Biomedical subjects

R Bloebaum

Publications and source records attributed to R Bloebaum.

3 recordsLinked to original sources

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↗