PubMed Health⌕ Search

Biomedical subjects

H K Uhthoff

Publications and source records attributed to H K Uhthoff.

At least 91 records · Page 5Linked to original sources
PubMed1983

The effects of metal plates on post-traumatic remodelling and bone mass.

The long-term effect of stainless steel and titanium alloy plates on structural remodelling and bone mass of osteotomised canine femora was studied and the effects of early and late removal of plates were compared in 27 adult Beagles. Radiological, histological, histomorphometric and tetracycline fluorescence studies led to three conclusions. First, the continuous (60 weeks) presence of plates, irrespective of their composition, delays remodelling and leads to a reduction of bone mass. This loss is significantly greater under stainless steel plates. Secondly, the removal of plates at eight weeks leads during the 52 ensuing weeks to a marked and widespread structural remodelling and to a return to normal bone mass, irrespective of the type of plate used. However, remodelling is more intense after titanium alloy plates have been used; it is not complete 60 weeks after osteotomy. Thirdly, removal of plates at 40 weeks activates remodelling during the ensuing 20 weeks to a lesser degree and to a more limited extent than early plate removal. The clinical significance of this study is that less rigid but stable internal fixation permits the radiological assessment of healing and thus the determination of the optimal moment for removal of the plates. It also reduces the degree of bone loss should the plate be left in situ for any reason.

Alloys↗
PubMed1983

Coronal cleft of vertebrae, a variant of normal enchondral ossification.

In 157 spontaneously aborted human embryos and fetuses the incidence and evolution of coronal cleft formation was investigated radiologically and histologically. Complete clefts were formed in nine cases and incomplete clefts in 16 cases. There was a predominance of males. It is concluded that coronal clefts are variations of normal enchondral ossification and that the notochord plays no role in its pathogenesis. Coronal clefts seen on radiographs of newborn should not be interpreted as a malformation. Thus no preventive or treatment regimen is indicated.

Abortion, Spontaneous↗
PubMed1982

Rotator cuff tears: the role of surgery.

The indications for operative intervention in patients with rotator cuff tears and the reasonable expectations of such surgery are not well defined. This retrospective study of 37 such patients treated operatively at Ottawa General Hospital showed good results in 65% of cases. However, efforts to re-establish continuity of the cuff did not always result in a permanent cuff reconstruction. The persisting defect did not impede functional recovery as long as the edges of the tear were debrided along with division of the coracoacromial ligament, acromioplasty, or excision of osteophytes at the greater tuberosity. Impingement plays a major role in the disability associated with this condition.

Adult↗
PubMed1982

[Significance of density and demarcation of calcifications in calcifying tendinitis (author's transl)].

Calcification of tendons can be either degenerative and progressive in nature or reactive and selfhealing. Radiologic examinations permit to distinguish between both kinds. The reactive calcification, known also as calcifying tendinitis, passes through two main phases, the formative and the resorptive phase. Since treatment is different for each phase, their roentgenologic distinction is important. Dense, well demarcated and homogenous calcifications indicate the presence of a formative phase whereas less dense, ill defined and fluffy deposits point toward an ongoing resorption.

Calcinosis↗
PubMed1982

Epiphysiolysis, a possible cause of limb deformities in lambs.

The process of enchondral growth of long bones of four three month old lambs raised in total confinement and showing bowed forelimbs was investigated. The results, based on radiologic, histologic, and fluorescence microscopic examinations were compared to findings made in four age-matched controls. The principle finding was that the transition from cartilage cores to primary trabeculae at the growth plate was deficient. In two instances a slipping of the distal radial epiphysis and in one instance a slipping of the metacarpal epiphysis was found. In the others, evidence of a healed slipping was present. It is postulated that the slip is responsible for the deformity.

Animals↗
PubMed1981

A clinical study of quazepam in hospitalized patients with insomnia.

The efficacy of quazepam (Sch-16134) 15 mg capsules as a hypnotic has been compared with that of placebo in a 9-day study, using a parallel-group design. The physician's global evaluation numerically favoured quazepam 63% (nineteen of thirty) over placebo 50% (fifteen of thirty). Furthermore, it demonstrated greater improvement in Hypnotic Activity Index and Sleep Quality Index from baseline scores, and caused no adverse reactions.

Adolescent↗
PubMed1981

The ultrastructure of nephrocalcinosis induced in chicks by Cestrum diurnum leaves.

Powdered Cestrum diurnum leaves, mixed with two diets differing in calcium and phosphorus contents, produced nephrocalcinosis in young chicks regardless of serum calcium elevation. The calcific deposits, found in both proximal and distal portions of cortical tubules, began either in the cytoplasm or in lysosomal bodies as a unilaminar spheroid structure containing apatite crystals. The ultrastructural characteristics of intraluminal concretions suggested that they were formed intracellularly but later were extruded into the lumen. The extent of calcific deposits increased with duration and with hypercalcemia. Although Cestrum contains an analog of 1,25-dihydroxycholecalciferol, neither mitochondria nor basal lamina contained calcific deposits described in nephrocalcinosis secondary to hypervitaminosis D.

Animals↗
PubMed1981

The advantages of titanium alloy over stainless steel plates for the internal fixation of fractures. An experimental study in dogs.

An experimental study is reported of fracture healing in the femora of 36 Beagle dogs, comparing the results of using stainless steel plates with those of using less rigid titanium alloy plates. The alloy plates led to the appearance of a small amount of periosteal callus without any histological evidence of fracture instability, thus allowing the radiological assessment of fracture union. This also produced less bone loss during the remodelling phase. Radiological measurements 24 weeks after osteotomy showed cortical thickness to be reduced by six per cent under titanium alloy and by 19 per cent under stainless steel, while histological measurements showed a total bone loss of 3.7 per cent under titanium alloy and of 11 per cent under stainless steel plates. Removal of the titanium alloy plates after eight weeks followed by a recovery period of 16 weeks produced an increase of cortical thickness of 69 per cent and a gain in total bone mass of 30 per cent. Titanium alloy plates also produced less soft-tissue reaction than stainless steel plates. It is concluded that this alloy is a promising material for internal fixation devices.

Alloys↗
PubMed1981

Significance of resegmentation in the pathogenesis of vertebral body malformation.

Human embryos and fetuses were investigated histologically to elucidate the possible pathogenesis of congenital malformations of the vertebral body. Special attention was paid to early development of the vertebral column, particularly the often-questioned stage of resegmentation, important as the stage during which the malformations might develop. Evidence of resegmentation was found in 7 embryos ranging from 7 mm C-R length (5 weeks after fertilization) to 13 mm (6 weeks). Moreover, the formation of the definitive vertebral body was considered to be intimately related to the intersegmental artery. As for Junghanns' concept that the cartilaginous body consists of two lateral halves, it was not observed in our specimens, nor was it found in the latest literature on normal vertebral development. Congenital malformations of the vertebral body were classified into two categories: failure of formation and failure of segmentation. They were demonstrated in an embryo of 13 mm and a fetus of 70 mm which were in the developmental stages of chondrification and early ossification, respectively. According to these observations, we conclude that most malformations of the vertebral body occur in the early stage of definitive vertebral body anlage formation.

Humans↗
PubMed1981

The pathogenesis of congenital vertebral malformations. A study based on observations made in 11 human embryos and fetuses.

The pathogenesis of congenital vertebral malformations was investigated histologically in 266 human embryos and fetuses. Malformations were found in 11 specimens, and were grouped according to a detailed classification. All the malformations were observed as abnormalities of the cartilaginous anlage of the vertebral body, and permitted some conclusions as to their pathogenesis. A hemivertebra or other defect of formation of the vertebral body is considered to be caused by abnormal differential growth of the loose-celled area. Defects of segmentation are due to complete chondrification of the dense-celled area or to an absence of the dense-celled area. The notochord does not seem to be responsible for malformations. Compensatory growth of other vertebral bodies resulting from a partial defect or a peculiar shape of the body is already present in this very early stage of development. Some specimens show a relationship between the abnormal distribution of the intersegmental arteries and the abnormality of the vertebral segments. Considering the importance of the intersegmental artery in the formation of the definitive vertebral body anlage, as mentioned in a previous paper, it may be concluded that congenital vertebral malformations are likely to occur during the stage of resegmentation and to be related to the abnormal distribution of the intersegmental arteries.

Humans↗
PubMed1981

Healing patterns of metaphyseal fractures.

Metaphyseal fractures having different degrees of stability were produced in rats, rabbits, and dogs. The progress of healing various radiologic patterns, observed by correlated roentgenographic and histologic observations, show that the appearance on radiographs of one or two broad, ill-defined bands of increased density indicates a normal healing process. Cortical healing lags behind cancellous bone healing. No external callus develops. The appearance of two dense, well-defined bars bordering a radiolucent gap indicates delayed union or nonunion and usually can be attributed to instability at fracture site. The appearance of an external callus and the elaboration of a fibrocartilaginous bridging by callus portrays delayed union, secondary to gross instability and/or displacement. Similar patterns appear when there is an avascular fragment, in which case osteogenic activity is limited to one fracture line. Radiologic criteria based on histologic observations permit assessment of metaphyseal fracture healing.

Animals↗
PubMed1980

Ultrastructure of the common extensor tendon in tennis elbow.

In patients with tennis elbow, the common extensor tendon showed a pronounced reactive change consisting of mesenchymal cell proliferation along with aggregates of newly formed vascular channels. When studied ultrastructurally, many of the mesenchymal cells adjacent to the vascular channels were surrounded by a basal lamina, which is not normally seen around tenocytes. The cytoplasm of these cells showed features of both endothelial cells and tenocytes. It thus appeared, that the endothelial cells of the newly formed vascular channels were the source of proliferating mesenchymal cells differentiating toward tenocytes, and together they represented an intrinsic healing mechanism in the tendon.

Adult↗
PubMed1980

Morphological studies of front limb deformities in lambs.

Long bones of 16 3- to 6-month-old lambs with bowed forelimbs underwent radiologic, microradiographic and histologic examinations. The distal ends of the radii showed a combination of valgus, flexion and internal rotation. There were thin cortical bone and large marrow cavity adjacent to the growth plate in the radii and metacarpi. Histological studies showed increased numbers of osteoclasts adjacent to the zone of calcified cartilage of the growth plate. The trabeculae of primary and secondary spongiosa were fewer and thinner than those of controls. The length of secondary spongiosa were greatly reduced and the lateral compaction of the metaphysis was defective. The growth plate was normal. The predominant finding was osteoporosis resulting from increased osteoclastic resorption of bone trabeculae.

Animals↗
PubMed1978

Bone loss in response to long-term immobilisation.

The histodynamic response to long-term "non-traumatic" immobilisation was studied in young adult Beagle dogs by means of radiomorphometry and histomorphometry, the right forelimb being encased in plaster and the left forelimb serving as a control. The dogs were killed at two, four, six, eight, twelve, sixteen, twenty, twenty-four, thirty-two and forty weeks and the third metacarpal, radius, ulna and humerus removed for analysis of the contributions of the periosteal, haversian and endosteal envelopes to the bone loss at the mid-diaphysis. The bone mass responded to long-term immobilisation in three stages. First there was a rapid initial loss of bone, reaching its maximum (some 16 per cent of original mass) at six weeks, to which all three bone envelopes, to some extent, contributed. A rapid reversal followed, the bone mass approaching the control values between eight and twelve weeks after immobilisation. A second stage of slower but longer lasting bone loss ended twenty-four to thirty-two weeks after immobilisation; the periosteal envelope was the main contributor (80 to 90 per cent of the total loss). The third stage was characterised by maintenance of the bone mass which had been reduced by some 30 to 50 per cent of original values. This pattern was qualitatively similar in all four bones but the distal bones lost more bone than the proximal bones. The extent of resorption surface and the total histologically "active" periosteal envelope increased parallel to the phases of bone loss. The linear mineralisation rate did not differ significantly between the experimental and control sides.

Animals↗