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Biomedical subjects

E L Radin

Publications and source records attributed to E L Radin.

At least 73 records · Page 4Linked to original sources
PubMed1982

Wear of polyethylene in the total hip prosthesis.

Direct in vivo measurement of wear of total hip prostheses by radiography is not possible. However, improved in vitro approaches have been developed that agree with clinical observations in all salient points. Such measurements show that the wear of the polyethylene component depends crucially on the molecular weight distribution (and probably on other structural variables). Combined with clinical retrievals, there is evidence that relatively high wear may occur even in the absence of acrylic debris. Although sufficient knowledge exists to reduce wear of the total hip prosthesis to a negligible level, for the total knee replacement with higher contact stresses, presently, this is not the case.

Equipment Failure↗
PubMed1982

Changes in the bone-cement interface after total hip replacement. An in vivo animal study.

UNLABELLED: In order to study the temporal sequence of radiographic, histological, mechanical, bacteriological, and chemical changes around the femoral component following total hip replacement, a model was created by implanting plastic-on-metal total hip replacements in sheep and walking the animals on a concrete surface beginning six weeks postoperatively. This model demonstrated a decreased torsional rigidity between the prosthesis and the femoral cortex in all sheep. Failure of bonding occurred at the bone-cement interface and appears from our results to be most probably due to alterations in the functional stress of the proximal end of the femur following insertion of the femoral component rather than exothermic polymerization, toxicity of free monomer residue, or infection. CLINICAL RELEVANCE: An understanding of the causes of loosening of cemented metal femoral components in total hip replacement has been thwarted by a lack of specimens at sequential times in the loosening process. Since a patient is not operated on until the prosthetic components are completely loose, such specimens are difficult to obtain clinically. For this reason a model for examining the bone-cement interface, measured by decreased torsional rigidity of the prosthesis relative to the bone, was developed in sheep. Of all the parameters studied, those inherent in the effects (mechanical or vascular, or both) of insertion of the prosthesis itself appeared to be the most likely cause of the change in the mechanical properties of the interface. This suggests that degenerative changes of the bone-cement interface may be inevitable.

Animals↗
PubMed1981

The lubricating activity of synovial fluid glycoproteins.

Friction measurements were performed on fractions prepared from bovine synovial fluid by using a cartilage on glass apparatus. A fraction containing lubricating glycoprotein-I (LGP-I) as the only detectable component at concentrations of 30-50 microgram/ml was able to lubricate in an identical manner to whole synovial fluid. These data indicate that LGP-I is th molecule responsible for the lubricating ability of synovial fluid. 125Iodine-labeled LGP-I also lubricated in a manner similar to synovial fluid, whereas when this sample was reduced and alkylated or treated with neuraminidase, the lubricating activity was greatly decreased. In tests to measure binding of 125I LGP-I to cartilage, an initial linear increase in binding was observed, followed by a decrease in binding at higher concentrations. In contrast, both the reduced and alkylated and the neuraminidase treated samples did not show the same concentration-dependent binding to the cartilage. It is suggested, therefore, that at least part of the lubricating ability of LGP-I is dependent upon its ability to bind to articular cartilage.

Amino Acids↗
PubMed1980

Biomechanics of the human hip.

The hip joint is one of the body's most amenable joints to a lowering of its interarticular pressure by surgery. It has been shown that such a lowering of pressure can predictably have a significant amelioratory effect on osteoarthrotic degeneration. A workable understanding of the biomechanics of the hip is essential in the planning of any meaningful orthopedic intervention to attempt to delay or reverse hip joint degeneration.

Animals↗
PubMed1979

A rational approach to the treatment of patellofemoral pain.

Chondromalacia of the patella should be considered a separate entity and not the necessary precursor of osteoarthrosis. It is rarely associated with significant discomfort. Isolated softening, fibrillation of the central medial facet, and a diagnosis of chondromalacia of the patella should be limited, in our view, to isolated fibrillation occurring in the central medial facet and is probably asymptomatic. Symptomatic patellar pain can be treated by realignment if the patella is malaligned, by lateral release and synovial fringe excision if there is an anomalous facet or synovial fringe entrapment syndrome, and by drilling and curettage and stress-relieving operations (if necessary) if there is an osteochondral injury. For osteoarthrosis stress can be relieved on a permanent basis by the Maquet anterior tibial tubercle advancement operation. We recommend approaching patellofemoral pain by establishing a specific diagnosis and applying a specific treatment.

Cartilage Diseases↗
PubMed1979

Chondromalacia as a separate entity: new perspectives on osteoarthrosis.

Cartilage fibrillation does not necessarily progress. There appears to be different mechanical factors involved in the initiation and the progression of cartilage changes in osteoarthrosis. This means there is some rationale behind what we see clinically happening after successful osteotomy or other operations that lower the stress on degenerating joints, and it means that if we can do something about the level of stress and, therefore, the level of bone remodeling in patients with fibrillation, we may be able to keep that cartilage from further degenerating.

Adult↗
PubMed1978

Is chondromalacia patellae a separate clinical entity?

The articular cartilage of the patella was studied in 100 knees at necropsy. In twenty-one of these knees the cartilage changes were related to the trabecular architecture of the underlying bone. It would appear that the initiation and location of cartilage damage and its rate and degree of progression are related to the relative stiffness of the underlying cancellous bone. On the basis of our observations we suggest that the diagnosis "chondromalacia of the patella" should be reserved for patients with asymptomatic or transiently symptomatic fibrillation of the articular cartilage of the central medial patellar facet. Those patients with persistent patellofemoral pain should be considered to have some other syndrome.

Cartilage Diseases↗