Biomedical subjects
H K Uhthoff
Publications and source records attributed to H K Uhthoff.
Lack of association between HLA and rotator cuff rupture.
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Vertebral ontogenesis. Resegmentation refuted.
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Repair of trabecular fatigue fractures. Cadaver studies of the upper femur.
The healing process and the distribution of trabecular fatigue fractures were studied on upper femora obtained at autopsy. Macroscopically, two main types of trabecular fatigue fractures were found on the basis of callus formation that in histologic sections were composed of woven and lamellar bone. A third type characterized by its vestigial callus was found only in histologic sections. Fatigue fractures were more numerous in regions of the femoral head submitted mainly to compressive rather than tensile stress. Trabeculae submitted to compressive stress had a majority of the type of fatigue fractures with an exuberant thorny callus composed of woven bone (most of them located subjacent to the subchondral bone plate), whereas trabeculae submitted mainly to tension or to minimal stress, as in Ward's triangle, had a majority of fatigue fractures with a small, smooth-surfaced callus composed of lamellar bone.
Intra-articular fractures of the calcaneus.
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The role of the coracoacromial ligament in the impingement syndrome. A clinical, radiological and histological study.
Seventeen patients with a painful arc syndrome and tenderness over the coracoacromial ligament were selected to demonstrate the changes in the coracoacromial ligament in the impingement syndrome. Plain X-ray examination was normal and a preoperative subacromial bursogram demonstrated impingement in only three out of 17 patients. However, at operation the subacromial space under the coracoacromial ligament, which normally admits the tip of the little finger, appeared unusually tight and barely accessible in 15 out of 17 patients. Histological examination of the biopsied ligament showed degenerative changes but no increase in fibrous tissue. We conclude that in the absence of bony overgrowth the initial change is an increased volume of the soft tissues in the subacromial space. Consequently, the space is compromised by the swelling of its contents, which exert abnormal pressure on the overlying coracoacromial ligament and cause degenerative changes in the ligament. The symptoms of impingement appear because of the unyielding nature of the coracoacromial ligament. Subacromial bursography may not be a reliable test when the coracoacromial ligament is the site of impingement.
Influence of stable fixation on trabecular bone healing: a morphologic assessment in dogs.
The healing patterns of trabecular bone are different from those of compact bone. In order to investigate further this observation, a histomorphometric assessment was undertaken. The influence of internal fixation devices on trabecular bone healing was also studied. Intercondylar osteotomies were produced in 19 dogs and fixed with screws. All dogs were killed between 1 and 14 weeks; eight of them had the screws removed 4 weeks after osteotomy and were killed 4 or 10 weeks later. The results of morphometry were compared to the histologic and radiologic pictures. Anatomic reduction with stable fixation led to contact healing characterized by a narrow endosteal bone formation at the osteotomy site that disappeared only after union was complete (4 weeks). In gap healing, the endosteal bone formation was greater. Internal fixation devices appeared to cause a diffuse osteopenia once union was complete. Their removal just after completion of union seems to prevent the bone loss. Screws induced bone formation around their threads; after they were removed, the reaction disappeared but the screw holes were not filled with normal trabeculae 10 weeks later. Union of fractures through trabecular bone can be assessed radiologically. A decrease of band-like bone density at the fracture site indicates completion of union. This is the optimal time for implant removal. It prevents the osteopenia observed in cases of continuous presence of screws.
Increased frequency of HLA-A1 in calcifying tendinitis.
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Liposarcoma simulating a Baker's cyst: a case study.
We present a case of liposarcoma in a 65-year-old man in whom the tumor first appeared as a soft, cystic mass at the medial margin of the left popliteal fossa. The mass simulated a Baker's cyst. The patient remained untreated for almost 7 months from the discovery of the mass. With worsening pressure symptoms, a biopsy was done that confirmed the clinical diagnosis of liposarcoma. The leg was amputated, but the patient died 2 years later with clinical evidence of pulmonary metastasis. By presenting this case report, we stress the importance of carefully investigating for malignancy all masses presenting as a Baker's cyst in persons past middle age.
Reversibility of nontraumatic disuse osteoporosis during its active phase.
The potential for the recovery of bone lost during the active phase of disuse osteoporosis, both in the diaphyseal compacta and metaphyseal spongiosa was tested in young adult and old Beagle dogs. Immobilization for up to 60 weeks was achieved by placing the forelimb in a spica cast and remobilization by removing it. Bone volume was estimated in the third metacarpus, radius, ulna and humerus at the mid-diaphysis and at the level of distal metaphyseal spongiosa in both forelimbs by radiography and histomorphometry. Measurements carried out on animals remobilized showed considerable recovery of the original bone loss. In both age groups, the residual deficits increased, however, with the duration of immobilization and were similar in the metaphyseal spongiosa and in the diaphyseal compacta. The old dogs which began the study with 10% less bone than the younger dogs, showed smaller proportional losses than the younger dogs but greater residual deficits, most evident in the diaphysis. In both age groups the distal, weight-bearing bones tended to show greater losses and also greater recovery both in diaphyseal compacta and the metaphyseal spongiosa. Thus, 28 weeks after cast removal following 32 weeks of immobilization the following findings were noted: In the third metacarpal diaphyseal compacta in the younger dogs, a 53.6% loss (mostly from the periosteal envelope) decreased to 16.3% (a 70% recovery) while in the older dogs a 37.6% loss (mostly from the endosteal envelope) decreased to 23% (a 40% recovery).(ABSTRACT TRUNCATED AT 250 WORDS)
Anteversion of the acetabular cup. Measurement of angle after total hip replacement.
We describe a new method for the accurate measurement of the angle of anteversion of an acetabular cup from standard anteroposterior radiographs, and provide the conversion tables required. The effect of the centering of the radiograph is discussed and a method of distinguishing between anteversion and retroversion by using a caudally directed x-ray beam is described.
Notochord action on spinal development. A histologic and morphometric investigation.
Forty-seven human embryos and fetuses of a gestational age from 5 to 13 weeks were studied histologically and histomorphometrically in an attempt to elucidate the possible action of the notochord on spinal development, in particular as it relates to segmentation. Segmentation occurred first in the tissue surrounding the notochord and not in the notochord itself; notochordal development at its most cranial part lagged behind that of its surrounding tissue. We also found that in later stages the decrease of notochordal cells at the level of the body was due to degeneration and not to migration of cells toward the intervertebral space. This observation puts into doubt the theory of squeezing or migration of notochordal cells from their vertebral position into the intervertebral disc space.
Notochord and spinal malformations.
Fourteen spinal malformations were found in 328 spontaneously aborted human embryos and fetuses. Of these, 13 were investigated histologically and histomorphometrically and compared with 47 age- and stagematched normal specimens to document any possible relationship between spinal and notochordal malformations. Although six notochordal malformations, such as bifurcation, were found in 14 spinal malformations, the respective sites did not correspond. Abnormality of notochordal tissue--such as degeneration and delayed development, which was observed in nine of 14 spinal malformations--was not restricted to the site of the spinal malformation. Moreover, tissue changes responsible for spinal malformations usually did not occur in direct contact with the notochord. On the other hand, malformed notochords were found in normal specimens. We therefore were unable to confirm in human specimens that notochordal abnormalities induce spinal malformations, a fact well established in lower vertebrates.
Ultrastructure of the fibrous tissue surrounding internal fixation devices.
The possible bursal nature of the fibrous tissue that develops like a capsule over internal fixation devices was studied ultrastructurally in 13 human and four canine cases. In both species, the basic structural pattern was similar. The capsule had two distinct zones. The superficial compact zone appeared as a pseudomembrane, and consisted of elongated fibrocytes arranged transversely in a collagenous and microfilamentous matrix. In the deep zone, the cytoplasm and its constituents of connective tissue cells varied from meager to abundant. The structural organization of the capsule as well as its cellular characteristics did not conform to the specificities of an adventitious bursa. The capsular tissue did not appear to be affected by such host factors as age; implant alloy composition; the type of the underlying bone or its abnormalities; duration of implantation, or superficial or deep location of the metal device. Inflammation rarely occurred in the capsular soft tissue, including those cases where pain developed over the implants following an uneventful bone union. Because metal implants do not induce formation of adventitious bursa, pain over an uncomplicated implant is not likely to be due to a bursitis.
Anterior capsular redundancy of the shoulder: congenital or traumatic? An embryological study.
A study of the attachment of the joint capsule to the scapula, and of the shape of the humeral head, has been carried out in 52 fetal and embryonic shoulders. In 77% of cases the anterior capsule was attached to the labrum or close to it; in the remaining 23% it was inserted into the neck of the scapula, so creating a pouch. In all 52 specimens the humeral head was spherical. It was concluded that the pouched and redundant anterior capsule sometimes seen during surgery for recurrent dislocation of the shoulder, may not be traumatic in origin, but could be a developmental variant.
Periosteal stress-induced reactions resembling stress fractures. A radiologic and histologic study in dogs.
An external callus is always associated with so-called stress fractures, but a fracture line cannot always be demonstrated by radiologic means. In such instances it is assumed that an undisplaced fracture or microfracture must nevertheless exist for an external callus to form. In this experimental study, 18 beagles were immobilized in a shoulder spica for periods of time ranging from 6 to 32 weeks and then remobilized. At the time of sacrifice, which varied from four to 28 weeks after remobilization was started, eight showed on radiographs an external fusiform bone formation on the distal metacarpal metaphysis during the remobilization period without evidence of a fracture line. Serial histologic examination, in seven metacarpi, also failed to reveal the presence of any break in the bone's continuity. Although this does not exclude the accumulation of microdamage (mechanical fatigue) at such sites, there is sufficient evidence that the circumscribed periosteal reaction occurred at a site of increased stress in the absence of an actual fracture. Consequently, this condition is called a periosteal stress-induced reaction.
The role of rigidity in fracture fixation. An overview.
UNLABELLED: The optimal degree of rigidity of internal fixation of fractures is still a matter of controversy. Since any attempt to clarify this situation must rest on a clear terminology, we propose terms relating to different degrees of rigidity. They are based on the material and the design of implants as well as the morphologic features of repair. From our morphologic findings it is obvious that the healing response and the subsequent structural remodelling depend on bone deformation and gap motion. CLINICAL SIGNIFICANCE: For sound patient care, the most ideal mode of internal fixation by plates, yielding rapid and efficient fracture healing, has to be established scientifically in a comparative study.
Ultrastructure of the subacromial bursa in painful shoulder syndromes.
In order to determine if inflammation of the subacromial bursa or "bursitis" is as common an occurrence as believed in painful conditions of the shoulder, eight bursae were obtained during surgery from 3 cases of calcifying tendinitis, 2 of tight coracoacromial ligament, 2 of rotator cuff tear and 1 of acromioclavicular osteoarthritis. In the cases of calcifying tendinitis, tight coracoacronial ligament and rotator cuff tear the morphological changes mainly consisted of a numerical increase in cells throughout the bursal wall along with proliferation of endothelial cells in the vascular channels. All of the cells including the endothelial had densely packed, intermediate type filaments in their cytoplasm but no appreciable diminution of metabolic organelles. Lipid droplets were abundant in the extracellular connective tissue of the bursae from the cases with rotator cuff tear. In contrast to the other cases, the bursa from the case of acromioclavicular osteoarthritis showed widespread fibrin deposition in association with cell necrosis. In none of the cases did inflammatory leukocytic cells infiltrate bursal tissue. We conclude, that the subacromial bursa tends to undergo proliferative or degenerative changes in rotator cuff tendinopathies but bursal inflammation with polymorphonuclear cell infiltrate does not occur commonly.