1 wk, the macrophage response to Co-Cr particles was significantly greater (p less than or equal to 0.01) than that to AL2O3 particles but no difference was detected at 4 and 13 wk. The difference may be due to necrosis of macrophages induced by Co-Cr particles.

Aluminum↗
PubMed1988

Long-term effects of intraarticular cobalt-chrome alloy wear particles in rats.

The long-term effects of cobalt-chrome alloy prosthesis wear particles were studied using intraarticular injection of particles into rat knees and killing the rats at regular periods from 1 week to 2 years following injection. The initial response was synovial ulceration, macrophage infiltration, and necrosis. A transient lymphocyte response was present at 1 week. Fibrosis of the subsynovium occurred subsequently at the sites of necrosis. A semiquantitative assessment of the number of particles and macrophages in the synovium demonstrated that the distribution of particles did not alter during the period from 1 week to 1 year. The macrophage response decreased between 1 and 2 weeks and then remained constant for 1 year. No tumors developed. This study emphasizes that cobalt-chrome wear particles and the associated macrophage response persist in the tissues for up to 2 years. The findings are relevant to the effects of wear of all designs of cobalt-chrome alloy prostheses.

Animals↗
PubMed1988

A rat model of resorption of bone at the cement-bone interface in the presence of polyethylene wear particles.

Resorption of bone and the formation of a membrane at the interface between acrylic cement and bone were induced by particles of high-density polyethylene that were similar in size to those that are present in the tissues surrounding a human joint prosthesis. A non-weight-bearing plug of methylmethacrylate was inserted through the knee joint into the distal part of the femur of the rat. The plug rapidly became surrounded by a shell of bone. After repeated injections of particles of high-density polyethylene into the knee joint, resorption of bone occurred at this stable interface. No resorption of bone occurred after the opposite knee was injected with a control preparation that did not contain particles. The resorption of bone that occurred around the plug after the injection of particles of polyethylene took place in the absence of mechanical causes for loosening and in the absence of infection.

Animals↗
PubMed1988

The synovial response to intraarticular cobalt-chrome wear particles.

The intraarticular effects of alloy wear particles similar in size to those present in the tissues around loose total joint prostheses were studied in rat knee joints injected with laboratory-prepared particulate cobalt-chrome. The particles induced rapid proliferation of macrophages and focal degeneration of synovial tissues similar to the response seen in the articular tissues around loose total joint prostheses in humans. Bacteriologic tests excluded infection as a factor. Wear particles may contribute to the changes in the tissues around total joint prostheses and may contribute to bone resorption resulting in prosthetic loosening. Experiments on animals provide useful information about the biocompatibility of materials used in the manufacture of total joint prostheses.

Animals↗
PubMed1983

Failure of ultrasound in the investigation of sciatica.

This paper reports a prospective study of the value of ultrasonography in detecting lesions of the lumbar spine in patients with compressive sciatica. The measurements of the diameter of the spinal canal obtained by using ultrasound were compared with the findings at operation in 17 patients in whom a total of 50 sites were examined. The ultrasound beam failed to penetrate the spinal canal at 15 sites and at only 10 of the remaining 35 sites did the ultrasound correctly detect narrowing. It is concluded that ultrasonography is unreliable in identifying the site of compression of the spinal cord and nerve roots. The technical limitations and the probable causes of failure of the technique are discussed.

Adult↗
PubMed1983

The technetium phosphate bone scan in the diagnosis of osteomyelitis in childhood.

We reviewed the technetium phosphate scans of 280 patients who had been referred with a clinical diagnosis of osteomyelitis in order to establish the diagnostic accuracy of this procedure. Strict criteria were established to define two subgroups: one of patients with proved osteomyelitis and one of patients who definitely did not have osteomyelitis. The scan correctly identified osteomyelitis at fifty-five of sixty-two sites, and was correctly negative in seventy-four of seventy-nine patients without osteomyelitis. The scan correctly distinguished all cases of cellulitis or soft-tissue abscess from osteomyelitis, but identified osteomyelitis in eight of thirty-nine patients with septic arthritis. The phosphate bone scan maintained this accuracy through any duration of symptoms, and performed almost equally well at all skeletal sites and in all age groups.

Abscess↗