Biomedical subjects

R D Bloebaum

Publications and source records attributed to R D Bloebaum.

64 records · Page 4Linked to original sources

PubMed1989

Histological analysis of a central tarsal implant in a racing greyhound.

The hock of a greyhound containing a titanium alloy central tarsal replacement was examined histologically. The animal had raced competitively 43 times before retirement. The examination showed that the adaptation and encapsulation of the implant by the surrounding bones, together with the excellent purchase of the screw into the fourth tarsal bone, had maintained the implant in excellent position during vigorous load-bearing. There was no histopathological evidence to suggest that the fixation of the implant was failing. The results provide evidence for the value of titanium alloy implants as a central tarsal replacement in greyhounds with type V fractures, and as a feasible alternative to euthanasia.

Animals↗

PubMed1988

Central tarsal implant in a racing greyhound.

Although most type IV fractures in dogs can be treated with screw fixation, type V fractures usually lead to an unsuccessful clinical result. A central tarsal replacement composed of a titanium alloy was developed by our investigation team to treat type V fractures. The implant was used to successfully treat a greyhound and to allow it to return to racing. Continual development of this new surgical procedure hopefully will give the veterinarian predictable and reliable clinical results and return injured greyhounds to active racing.

Animals↗

PubMed1987

A polymethyl methacrylate method for large specimens of mineralized bone with implants.

A simple modified polymethyl methacrylate method is described for large mineralized bone specimens with implants and bioactive materials which produces consistently good histological preservation of the interface between bone and implant. Human femoral heads, whole rabbit condyles and canine tibias and femurs containing implants consisting of hydroxyapatite, smooth polyethylene, porous polyethylene and carbon were dehydrated in ascending grades of ethanol and cleared with xylene on an automated tissue processor which alternated vacuum and pressure for 22 hr. Infiltration was done with washed polymethyl methacrylate at 4 C under vacuum for 13 days. Polymerization was carried out in wide-mouth glass jars at 38 C for 36 hr so that the total processing time was less than 20 days. The only important modification was in the polymethyl methacrylate, which had less plasticizer than usual in order to give a harder block. This enabled production of 4 micron sections with good preservation of mineralized and cellular areas for the study of metabolic bone diseases, morphometry, fluorochrome labelling and interface analysis with the implant in situ.

Animals↗

PubMed1985

Normal human synovial fluid: osmolality and exercise-induced changes.

We measured the osmolality of human synovial fluid in the knees of healthy young adults following minimum activity and exercise. These results were compared with each subject's blood-serum osmolality. The synovial fluid was hyperosmolal with minimum activity, decreasing to blood-serum levels after exercise.

Adult↗

PubMed1980

The morphology of the surface of artcular cartilage in adult rats.

Articular cartilage from the weight-bearing area of the femoral concyles in adult rats is smooth in the normal, non-weight-bearing condition, showing none of the surface irregularities (8-15 micrometer) reported by previous authors. Demonstrable changes in the surface characteristics of articular cartilage may be attributable to preparation procedures. The normal smoothness observed in TEM studies has been confirmed by an SEM method. 'Quarternary ridges' described as evidence of ageing may be analogous to 'wrinkles' observed on the surface cartilage exposed to ambient atmospheric conditions.

Animals↗

PubMedDate not supplied

Influence of topography and specimen preparation on backscattered electron images of bone.

Backscattered electron (BSE) images of bone exhibit graylevel contrast between adjacent lamellae. Mathematical models suggest that interlamellar contrast in BSE images is an artifact due to topographic irregularities. However, little experimental evidence has been published to support these models, and it is not clear whether submicron topographical features will alter BSE graylevels. The goal of this study was to determine the effects of topography on BSE image mean graylevels and graylevel histogram widths using conventional specimen preparation techniques. White-light interferometry and quantitative BSE imaging were used to investigate the relationship between the BSE signal and specimen roughness. Backscattered electron image graylevel histogram widths correlated highly with surface roughness in rough preparations of homogeneous materials. The relationship between BSE histogram width and surface roughness was specimen dependent. Specimen topography coincided with the lamellar patterns within the bone tissue. Diamond micromilling reduced average surface roughness when compared with manual polishing techniques but did not significantly affect BSE graylevel histogram width. The study suggests that topography is a confounding factor in quantitative BSE analysis of bone. However, there is little quantitative difference between low-to-moderate magnification BSE images of bone specimens prepared by conventional polishing or diamond micromilling.

Animals↗

PubMedDate not supplied

Thermal effects of the electron beam and implications of surface damage in the analysis of bone tissue.

Electron beam interactions with specimens in the scanning electron microscope (SEM) can lead to increased surface temperatures and damage. These changes may have significant consequences in the analysis of bone tissue. An investigation was performed to measure the surface temperature changes associated with the electron beam on a thermocouple with systematic variations in operating conditions. Probe currents, magnifications, and accelerating voltages were incrementally adjusted to measure the temperature changes and to make assessments for determining optimal operating conditions for the SEM in future analyses of bone tissue. Results from this study suggest that thermal effects were minimal at lower accelerating voltages (< 20 kV), lower probe currents (< 10 nA), and lower magnifications, but surface damage may still occur during the analysis of bone tissue.

Animals↗

PubMedDate not supplied

Cortical aging differences and fracture implications for the human femoral neck.

Clinical imaging techniques cannot consistently identify individuals at risk for hip fracture. Individual differences in falling likelihood partly account for these inconsistencies, but it is also thought that microscopic bone changes may play a role. In this study, subcapital, mid-neck, and trochanteric sites from eight young adult (26 +/- 7 years) and nine older (63 +/- 3 years) males were studied using backscattered electron imaging to identify age-related microscopic structural and mineral changes around the cortex. Cortical bone volume (BV(Ct)/TV), cortical void volume (Vd.V(Ct)/TV), hypermineralized bone volume (BV(H-min)/TV), the number of osteons/mm2 (N.On/B.Ar), lacunae/mm2 (N.Lc/B.Ar(Ct)) in the cortex, lacunae/mm2 (N.Lc/B.Ar(H-min)) in the hypermineralized phase, and cortical thickness (Ct.Th) were measured at subcapital, mid-neck, and trochanteric levels. Cortical void volume showed no differences (P = 0.26) between levels in the younger group, but differences (P < 0.05) were observed in the older group, indicating locational osteopenic differences. Cortical thickness differences were greater at the subcapital (27.7%) and mid-neck (25.2%) levels than at the trochanteric level (10.5%). Both age (P = 0.0022) and level-location interaction (P < 0.0001) influenced the hypermineralized bone volume present, with larger hypermineralized regions generally occurring at the thinner superior locations. Significant (P < 0.05) lacunar differences with aging in the hypermineralized phase suggest a necrotic origin. Artifactual cracks occurred preferentially within the hypermineralized phase, indicating localized reductions in fracture toughness, which may provide a site for crack initiation following an impact.

Adult↗

PubMedDate not supplied

Aging changes in osteon mineralization in the human femoral neck.

Age-related mineral changes are associated with material property changes in cortical bone, which may affect its ability to transmit loads and resist fracture from falling. Aging changes in the mineral content of the femoral neck cortical bone are partly determined by osteonal remodeling events. The objective of this study was to measure mineral differences within the osteonal unit in the human femoral neck. In this study, cadaveric femora from male caucasians of two age groups (25 +/- 7, n = 6; 64 +/- 4, n = 6) were sectioned at the midfemoral neck. Using backscattered electron imaging, osteons from each of eight circumferential cortical regions were analyzed to determine osteonal mineral differences between regions, between the two age groups, and due to radial location within the osteons. Graylevel values from the backscattered electron imaging method were calibrated in equivalent ash content (wt%) units to provide a better understanding of the magnitude of differences observed. A pattern (p < 0.05) of decreasing osteonal mineralization was observed with distance from the central Haversian canal. Additionally, osteonal mineralization was highest in the superior (most lateral) regions of the femoral neck from both age groups, indicating that circumferential location is an influencing factor. The average overall equivalent ash content of osteons from the 17-35-yr group was 59.4 +/- 0.4% (mean +/- SE) by weight, while osteons of the group aged 60-71 measured 52.0 +/- 0.4% equivalent ash content, a decrease of 12.4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Short-term effects of knee washout for osteoarthritis.

Twenty-nine knees in 23 patients with symptomatic osteoarthritis underwent washout with lactated Ringer's solution. Two arthroscopic cannulas were placed into the knee under local anesthetic. Three liters of fluid were run through the knee using varying inflow and outflow to alternately inflate and deflate the knee. We obtained Hospital for Special Surgery knee scores, Knee Society pain and function ratings, and visual analog pain scales before washout and up to 2 years after washout. At 1 year, the mean Hospital for Special Surgery score increased from 72 to 87, the Knee Society pain rating from 64 to 89, and the Knee Society function rating from 62 to 82. Twenty-five knees had a good or excellent result at 1 year. Twenty-one of these were observed at 2 years; 17 had good or excellent results. This study confirms the value of a fluid washout in an arthritic knee for some patients. This may explain some of the symptom relief seen with arthroscopic procedures in this condition.

Adult↗