Biomedical subjects

R Bloebaum

Publications and source records attributed to R Bloebaum.

5 recordsLinked to original sources

PubMed1996

Osseointegration and growth effects of temporal bone percutaneous pedestals.

The percutaneous temporal bone pedestal has shown significant utility for the attachment of bone-anchored hearing aids, attachment of cosmetic auricular prostheses, and as connector between external sound processors and implanted cochlear implants. The biological acceptance of these implants by temporal bone hosts is affected by many factors including the maturity of the bone, the design of the pedestal-fixation system, and the pedestal-construction material. The first phase of this study evaluated the effect of the pyrolized graphite pedestal fixation on maturing temporal bones. Pedestals were implanted in young swine temporal bones using single screw and multiple screw fixation systems. The effect on temporal bone growth is demonstrated with photomicrographs and gross photography showing acceptable host-tissue response to the presence of multiple and single screw attachment techniques. Osseointegration of the attaching screws occurred. The second phase of the study evaluated osseointegration of smooth, beaded, and textured titanium pedestals in feline temporal bones. High-resolution temporal bone/pedestal sectioning has been accomplished with high-performance microtomes, showing the osseointegration of the pedestal by the temporal bone. This is demonstrated with tetracycline labeling and histologic assessment. Percutaneous pedestals are of increasing importance in otologic practice. This study assists in the understanding of biologic acceptance of pedestals as influenced by the pedestal composition and fixation design. This basic understanding is essential for design improvements in percutaneous temporal bone pedestals.

Animals↗

PubMed1996

Modern metal on metal articulation for total hip replacements.

Between 1991 and 1994, 70 patients received total hip replacements with metal on metal articulation. The results of 54 of these patients with 54 hips who have a 2- to 4-year (2.7-year average) followup are reported. Patients were prospectively evaluated using the Harris hip score, a patient self assessment form, and radiographs. Hip aspiration was performed preoperatively and 6 to 24 months postoperatively in 24 hips with metal on metal articulations. Implant retrieval was obtained from 2 patients. Harris hip score averages increased from 49 to 93. No patient had revision surgery for loosening, but 1 had revision surgery for dislocation. Patient self assessment forms showed 51 of 54 patients scored their results as good or excellent. Serial radiographs did not show loosening or osteolysis. Wear could not be measured radiographically. Synovial fluid samples had metal particles of 1 to 10 microm in 10 hips. Twenty patients had bilateral total hip replacements with 1 hip metal on polyethylene articulation, and patients could not determine any difference between the hips. Compared with historic results of previous metal on metal prostheses, the modern metal on metal articulation investigated in this study did not have early acetabular loosening or clinical symptoms of component impaction. Retrieval implants and synovial fluid analysis suggest early wear was minimal.

Adult↗

PubMed1994

Materials testing protocol for small joint prostheses.

In this article, a protocol for the evaluation of new materials for small joint prostheses is introduced. The testing methods employed in the protocol were developed by reviewing reported clinical failure modes and conditions found in vivo. The methods developed quantitatively evaluates the fatigue, fatigue crack propagation, and wear resistance properties of materials. For this study, a silicone elastomer similar to Dow Corning Silastic HP100, a radiation stable polypropylene, and a copolymer of polypropylene and ethylene propylene-diene monomer (EPDM) are evaluated. None of the materials tested demonstrated the ideal properties that are sought in a self-hinging joint prostheses. The silicone elastomer had excellent wear properties; however, cracks quickly propagated, causing catastrophic failure when fatigued. Conversely, the copolymer showed excellent fatigue crack propagation resistance and less than favorable wear properties. The polypropylene did not perform well in any evaluation.

Biocompatible Materials↗

PubMed1990

Histologic, biochemical, and ion analysis of tissue and fluids retrieved during total hip arthroplasty.

Large amounts of metal and polyethylene debris and high ion readings are found in capsule and fibrous membranes of both loose titanium and cobalt-chromium stems. Prostaglandin E2, interleukin-1, and collagenase levels are elevated when compared to control values with collagenase having the highest and most consistent elevations. Synovial fluid and blood ion readings were elevated in loose cemented and cementless stems made from both materials. Blood ion readings were not elevated in fixed stems. Fixed stems had much less particulate debris in soft tissues. The data showed that failure of most metal hip stems was initially due to a mechanical cause, with high debris and ion counts occurring secondarily in capsule and fibrous membranes. Particulate debris and high ion readings are primarily a focal problem contained by the periprosthetic fibrous connective-tissue encapsulation within the femoral canal and joint capsules. No systemic problems were manifest in any of the patients examined and followed in this study.

Aluminum↗

PubMed1988

Synovial fluid osmolality in osteoarthritis and rheumatoid arthritis.

The osmolality of synovial fluid aspirated from the knees of 15 rheumatoid and 15 osteoarthritic patients was observed concurrently with the same measurement on blood serum. The group averages were compared to a group of 13 with identical apparati. Synovial fluid osmolality in rheumatoid arthritics (280 +/- 7.7 mmol/kg) was significantly different from that in osteoarthritics (297 +/- 16.9 mmol/kg), and both group averages were significantly different from normal (404 +/- 57 mmol/kg). Blood serum osmolality also differed between the normal and the two arthritic groups. The potential application of vapor pressure osmometry techniques in the diagnosis and management of joint disease is discussed.

Aged↗