Mean Cortical Width Research Articles

Femoral neck cortical bone in female and male hip fracture cases: Differential contrasts in cortical width and sub-periosteal porosity in 112 cases and controls.

To quantitate differences between cases of hip fracture and controls in cortical width around the mid-femoral neck in men and women. Over 5 years, 64 (14 male) participants over age 55 (mean 79) years, who had never taken bone-active drugs and suffered intra-capsular hip fracture treated by arthroplasty, donated their routinely discarded distal intra-capsular femoral neck bone for histomorphometry. After embedding, complete femoral neck cross sections from the cut surface near the narrowest part of the neck were stained with von Kossa and cortical width was measured radially every 5 degrees of arc. Control material (n = 48, 25 male) was available through consented post mortems prior to the year 2000. Cortical widths were averaged for circumferential octants, each representing 45 degrees of arc. Divergence of individual cortical widths from their means was also examined. Because sections were required to have a complete cortex, sampling was biased towards cases with sub-capital versus trans-cervical fractures. Compared to sex- and age matched controls, male cases showed larger relative differences in cortical widths than female cases. Unexpectedly, cortical widths in female but not male cases also showed marked over-representation of extremely narrow (<0.1 mm) cortical widths, located mainly posteriorly. The numbers of these very narrow cortical widths observed per subject retrospectively predicted female fracture status in logistic regression independently of mean cortical width values. Together with mean cortical width differences, the numbers of measured cortical widths <0.1 mm (out of 72 measured) raised the sensitivity of predicting fracture status in women from 48 to 80% at 80% specificity. In almost all cases, very narrow cortical widths were identified in regions enclosing a cortical pore roofed on its endosteal surface by thin structural bone defined a priori as trabecular. Cortical widths <0.1 mm probably reflect zones where endosteal cortex has been trabecularised through expansion of an un-refilled sub-endosteal canal close to the periosteum. Persistent cortical defects occurring near the periosteal surface, where mechanical loading exerts its greatest stresses, are likely to result in extremes of localized concentrations of stress during a fall, unknown in young normal fallers. Such defects have the potential to help explain the excess of hip fractures among elderly women. Prevention of sub-periosteal tunnelling by osteoclasts might explain in part the additional benefits, beyond an increase in bone density, of treatments that reduce excessive bone resorption or else stimulate new bone formation on previously resorbed surfaces.

Iliac crest histomorphometry and skeletal heterogeneity in men

PurposeThe cortical characteristics of the iliac crest in male have rarely been investigated with quantitative histomorphometry. Also it is still unknown how cortical microarchitecture may vary between the iliac crest and fractures related sites at the proximal femur. We studied the microarchitecture of both external and internal cortices within the iliac crest, and compared the results with femoral neck and subtrochanteric femoral shaft sites. MethodsUndecalcified histological sections of the iliac crest were obtained bicortically from cadavers (n=20, aged 18–82years, males). They were cut (7μm) and stained using modified Masson-Goldner stain. Histomorphometric parameters of cortical bone were analysed with low (×50) and high (×100) magnification, after identifying cortical bone boundaries using our previously validated method. Within cortical bone area, only complete osteons with typical concentric lamellae and cement line were selected and measured. ResultsAt the iliac crest, the mean cortical width of external cortex was higher than at the internal cortex (p<0.001). Also, osteon structural parameters, e.g. mean osteonal perimeter, were higher in the external cortex (p<0.05). In both external and internal cortices, pore number per cortical bone area was higher in young subjects (≤50years) (p<0.05) while mean pore perimeter was higher in the old subjects (>50years) (p<0.05). Several cortical parameters (e.g. osteon area per cortical bone area, pore number per cortical area) were the lowest in the femoral neck (p<0.05). The maximal osteonal diameter and mean wall width were the highest in the external cortex of the iliac crest (p<0.05), and the mean cortical width, osteon number per cortical area were the highest in the subtrochanteric femoral shaft (p<0.05). Some osteonal structural parameters (e.g. min osteonal diameter) were significantly positively correlated (0.29≤R2≤0.45, p<0.05) between the external iliac crest and the femoral neck. ConclusionsThis study reveals heterogeneity in cortical microarchitecture between the external and internal iliac crest cortices, as well as between the iliac crest, the femoral neck and the subtrochanteric femoral shaft. Standard iliac crest biopsy does not reflect accurately cortical microarchitecture of other skeletal sites.

Content Validity of Temporal Bone Models Printed Via Inexpensive Methods and Materials.

Computed tomographic (CT) scans of the 3-D printed temporal bone models will be within 15% accuracy of the CT scans of the cadaveric temporal bones. Previous studies have evaluated the face validity of 3-D-printed temporal bone models designed to train otolaryngology residents. The purpose of the study was to determine the content validity of temporal bone models printed using inexpensive printers and materials. Four cadaveric temporal bones were randomly selected and clinical temporal bone CT scans were obtained. Models were generated using previously described methods in acrylonitrile butadiene styrene (ABS) plastic using the Makerbot Replicator 2× and Hyrel printers. Models were radiographically scanned using the same protocol as the cadaveric bones. Four images from each cadaveric CT series and four corresponding images from the model CT series were selected, and voxel values were normalized to black or white. Scan slices were compared using PixelDiff software. Gross anatomic structures were evaluated in the model scans by four board certified otolaryngologists on a 4-point scale. Mean pixel difference between the cadaver and model scans was 14.25 ± 2.30% at the four selected CT slices. Mean cortical bone width difference and mean external auditory canal width difference were 0.58 ± 0.66 mm and 0.55 ± 0.46 mm, respectively. Expert raters felt the mastoid air cells were well represented (2.5 ± 0.5), while middle ear and otic capsule structures were not accurately rendered (all averaged <1.8). These results suggest that these models would be sufficient adjuncts to cadaver temporal bones for training residents in cortical mastoidectomies, but less effective for middle ear procedures.

Vertebral Implantation of NELL-1 Enhances Bone Formation in an Osteoporotic Sheep Model.

Vertebral compression fractures related to osteoporosis greatly afflict the aging population. One of the most commonly used therapy today is balloon kyphoplasty. However, this treatment is far from ideal and is associated with significant side effects. NELL-1, an osteoinductive factor that possesses both pro-osteogenic and anti-osteoclastic properties, is a promising candidate for an alternative to current treatment modalities. This study utilizes the pro-osteogenic properties of recombinant human NELL-1 (rhNELL-1) in lumbar spine vertebral defect model in osteoporotic sheep. Osteoporosis was induced through ovariectomy, dietary depletion of calcium and vitamin D, and steroid administration. After osteoporotic induction, lumbar vertebral body defect creation was performed. Sheep were randomly implanted with the control vehicle, comprised of hyaluronic acid (HA) with hydroxyapatite-coated β-tricalcium phosphate (β-TCP), or the treatment material of rhNELL-1 protein lyophilized onto β-TCP mixed with HA. Analysis of lumbar spine defect healing was performed by radiographic, histologic, and computer-simulated biomechanical testing. rhNELL-1 treatment significantly increased lumbar spine bone formation, as determined by bone mineral density, % bone volume, and mean cortical width as assessed by micro-computed tomography. Histological analysis revealed a significant increase in bone area and osteoblast number and decrease in osteoclast number around the implant site. Computer-simulated biomechanical analysis of trabecular bone demonstrated that rhNELL-1-treatment resulted in a significantly more stress-resistant composition. Our findings suggest rhNELL-1-based vertebral implantation successfully improved cortical and cancellous bone regeneration in the lumbar spine of osteoporotic sheep. rhNELL-1-based bone graft substitutes represent a potential new local therapy.

Comparison of Accuracy of Prediction of Osteoporosis in Digital Panoramic Radiography with DEXA Scan in Postmenopausal Women: A Pilot Study

Aims and objectives: To compare the accuracy of prediction of osteoporosis in digital panoramic radiography with Dual Xray absorptiometry (DEXA) scans and serum investigations such, as calcium, phosphorous, alkaline phosphatase in postmenopausal women. The objective of the study is to detect the appearance of eroded mandibular cortex (cortical shape), inferior cortical width appearance on Digital panoramic radiographs in post menopausal women, bone mineral density, with DEXA scan and serum calcium, phosphorous and alkaline phosphatase levels in postmenopausal women. The main objective of this study is to compare both tools (Digital OPG and DEXA scans) to detect similar diagnostic performances in identifying post-menopausal women with osteoporosis. Materials and methods: This is a study in the Outpatient department of Oral Medicine Diagnosis and Radiology and Bharat Scan Centre designed to compare the accuracy of prediction of osteoporosis in digital panoramic radiography with DEXA scan in postmenopausal women without estrogen use and with and without history of hysterectomy, oopherectomy and with normal values of serum calcium, phosphorous and alkaline phosphatase. The study includes 10 postmenopausal women varying in age group between 60 and 75 years who reported to the outpatient department of oral medicine diagnosis and radiology, seeking dental treatment. The BMD with digital panoramic radiography, DEXA-scan and serum calcium, phosphorous, and alkaline phosphatase levels were calculated and compared. Results: In our study, out of the10 postmenopausal women with no previous diagnosis of osteoporosis, who participated in this study, 3 women (30%) were normal, 1 woman (10%) had osteopenia and 6 women (60%) had osteoporosis on the basis of BMD. There is significant relationship in the width of the mandibular cortex for normal, osteopenic and osteoporosis patients. The cortical width was reduced and less than 4 mm in our study for patients with osteoporosis. The cortical width was normal and greater than 4 mm in our patients without osteoporosis. The mean cortical width of patients with osteoporosis was 2.7 mm, 3.9 mm for osteopenic patients, 4.18 mm for patient without osteoporosis. Conclusion: The purpose of this study is that dentists may be able to refer postmenopausal women with undetected low skeletal BMD or osteoporosis to medical professionals for further examination on the basis of incidental findings on dental panoramic radiographs.

Changes in mandibular cortical width measurements with age in men and women

Automated software was used to measure the mandibular cortical width in a large sample of dental radiographs. We determined that cortical thinning normally starts in women at age 42.5 years and accelerates thereafter. We can estimate population referral rates and thus enable cost benefit analyses for osteoporosis detection by dentists. Previous studies have shown that the mandibular cortical width is significantly correlated with the bone mineral density at sites which may undergo osteoporotic fracture, e.g. hip. Mandibular cortical width can be determined automatically from dental panoramic radiographs that dentists frequently request, using appropriate software. We study the distribution of cortical width given age to predict those patients requiring further investigation for osteoporosis. The mandibular cortical width was measured in 4,949 dental panoramic tomograms, in patients aged 15-94 years. The inferior and superior cortical edges were detected automatically using a global active shape model image search, followed by an active appearance model search. Nonparametric statistical analysis and nonlinear piecewise linear/quadratic regression were used to analyse the data. For females, the mean cortical width had a linear increase before the age of 17 years, a period of no change (estimate = 3.25 mm, se = 0.01) until the age of 42.5 years, followed by a quadratic decrease with age. For males, it had a linear increase before the age of 19 years, a constant value (estimate = 0.37 mm, se = 0.01) until the age of 36 years and then a slow linear decrease. The rate of decrease in mean cortical width goes from 0.049 to 0.105 standard deviations per year in the 60-80-year-old female age group, in line with published bone mineral density T-score reductions. The pattern of decrease in mandibular cortical width with age was similar to the known pattern of bone loss from the hip, accelerating in women after the age of 42.5 years.

Fetal brain asymmetry: in utero sonographic study of normal fetuses

The objective of the study was to evaluate the magnitude of normal fetal brain asymmetry. This was a prospective study. Normal fetuses between 19-28 weeks of gestation were studied. The cerebral atria, occipital cortex, and hemispheres in both sides were measured. The difference between each side was evaluated and was correlated with sex, head biometry, and estimated weight. Four hundred six fetuses were studied. Mean atrial width was larger in the males and on the left side (5.2% and 6.5%, respectively). Mean cortical width was 2.6% larger in males but 5.5% thinner on the left side. Mean hemisphere width was larger in males and on the left side (2.3% and 1.5%, respectively). The atria and the cortex presented an inverse relationship regarding fetal growth parameters. Brain asymmetry represents normal fetal brain developmental phenomena. It is sex dependent and lateralized in most cases to the left. Lateralization was more accentuated in males.

Growth hormone treatment prevents osteoporosis in uremic rats

Growth hormone (GH) is responsible for longitudinal bone growth. GH-receptor in the growth plate was found to be decreased in chronic renal insufficiency. A therapeutic use of GH in chronic renal insufficiency is not established. The current study aims to clarify the effects of GH treatment on bone metabolism in a uremic rat model. Sprague Dawley rats were subjected to subtotal surgical renal ablation (SNX) or sham operation. SNX rats were randomized into 4 groups: treated with different doses of GH (1.5, 4.0, or 10.0 mg/kg) or vehicle after 10 weeks of uremia and treated for 6 weeks. Bone and renal morphology was evaluated: bone density, thickness of spongiosa, osteoblast surface, osteoid volume, osteoclast quantity, and resorptive volume. GH treatment resulted in a decrease of resorption area and lower number of osteoclasts. Osteoid volume, number of osteoblasts, percentage of active osteoblasts, thickness of the growth plate and mean cortical width increased. GH receptor (GHR) protein expression increased in GH treated rats. IGF-1 expression was decreased in osteoblasts and chondroblasts of SNX-V rats and increased following GH treatment. The TGF-beta expression was down regulated in SNX+V group in osteocytes and chondroblasts as compared to sham operated animals. The down regulation was prevented in treated animals irrespective of the dose given. Treatment with GH in uremic animals increased bone density to the levels of non-uremic controls. Thus GH seems to have a potential of preventing renal osteodystrophy.

Pamidronate in Children with Osteogenesis Imperfecta: Histomorphometric Effects of Long-Term Therapy

Intravenous pamidronate treatment is beneficial to children and adolescents with osteogenesis imperfecta (OI), but the effects of prolonged therapy are not well characterized. The objective of this study was to assess the effect of long-term pamidronate treatment on the bone tissue of children and adolescents with OI. This is an observational study on OI patients receiving iv pamidronate for more than 4 yr. The study was carried out in a pediatric metabolic bone research unit. Patients were 25 moderately to severely affected OI patients (seven girls) aged 1.4-15.3 yr at baseline. Intervention was cyclical iv pamidronate at a dose of 9 mg/kg.yr. Iliac bone biopsy and lumbar spine bone mineral density measures were obtained at treatment start, after 2.7 +/- 0.5 yr (mean +/- sd), and after 5.5 +/- 0.7 yr of therapy. Average areal bone mineral density increased by 72% in the first half of the observation period, but by only 24% in the second half. Mean cortical width and cancellous bone volume increased by 87 and 38%, respectively, between baseline and the first time point during treatment (P < 0.001 for all changes). Thereafter, cortical width did not change significantly, but there was a trend (P = 0.06) toward higher cancellous bone volume. Average bone formation rate on trabecular surfaces decreased by 70% after pamidronate treatment was initiated and showed a trend (P = 0.08) toward a further decline in the second part of the study interval. The gains that can be achieved with pamidronate treatment appear to be largely realized in the first 2-4 yr.

Intracapsular hip fracture and the region-specific loss of cortical bone: analysis by peripheral quantitative computed tomography.

Generalized bone loss within the femoral neck accounts for only 15% of the increase in intracapsular hip fracture risk between the ages of 60 and 80 years. Conventional histology has shown that there is no difference in cancellous bone area between cases of intracapsular fracture and age and sex-matched controls. Rather, a loss of cortical bone thickness and increased porosity is the key feature with the greatest change occurring in those regions maximally loaded during a fall (the inferoanterior [IA] to superoposterior [SP] axis). We have now reexamined this finding using peripheral quantitative computed tomography (pQCT) to analyze cortical and cancellous bone areas, density, and mass in a different set of ex vivo biopsy specimens from cases of intracapsular hip fracture (female, n = 16, aged 69-92 years) and postmortem specimens (female, n = 15, aged 58-95 years; male, n = 11, aged 56-86 years). Within-neck location was standardized by using locations at which the ratio of maximum to minimum external diameters was 1.4 and at more proximal locations. Cortical widths were analyzed using 72 radial profiles from the center of area of each of the gray level images using a full-width/half-maximum algorithm. In both male and female controls, cancellous bone mass increased toward the femoral head and the rate of change was gender independent. Cancellous bone mass was similar in cases and controls at all locations. Overall, cortical bone mass was significantly lower in the fracture cases (by 25%; p < 0.001) because of significant reductions in both estimated cortical area and density. These differences persisted at locations that are more proximal. The mean cortical width in the cases was significantly lower in the IA (22.2%;p = 0.002) and inferior regions (19%;p < 0.001). The SP region was the thinnest in both cases and controls. These data confirm that a key feature in the etiology of intracapsular hip fracture is the site-specific loss of cortical bone, which is concentrated in those regions maximally loaded during a fall on the greater trochanter. An important implication of this work is that the pathogenesis of bone loss leading to hip fracture must be by a mechanism that varies in its effect according to location within the femoral neck Key candidate mechanisms would include those involving locally reduced mechanical loading. This study also suggests that the development of noninvasive methodologies for analyzing the thickness and estimated densities of critical cortical regions of the femoral neck could improve detection of those at risk of hip fracture.

Precision and Accuracy for Peripheral Quantitative Computed Tomography Evaluated Using Cadaveric Radii

We evaluated the precision and accuracy of a peripheral quantitative computed tomography (pQCT) device, Densiscan-1000 (Scanco Medical AG Bassersdorf, Switzerland). Seven forearms of cadaveric specimens were scanned on the pQCT device using the procedure recommended by the manufacturer. Bone mineral density (BMD) was determined in the distal radius and in the more proximal, largely cortical site. Cortical area was assessed on tomograms and mean cortical width calculated assuming a circular ring model. The procedure was repeated five times either with repositioning or without repositioning to obtain the short-term precision error. The coefficients of variation (CV) of BMD at the distal and the proximal site were 0.32% (90% CI = 0.26–0.41) and 0.20% (0.16–0.26), respectively. The CV of cortical width was 1.76% (1.45–2.26). Both BMD and cortical width were not significantly influenced by repositioning. After these measurements, we evaluated the effects of soft tissue on the BMD determination. The BMD was slightly underestimated by removing the surrounding soft tissue, and the difference was 1.4% on average. Subsequently the bone segments corresponding to the measurements were dissected. Cortical area and cortical width estimated from tomograms were compared with those from the surface images of dissected bone sections. Cortical width above 1 mm could be accurately estimated. Finally, the bone segments were ashed to evaluate the accuracy of bone mineral content (BMC) determination. Ash weight and BMC were highly correlated ( r = 0.976) with an error of 10.75%. In summary, pQCT using Densiscan-1000 appears to be able to be assess both the BMD and the cortical width at the radius with high precision and moderate accuracy.

Mandibular anatomy related to sagittal split ramus osteotomy in Koreans.

Sagittal split ramus osteotomy (SSRO) is one of the surgical techniques used to correct mandibular deformities. In order to prevent many surgical anatomical problems, we observed the anatomical structures related to SSRO. In dry mandibles of Koreans, lingular tips were located somewhat posteriorly and superiorly on the mandibular ramus. On the coronal sections of mandible, the mean cortical width of facial cortex was increased toward the ramus region while the lingual cortex was thinnest in the ramus region. On the same sections, all the fusion points of the buccal and lingual cortical plate were located above the mandibular lingula and beneath the mandibular notch. So, performing the SSRO on Koreans, medial horizontal osteotomy should be done through the superior aspect of the mandibular lingula. The cut line is extended 5-8 mm posterior to the mandibular lingula to preserve sufficient cortical width to strengthen the involved osseous segments and reduce possible surgical complications.

Skeletal disease in primary hyperparathyroidism.

Most patients with primary hyperparathyroidism in the 1980s do not have evidence of bone disease when they are evaluated by conventional radiography. We sought to determine whether skeletal involvement can be appreciated when more sensitive techniques, such as bone densitometry and bone biopsy, are utilized. We investigated 52 patients with primary hyperparathyroidism. They had mild hypercalcemia, 2.8 +/- 0.03 mmol/liter (11.1 +/- 0.1 mg/dl), low normal phosphorus, 0.9 +/- 0.03 mmol/liter (2.8 +/- 0.1 mg/dl), and no symptoms or specific radiological signs of skeletal involvement. The greatest reduction in bone mineral density was found at the site of predominantly cortical bone, the radius (0.54 +/- 0.1 g/cm; 79 +/- 2% of expected), whereas the site of predominantly cancellous bone, the lumbar spine (1.07 +/- 0.03 g/cm2), was normal (95 +/- 3% of expected). The site of mixed composition, the femoral neck (0.78 +/- 0.14 g/cm2), gave an intermediate value (89 +/- 2% of expected). Preferential involvement of cortical bone with apparent preservation of cancellous bone in primary hyperparathyroidism was confirmed by percutaneous bone biopsy. Over 80% of patients had a mean cortical width below the expected mean, whereas cancellous bone volume in over 80% of patients was above the expected mean. The results indicate that the majority of patients with asymptomatic primary hyperparathyroidism have evidence by bone densitometry and bone biopsy for cortical bone disease. The results also indicate that the mild hyperparathyroid state may be protective of cancellous bone. The therapeutic implications of these observations await further longitudinal experience with this study population.

Bone Loss in Hypothyroidism With Hormone Replacement

To determine the influences of hormone replacement on bone tissue in primary hypothyroidism, a histomorphometric study on undecalcified transiliac bone specimens was performed before treatment in ten patients, during the first month of treatment in 16 patients, and after more than six months of treatment in 15 patients. There were no obvious clinical or biologic signs of excessive replacement therapy. Before treatment, trabecular resorption surfaces were lower and bone cortical thickness was increased. From as early as the first month of treatment, trabecular resorption surfaces and cortical porosity were higher than normal but cortical thickness was still increased. After more than six months of treatment there was a significant loss of trabecular (decreased trabecular bone volume) and cortical (normal mean cortical width; increased porosity) bone with hyperremodeling (increased trabecular resorption surfaces and trabecular osteoid surfaces). This osteoporosis is similar to that observed in hyperthyroidism.

Microradiographic and histomorphometric indices of mandibles for diagnosis of osteopenia.

Mandibular autopsy specimens of 100 Danish subjects without known systemic diseases were obtained. Microradiograms of 100-micrometer-thick undemineralized vertical buccolingual grounds cross-sections and these sections, stained with basic fuchsin, were used. Microradiographic and histologic readings of bone turnover foci on Haversian canal and endosteal-trabecular surfaces were compared and combined. The analyses show the following. 1) number/area Haversian canals with bone formation and resorption foci and total of Haversian canals are reproducible and representative measures for bone turnover, while estimation of % bone turnover surfaces on periosteal and endosteal-trabecular surfaces in biopsies of mandibles has no diagnostic value. 2) Percentage of bone mass and mean cortical width in standard locality indicate the level in group of mandibles. 3) the cortical variables of bone turnover are sex independent; number/area Haversian canals with resorption foci is age independent; number/area Haversian canals with bone formation foci, total of Haversian canals and percentage of subendosteal (Haversian canals + marrow spaces) are increased with age.

Pattern of age related bone loss in mandibles.

A study was carried out to analyze the pattern of the age related bone loss in the mandibular cortex and to establish normal values and the observed range of morphometric variables on microradiograms of bone sections taken from a well defined site anterior to and below the mental foramen. Specimens were obtained from 100 Danish subjects with no known systemic bone disease or severe mandibular atrophy. Microradiograms of 100-micron-thin undemineralized vertical ground cross-sections were produced. An electric point-counting system was used for the determination of 1) percentage bone mass, 2) mean cortical width (MCW), and 3) the percentage of Haversian canals with resorption surfaces. The analysis showed that cortical porosity and the percentage of Haversian canals showing resorption are unrelated to sex and increased after the age of 50. MCW and absolute bone mass (MCW x % bone mass) are greater in males than in females and show a parallel age related decrease after the age of 50. Furthermore, the age related increase in cortical thinning and porosity is dependent on the individual as well as on age. Marked individual variation confined the use of these parameters to group analysis.

Comparative bone morphometric analysis of mandibles and 2nd metacarpals

Abstract – A comparative analysis of bone mass in the mandible and the metacarpal index: (D–d)/D% has been carried out on autopsy specimens of mandibles and standard hand radiographs from 40 subjects aged 20–90 years. Microradiograms of standardized 100‐μm‐thick sections of the undemineralized plastic embedded material from a standard site of the mandible were used for quantitation of 1) percentage of cortical bone mass, 2) mean cortical width (MCW), 3) largest mandibular width (K), and 4) corresponding width between the endosteal surfaces (k). The outer (D) and inner (d) shaft diameter of the second right metacarpal were measured on the hand radiographs. The present study indicates that: 1) K, k and (K– k)/K% are unsuitable for revealing any possible age‐related bone loss in the mandible; 2) a positive correlation exists between bone mass and MCW, while 3) MCW and K are unrelated, 4) bone mass and MCW of the mandible are both significantly correlated to the metacarpal index. However, while the levels of bone mass and MCW in the mandible to some extent can be predicted from that of the metacarpal index, a knowledge of the precise rnandibular changes necessitates the study of a mandibular biopsy.

Comparative bone morphometric analysis of mandibles and iliac crests

A comparative analysis of bone mass in the mandible and the iliac crest has been carried out in autopsy specimens from 30 subjects aged 23-84 years. Microradiograms of standardized 100-micrometer-thick sections of the undemineralized plastic embedded material from the two locations were used for quantitation. The following measurements were carried out by electronic point-counting: 1) the percentage of cortical bone mass in the subperiosteal and subendosteal layers, 2) mean cortical width, and 3) the percentage of trabecular bone mass in the iliac crest. Positive correlations were found in the expressions of bone mass within the mandible; the values were significantly higher in the 200-micrometer-thick subperiosteal layer than in the remaining part of the mandibular cortex. Only a poor or no correlation was found in the expressions of bone mass from the two sites. The investigation, therefore, shows that bone mass and cortical width in the mandible cannot be predicted from a biopsy from the iliac crest. This finding may partly be due to different age-dependent functional changes of the two bones.

MORPHOMETRIC AND DYNAMIC STUDIES OF BONE CHANGES IN HYPERTHYROIDISM

Bone biopsies were performed after tetracycline double‐labelling by transfixing the right iliac crest in forty hyperthyroid patients. The bone changes in cortical and trabecular bone were determined by simple measurement and point counting on decalcified and undecalcified stained sections. A slight decrease in the amount of cancellous bone was found. The mean cortical width was normal. The amount of osteoid and the length of the osteoid seams were increased, whereas the mean width of osteoid seams was decreased. The cortical osteoclastic activity and porosity were markedly increased. The trabecular osteoclastic activity was moderately increased and the mean size of periosteocytic lacunae was slightly increased. The calcification rate in cancellous bone was increased as were the active calcification surfaces (tetracycline‐labelled). The osteoclastic activity in cortical bone was positively correlated to the free thyroxine index and to the urinary calcium and phosphorus excretion. The findings indicate that the bone changes in hyperthyroidism are specific and that thyroid hormone(s) stimulates both bone formation and resorption followed by increased porosity in cortical bone and by mobilization of bone mineral.

Non-linear bone loss in oophorectomized women.

Sequential bone loss in 37 women with bilateral oophorectomy was monitored by radiographic morphometry. The changes in mean width of the cortices of the 2nd, 3rd and 4th metacarpals of both hands were determined using a semiautomated computer-controlled morphometer. It was found that a significantly greater rate of decrease of mean cortical width occurred in those women first observed within three years of the artificial menopause than in the other members of the group.