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Biomedical subjects

H K Uhthoff

Publications and source records attributed to H K Uhthoff.

At least 37 records · Page 2Linked to original sources
PubMed1997

Degeneration at the insertion weakens the tensile strength of the supraspinatus tendon: a comparative mechanical and histologic study of the bone-tendon complex.

The purpose of this investigation was to determine the relationship between the degree of degeneration at the supraspinatus insertion, the tensile strength, and the site of failure of this tendon. Thirty-three fresh cadaveric shoulders (average age: 62 years; range: 39-83 years) were examined. A tensile load to failure was applied at a constant crosshead speed of 25.4 mm/min to a 10 mm wide strip of the supraspinatus tendon that remained attached to the bone. Preexisting degenerative changes at the insertion were assessed and scored histologically and compared with the ultimate tensile stress. Twenty tendons failed at the insertion (the insertion group), and 11 failed in the midsubstance (the midsubstance group). The histologic score of degeneration for the insertion group was significantly higher than that for the midsubstance group (p = 0.0026). There was a negative correlation between the ultimate tensile stress at the insertion and the degeneration score for the insertion group (r = -0.60; p = 0.013). Histologic observations revealed that disruptions of tendon fibers were located mostly in the articular half of the tendon and that they enlarged during mechanical testing in 90% of the specimens of the insertion group. It seems that degenerative changes at the supraspinatus insertion reduce the tensile strength of the tendon and constitute a primary pathogenetic factor of rotator cuff tear.

Adult↗
PubMed1997

[Embryology of the human hip].

This description of the prenatal development of the hip joint is based on observations made in 126 spontaneously aborted human embryos and fetuses. Their gestational age varied between 6 weeks and term. Particular attention was paid to structures that can be recognized during the sonographic examination of the hip, be it during pregnancy or at the time of birth. At 6 weeks, the anlage of the hip joint is already visible. By the time the fetal period starts, all components of the hip joint are clearly recognizable. Serial sections allow the histomorphometric determination of the coverage of the femoral head.

Female↗
PubMed1997

Estimation of total collagen and types I and III collagen in canine rotator cuff tendons.

The collagen composition of the supraspinatus, infraspinatus, and subscapularis tendons, which form part of the rotator cuff of the shoulder, was determined. Tendons were obtained from adult, male beagle dogs and total collagen was estimated by measurement of hydroxyproline. There was little variation in collagen content among the three major cuff tendons and the quantity approximated that cited in the literature for other tendons. However, the collagen content in the insertion zone of the supraspinatus tendon was significantly higher than in the tendon proper. NaCl fractionation of supraspinatus collagen indicated that type I was the predominant collagen but significant amounts of type III and possibly some type II and type V were also present. Interestingly, there appeared to be more type III collagen in the insertion zone than in the tendon proper, cyanogen bromide digestion and peptide mapping confirmed this finding. The differential collagen composition of the supraspinatus tendon may contribute to the high incidence of tear that is associated with this rotator cuff tendon.

Animals↗
PubMed1997

Pathology of failure of the rotator cuff tendon.

In failure of the rotator cuff tendon, interference with its function prevents the rotator cuff from fulfilling its physiologic role. Trauma in younger individuals, calcifying tendinitis, degenerative changes of cuff tendon, and partial- or full-thickness tears cause cuff failure intrinsically. Degenerative changes constitute the most frequent cause of cuff failures and correlate with tendon tearing. An acromial spur, long coracoid process, subacromial bursitis, and thickening of the corocoaromial ligament causes cuff failure extrinsically.

Humans↗
PubMed1997

Improved fracture healing with less rigid plates. A biomechanical study in dogs.

The effect of axial plate flexibility on bone healing was investigated with four experimental plating systems using elastic inserts to manage their axial flexibility in compression. The plates were tested in 72 dogs that underwent unilateral femoral osteotomy and noncompression plating on alternate sides. The femurs of 18 dogs were plated with each of the four plating systems: six for 8 weeks, six for 16 weeks, and six 6 for 24 weeks. Each osteotomized femur and its contralateral control were removed at the end of the plating periods and tested in multidirectional nondestructive bending to evaluate the polar distributions of their flexural rigidity. Results from each pair of bones were used to calculate parameters defining the relative mechanical status of the healing bone. These parameters were used to evaluate the effects of plating system axial flexibility and time on healing. It was found that: within the selected range of axial flexibility there was an optimal value that produced the best healing; healing progressed with a diminishing rate leading to a steady state; and all four plating systems produced healing superior to that obtained with dynamic compression plates.

Animals↗
PubMed1996

Histologic analysis of fetal ulnar variance.

Twenty-eight fetal wrists aged 5 to 21 weeks gestation were examined histologically to assess ulnar variance. There was a trend from ulna negative to ulna neutral among this population. Of 10 wrists in group I (5-8 weeks gestation), 8 were ulna negative and 2 were ulna neutral. Of nine wrists in group II (11-13 weeks gestation), three were ulna negative and six were ulna neutral. Of nine wrists in group III (18-21 weeks gestation), two were ulna negative and seven were ulna neutral. Overall, 13 embryos demonstrated an ulna negative variance; the remainder had ulna neutral variance. These results are significantly different than the incidence of ulnar variance in adults. With growth, factors must occur that change this fetal relationship of radius to ulna.

Fetus↗
PubMed1996

Recent advances in shoulder surgery.

Major changes have taken place in the diagnosis and treatment of rotator cuff tears. It seems that magnetic resonance imaging alone as a diagnostic tool is still not sensitive enough, particularly in the diagnosis of partial tears. Arthrography and arthroscopy are still considered essential for an accurate preoperative diagnosis. To guarantee a better postoperative result, a carefully planned course of preoperative physiotherapy is mandatory. In experienced hands, arthroscopic surgery gives results comparable to those obtained with open procedures. A careful debridement, anterior acromioplasty, and decompression have replaced extensive surgical intervention in the treatment of massive tears. The first results in treating calcifying tendinitis with shock-wave therapy seem encouraging. A more refined diagnosis of the impingement syndrome is a prerequisite for a successful outcome because impingement is not caused by a narrowing of the subacromial space in all patients. Increase in contents of this space and instability are equally important factors.

Arthroscopy↗
PubMed1996

Structural and functional changes in the canine shoulder after cessation of immobilization.

The functional and structural consequences of remobilization of the glenohumeral joint after 12 weeks of immobilization were studied in 10 beagle dogs. The dogs were grouped in pairs: 2 were used as controls, and in 8 others 1 forelimb was immobilized. At the end of 12 weeks, 2 dogs in the experimental group were euthanized, as were the 2 dogs used as controls. The cast was removed from the other 6 dogs, and the remobilized animals were euthanized in pairs at the end of 4, 8, and 12 weeks. It was found that after 12 weeks of immobilization, the passive range of motion was markedly impaired, intraarticular pressure was raised during movements, and the filling volume of the joint cavity was reduced. Histologically, the capsule showed synovial lining hyperplasia and vascular proliferation in the wall. Immunohistochemical labeling for collagen Types I and III failed to show an increase of fibrous collagens in the capsular wall. Both the functional and structural changes were unaltered after 4 weeks of remobilization, but after 8 weeks they began to reverse, and they returned to normal levels after 12 weeks. Both functional and structural changes after 12 weeks of immobilization of the uninjured glenohumeral joint are reversible by remobilization. The collagen composition of the capsule seems unrelated to the degree of capsular contraction that occurs during 12 weeks of immobilization and subsequent remobilization.

Animals↗
PubMed1996

Calcifying tendinitis.

Calcifying tendinitis is not due to a dystrophic calcification of the degenerative tendinous tissue but due to a cell mediated reactive process. In fact, following formation of a deposit resorption usually ensues which in turn will be followed by a tendon reconstitution. If patent conservative measures fail, surgery should only be contemplated in the presence of radiologically dense, homogenous and well delineated deposits which indicate that the resorptive activity has not set in. If, on the other hand, there is evidence of ongoing resorption the decision for surgery should be postponed since only exceptionally natural resorption will not occur.

Calcinosis↗
PubMed1996

[Calcareous tendinitis].

Explore the source record for details and available documents.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1995

Flexural rigidity in partially demineralized diaphyseal bone grafts.

Control of biomechanical properties of demineralized diaphyseal bone allografts is required for their clinical application. Therefore, the changes in flexural rigidity in human fibulae were investigated as a function of the demineralization depth using a nondestructive bending test. Starting at the facies medialis, the flexural rigidity was determined in 24 planes at 15 degrees sequential angular increments, which allowed data collection around the circumference of the bone. Test bones included 4 pairs of left and right human fibulae and 15 single fibulae. The elliptical distribution of the flexural rigidity of left and right fibulae and single fibulae before and after demineralization was compared. The stiffness index and the area ratio were defined as parameters to describe the mechanical status of the test bones. Results show that the rigidity of diaphyseal bones is strongly dependent on the reduction of their cortical thickness by demineralization. A mathematical model allowing prediction of the reduction of the rigidity of diaphyseal bone grafts as a function of the demineralization depth is presented.

Adult↗
PubMed1995

[Anatomy and pathology of the rotator cuff].

In this contribution we stress the fact that not all rotator cuff tendinopathies are degenerative in nature. Moreover, we insist on a clear distinction between intrinsic and extrinsic tendinopathies. In a final note we point out that the impingement syndrome is not always due to a developmental or acquired spur of the anterior part of the acromion.

Collagen Diseases↗
PubMed1994

Cortical porosis under plates. Reaction to unloading or to necrosis?

Cortical porosis under plates used for the fixation of fractures is often attributed to the interference of the plates with cortical perfusion, resulting in necrosis, which in turn induces remodeling. To our knowledge, no histomorphometric studies have been published that demonstrate the correlation between cortical necrosis and porosis. The objective of this study was to test the hypothesis that cortical necrosis is related to changes associated with porosis. Standard and railed plates were applied to intact femora in ten dogs. Histomorphometric studies done at eight and twenty-four weeks after insertion of the plate failed to show a significant positive correlation between necrosis and porosis irrespective of the type of plate used. Porosis was always greater in the inner cortical sector, where no increased necrosis was noted, than in the outer cortical sector, where necrosis was present.

Animals↗
PubMed1994

The collagen types in the attachment zone of rotator cuff tendons in the elderly: an immunohistochemical study.

OBJECTIVE: The attachment zone of the rotator cuff tendons in the elderly was studied immunohistochemically in order to determine how degenerative changes affected the pattern of collagen fiber distribution. METHODS: Twenty-seven cuffs with their bony insertion were obtained from 22 postmortem cases of both sexes ranging in age from 52 to 90 years and without a history of shoulder ailments. In addition, 3 cuff specimens from cadavers in the 3rd and 4th decades were examined for comparison. Sections of formalin fixed tissues were stained by peroxidase antiperoxidase (PAP) technique using monoclonal antibodies against types I, II and III collagen. RESULTS: Degenerative changes affecting the fibrocartilage primarily were characterized by calcification, fibrovascular proliferation and microtears. In addition, they were found in all the cuff tendons of elderly individuals but not in those from younger subjects. Immunohistochemically, the attachment zone in areas without degenerative lesions showed collagen type I labelling strongly in bone but only moderately in the fibrocartilage. The predominant labelling in the fibrocartilage was for collagen type II, and collagen type III labelled principally in perichondrocytic areas. The tide-mark showed inconsistent labelling for any of the collagen types. In the presence of degenerative lesions, the disposition of fiber types was interrupted by calcification and microtears. Collagen type II composition of the fibrocartilage was markedly altered by the presence of fibrovascular tissue which labelled only for collagen type III. CONCLUSION: We conclude that severe degenerative changes in the cuff tendons of elderly individuals, alter the collagen characteristic of the rotator cuff and that the changes could be associated with impairment of biomechanical properties of the attachment zone, and may give rise to the clinical syndrome of enthesopathy.

Aged↗
PubMed1994

Immunohistochemical distribution of type I, II and III collagens in the rabbit supraspinatus tendon insertion.

The collagen fibres in the area of attachment of the supraspinatus tendon to bone were studied immunohistochemically in 12 mature female New Zealand white rabbits. The labelling of type I collagen was uniformly prominent in the bone as well as in the fascicles of the tendon proper but inconspicuously scattered in the unmineralised and mineralised zones of the fibrocartilage. Type II collagen, not detected in the tendon proper, was widespread in both zones of the fibrocartilage. Type III collagen, on the other hand, appeared to be confined mainly to the zone of unmineralised fibrocartilage, in addition to its presence in the endotenon of the tendon proper. The region of the tidemark failed to show immunostaining for any of the collagen fibre types. In conclusion, this study demonstrates that, although all the principal fibrous collagen types are constituents of the supraspinatus tendon at its attachment site, the distribution pattern of immunolabelling varies from zone to zone.

Animals↗
PubMed1994

Effects of immobilization on the capsule of the canine glenohumeral joint. A structural functional study.

The effects of immobilization on the function of the glenohumeral joint and its capsule were investigated in eight beagle dogs. One foreleg of each animal was immobilized in a spica cast, and the dogs were euthanized after 4, 8, 12, and 16 weeks of immobilization in groups of two. The contralateral limb and the forelegs of two normal beagles were used as controls. At the time of euthanasia, the range of motion, intraarticular filling volume during passive movements of the joint, and intraarticular filling volume to rupture the capsule were measured. The synovium, including the capsule and the subscapular bursa, were examined histologically. In the immobilized limb, there was progressive restriction in the range of motion with increases in intraarticular pressure, and the filling volume that was required to cause a rupture of the capsule diminished. Morphologically, the capsule and the subscapular bursa showed focal adhesions. Thus, it appeared that immobilization of these canine forelimbs produced changes in the glenohumeral joint that resembled those of frozen shoulder in humans.

Animals↗
PubMed1994

The pathogenesis of club foot. A histomorphometric and immunohistochemical study of fetuses.

We studied 16 club feet and 27 normal feet from spontaneously aborted human fetuses in the second trimester of gestation and measured the length of the spring ligament, and the declination angle and size of the talus. We also studied the cellular characteristics of the spring ligament and the immunohistochemical features of the medial ankle ligaments using monoclonal antibodies against type-III collagen, desmin, vimentin, and smooth muscle actin. Histomorphometric results indicated that the talar deformity was not the primary lesion. Histological and immunohistochemical findings showed that the cells and collagen fibres of the medial ankle ligaments of club feet appeared to be the site of the earliest changes, in that they had lost their spatial orientation and had contracted. In severe club feet before the third trimester of gestation, myofibroblast-like cells seemed to create a disorder of the ligaments resembling fibromatosis. This led to contraction and resulted in typical club-foot deformity.

Ankle↗