Biomedical subjects

T M Ganey

Publications and source records attributed to T M Ganey.

31 records · Page 2Linked to original sources

PubMed1994

Basement membrane of blood vessels during distraction osteogenesis.

A canine model of distraction osteogenesis has recently been developed that permitted the evaluation of bone formation and its vascularization during bifocal callotasis. In this model, the authors examined the composition of the blood vessels during distraction osteogenesis of the mandible for laminin and for Type IV collagen, both constituents of the vascular basement membrane. At the fibrous distraction site, at the juncture of the free cortical surface and the regenerated bone, and at the abutting cortical surfaces at the distal margin of the defect, laminin and Type IV collagen were present in all vessels.

Animals↗

PubMed1994

Evaluation of distraction osteogenesis by scanning electron microscopy.

A model of bifocal distraction osteogenesis in the canine model was used to assess and quantitate the mineral content of the newly forming bone within the canine mandible. A 2-cm defect was created in the body of the mandible, and after a posterior osteotomy, the transport disk was advanced at 0.25 mm per 8 hours for 21 days and then held in rigid fixation for an additional week. As a control for this study, three additional dogs underwent the same procedure with the exception that the transport disk was not advanced. Electron dispersive spectroscopy analysis was performed on the newly formed regenerate bone and compared with areas of existing cortical bone of both the transport disk and the mandible. In the control model, special note was made of the pericortical callus at the osteotomy site as well as of the regenerative bone that filled the 2-cm defect in the body of the mandible. Calcium/phosphorous ratios were used to assess the composition of the mineralized regions of the mandible. The regenerate bone that filled the defect and the mineralized callus surrounding the site of osteoclasis in the control mandible were significantly different in composition when compared with the regenerate bone that formed during distraction osteogenesis. This suggests that distraction osteogenesis may effect an initial matrix production that is more similar in composition to the mature cortical bone from which it was derived than does periosteal regeneration and filling of an osseous defect.

Animals↗

PubMed1994

The embryology of lower-extremity torsion.

The presence of torsional deformities in the lower extremities of otherwise normal children is based on a variety of developmental processes. With intrauterine maturation, both rotation and external compression of the extremities take place. These forces result in the normal molding and final position of the limbs. Torsion of the extremities is, thus, a normal embryological process. It is imperative for the treating physician to understand these factors in human development to decide which cases are significant deviations from normal torsion. Knowledge of the embryology and natural history of these conditions is a key to appropriate treatment of patients with torsional or angular malalignments.

Bone Diseases, Developmental↗

PubMed1993

Pleiotrophin is an abundant protein in dissociative extracts of bovine fetal epiphyseal cartilage and nasal cartilage from newborns.

An abundant protein that is identical to the growth-associated protein pleiotrophin (PTN) has been isolated from dissociative extracts of bovine nasal and fetal epiphyseal cartilage. The yield from these tissues was at least 15 micrograms/g wet weight of cartilage. PTN was absent or was present only in trace amounts in mature articular cartilage. An analysis of tryptic fragments of PTN, held together with disulfide bonds, did not indicate any set pattern of cystine cross-links, which suggests a propensity for rapid refolding of the protein. PTN could not be isolated from thin (10 microns) slices of nasal cartilage in physiological extraction buffers, which indicates that it was tightly associated with the cell surface, was tightly associated with nonextractable matrix, or was an intracellular protein. Its appearance in various extraction media parallels that of histone H2b, a nucleosomal protein; this suggests a possible intracellular location for the protein. Immunohistochemical analysis of its distribution in fetal epiphysis indicated that it is associated with chondrocytes.

Amino Acid Sequence↗

PubMed1992

Development of vascularization in the chondroepiphysis of the rabbit.

Although numerous studies have addressed the presence of cartilage canals within developing epiphyses, the chronology of their appearance and their vascular contribution to the developing chondroepiphysis remain to be studied. We have selected a model, similar to the developing human skeletal system, in which extensive cartilage canal development precedes the subsequent secondary ossification process. In the rabbit proximal tibia, both chondroepiphyseal and vascular (cartilage canals) development were quantified from the first evidence of vessels until the formation of the secondary center of ossification. The volume of hyaline cartilage increased 25 times after intraepiphyseal vessels were initially observed. The blood supply, measured in cartilage canal volume, increased 400-fold over the same period. Three distinct cartilage canal morphologies were identifiable before the formation of the secondary center of ossification: (a) an early phase, in which the canals appeared as infoldings derived from the perichondrium; (b) a reactive phase, occurring simultaneously with chondrocyte hypertrophy and characterized by a very large increase in mesenchymal cells within the cartilage canal; and (c) a vascular phase, coincident with mineralization of the matrix, in which the familiar, unitary canal morphology was replaced by that of a vascular plexus. While matrix mineralization and the formation of bone seem dependent on critical cellular events, notably chondrocyte hypertrophy, the role that the vascular supply plays in developing sufficient biological inertia for the ossifying transition must not be underestimated.

Animals↗

PubMedDate not supplied

Osseous overgrowth after amputation in adolescents and children.

We retrospectively studied the incidence of primary surgical revision for stump overgrowth in a population of childhood and adolescent amputees. The anatomic location and the etiology of amputation are critical to the occurrence of overgrowth needing revision. Metaphyseal-level amputations are the most likely to develop overgrowth requiring revision (50%), whereas diaphyseal amputations are slightly less likely (45%). Joint disarticulations never develop overgrowth. Traumatic amputations are the most frequent mode of injury requiring revision of overgrowth (43%), followed by congenital or intrauterine amputations (30%) and elective amputations (20%). Radiographic classification of the osseous overgrowth helps define its severity and degree of ossific progression. Surgical revisions are usually performed when overgrowth reaches a grade 3 classification. The majority of skeletally immature diaphyseal- or metaphyseal-level amputees, including those with certain preexisting orthopaedic conditions, retain the ability to develop osseous overgrowth at the apex of the stump skeleton.

Adolescent↗

PubMedDate not supplied

Overgrowth management in Klippel-Trenaunay-Weber and Proteus syndromes.

Twenty-eight patients with limb overgrowth and the diagnosis of Klippel-Trenaunay-Weber or Proteus syndromes were evaluated retrospectively. These disorders are part of the phakomatosis spectrum of syndromes. The orthopedic problems consisted of asymmetric limb overgrowth, localized gigantism, angular deformities, scoliosis, vascular malformations, and skin anomalies. Systemic abnormalities are common and deserve full evaluation before treatment. Surgical treatment consisted of epiphysiodesis, osteotomies, debulking procedures, and amputation. Mixed results were obtained with surgery, and conservative or supportive treatment should be the primary mode of orthopedic care.

Adolescent↗

PubMedDate not supplied

Nonepiphyseal ossification and pseudoepiphysis formation.

Direct ossification extending from the metaphysis into the epiphysis preceded and continued to be more mature than formation and expansion of the typical epiphyseal ossification center at the opposite end of each longitudinal bone of the hand and foot. Direct metaphyseal to epiphyseal ossification usually started centrally and expanded hemispherically, replacing both physeal and epiphyseal cartilage simultaneously. When remnants of the "physis" were retained, however, while juxtaposed epiphyseal cartilage was replaced, a pseudoepiphysis formed. Three basic patterns of pseudoepiphysis formation were evident: (a) a central osseous bridge, (b) a peripheral osseous bridge, and (c) multiple bridging. In each condition, the remnant of the "physis" lacked typical cell columns capable of contributing to the postnatal longitudinal growth of the involved bone. Pseudoepiphyses were well formed by 4-5 years and coalesced with the rest of the bone months to years before skeletal maturation was attained at the opposite epiphyseal end.

Adolescent↗

PubMedDate not supplied

Development of the cartilage canals and the secondary center of ossification in the distal chondroepiphysis of the prenatal human femur.

The cartilaginous epiphysis of the distal femur is vascularized by a network of cartilage canals during prenatal development. The vascular invasion of the epiphysis begins at approximately eight to ten weeks of gestation with the initiation of cartilage canal formation. A complex vascular system develops within the canals and is well defined by fourteen weeks of gestation. The vascular system is fully developed several months prior to the development of the secondary center of ossification. The formation of the secondary center of ossification within the distal femoral epiphysis is preceded by changes that occur simultaneously within both the chondrocytes in the central portion of the epiphysis and the vascular and perivascular elements contained within the cartilage canals in the central portion of the epiphysis. These concurrent changes in the cellular morphology of the central chondrocytes and in the cellular structure of the central cartilage canals appear to be linked with the initiation of the process of osteogenesis.

Cartilage↗

PubMedDate not supplied

Fractures of C1 and C2 in an infant gazelle: a model of the human fracture pattern.

Spontaneously occurring fractures of the anterior and posterior synchondroses of C1 and the superior facet of C2 of an immature mammal were analyzed. The posterior C1 injury showed comminution, with involvement of both sides of the synchondrosis. Just below the anterior C1 fracture was an incomplete, comminuted fracture of the C2 superior facet. These fractures, especially the C1 injury, appear similar to the radiographic injury patterns in skeletally immature humans. Presumably the histologic failure patterns in the child would also be similar.

Animals↗

PubMedDate not supplied

The histopathology of injury to the accessory malleolar ossification center.

The evaluation of a traumatic lower limb amputation specimen revealed an incomplete fracture between the main and accessory malleolar ossification centers. This was not associated with extensive subperiosteal or intraarticular bleeding. This pattern of injury, without any displacement or completion to an unstable fracture, should be considered in a patient with specific tenderness over a malleolus after a twisting injury or direct blow to the ankle.

Amputation, Traumatic↗

PubMedDate not supplied

Postnatal development of the human sternum.

Postnatal development and maturation of the human sternum are highly variable. Endochondral ossification centers (sternebrae) form within each cartilaginous segment of the sternum, with each center enveloped by a spherical growth plate. Within a cartilaginous center there may be either one or two ossification centers, those with two centers retaining and reflecting features of their bilateral embryonic origin. Malaligned bifid centers are clearly associated with rib articulation asymmetry as well. Expansion of individual ossification centers progresses within the peripheral cartilaginous domains of the sternum. With respect to the rostrocaudal axis, sternebrae form between the costosternal articulations. Consistent with the biology of endochondral transition, cartilage canals are evident throughout unossified regions of the hyaline matrix. Expanding ossification of adjacent sternebrae results in depletion of the common area of cartilage between the two sternebrae, and eventually in physiologic epiphysiodesis. Fusion of the mesosternebrae reciprocates the initial pattern of sternebral ossification site appearance, proceeding in a caudal-to-cranial direction. Union of adjacent sternebrae, initiated through a central osseous bridge, progresses through anterior, lateral, cephalocaudal, and posterior domains to achieve synostosis. Accessory and bifid centers of ossification within the same intercostal space coalesce prior to adjoining adjacent sternebrae. Manubriosternal fusion is rare due to the presence of a fibrocartilaginous joint restricting ossification. The xiphoid process remains connected to the most caudal mesosternum via a common zone of hyaline cartilage that ossifies by middle to late adulthood. A single pattern of development does not appear fundamental to successful growth of the sternum, as morphological variants were common.

Adolescent↗

PubMedDate not supplied

Pathologic morphology of the dislocated proximal femur in children with cerebral palsy.

We describe the gross and microscopic anatomic changes in the hip that result from the deforming forces in children with neuromuscular imbalance. Twelve dislocated proximal femora that had been resected from children with spastic diplegia or tetraplegia were evaluated with respect to their gross, microscopic, and radiographic structure. The epiphyses were wedge shaped with deformation of the femoral head apparent in all cases. In addition to a severe loss of articular cartilage, a furrowed erosion of epiphyseal bone suggested a sustained, blunt, band-like force across the surface of the hip where it opposed the acetabular labrum. The underlying physis of the capital femur was irregular with aberrant histologic structure, whereas that of the lesser trochanter was hypertrophic and angulated in a superior and anterior direction. A significant degree of valgus was not noticeable in most specimens. In summary, the spastic adductor and iliopsoas, responsible for the changes in the lesser trochanter, work in conjunction with the hip flexor and internal rotator muscles to subluxate the proximal femur. In the process, the superior rim of the acetabulum and capsule causes focal deformation of the superolateral femoral head, creating a fulcrum upon which the hip then progressively subluxates. The indentation locks the femoral head at the lateral acetabular margin, preventing complete dislocation, but leading to bone pain consequent to cartilage erosion.

Adolescent↗