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Biomedical subjects

R J Minns

Publications and source records attributed to R J Minns.

At least 55 records · Page 3Linked to original sources
PubMed1982

The repair of osteochondral defects in osteoarthritic rabbit knees by the use of carbon fibre.

Implants of carbon fibres and carbon fibre patches were tested for their biocompatibility in osteochondral defects in rabbits with instability induced knee osteoarthrosis. The resulting repairs were compared to control holes in which no implant was inserted. There was no apparent biodegradation when fibre bundles were implanted for periods from 2 to 18 weeks, and the carbon fibre patches appeared to induce the gross appearance of a restored joint surface, mechanically strong to loading for periods from 2 to 26 weeks. Also carbon fibre in the form of a patch promoted the healing of the osteochondral defects in osteoarthritic femora with well organised fibrous tissue over repaired subchondral bone. The use of these carbon-fibre patches is suggested as an implant material for the restoration of articular surfaces in osteoarthritis.

Animals↗
PubMed1982

The role of the meniscus in an instability model for osteoarthritis in the rabbit knee.

After division of the cruciate ligaments and one meniscus in the knee joint of the rabbit, degenerative changes were observed in both the articular cartilage and bone. This was more apparent on the tibial plateau in which the meniscus had been removed, progressive changes occurring from 3 to 16 weeks after trauma. A parallel in vitro experiment, involving measuring the lateral displacement of the tibia in the rabbit knee during medial-lateral leading, was performed before and after transverse division of the meniscus alone. The resulting displacements during medial-lateral shear loading approximately doubled after meniscectomy in the mechanical tests, the apparent clinical stability still being provided after meniscus division by the collateral ligaments, joint capsule, cruciates and bone geometry.

Animals↗
PubMed1980

Local denaturation of collagen fibres during the mechanical rupture of collagenous fibrous tissue.

Human extensor tendons of the hand were pulled to rupture, and the torn ends, when observed in the scanning electron microscope, appeared to be knotted, possibly owing to the denaturation of the collagen. This confirmed by fluorimetry assays of both the ruptured ends and the middle unbroken sections of the same tendons. The use of a proteolytic enzyme, trypsin, to remove the denatured material and enhance the repair of organised collagen fibres from both ends is suggested if the ruptured ends have the denatured knotted appearance commonly observed clinically.

Adult↗
PubMed1979

Computed tomography and biomechanical analysis of fossil long bones.

Computerized transverse axial scanning (computed tomography) is a relatively new radiographic technique designed to recover precise cross-sectional images (tomograms) of 3-dimensional objects. This highly sensitive process permits tissues of similar density to be separated and displayed unambiguously. These special features are, therefore, ideal for analyzing the cross-sectional geometry of intact fossil long bones, even when they are highly mineralized and their medullary cavities are occluded by matrix. In order to demonstrate the utility of this method in assessing the complex relationship between fossil structure and probable function, geometrical and biomechanical properties of midshaft tomograms of femora and tibiae have been analyzed for a comparative primate sample consisting of Megaladapis edwardsi (an extinct giant prosimian from Madagascar), Indri indri (the largest extant prosimian), and Homo sapiens.

Animals↗
PubMed1979

Design and evaluation of a low cost columnar flow ventilation scheme in an operating theatre.

A plenum chamber type ventilating system which produces a column of clean filtered air in an orthopaedic operating theatre has been designed using conventional air conditioning equipment. Its performance has been evaluated by carrying out smoke studies, and air velocity studies, and its cleanliness evaluated by bacteriological sampling. Two hundred and fifty operations involving implants have been conducted since this system has been installed, and the infection has been zero. This paper reports on the performance of this low cost ventilating system.

Air Microbiology↗
PubMed1978

Intra-articular implant of filamentous carbon fibre in the experimental animal.

The effects of filling drilled holes and articular cartilage grooves in rabbit femora with 9 micrometer diameter filamentous carbon fibre in vivo were studied. The animals were killed at four weeks and five months and the medial and lateral femoral condyles removed and studied morphologically by gross and scanning electron microscopic examination, and histologically using hematoxylin and eosin, van Gieson, toluidine blue and safranin O staining techniques. Fibrous tissue appeared to surround the carbon fibre bundle and emerge at the surface in large organised bundles, overflowing to cover the surface adjacent to the hole defects. Fibrous tissue surrounds the carbon fibre bundle, and forms a new surface over grooves made in the articular cartilage of rabbits that were kept alive for five months, the tissue within the control grooves filled with disorganised fibrous tissue. There was very little foreign body reaction and the fibrous tissue appeared to grow parallel and surround the carbon fibre bundle.

Animals↗
PubMed1977

Osteoarthrotic articular cartilage lesions of the femoral head observed in the scanning electron microscope.

A topographical study of the articular surface of 21 femoral heads removed for surgery of osteoarthrosis was made using the scanning electron microscope. Sections of degenerate cartilage were pretreated with H2O2 and trypsin to reveal the collagenous framework. Torn and frayed collagen bundles were evident on all the specimens studied, the length of these bundles varying from 20 to 150 micron. The frequency of the bundles over the degenerate fibrous areas varied considerably, and bundle sizes ranged from 20 to 70 micron. The topography of a single femoral head removed from a rheumatoid arthritic was very much smoother, with torn fibre ends ruptured at the same level. Although the exposed bone was considerably "smoother" than the residual fibrocartilage, ruptured osteons and trabeculae revealed large voids in the surface which would presumably alter the lubrication and fluid flow characteristics of the functioning joint. The effects of these changes on joint tension and lubrication are discussed.

Aged↗
PubMed1977

Preliminary report of a compression technique to apply tension to sliding bone grafts in tibial shaft fractures.

A new compression device is described that applies tension to sliding bone grafts on the medial aspect of the tibia in tibial shaft fractures. The mechanical aspects of the operation are outlined and the advantages and disadvantages of the system discussed. There have been no complications and rigidity has been obtained in two clinical cases. Mechanical tests in bending and torsion show that rigidity can be obtained without breaking the graft.

Bone Transplantation↗
PubMed1977

The effect of calcium on the mechanical behaviour of aorta media elastin and collagen.

Mechanical tests were conducted on rings of pig thoracic aorta that had been treated with calcium ions to evaluate their effect on aorta media collagen and elastin. There was an increase in stiffness just before rupture and a decrease in storage energy when calcium was introduced into intact rings, but there was no significant difference in mechanical properties when it was introduced into the elastin framework of the media. The calcium was able to bind to the intact aorta media far more readily than to the elastin alone, suggesting that the collagen and muscle framework were far more susceptible to the introduction of calcium than elastin. The calcium content rose along the length of the aorta, as did the collagen content, whilst the elastin content fell, which was also reflected in the change in mechanical properties along the aorta.

Animals↗
PubMed1977

The collagen fibril organization in human articular cartilage.

In this scanning electron microscopic study blocks of collagen fibrils were prepared from human articular cartilage, using two techinques which selectively removed either the proteoglycans alone, or both the proteoglycans and the collagen fibrils, of the non-calcified cartilage layer. Amino acid analysis of the fibrils confirmed the purity of the collagen after proteoglycan extraction. The cartilage was scanned in four different ways: (1) normal to the articular surface, (2) in superficial sections, (3) on surfaces of blocks which had been broken in planes parallel to artificial splits make by the insertion of a pin, and (4) on fracture surfaces which traversed the calcified cartilage and the subchondral bone. Five features of the organization of the collagen fibrils were specially noted: (1) Individual fibrils within the trabeculae joined to form small fibre bundles which became grouped into larger bundles at the calcified/uncalcified interface. (2) Fibrils in the deep and middle zones which, exhibiting the characteristic surface periodicity of collagen, were generally oriented towars the articular surface in large bundles approximately 55 micronm across. (3) In the superficial zone, fibrils ran parallel to the surface. (4) The surface fibrils had random orientation, even at the bases of empty lacunae vacated by chondrocytes during specimen preparation. (5) The collagen fibrils of the lacunar walls appeared to be thinner and more closely packed than thos between the lacunae. The fine collagen fibrils associated with the lacunar walls were frequently observed to pass through a large lacunar space, resulting in the formation of two or more compartments, each of which was presumably filled with a chondrocyte in the living cartilage.

Adult↗