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Biomedical subjects

R T Chiroff

Publications and source records attributed to R T Chiroff.

18 recordsLinked to original sources
PubMed1978

Bone changes induced by diphenylhydantoin in chicks on a controlled vitamin D intake.

Florid rickets developed in chicks receiving doses of diphenylhydantoin analogous to doses used in humans as anticonvulsants, vitamin D3 being given in amounts sufficient for normal bone mineralization in controls. The changes in the bones were directly related to the dose of diphenylhydantoin and inversely related to the dose of vitamin D3. Bone mineralization was assessed by roentgenography, histological examination, microradiography, and measurement of bone ash. Of these methods, roentgenography was the least sensitive. Rachitic changes were detectable by light microscopy and microradiography in chicks whose skeletons appeared normal roentgenographically. Roentgenographic evidence of rickets became detectable only when the rickets was far advanced. Rickets developed at serum levels of diphenylhydantoin similar to those found in patients taking anticonvulsant medication.

Animals↗
PubMed1977

The restoration of the articular surfaces overlying Replamineform porous biomaterials.

Replamineform porous implants (4 mm X 4 mm diameter) were placed into full-thickness cartilage and bone defects of the weight-bearing surface of the lateral femoral condyles of adult male white rabbits. These were analyzed at 1 day, 1 week, 6 weeks, 3 months, and 6 months for 1) ingrowth of tissue within the implants and 2) restoration of the articular surface overlying them. Appropriate unfilled, but similar, control defects were also studied. Mineralized bone was seen within the substance of both the TiO2 and hydroxyapatite implants at 1 week; this extremely rapid response was present in every specimen studied and was not seen with alphaAl2O3 or control animals. With the passage of time, maturation of this bone ingrowth occurred so that by 3 months, they were all incorporated into the surrounding bone. Only the hydroxyapatite implants showed consistent regenerative healing of hyaline articular cartilage from the margins of the defects with the passage of time; this occurred whenever the subchondral bone adjacent to the defect proliferated in a "creeping" fashion over the articular aspect of the implant, and the undamaged cartilage then followed it. Fibrocartilage, and not hyaline cartilage, formed the articular surface over the TiO2 and alphaAl2O3 implants and in the controls.

Aluminum↗
PubMed1977

A new technique for the treatment of comminuted, transverse fractures of the patella.

In an attempt to re-establish continuity of the quadriceps mechanism following partial patellectomy more securely in patients with comminuted, transverse fractures of the patella, a technique whereby the patellar ligament is inserted into a transverse groove created in the proximal patellar fragment and this anastomosis is then protected by a tension band wiring, is described and depicted. Using this method, it is possible to provide a larger surface area fro more satisfactory tendon to bone healing and to initiate relatively early motion of the knee, without compromising the site of reconstitution of the extensor mechanism.

Fracture Fixation, Internal↗
PubMed1976

Discontinuity of the spinous process on standard roentgenographs as an aid in the diagnosis of unstable fractures of the spine.

It has been observed that discontinuity in the outline of the spinous process on standard anteroposterior radiographs is a characteristic finding in some unstable spine fractures. Since the spinous processes are often not depicted clearly on lateral views of the trauma victim's spine, these are less reliable; however, if a transverse fracture through the spinous process at the level of, or adjacent to, an anterior compression fracture is demonstrable, this confirms the unstable nature of the injury. Recognition of this sign, when present, may eliminate excessive pretreatment manipulations in some patients who have sustained major trauma and are suspected of having unstable spine fractures.

Accidents, Traffic↗
PubMed1976

Operative and non-operative treatment of rachitic lower extremity deformities. A long term study with forty-six year average follow-up.

The long term sequelae of rachitic deformities includes degenerative arthritis. Surgery at an early age will be beneficial in preventing degenerative arthritis in children with severe deformities. Of the many metabolic processes involved with Vitamin D, there must be some that vary quantitatively so that a small alteration may produce rickets in one child, go completely unnoticed in another, and persist in still another as a subclinical disease. Furthermore, it is entirely probable that some children then diagnosed as having classical D-deficiency rickets, in fact, would now be found to have D-resistant states.

Child, Preschool↗
PubMed1975

Replamineform porous biomaterials for hard tissue implant applications.

By means of the newly developed Replamineform process, the unique pore microstructures found in the skeletal calcium carbonate of certain reef corals can be replicated or reproduced with high precision in a wide variety of materials suitable for hard tissue implant and prosthetic applications. The advantages of fabricating porous biomaterials with this method include closely controlled size of both the pore diameters and the diameters of the pore interconnections, and virtually complete interconnection of the uniformly spaced pores. These properties are of great importance in implant devices, because tissue ingrowth, the stimulation of new bone formation, the suppression of undesirable scar tissue, the inhibition of adverse body responses, and firm biological fixation of the implanted material all depend upon the nature of the pore-microstructure configuration. Replamineform preparation of Al2O3, TiO2, hydroxyapatite, silver, Co-Cr-Mo alloys, and polymers is described in detail, and the characterization procedures used to determine the physical and structural properties of their materials are discussed. A few of the routinely measured characteristics include (1) quantitative computerized SEM image analysis for determining the volume, size and shape distributions of the macro and microporosity and the grain size measurement of the solid; (2) nondestructive x-radiography of specimens to reveal any internal defects; (3) mechanical strength measurements of randomly selected specimens. Experimental results up to now clearly demonstrate the superiority of microstructures imparted to metals, ceramics, and polymers with the Replamineform process.

Aluminum↗
PubMed1975

Tissue ingrowth of Replamineform implants.

The Replamineform process, a new technique for the fabrication of porous hard tissue implant materials which replicates the skeletal configuration of certain marine invertebrates, was used to manufacture 1 cm long by 0.5 cm diam cylinders. The inherent advantages of porous configurations obtained through this process are controlled, uniform pore size, controlled pore-microstructure ratio, and complete interconnection of pores. The specific materials studied were chrome-cobalt-molybdenum alloy, alphaA103, hydroxyapatite prepared by hydrothermal conversion, and the basic (aragonite) CaCO3 skeleton of the coral genus Porities. The implants were placed in the canellous bone of the distal femora and proximal tibiae of adult, mongrel dogs and analyzed at 8 weeks for tissue response and ingrowth. Uniformly, new bone was found to grow into the pores of these materials and become normally mineralized. These findings were determined by microradiography, scanning electron microscopy, electron microprobe analysis, and histology. No evidences of infection, rejection, or encapsulation were seen. In the case of those CaCO3 implants left in place for 1 year, there was almost complete resorption of the cylinders, with both bony trabeculae and unmineralized collagen (presumably osteoid) found at the sites of insertion.

Aluminum↗
PubMed1975

Experimental replacement of the anterior cruciate ligament. A histological and microradiographic study.

In each of four dogs, teno-osseous autogenous grafts were used to reconstruct the anterior cruciate ligament. The transplanted strips first underwent ischemia and cellular death, with necrosis of both bone and tendon. Ingrowth of tissues then occurred rapidly, but complete incorporation of the tendon or the bone did not occur at one year. However, the tunnel-to transplant bone was functional and provided sufficient stability to the knee so that disruption of the reconstructed anterior cruciate ligament did not occur.

Animals↗
PubMed1975

Osteochondritis dissecans: a histologic and microradiographic analysis of surgically excised lesions.

The excised fragments of six osteochondritis dissecans lesions of the lateral aspect of the medial femoral condyle were found to be composed of viable hyaline articular cartilage over-lying a totally cellular, metabolically active ossific nucleus, which in turn rested in a bed of fibrocartilage. At the interface between the fibrocartilage and the bone, enchondral ossification was seen histologically and verified by microradiographic evidence of bone formation and resorption. The present authors propose that this classical dissecans lesion is a reparative process and, in most cases, will proceed to complete union of the ossific nucleus with the remainder of the bone of the femoral condyle.

Adolescent↗
PubMed1974

Diphenylhydantoin: effects on calcium metabolism in the chick.

Rickets, hypocalcemia, decreased duodenal calcium transport, and reduction of calcium binding protein have been produced in chicks treated with diphenylhydantoin. These effects are directly related to diphenylhydantoin dose and inversely related to the intake of vitamin D(3) (cholecalciferol).

Animals↗
PubMedDate not supplied

Diffuse pigmented villonodular synovitis. An indication for total hip replacement in the young patient.

Diffuse pigmented villonodular synovitis of the hip is a special problem because in this location it uniformly results in severe bony and cartilaginous destruction of the joint. In 2 cases treated by total hip replacement, both were successful at periods longer than 1 and 3 years follow-up with no evidence of recurrence of the disease, prosthetic failure, loosening, or any other complication despite the patients' young age and extremely active life styles. Continuous follow-up and frequent admonition about the wear erosion and recurrences of the synovitis is an essential part of the aftercare of these patients.

Adolescent↗