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At least 343 records · Page 19Linked to original sources
PubMed2004

The influence of slouching and lumbar support on iliolumbar ligaments, intervertebral discs and sacroiliac joints.

OBJECTIVE: To investigate lumbopelvic kinematics when moving into a slouch. DESIGN: A biomechanical model was developed. Load tests in vitro verified the model. BACKGROUND: The precise mechanism causing disc herniation and back sprain is still debated. Most biomechanical studies have focused on lifting in a stooped posture. Previous studies address instability situations due to Euler buckling of the spine under axial load. However, no studies address lumbosacral, iliolumbar and sacroiliac kinematics in slouching, i.e. flexing the spine in situations with negligible compressive spinal load. METHODS: Modeling started with the click-clack movement, i.e. the transition from lumbar lordosis to lumbar kyphosis by the combination of backward rotation of the pelvis and ventral flexion of the spine. The flexed spine was compared with a crowbar which uses the iliolumbar ligaments as fulcrum and pivot. To analyse the click-clack movement in sitting, unembalmed erect human trunks were moved from a forward position to a backward position, recording angular changes between L5, sacrum and ilium. RESULTS: When moving the trunk stepwise backward with support at shoulder level, L5 showed forward rotation with respect to the sacrum, but rotation of the sacrum with respect to the iliac bones was reversed (i.e. counternutation). L5 showed displacement in ventral direction with respect to the ilium. Measurements were in agreement with prediction from the crowbar model of the spine. CONCLUSIONS: Backward rotation of the pelvis combined with flexion of the spine, i.e. slouching, results in backward rotation of the sacrum with respect to the ilium, dorsal widening of the intervertebral disc L5-S1 and strain on the iliolumbar ligaments when protection from back muscles against lumbar flexion is absent. Lumbar backrest support almost eliminates lumbosacral and sacroiliac movement. RELEVANCE: Understanding why the iliolumbar ligaments are loaded in slouching contributes to the understanding of the biomechanics of low back pain in everyday situations with small or negligible compressive spinal load. The results recommend lumbar support: backrests with free shoulder space.

Aged↗
PubMed2001

Effects of suppressed bone turnover by bisphosphonates on microdamage accumulation and biomechanical properties in clinically relevant skeletal sites in beagles.

We recently demonstrated that suppression of bone remodeling allows microdamage to accumulate, leading to reduced bone toughness in the rib cortex of dogs. This study evaluates the effects of reduced bone turnover produced by bisphosphonates on microdamage accumulation and biomechanical properties at clinically relevant skeletal sites in the same dogs. Thirty-six female beagles, 1-2 years old, were divided into three groups. The control group was treated daily for 12 months with saline vehicle (CNT). The remaining two groups were treated daily with risedronate at a dose of 0.5 mg/kg per day (RIS), or alendronate at 1.0 mg/kg per day (ALN) orally. The doses of these bisphosphonates were six times the clinical doses approved for treatment of osteoporosis in humans. After killing, the L-1 vertebra was scanned by dual-energy X-ray absorptiometry (DXA), and the L-2 vertebra and right ilium were assigned to histomorphometry. The L-3 vertebra, left ilium, Th-2 spinous process, and right femoral neck were used for microdamage analysis. The L-4 vertebra and Th-1 spinous process were mechanically tested to failure in compression and shear, respectively. One year treatment with risedronate or alendronate significantly suppressed trabecular remodeling in vertebrae (RIS 90%, ALN 95%) and ilium (RIS 76%, ALN 90%) without impairment of mineralization, and significantly increased microdamage accumulation in all skeletal sites measured. Trabecular bone volume and vertebral strength increased significantly following 12 month treatment. However, normalized toughness of the L-4 vertebra was reduced by 21% in both RIS (p = 0.06) and ALN (p = 0.05) groups. When the two bisphosphonate groups were pooled in a post hoc fashion for analysis, this reduction in toughness reached statistical significance (p = 0.02). This study demonstrates that suppression of trabecular bone turnover by high doses of bisphosphonates is associated with increased vertebral strength, even though there is significant microdamage accumulation and a reduction in the intrinsic energy absorption capacity of trabecular bone.

Animals↗
PubMed2003

An alternative design of locked percutaneous device for skeletal extension through skin.

A skeletal extension bar (SEB) through the skin may be involved with many treatments of orthopedic diseases. A new locked percutaneous device (LPD), LPD-III, was designed for the SEB not only to allow the skin to bind onto the SEB, similarly to the LPD, but also to allow the skin binding to shift up or down the SEB while the body changes weight. Two designs of LPD-III were tried. The LPD-III-F was made from a formation of nylon hooks, fixed directly onto the SEB surface. Soft tissue can lock and shift onto the hook formation naturally. The LPD-III-S was made by attaching a stainless steel spring as a single row of rings on a nylon sleeve. Tissue can lock through the spring rings and the nylon sleeve can be manually shifted on the SEB to follow the change of thickness of soft tissue. The SEB is a stainless steel bar implanted in the sheep ilium through the skin and buttock. Two sheep were employed, both implanted with a SEB with LPD-III-F in one ilium and another SEB with LPD-III-S in the other ilium. Our experiment demonstrates that: first, both designs, LPD-III-F and LPD-III-S, function well as a skin junction shifting device; second, the LPD-III-F has abilities to re-bind the skin that not only repair damaged binding junction but also shift the skin binding up to overcome skin downgrowth; and third, powerful evidence certifies again that the mechanical connection exists in LPD.

Adipose Tissue↗
PubMedDate not supplied

[Superselective angiography as a therapy control of femur head necrosis treated with a vascular pedicled pelvic bone graft].

This is a report of special operative therapy of idiopathic necrosis of the femoral head. This is based on the idea, that the necrosis of the femoral head is caused by an occlusion of the arteries of the femoral head, especially the arteria circumflexa femoris medialis. The necrotic area of the femoral head is filled up with a pedicle bone graft, which is apart from the spina iliaca and supplied from the art, circumflexa ilium profunda. From a total of 28 superselective angiographies of the arteria circumflexa femoris medialis, which where conducted preoperatively, a pathological finding was shown in 21 cases. Furthermore it is possible, to determine different courses of the art. circumflexa ilium profunda. A superselective angiography of the reset art. circumflexa ilium profunda was conducted in seven patients following the bone graft operation. These findings will be discussed. The angiographies were processed by electronic subtraction to better illustrate the state of the smallest vessels.

Angiography↗
PubMed1998

A paramedian tangential approach to lumbosacral extraforaminal disc herniations.

OBJECTIVE: Extraforaminal disc herniations today are operated on via the so-called lateral approach. Clinical experience has shown that in contrast to levels L2/3-L4/5, this approach may become extremely difficult at the L5-S1 level. According to new microanatomic studies, the previous lateral approaches at this level often do not allow access to the neuroforamen without partial or total destruction of the L5-S1 facet joint. Postoperatively, this may lead to joint irritation with consecutive low back and pseudoradicular pain. To preserve the facet joint, a new approach was developed based on an anatomic study. METHODS: The approach was first considered with the help of bone specimens including ilium, vertebra 5, and sacrum. Thereafter, lumbar maceration specimens were prepared leaving ligaments, intervertebral discs, and joints intact. From these specimens, bony and ligamentous landmarks were deduced. Finally, the approach was tested on seven cadavers. Subsequently, the approach was performed on 13 patients and the intraoperative findings, the clinical feasibility, and the postoperative results were analyzed. APPROACH: After a transverse skin incision above the dorsal curvature of the ilium, the paravertebral muscles are dissected from the ilium medially toward the spinous process. Lateral from the apophyseal joint, a canal is drilled through the spongiosa of the sacrum. Primarily, a thin layer of inner cortex is spared to protect the content of the neuroforamen. Subsequently, it can easily be removed with the dissector to enter the extraforaminal space. In the depth of the drilled canal, the nerve root is found, because it is fixed at the sacrum near the disc space by the anterior lumbosacral ligaments. Riding on the nerve root, the intertransverse ligament and muscle can be removed with the punch. It is then possible to see the neuroforamen and extraforaminal space in front of the joint. Free fragments and contained discs can then easily be found and removed. CONCLUSION: Using this new approach, the L5-S1 joint remains intact. Space for instrumental manipulations is created in areas not essential for joint function. For this procedure, newly defined anatomic landmarks, such as the ileolumbar ligament, upper edge of the sacrum, lateral rim of the apophyseal joint, and para-articular notch, guide the operative route. In accordance with the preliminary anatomic studies, this approach was successfully used in 13 patients, and we think that it is a promising alternative that helps to preserve joint function and dorsal root ganglion integrity.

Adult↗
PubMed2001

Mandibular reconstruction using microvascular free flaps: a statistical analysis of 178 cases.

For this article, 178 consecutive cases of mandibular reconstruction using microvascular free flaps and performed from 1979 to 1997 were studied. The purpose of this report is to compare flap success rates, complications, and aesthetic and functional results. The ages of the 131 men and 47 women ranged from 13 to 85 years, with an average of 55 years. Donor sites included the rib (11 cases), radius (one case), ilium (36 cases), scapula (51 cases), fibula (34 cases), and soft-tissue flaps with implant (45 cases). Complications included total flap necrosis, partial flap necrosis, major fistula formation, and minor fistula formation. The rate of total flap necrosis involving the ilium and fibula was significantly higher than that of all other materials combined (p < 0.05). The overall rate of implant plate removal, which resulted from the exposure or fracture of the plate, was 35.6 percent (16 of 45 cases). Each mandibular defect was classified by the extent of the bony defect and by the extent of the soft-tissue defect. The extent of the mandibular bony defect was classified according to the HCL method of Jewer et al. The extent of the soft-tissue defect was classified into four groups: none, skin, mucosal, and through-and-through. According to these classifications, functional and aesthetic assessments of deglutition and contour were performed on 115 subjects, and speech was evaluated in 110. To evaluate the postoperative results, points were assigned to each assessment of deglutition, speech, and mandibular contour. Statistical analysis between pairs of bone-defect groups revealed that there was no significant difference in each category. Regarding deglutition, statistical analysis between pairs of soft-tissue-defect groups revealed there were significant differences (p < 0.05) between the none and the mucosal groups and also between the none and the through-and-through groups. Regarding speech, there was a significant difference (p < 0.05) between the none and the through-and-through groups. Regarding contour, there were significant differences (p < 0.01) between the none and the through-and-through groups and between the mucosal and the through-and-through groups. The points given for each function, depending on the reconstruction material, revealed that there was no significant difference between pairs of material groups. From this prospective study, the authors have developed an algorithm for oromandibular reconstruction. When the bony defect is lateral, the ilium, fibula, or scapula should be chosen as the donor site, depending on the extent of the soft-tissue defect. When the bony defect is anterior, the fibula is always the best choice. When the soft-tissue defect is extensive or through-and-through with an anterior bony defect, the fibula should be used with other soft-tissue flaps.

Adolescent↗
PubMed2002

A case of TSH receptor antibody-positive hyperthyroidism with functioning metastases of thyroid carcinoma.

The presence of TSH receptor antibody (TRAb) is rarely responsible for hyperthyroidism due to metastatic lesions of thyroid carcinoma. A 70-year-old woman was incidentally found to be thyrotoxic around the time that external irradiation was performed for multiple bone metastases 9 years after subtotal thyroidectomy for follicular carcinoma. Hyperthyroidism persisted after oral administration of thiamazole. Relevant laboratory data were as follows: FT4 9.6 ng/L, FT3 7.3 ng/L, TSH <0.19 mU/L, TBII 70, TSAb 735, and Tg 32,000 microg/L. 131I-total body scan showed 131I accumulation in the occipital bone, cervical vertebra, thoracic vertebra, ilium, and residual thyroid gland. Since the ilium uptake (11.6) was markedly higher compared to the residual thyroid gland uptake (0.14), four subsequent 131I therapies were performed. The patient became hypothyroid, and TBII became negative. TSAb became negative after the first 131I-therapy but has increased again to 204 at present. Tg was 1,962 microg/L despite high TSH levels. 131I accumulation in the residual thyroid, cervical vertebra, and thoracic vertebra disappeared. Also 131I accumulation in the ilium has gradually decreased, but the image in the occipital bone has become markedly distinctive. This is a rare case characterized by TRAb-positive hyperthyroidism, by T3-predominant thyrotoxicosis, and by stronger accumulation of 131I in the metastatic tumor than in the residual thyroid gland. Thus, the response to TRAb and 131I-therapy is different among metastatic thyroid tissues.

Adenocarcinoma, Follicular↗
PubMed2006

Anatomy of the interosseous region of the sacroiliac joint.

STUDY DESIGN: Anatomical study of the interosseous region of the sacroiliac joint (SIJ) complex. OBJECTIVES: To document and quantify the surface topography of the interosseous region of the SIJ. BACKGROUND: A review of the literature reveals that little consideration has been given to the interosseous region of the SIJ anatomically, biomechanically, and clinically. METHODS AND MEASURES: The interosseous region of 11 cadaveric specimens (9 formalin embalmed and 2 fresh frozen) were studied. Ten specimens were 55 years of age or older and 1 was 20 years old. To view the interosseous surfaces of the sacrum and ilium the specimens were either axially sectioned (1-cm slices) or disarticulated. One fresh-frozen and 6 embalmed specimens were disarticulated and the remainder axially sectioned. The topography (surface ridging and areas of ossification) of the interosseous region was documented in all specimens and in 2 specimens the surfaces were 3-dimensionally reconstructed using modeling and animation software (MAYA; Autodesk, Inc, San Rafael, CA). RESULTS: Surface characteristics of the SIJ complex observed in specimens 55 years of age or older included moderate to extensive ridging of the interosseous region of the sacrum and ilium in 100% of specimens and ossification of the central interosseous region of the sacroiliac (SI) ligament in 60% of specimens. CONCLUSIONS: Central region ossification of the interosseous SI ligament and the presence of ridges and depressions over the opposing interosseous surfaces of the sacrum and ilium are features common to specimens that are in or beyond their sixth decade. These findings further support the contention that there is little to no movement available at this joint in older individuals.

Adult↗
PubMed2006

[An anatomic study of lag screw placement in anterior column of acetabulum and design of targeting device].

OBJECTIVE: To provide the anatomic basis for the lag screw placement in the anterior column of the acetabulum. METHODS: Twenty-two pelvis specimens with 44 acetabula of the native adult cadavers were studied. The anthropometric measurement was performed on 44 acetabula to determine the shape of the transverse section of the anterior column of the acetabulum, the optimal entry point for the lag screw on the outer table of the ilium, the direction of the screw, and the distance from the entry point to the obturator groove. RESULTS: The transverse section of the anterior column of the acetabulum was almost triangle-shaped. The path for the lag screw placement was 10.5 +/- 0.8 mm in diameter. The optimal entry point on the posterolateral ilium for the screw fixation was found to exist 9.2 +/- 2.4 mm superior to the line between the anterior superior iliac spine and the greater sciatic notch and 38.5 +/- 3.8 mm superior to the greater sciatic notch. The distance from the entry point to the obturator groove was 84.1 +/- 6.2 mm. The inclination of the lag screw was 54.2 +/- 5.5 degrees at the caudal direction in the sagittal plane and 40.7 +/- 3.8 degrees in the horizontal plane. The device for the safe screw placement in the anterior column was designed. CONCLUSION: The above data can facilitate an insertion of one 6.5 mm lag screw into the anterior acetabular column and minimize the risk of articular violation or cortical penetration, which has a narrow margin of safety. The safe length of the lag screw should be 70 mm. The optimal entry point on the posterolateral ilium for the screw fixation is determined to be 10 mm superior to the line between the anterior superior iliac spine and the greater sciatic notch and 40 mm superior to the greater sciatic notch. The inclination of the lag screw should be 55 degrees at the caudal direction in the sagittal plane and 40 degrees in the horizontal plane. It is safe to place the lag screw in the anterior column with the help of the targeting device.

Acetabulum↗
PubMed1989

[Bone and suppurative lesion distribution of antimicrobial agents (ampicillin and ofloxacin) in experimental infected rabbits].

Using Streptococcus milleri and Bacteroides fragilis in the mandibula of the domestic rabbit, a jaw-bone infected model was prepared; ampicillin (ABPC) a penicillin derivative and ofloxacin (OFLX) a pyridonecarboxylic acid derivative, were administered orally, injected intramuscularly, or infused intravenously; their concentration in the pus, mandibula, supramaxilla, humerus, femur, sternum, ilium and serum were measured. Pharmacokinetic studies compared the penetration. (1) By oral administration, the maximum ABPC concentration in the pus and bone tissues was 5.9 to 34.3% of the serum, by intramuscular injection 10.4 to 27.5% and by i.v. infusion 12.1 to 42.4%. (2) The maximum concentration of orally administered OFLX in the pus and bone tissues was 52.5 to 111.7% of the serum, by intramuscular injection 56.4 to 100.3% and by i.v. infusion 61.2 to 121.8%. (3) When administered orally, injected intramuscularly, or infused intravenously ABPC showed good penetration into the pus, mandibula and ilium, and OFLX into the pus, sternum and ilium. When infused intravenously, OFLX in the pus and bone tissues was higher than the MIC of both strains. (4) When ABPC was administered as under 3 routes, T1/2 was longer in the pus and most bone tissues than in the serum. T1/2 of OFLX was shorter in most bone tissues by all administration routes than in serum, T1/2 was longer for OFLX than for ABPC, except when orally administered. (5) AUC of ABPC was in the order of intravenous infusion, intramuscular injection and oral administration. About the same AUC of OFLX was shown after i.v. infusion and i.m. injection, both values being about double after oral administration. In all administration routes, AUC of pus surpassed AUC of serum and AUC of OFLX greatly surpassed that of ABPC.

Ampicillin↗
PubMed1985

[Resection with preservation of the lower limb in chondrosarcoma of the pelvis].

Twenty-seven chondrosarcomata of the pelvis were treated by local resection with preservation of the limb. Twenty-two were grade I or II, and 5 were grade III or IV. Attention is drawn to the importance of tomodensitometry in assessing the extent of the tumor before operation. An en bloc resection was well wide of the tumour in 16 cases, close to the tumour in 10 cases and involved the tumour in one case. Post-operative complications were varied. There were 6 nerve paralyses after iliac resection, 3 cases of sepsis after resection of the anterior part of the pelvic ring, and 3 cases of sepsis and 2 vascular complications after peri-acetabular resections. The average follow-up was 5 years. Three had metastases and three had local recurrences, one of whom died later from pulmonary metastases. No local recuRrence was seen in cases with wide resection. The functional results were satisfactory in 6 out of 7 partial resections of the ilium and in 4 out of 5 resections of the anterior part of the pelvic ring. They were only fair after peri-acetabular resections and complete resections of the ilium. After peri-acetabular resections, the results were about the same after ilio-femoral arthrodesis or Girdlestone operations. It is not appropriate to reconstruct the pelvic ring after resection limited to the anterior part of the pelvis but it is indicated after resections of the whole of the ilium, particularly in children to avoid shortening of the limb with pelvic shift.

Adult↗
PubMed1999

Bone turnover associated with antler growth in red deer (Cervus elaphus).

Although it is known that skeletal bone depletion occurs during antler growth in deer, it is not clear whether repletion of the skeleton takes place before or after completion of antler development. This study attempted to correlate repeated scanning electron microscopic measures of ilium and rib bone porosity from six approximately 2-monthly biopsy samples (using back-scattered imaging) and biochemical markers of bone turnover (serum hydroxyproline and osteocalcin concentrations) taken for 11 months with antler growth in six red deer stags. No changes were detected in ilium samples but changes in porosity of rib bones and an elevation of the biochemical markers indicated that skeletal depletion occurred during the antler growth period. However, the decrease in rib bone porosity and decline in markers of bone turnover took place before completion of antler growth, indicating that a considerable amount of skeletal repletion could have occurred whilst antlers were also undergoing bone accretion. This latter finding extends the current view of antler growth being accompanied by a form of reversible osteoporosis in the skeleton by showing that there is a period when the antlers and skeleton are both undergoing net bone formation.

Animals↗
PubMed1993

Hypertrophy of the acetabulo-cristal buttress in Homo sapiens.

In the early 1970s, excavation at the King site, a contact period Mississippian village in northwest Georgia, yielded the skeletal remains of a robust male (King 65) possessing marked hypertrophy of the acetabulo-cristal buttress. The buttress is morphologically similar to that of Plio-Pleistocene Homo but it is accompanied by an anatomically modern degree of thickening of the gluteal table of the ilium. Although the degree of cortical thickness of the gluteal table of the ilium is apparently species-specific, hypertrophy of the acetabulo-cristal buttress is developmental and may be expressed in all species of Homo.

Acetabulum↗
PubMed1995

Comparison of radiologic and gross examination for detection of cancer in defleshed skeletons.

The reliability of visual examination of defleshed bones was assessed for detection of postcranial metastatic disease in individuals known to have had cancer. This was compared with standard clinical radiologic techniques. The skeletons of 128 diagnosed cancer patients from an early 20th century autopsied skeletal collection (Hamann-Todd Collection) were examined. Radiologic examination detected evidence of metastatic disease in 33 individuals, compared to 11 by visual examination of the postcranial skeletons. Four of these cases were detected by both techniques. Blastic lesions were most commonly overlooked on visual examination, because they were localized to trabecular (internal bone) structures. The ilium was the most commonly affected bone, with lytic or blastic lesions detected in 30 of 33 individuals. While the proximal femur was affected in only nine individuals, x-ray of the proximal femur and ilium detected all individuals with postcranial evidence of metastatic disease. Skeletal distribution of metastases provides no clue to the location of origin or histologic subtype of the cancer. Survey of archeological human remains for metastatic cancer requires radiologic examination. Such skeletal surveys should x-ray at least the ilia and femora.

Anthropology, Physical↗
PubMed1995

Natural selection and developmental sexual variation in the human pelvis.

This research examines ontological patterns of change in variation of the human pelvis as a means of identifying regions of differential growth, growth canalization and evidence of selection. Data were derived from pelvic radiogrammetry of 180 8-year-olds and 89 subjects at age 18 who were part of the Fels Longitudinal Growth Study. Coefficients of variation (CVs) and total growth increments were compared between sexes and between ages 8 and 18 for 14 pelvic measures. Sex-specific comparisons of mean size were tested per age using Student's t, whereas coefficients of variation were calculated and compared using the methods suggested by Sokal and Braumann ([1980] Syst. Zool. 29:50-66). The Mann-Whitney U-test was used to test median growth increments between ages 8 and 18. Results of these comparisons show significant sex differences in breadth of the ischium and acetabular regions among 8-year-olds. Most of the sexual dimorphism in the pelvis at age 18, however, develops during the adolescent growth period, during which both male and female pelves undergo growth remodeling of the pelvic cavity. Over the same time period, males show significantly greater incremental growth in the acetabulum, and females show differentially greater growth in the pelvic cavity. At age 18, the pelvis demonstrates a posterior-to-anterior gradient of increasing dimorphism within the inlet and midplane of the pelvic birth canal. As a means of interpreting the effects of natural selection on the pelvis, it is argued that appropriate comparisons are within-sample comparisons of CVs over time, rather than comparisons between sexes of adult coefficients as has been argued by others (Meindl et al. [1985] Am. J. Phys. Anthropol. 68:79-85). Analyses of change in coefficients of variation over time show evidence of concordantly reduced within-sample variation in 7 pelvic dimensions indicating canalization of growth. These results are attributed to the effects of stabilizing selection operating on both males and females and include transverse diameters of the sacrum, inlet, anterior inferior iliac spines, and breadths of the ilium and ischium. Six pelvic dimensions show evidence of increased total sample CVs and discordant change in within-sex comparisons of CVs as well as differential growth between sexes over time. This pattern is indicative of the effects of disruptive selection on the pelvis for interacetabular diameter, breadths of the anterior superior and posterior inferior iliac spines, public length, and ilium height.

Adolescent↗
PubMed1996

Effect of ethnicity and age or menopause on the structure and geometry of iliac bone.

We measured indices of bone volume (cancellous, cortical) and bone surface (cancellous, endocortical, and intracortical) in intact full-thickness transiliac bone biopsies obtained from 144 healthy women aged 20-74 (35 black and 109 white, 62 premenopausal and 82 postmenopausal). The data were analyzed by two-way analysis of variance of the four groups defined by age/menopause and ethnicity and by linear regression of major variables on age. None of the interaction terms was significant, and none of the regression slopes on age differed between blacks and whites, indicating that the effects of ethnicity and of age/menopause were independent. Accordingly, the data were also analyzed separately for the effects of ethnicity (pre- and postmenopausal combined) and age/menopause (blacks and whites combined). The analyses led to the following conclusions. (1) Blacks have more cancellous and cortical bone than whites in the ilium; the difference was due to thicker trabeculae and thicker cortices with no difference in trabecular number or cortical porosity. (2) The magnitude of the black/white differences was the same throughout the age range covered by the study, indicating differences in peak adult values, not in rates of loss with age. (3) As the result of age/menopause, there were significant reductions in all indices of the amount and structure of bone except for trabecular thickness; the magnitude of the reductions was the same in blacks and whites. (4) Cancellous bone loss was mainly the result of the complete removal of some trabecular elements with increased separation between remaining elements. Cortical bone loss was due to thinning from the endocortical surface with a small but significant contribution from increased cortical porosity, due to an increased number of intracortical canals. These patterns of bone loss were the same in blacks and whites. (5) Although the percentage losses of bone with age/menopause were higher for cancellous than for cortical bone, the absolute amounts of bone lost were about the same for cortical as for cancellous bone. (6) The ratio of surface to tissue volume decreased with age/menopause in cancellous bone but increased in cortical bone; rates of bone loss would change in the same manner if the loss per unit of surface remained constant. (7) The total extent of bone surface in the ilium did not change with age/menopause, so that the surface/volume ratio for the entire bone increased; volumetric bone turnover would increase and bone age decrease if remodeling activity per unit of surface remained constant.

Adult↗
PubMed1991

Regional blood flow and strontium-85 incorporation rate in the rat hindlimb skeleton.

Regional distribution of radioactive microspheres and 85Sr incorporation rate in the os ilium, femur, and tibia were determined in 44 rats. In 15 additional animals, regional blood flow was measured with the reference sample technique. Highest numbers of microspheres were found in the distal femoral and proximal tibial metaphyses. Highest blood flow rates were found in the os ilium, the caput femoris, and distal femoral and proximal tibial metaphyses. The diaphyses and epiphyses of the femur and tibia had a relatively lower perfusion. The regional 85Sr incorporation rate was correlated (r = 0.67) to the regional distribution of the microspheres. The dispersion of the data was large and this was mainly due to biological variation. The results describe the regional distribution of blood flow in the rat hindlimb and demonstrate a close association between blood flow and mineral turnover in normal rat skeletal tissue as shown by the correlation between microsphere and 85Sr incorporation rate distribution.

Animals↗
PubMed1987

Ovariectomy and trabecular bone remodeling in the dog.

The early effects of ovariectomy (OX) on serum biochemistry and trabecular bone remodeling in the dog were investigated. Adult beagle dams were ovariectomized (n = 8) or sham-ovariectomized (n = 6) and followed for 6 months. All dogs received an iliac crest biopsy at the time of surgery to establish baseline remodeling data. A second contralateral biopsy was obtained at sacrifice. Serum osteocalcin became significantly elevated approximately 8 weeks following OX and remained elevated for the duration of the study. Histomorphometric analysis of serial transilial specimens showed that, at 6 months, OX had significantly increased the rate of bone remodeling in the ilium. Six months following OX in the dog, changes in serum biochemistry and trabecular bone remodeling in the ilium are consistent with those seen in postmenopausal women suffering from "high remodeling osteoporosis".

Animals↗