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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The distal femoral growth plate has a uniquely convoluted structure comprised of four mammillate processes. Factors contributing to the development of these processes and overall plate geometry were explored using three-dimensional image analysis of the canine distal femoral epiphysis. The growth plate at birth remains relatively flat until ossification of the epiphysis begins at 1 week of age. Epiphyseal ossification proceeds eccentrically, projecting in the medial-lateral and anterior-posterior directions. Growth plate activity indexed by [3H]thymidine labeling and plate thickness revealed regional differences in cell proliferation. This was measured as a decreased labeling index and thinning of the growth plate in areas capped by the ossifying epiphysis. The eccentric ossification pattern and associated variations in growth plate activity result in definition of an "intraphyseal" groove and medial-lateral oriented sulcus. The groove and sulcus bisect the plate into four quadrants, giving rise to a convoluted structure composed of four areas of plate elevations termed mammillary processes (MP). By 5 weeks, the pattern of ossification results in greater development of the MP in the anterior-medial quadrant and in decreasing order, in the posterior-medial, anterior, and posterior-lateral quadrants. By 10 weeks, a uniform rate of cell proliferation was observed coincident with completion of ossification of the epiphysis. The data suggest that localized variations in growth plate proliferation are associated with ossification of the epiphysis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Stereological study of the developing distal femoral growth plate. 279 27

Two children are described who developed premature epiphyseal closure while receiving etretinate for treatment of congenital hyperkeratotic disorders. The first patient was an 8 1/2-year-old boy with nonbullous ichthyosiform erythroderma who had been on treatment for 6 years, 4 months when premature fusion of the right distal tibial epiphysis was detected. Shortness of stature, thinning of long bones, and traumatic fractures were also observed in this patient. The second child was an 11-year-old girl with systematized verrucous nevi in whom symmetric fusion of both elbow epiphyses and narrowing of the femoral epiphyses bilaterally were noted following treatment with etretinate for 5 years, 5 months.
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PMID:Premature epiphyseal closure--a complication of etretinate therapy in children. 380 66

Flattening of the epiphysis of the long bones is seen in several bone dysplasias. It is the hallmark of multiple epiphyseal dysplasia and is an important sign in the diagnosis of spondyloepiphyseal dysplasias, diastrophic dysplasia, and pseudoachondroplastic dysplasia. The goal of this study was to determine norms for the height of the distal femoral epiphysis and to apply these standards to patients with bone dysplasias. Ratios of the distal femoral epiphysis height to both the distal femoral metaphysis width and the distal femoral epiphysis width were obtained from 640 radiographs of healthy children of different ages. Application of these standards to 41 patients with the bone dysplasias mentioned above proved useful in ascertaining decreased height of the distal femoral epiphysis. These standards are of particular value in subtle or early cases in which the thinning of the epiphysis may not be apparent upon simple observation. Obtaining three simple measurements from the anteroposterior knee radiographs allows determination of the presence or absence of flattening of the epiphysis.
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PMID:Distal femoral epiphysis: normal standards for thickness and application to bone dysplasias. 396 Nov 86

To investigate the manner in which cancellous bone in different skeletal sites and within a bone site adapts to strenuous training, 5-wk-old male rats were subjected to intensive treadmill running [80% of maximal O2 consumption (VO2max)] for 11 wk. VO2max, tibia length, and bone mineral density were measured. Histomorphometric analysis was performed in the epiphysis, primary spongiosa (1 zero sp) and secondary spongiosa (2 zero sp) of the contralateral proximal tibia, and the 2 zero sp of thoracic and lumbar vertebrae. VO2max was increased by 39%. No changes were observed in vertebrae. Tibia length, 1 zero sp bone volume, and number of trabeculae were significantly decreased, indicating a retarded longitudinal bone growth. Bone mineral density in the proximal tibia was significantly decreased. In the epiphysis, a trabecular thinning and an increase of trabecular number were shown. In the 2 zero sp, bone volume and number of trabeculae were significantly decreased. The increased total eroded surfaces could indicate an early but transient increase in bone resorption activity. Osteoid thickness was reduced, whereas osteoclast number and osteoid surfaces were unchanged, suggesting that the observed bone loss was mostly due to an impaired osteoblastic activity. In conclusion, 1) strenuous training in young rats reduces longitudinal bone growth and induces bone loss, 2) the cancellous bone adaptation is site specific, and 3) the bone loss is mainly due to decreased osteoblastic activity rather than a global adaptation of bone remodeling.
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PMID:Adverse effects of strenuous exercise: a densitometric and histomorphometric study in the rat. 806 62

A 3.3-year-old 125-kg castrated male llama was evaluated because of acute non-weight-bearing lameness on the left hind limb. Physical examination revealed crepitus in the midportion of the femur. On radiographs, a comminuted middiaphyseal fracture was seen. There was also a region of bone lysis with cortical thinning and expansion in the distal metaphysis and epiphysis of the left femur. Multiple small circular lesions were observed in the proximal metaphysis of the left femur, and the proximal portion of the left tibia appeared irregular. The owner elected to pursue treatment, and the fracture was repaired with 2 compression plates. Multiple bone biopsy specimens were obtained and submitted for bacterial culture and histologic examination. Cultures yielded neither bacteria nor fungi. Histologic examination revealed fibrous connective tissue, normal appearing cortical bone, and an absence of medullary structures. The llama was maintained in a hind-limb sling for 14 days after surgery, at which time follow-up radiography revealed a comminuted fracture of the proximal portion of the femur. The llama was euthanatized, and multifocal polyostotic aneurysmal bone cysts were found in the proximal and distal metaphyses of the left femur and tibia. Cysts were lined by fibroblasts or endothelial-like cells.
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PMID:Multifocal polyostotic aneurysmal bone cysts in a llama. 907 85

Normal development of the acetabulum is crucial to the growth and stability of the hip. Twenty-five New Zealand White rabbits (postweaning) weighing 1.5-2.2 kg were used. Both hips were exposed through an anterolateral approach. On the right hip, a fixed area of superolateral physeal cartilage was damaged with drills. Sham open reduction was performed for the left hip. Radiographic changes of the right hips were evident at 6 weeks. At 12 weeks, the right hip dislocated in a posterior and superior direction. The left hip remained normal. Histopathologic analysis correlated strongly with the radiographic findings. There were thinning of cartilage cells of the acetabulum, with disorganization. The acetabular roof was poorly formed. The lateral acetabular epiphysis is vital to the development of the acetabular roof. Damage to this epiphysis may result in acetabular maldevelopment and subsequent hip instability. We tested the hypothesis that abnormality in this epiphysis can give rise to abnormal acetabular development.
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PMID:Significance of the lateral epiphysis of the acetabulum to hip joint stability. 1082 2

Although classified as benign neoplasms, giant cell tumors are locally aggressive with a high recurrence rate of 30-50%. The histological appearance include osteoclast-like, multinucleated giant cells and round to spindle-shaped mono-nuclear stromal cells. These neoplasms predominately affect adults in the third and forth decades of life (70-80%). Giant cell tumors predominately arise in long tubular bones (75-95%) with the majority occurring around the knee (50%). The next most common site being the distal radius (10%). The epicenter of giant cell tumors is in the epiphysis. The radiographic signs of giant cell tumors are a geographical radiolucency with no internal mineralization, a thinning of the cortex, eccentric in the epiphysis of long bones. MRI signs of giant cell tumors are high signal intensity in T2-weighted images, high contrast media enhancement, fluid levels, signs according to haemorrhage and haemosiderin deposition. CT shows the expanded and thinned cortex. Plain radiographs remain the mainstay of diagnosis of giant cell tumors. MRI and CT are important for staging and therefore for surgical planning.
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PMID:[Diagnostic imaging of giant cell tumors]. 1149 Jul 77

Normal development of the acetabulum is crucial to the growth and stability of the hip. Twenty-five New Zealand white rabbits (postweaning) weighing 1.5 to 2.2 kg were used. Both hips were exposed through an anterolateral approach. On the right hip, a fixed area of superolateral physeal cartilage was damaged with drills. Sham open reduction was performed for the left hip. Radiographic changes of the right hips were evident at 6 weeks. At 12 weeks, the right hip dislocated in a posterior and superior direction. The left hip remained normal. Histopathologic analysis correlated strongly with the radiographic findings. There were thinning of cartilage cells of the acetabulum, with disorganisation. The acetabular roof was poorly formed. The lateral acetabular epiphysis is vital to the development of the acetabular roof. Damage to this epiphysis may result in acetabular maldevelopment and subsequent hip instability. We tested the hypothesis that abnormality in this epiphysis can give rise to abnormal acetabular development.
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PMID:7th Yahya Cohen Lecture. Significance of the lateral epiphysis of the acetabulum to hip joint stability. 1277 31

Supraphysiological levels of glucocorticoids (GC) cause bone atrophy and growth retardation. In this study, we examine whether these adverse structural effects are reversible and whether treatment with bisphosphonate is protective by in vivo serial micro-magnetic resonance (micro-MR) imaging and spectroscopy. Rabbits (n = 16) were divided into four groups, a control group (n = 4) and three groups (n = 4 each) receiving GC in the form of dexamethasone (0.45 mg/kg/day). In one of the GC groups dexamethasone exposure was discontinued after 2 weeks, the other two groups were maintained on dexamethasone, with one receiving risedronate (5 microg/kg twice per week) from the beginning of treatment, the other one receiving risedronate after 2 weeks. Animals were imaged at baseline and at 2, 4, and 8 weeks. Trabecular bone volume fraction (trabecular bone volume/tissue volume, TB/TV), trabecular bone thickness (Tb.Th), and topological structural parameters were measured in the distal femoral epiphysis, as was the epiphyseal growth plate (EGP), and marrow fat fraction, which was computed from the integrated proton spectra. Two weeks of dexamethasone exposure substantially reduced TB/TV, along with thinning of the epiphyseal growth plate and conversion of hematopoietic to adipocytic marrow. However, TB/TV recovered to normal levels within 2 weeks after cessation of GC exposure and remained constant throughout the remainder of the protocol. In contrast, neither EGP thickness nor marrow composition returned to control levels after cessation of GC exposure as rapidly as did TB/TV. Besides increased TB/TV, bisphosphonate treatment resulted in a more connected platelike network than observable at baseline, but GP atrophy and marrow conversion caused by GC exposure were not affected. The data lend support to a protective effect of risedronate on trabecular architecture during GC exposure. The improvement in trabecular network parameters beyond baseline values further suggest a therapeutic effect of risedronate.
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PMID:Skeletal effects of short-term exposure to dexamethasone and response to risedronate treatment studied in vivo in rabbits by magnetic resonance micro-imaging and spectroscopy. 1707 39

After disastrous outcomes due to wear-induced osteolysis in the 1980s, hip resurfacing arthroplasty has undergone a renaissance, mainly because of the introduction of metal-on-metal bearings. However, there are still problems associated with this technique, such as femoral neck fractures, neck thinning, and aseptic loosening, and their causes are still being investigated. During the last years, increasing evidence has shown that both the frequently used posterior approach to the hip as well as preparation of the femoral epiphysis can impair blood supply to the femoral head. In the presence of mechanical stresses (impaction, heat development during cement polymerization) during the implantation, the epiphysis might not be able to compensate for this. This paper summarizes the current understanding of the blood supply to the femoral head and proposes a way to preserve the viability after hip resurfacing.
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PMID:[Blood flow to the femoral head and hip resurfacing arthroplasty]. 1859 69


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