Does a single local absorptiometric bone measurement indicate the overall skeletal status? Implications for osteoporosis and osteoarthritis of the hip

Spatial links between subchondral bone architectural features and cartilage degeneration in osteoarthritic joints

Early diagnosis of osteoarthritis (OA), before the onset of irreversible changes is crucial for understanding the disease process and identifying potential disease-modifying treatments from the earliest stage. OA is a whole joint disease and affects both cartilage and the underlying subchondral bone. However, spatial relationships between cartilage lesion severity (CLS) and microstructural changes in subchondral plate and trabecular bone remain elusive. Herein, we collected femoral heads from hip arthroplasty for primary osteoarthritis (n = 7) and femoral neck fracture (n = 6; non-OA controls) cases. Samples were regionally assessed for cartilage lesions by visual inspection using Outerbridge classification and entire femoral heads were micro-CT scanned. Scans of each femoral head were divided into 4 quadrants followed by morphometric analysis of subchondral plate and trabecular bone in each quadrant. Principal component analysis (PCA), a data reduction method, was employed to assess differences between OA and non-OA samples, and spatial relationship between CLS and subchondral bone changes. Mapping of the trabecular bone microstructure in OA patients with low CLS revealed trabecular organisation resembling non-OA patients, whereas clear differences were identifiable in subchondral plate architecture. The OA-related changes in subchondral plate architecture were summarised in the first principle component (PC1) which correlated with CLS in all quadrants, whilst by comparison such associations in trabecular bone were most prominent in the higher weight-bearing regions of the femoral head. Greater articular cartilage deterioration in OA was regionally-linked with lower BV/TV, TMD and thickness, and greater BS/BV and porosity in the subchondral plate; and with thinner, less separated trabeculae with greater TMD and BS/BV in the trabecular bone. Our findings suggest that impairment of subchondral bone microstructure in early stage of OA is more readily discernible in the cortical plate and that morphological characterisation of the femoral head bone microstructure may allow for earlier OA diagnosis and monitoring of progression.

Bone mineral density in patients with destructive arthrosis of the hip joint

Recent reports have shown the existence of subchondral insufficiency fracture in rapidly destructive arthrosis of the hip joint (RDA), and the findings suggest that osteopenia is related to the pathogenesis of the rapid progression of this disease. Therefore, we measured bone mineral density (BMD) in RDA patients. We measured BMD of the lumbar spine, radius, and calcaneus using dual-energy X-ray absorptiometry in 19 patients with RDA and 75 with osteoarthritis of the hip (OA) and compared BMD at different skeletal sites between RDA and OA patients. No significant differences were observed in BMD of the lumbar spine, ultradistal radius, mid-radius, and calcaneous between the RDA and OA groups. Our data suggest that RDA is not accompanied by generalized osteoporosis. Factors other than generalized bone status, for example, BMD around the affected hip joint before destruction, need to be analyzed to elucidate the pathophysiological mechanism of RDA.

Asymmetrical hip bone density in multiple sclerosis

As multiple sclerosis (MS) may affect one leg more than the other, we predicted that bone mineral density (BMD) would be lower in the limb self-identified as more affected. Therefore, the purpose of this study was to determine whether ambulatory individuals with MS displaying moderate-to-severe lower-extremity paresis exhibit asymmetrical femoral neck BMD. Dual-energy x-ray absorptiometry was used to assess proximal femoral neck BMD. Lower BMD was observed in the proximal femoral neck of the more paretic limb (P = .001) in a group (N = 23) of ambulatory individuals with relapsing-remitting MS (RRMS). Our preliminary findings suggest that bilateral hip screening may be important in the early detection of compromised bone health in ambulatory individuals with RRMS. Further research is warranted to fully characterize the factors and mechanisms associated with bone loss and identify effective strategies for optimizing bone health in people with MS.

Discrepancy in bone mineral densities at different skeletal sites in hip osteoarthritis patients

OBJECTIVE: Increased femoral neck bone mineral density (BMD) in a hip with osteoarthritis (OA) has been previously reported, however, it is possible that increased BMD at sites other than the hip joint is influenced by the disease process of OA. Therefore, we measured BMD at locations different from the hip joint and determined whether higher BMD was also observed at these different skeletal sites in hip OA patients. METHODS: We measured BMD in 68 women (average age 61.0 years) scheduled to undergo total hip arthroplasty for end-stage OA and 100 healthy women (average age 60.9 years) as age-matched controls. BMD at the lumbar spine, radius, and calcaneus was measured by dual-energy X-ray absorptiometry (DXA). Moreover, we measured speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness index of the calcaneus by quantitative ultrasonography (QUS). RESULTS: BMD obtained by DXA at the lumbar spine and radius was significantly higher in hip OA patients than in controls. However, at the calcaneus, no significant differences were observed between the groups in BMD obtained by DXA. SOS, BUA, and stiffness index obtained by QUS were significantly lower in the OA group than in controls. CONCLUSION: Higher BMDs of the spine and radius suggest that the incidence of osteoporosis is inversely associated with the incidence of OA. However, it remains unclear whether lack of difference in BMD and lower SOS, BUA, and stiffness index of the calcaneus in the OA group was secondary to the effect walking disturbance resulting from hip pain. Our data suggest that hip OA patients have higher BMD than healthy women, and that inactivity or immobilization caused by hip OA may reduce BMD in the lower limb.

Differences in bone mineral density between the right and left hips in postmenopausal women

Bone mineral density (BMD) using dual energy radiography absorptiometry are commonly used for the diagnosis of osteoporosis. It is usually measured at the spine and also at one hip joint. Controversy still exists regarding the use of bilateral hip scanning. We analyzed the difference of BMD at bilateral hips in 384 postmenopausal women, retrospectively. The concordance and discordance rates of the lowest T-score and BMD between both hips were evaluated. The BMDs of the femoral neck and trochanter were significantly different between both hips (P < 0.05). There were also discrepancies between the lowest T-scores of both hips (P < 0.05). The discordance rates were about 30%. Due to significant differences in BMD between both hips at the femoral neck and trochanter and high discordance rate, bilateral hip measurements using DEXA are recommended to avoid underestimating osteoporosis.

Bone mineral density is not related to heterotopic ossification after total hip arthroplasty

PURPOSE

Heterotopic ossification (HO) after total hip arthroplasty (THA) is a frequent complication that compromises the success of this procedure; however, its precise pathogenesis is unknown. Patient-related risk factors have previously been investigated to predict patients likely to have HO. In this study, we compared bone mineral density (BMD) between patients with and without HO after THA.

METHODS

We measured BMD of the lumbar spine, radius, and calcaneus using dual-energy X-ray absorptiometry in 98 females who were scheduled to undergo THA. Radiographs were graded for the presence of HO according to the criteria of Brooker at a minimum follow-up of two years following THA. BMD were compared between those with HO and those without.

RESULTS

In total, HO was observed in 20 of 98 hips. There were no significant differences in age, height, weight, body mass index, and pre-operative total hip score between the HO and non-HO groups. No significant difference was observed in BMD of the lumbar spine, distal radius, mid-radius, and calcaneus between the two groups.

CONCLUSIONS

Our findings suggest that generalized BMD is not related to the occurrence of HO after THA in women.

Bone mineral densities in patients with developmental dysplasia of the hip

Bone mineral density (BMD) of the lumbar spine, ultradistal radius, and calcaneus were significantly higher in the developmental dysplasia of the hip (DDH) patients than in the controls. Therefore, our data suggest that BMDs at different skeletal sites are greater in patients with DDH than in healthy women.

INTRODUCTION

DDH has been acknowledged as a potentially preosteoarthritic condition that results in the development of hip osteoarthritis. Patients with DDH have been reported to have abnormal morphology of the pelvis and spine. Additional research, including that of bone quality, needs to be conducted to elucidate the pathogenetic mechanism of this disease. We therefore sought to determine whether BMD differs between healthy women and women with DDH.

METHODS

We measured BMD in 40 women who were scheduled to undergo pelvic osteotomy for DDH (average age, 45.3 years) and in 31 healthy women used as age-matched controls (average age, 47.5 years). BMDs of the lumbar spine, radius, and calcaneus were measured.

RESULTS

BMDs of the lumbar spine, ultradistal radius, and calcaneus were significantly higher in the DDH patients than in the controls.

CONCLUSIONS

Therefore, our data suggest that BMDs at different skeletal sites are greater in patients with DDH than in healthy women.

Bone Mineral Density Is Not Related to Osteophyte Formation in Osteoarthritis of the Hip

Objective.

Reports have suggested that bone mineral density (BMD) is higher in patients with osteoarthritis (OA) of the hip than in healthy controls. Various types of OA of the hip caused by osteophyte formation were observed on radiographs during progression to the advanced degenerative stage, and the preoperative type of OA was reported to influence the results of surgical treatment. However, the mechanism underlying the development of different types of OA is still unknown. We measured BMD of patients with hip OA and determined whether higher BMD was observed in patients with osteophyte formation than in those without osteophytes.

Methods.

We measured BMD of the lumbar spine, radius, and calcaneus using dual-energy x-ray absorptiometry in 88 women who were scheduled to undergo total hip arthroplasty for endstage OA. Hips were evaluated for osteophyte formation using Bombelli’s classification; 31 were graded as atrophic type, 30 as normotrophic, and 27 as hypertrophic. BMD at different skeletal sites were compared among the 3 types of OA.

Results.

No significant difference in BMD of the lumbar spine, ultradistal radius, mid-radius, or calcaneus was observed among the atrophic, normotrophic, and hypertrophic types of OA.

Conclusion.

Our data suggest that osteophyte formation is not related to general BMD. Factors other than general bone status, for example the morphology of the hip joint, need to be analyzed to determine the pathomechanism of osteophyte formation in the osteoarthritic hip.

The effects of glucosamine hydrochloride on subchondral bone changes in an animal model of osteoarthritis

OBJECTIVE

To quantify periarticular subchondral bone changes in a rabbit model of experimental osteoarthritis (OA), and to determine the effects of continuous administration of a clinically relevant dose of glucosamine HCl on subchondral bone changes in this model.

METHODS

Anterior cruciate ligament transection (ACLT) was performed on the left femorotibial joints of 16 rabbits to induce OA. Ten rabbits that did not undergo ACLT served as unoperated controls. Eight rabbits that underwent ACLT and 6 control rabbits were treated with 100 mg of glucosamine daily, and the others were given a placebo. The articular cartilage was evaluated macroscopically and graded at the time of necropsy, 8 weeks after ACLT. Bone mineral density (BMD) was measured using dual-energy x-ray absorptiometry on the dissected distal femur and proximal tibia. Subchondral trabecular bone turnover, architecture, and connectivity, as well as subchondral plate thickness and mineralization were studied on the undecalcified tibia sections from each animal.

RESULTS

Eight weeks after ACLT, most of the operated joints had various degrees of cartilage damage and fibrillation. Compared with the control group, the ACLT group had significantly increased subchondral bone turnover and lower BMD, bone volume, connectivity, and bone mineralization. The high bone turnover was significantly reduced in glucosamine-treated animals that underwent ACLT. In fact, there were no significant differences between the ACLT/glucosamine group and the control/glucosamine group in most of the bone parameters studied.

CONCLUSION

This study shows that subchondral bone turnover, structure, and mineralization are significantly altered in the early stages of experimental OA, and that these changes are attenuated by glucosamine treatment.

The role of bone in the treatment of osteoarthritis

Bone, and especially the subchondral bone plate, is involved in the pathogenesis of osteoarthritis (OA). OA bone tissue is sclerotic yet undermineralized indicating abnormal bone cell metabolism. Studies in both human and animal models of OA support the concept that bone sclerosis could precede cartilage degradation and loss. Clinical studies show that the indices of bone resorption and formation are increased in OA patients. A working hypothesis of the sequence of changes leading to OA holds that enhanced bone remodeling is the initiating event triggering cartilage damage. The attempt to repair the damaged cartilage then leads to a number of biochemical adaptations in bone and cartilage. In bone, this repair attempt modifies insulin-like growth factor 1 (IGF-1), IGF binding proteins (IGFBPs), and transforming growth factor-beta (TGF-beta), and alters the urokinase plasminogen activator (uPA)/plasmin system. In the cartilage, it also modifies IGF-1/IGFBP levels and the uPA/plasmin system. However, bone changes may overwhelm the attempts to repair cartilage, and lead to further sclerosis and damage. Some of these specific pathways have been investigated, and indeed are modified in OA subchondral osteoblasts. Thus, subchondral bone sclerosis in OA may be due to abnormal osteoblasts characterized by increased metabolic activities that result in an increase in osteoid matrix that is undermineralized. The exact role played by cytokines and prostaglandins remains controversial. However, restraining collagen deposition and mineral removal, and/or improving mineral deposition, could provide a better, more mineralized, bone matrix in OA patients.

Subchondral bone in osteoarthritis: a biologic link with articular cartilage leading to abnormal remodeling

PURPOSE OF REVIEW

This review deals with new findings highlighting the concept of cross-talk between subchondral bone tissue and articular cartilage that may be crucial for the initiation and/or progression of osteoarthritis. In this review, new factors either produced by subchondral bone tissue or modifying osteoblast metabolism, yet implicated in osteoarthritis, are discussed.

RECENT FINDINGS

The development of cartilage degeneration is concomitant with subchondral bone thickness in osteoarthritis, whereas it is related to higher subchondral bone activity and dysregulation in the synthesis of bone proteins. As an immediate consequence, homotrimers of type 1 collagen are formed that could lead to undermineralization of this tissue. This dysregulation also leads to abnormal production of different factors by osteoblasts such as prostaglandins, leukotrienes, and growth factors. Because microcracks or neovascularization provide a link between the subchondral bone tissue and articular cartilage, these factors could contribute to the abnormal remodeling of osteoarthritic cartilage.

SUMMARY

These findings have an immediate implication for research because new tools need to be developed to study the subchondral bone-cartilage functional unit. Moreover, it could lead to a possible cure for osteoarthritis because this pathology should be considered both a bone and cartilage disease.

Osteoblast-like cells from human subchondral osteoarthritic bone demonstrate an altered phenotype in vitro: possible role in subchondral bone sclerosis

OBJECTIVE

Osteoarthritis (OA) is accompanied by subchondral bone sclerosis. The present study was undertaken to determine whether osteoblast-like cells in patients with OA show an abnormal phenotype that could contribute to this sclerosis.

METHODS

Explants and primary in vitro osteoblast-like cell cultures were prepared from subchondral bone specimens from OA patients or from bone removed at autopsy from individuals showing no signs of OA or metabolic bone disease. We measured the abundance and activity of urokinase plasminogen activator (uPA), and the levels of PA inhibitor (PAI-1) and insulin-like growth factor 1 (IGF-1) in conditioned media from both explants and osteoblast-like cells. The expression of osteoblast phenotypic biomarkers was also evaluated.

RESULTS

OA explants showed increased levels and activity of uPA, no changes in PAI-1 abundance, and increases in IGF-1 release, as compared with preparations from normal individuals. In vitro primary osteoblast-like cells showed results similar to the ex vivo findings for uPA, PAI-1, and IGF-1. Primary OA osteoblast-like cells also expressed higher alkaline phosphatase activity and osteocalcin release than normal cells, both under basal conditions and with 1,25(OH)2D3 (1,25-dihydroxyvitamin D) stimulation. Conversely, OA osteoblast-like cells showed blunted cAMP synthesis in response to human parathyroid hormone and prostaglandin E2 in contrast to the finding with normal osteoblast-like cells, a result that could not be attributed to altered adenylate cyclase activity.

CONCLUSION

Ex vivo and in vitro results indicate similar altered activities of OA osteoblasts as compared with normal cells. This suggests that an altered phenotype of subchondral osteoblasts may be a contributing factor in human OA.

Bone density and local growth factors in generalized osteoarthritis

Osteoarthritis is usually considered to be a primary disorder of chondrocyte function with secondary changes in bones. However, a defect in the subchondral bone resulting in loss of its shock absorbing capacity could transfer the stress of loading directly to the articular cartilage with secondary changes in the cartilage. Review of histomorphometric and bone densitometric studies at sites of osteoarthritis at the hip or knee revealed that cartilage fibrillation could not be dissociated from bony changes even in the earliest stages of osteoarthritis and that subchondral trabeculae are thickened and more spaced in osteoarthritis. Microfractures of subchondral trabecular bone were less frequently seen in osteoarthritis compared to controls. Changes of the tidemark were found to be multiform and metabolically active in the osteoarthritic process. Endochondral ossification depletes the calcified cartilage at the cartilage/bone interface and the tidemark has been thought of as a calcification front advancing in the direction of non-calcified cartilage. Duplication of the tidemark is cited as evidence of this advancement. In the few experimental animal studies of subchondral bone in osteoarthritis, thicker trabeculae which were closer together were found in guinea pigs already when only mild cartilage changes were present. In the dog, with cruciate ligament transection, changes in bone were later than in the cartilage, but the changes in bone could still contribute to the progression of osteoarthritis. To study if bone changes may precede injury to the cartilage and if metabolic and systemic influences can also alter the subchondral bone, rendering it less able to withstand normal mechanical stresses, bone at different sites in the body has been studied extensively by the authors. Epidemiological and case control studies have revealed that osteoarthritis cases have more bone at all sites than expected and that bone in cases with generalized osteoarthritis shows both quantitative and qualitative differences, including increased contents of growth factors and hypermineralization. These findings suggest that a more generalized bone alteration may be the basis of the pathogenesis of osteoarthritis.

Risk of underestimation of the bone mineral density of proximal femur

Decreased bone mineral density (BMD) in the elderly increases the risk of hip fracture. Measurement of proximal femoral BMD can help us predict the risk of hip fracture, especially in the elderly. Since the BMD of proximal femur is usually measured on the unilateral side, we studied the risk of underestimation with measurement of unilateral proximal femur BMD in 266 normal Chinese women. In order to evaluate the effect of age, these subjects were divided into group A (18-59 years, n = 189) and group B (60-88 years, n = 77). BMDs of both proximal femurs were assessed with Norland 2600 dual photon absorptiometry. Using a cutoff T score of -1, the negative predictive value (NPV) in the entire group was 86.9% for femoral neck BMD and 85.7% for trochanter, and 82.2% for Ward's triangle: in group A, the NPV was 88.9% for femoral neck, 88.8% for trochanter, and 97.2% for Ward's triangle, but in group B, the NPV was 60.0% for femoral neck, 71.0% for trochanter, and 24.1% for Ward's triangle. The accuracy in the entire group was 86.1% for femoral neck, 84.2% for trochanter, and 86.3% for Ward's triangle: in group A the accuracy was 84.6% for femoral neck, 84.9% for trochanter, and 92.8% for Ward's triangle, but in group B, the accuracy was 89.6% for femoral neck, 81.7% for trochanter, and 90.0% for Ward's triangle. In general, NPV and accuracy increased at the expense of positive predictive value when the cutoff T score was changed to -2.5. This study suggested that measurement of unilateral proximal femur BMD was sufficient for screening the contralateral hip BMD in group A at a cutoff T score of -1. However, a T score of -2.5 was recommended for group B, and one should be careful in its application to Ward's triangle.

Prediction of fracture load at different skeletal sites by geometric properties of the cortical shell

Quantitative bone assessment today is primarily based on the analysis of bone mineral density (BMD). The geometric properties of bone, which are an important parameter for skeletal strength, are generally not considered in the routine clinical assessment of osteoporosis. This study combined the geometric properties and the BMD values determined by peripheral quantitative computed tomography (pQCT) at the distal radius and at the femoral neck to predict fracture loads of the radius, femur, and lumbar vertebrae of 20 cadavers. Generalized osteopenia reduced the fracture loads at all three sites (p < 0.001). The strength of the radius and the femoral neck could best be predicted by considering either the second moment of inertia and trabecular BMD (R = 0.93) or the moment of inertia and the cortical BMD (R = 0.91). The geometric properties at the distal radius were highly correlated with the fracture load at the same skeletal site (R = 0.89) and were also used to estimate the fracture risk at the lumbar vertebrae (R = 0.75) and at the femoral neck (R = 0.87). We conclude that both geometry and density contribute substantially to the strength of the skeleton. The screening for osteoporosis and the prediction of fracture risk can be improved, therefore, by an additional consideration of the geometric properties of the cortex.

Bone mineral density in Chinese elderly women with hip fracture

In order to examine the status of osteoporosis of the patients with hip fracture, we assessed the bone mineral density (BMD) of the contralateral hip of 81 elderly females with hip fracture and compared those with 77 normal Chinese women. The age of fracture subjects was 73.5 +/- 6.6 years (mean +/- SD), and 69.2 +/- 6.9 years for the controls. All of these fractures were caused by minor trauma, such as falls from a standing position or slipping to the ground. The Norland 2600 dual-photon absorptiometer (DPA) was used to evaluate the BMD in the femoral neck, trochanter, and Ward's triangle areas. The BMD for the fracture subjects was significantly lower than those of the controls. By linear regression, the probability of fracture increased exponentially with age and low BMD. The mean BMD for femoral neck of the fracture subjects versus controls was 0.556 versus 0.624 g/cm2; for trochanter: 0.505 versus 0.566 g/cm2; for Ward's triangle: 0.432 versus 0.485 g/cm2. Both negative predictive value (NPV) and positive predictive value (PPV) were acceptable at the prevalence of hip fracture of 5% or 20% and at a cutoff point of 0.65 g/cm2. These data revealed that the degree of relative osteoporosis in the patients with hip fractures was more severe than that of controls.

Lateral spine dual-energy X-ray absorptiometry bone mineral measurement with fan-beam design: effect of osteophytic calcifications on lateral and anteroposterior spine BMD

Recently, fan beam (FB) designs have been made available by several manufacturers (Aloka, Hologic Lunar and Sophar) to measure lumbar spine bone mineral area density (BMD) in both an anteroposterior (AP) and a lateral projection. The present study was performed to evaluate some characteristics of a new dual energy X-ray absorptiometry (DXA) system for supine lateral scans in normals and to study possible advantages for patients with osteophytic calcifications (OC). The precision errors of in vitro and in vivo measurements were estimated by an anthropomorphic phantom and in healthy volunteers. To study the effect of osteoarthritic changes on AP and lateral DXA measurements, BMC (bone mineral content) and BMD were measured in age-matched women (n = 150) with and without OC. Precision errors for lateral BMD in vitro over 1 and 6 months were 0.58/0.67% (slow/fast scan modes) and 0.67/0.77% (slow/fast scan modes), respectively. The short- and mid-term reproducibility of BMD values were 2% and 3.5%, respectively, using the compare function (3.5% and 7.5%, respectively, without the compare facility). The analysis of women with and without OC (n = 150) demonstrated higher mean values for AP BMD (0.892 +/- 0.145 g/cm2) in patients with OC (n = 75) than in normals (0.836 +/- 0.135 g/cm2, n = 75, difference 6.3%). For lateral scans, BMD differed to a minor degree (3.1%) in patients with OC (0.629 +/- 0.133 g/cm2) compared with normals (0.610 +/- 0.117 g/cm2). Corresponding results were obtained in fast FB mode. Furthermore, we found significant (P < 0.0001) correlations between BMD in lateral and AP scans in patients without OC (r = 0.63) and in patients with OC (r = 0.57). Although the FB design facilitated fast AP and lateral scans, the higher precision errors of lateral scans could limit its application in longitudinal studies. The use of compare function should be recommended. However, BMD of lateral scans was less influenced by OC.

Radiographic osteoarthritis of the hip and bone mineral density. The Study of Osteoporotic Fractures Research Group

OBJECTIVE

To examine the cross-sectional association between radiographic features of hip osteoarthritis (OA) and bone mineral density (BMD) of the hip, spine, and appendicular skeleton among Caucasian women ages 65 and older who were participating in the Study of Osteoporotic Fractures.

METHODS

Pelvis radiographs of 4,855 subjects were assessed for individual radiographic features of hip OA: osteophytes, joint space narrowing, subchondral sclerosis, cysts, and femoral head deformity. Hips were graded on a summary scale of 0 (no OA) to 4 (severe OA) based on the number of radiographic features present. Appendicular BMD was measured in all subjects, and hip and spine BMD in 84% of the group. We used linear regression to examine the association of BMD with hip OA, and to adjust for age, weight, and other determinants of bone mass.

RESULTS

Three hundred fifty-one women (7.2%) had mild (grade 2) and 228 (4.7%) had moderate to severe (grade 3-4) radiographic evidence of hip OA. Women with grade 3-4 hip OA had a higher age-adjusted BMD at the femoral neck and Ward's triangle (9-10%; P < 0.0001), trochanter (4%; P < 0.01), lumbar spine (8%; P < 0.0001), and distal radius and calcaneus (5%; P < 0.0001 [for each comparison]) compared with those with grade 0-1 OA in the worse hip. Elevations in BMD were greatest in the femoral neck of hips with OA, in women with bilateral hip OA, and in women with hip osteophytes. These findings were essentially unchanged by adjustment for determinants of bone mass.

CONCLUSION

Elderly Caucasian women with moderate to severe radiographic hip OA had higher BMD in the hip, spine, and appendicular skeleton than did women without hip OA. Our findings are consistent with a role of elevated BMD in the pathogenesis of hip OA.

Mineral density quantitation of the human cortical iliac crest by backscattered electron image analysis: variations with age, sex, and degree of osteoarthritis

Bone samples from the rim of the iliac crest were obtained at autopsy from 59 patients aged 23 to 75 years, of whom 10 men and 10 women aged 50-75 years had osteoarthritis diagnosed by hand X-rays. An equal number in the same age group and 10 men and 9 women aged less than 50 years were without osteoarthritis. After embedding the bone in PMMA, the blocks were cut, polished, and coated with carbon. The fractions of bone falling within four consecutive bands of signal level were derived from digital backscattered electron imaging. Normal males had more low and medium density bone and normal females more very high density phase tissue proportionately. In both male and female osteoarthritis cases, low and medium fractions were low. The very high density fraction was mainly calcified fibrocartilage; when it was excluded from the calculations, the low, medium, and high phases occurred equally in normal males but increased stepwise in normal females and in osteoarthritis cases of both sexes. The results suggest a lower rate of bone renewal in females than males, and in male osteoarthritis subjects than normal males. An increased proportion of bone of high density would reduce the quality of the bone by increasing its stiffness.

Evaluation of dual-energy X-ray absorptiometry bone mineral measurement--comparison of a single-beam and fan-beam design: the effect of osteophytic calcification on spine bone mineral density

Dual energy X-ray absorptiometry (DXA) using a single-beam (SB) design is a well-established procedure for measuring bone mineral area density (BMD). Recently, fan beam (FB) techniques have become available to measure BMD. We evaluated the QDR1000 and QDR2000 densitometers with regard to precision and cross-compared values using single beam (SB) and FB techniques. To study the effect of osteoarthritic changes on bone measurement (BMC in g) and bone mineral area density (BMD in g/cm2), both parameters were measured in patients with and without osteophytic calcifications (OC) of the lumbar spine. Precision errors for BMD in vitro over 1 and 6 months using the QDR2000 were 0.4% and 0.6% for SB and 0.5% and 0.7% for the three FB modes. For QDR1000 only SB is available. Using this scan mode, the BMD difference (delta = 0.1%) in vitro between QDR1000 and QDR2000 was not significant. The short-term (same day) reproducibility of BMD in vivo was 0.85% for SB mode and 1.1% for FB scan mode (n = 33). The midterm (1 month) precision errors were 0.9% for SB and 1.5% for FB (n = 11). The spine BMD of 751 patients from our outpatient clinic and department of rheumatology was 1.7% lower with FB than with SB (0.878 +/- 0.137 versus 0.888 +/- 0.146 g/cm2). Lower (1.8%) BMD values were also found in the hip with FB compared to SB (0.805 +/- 0.111 versus 0.821 +/- 0.111 g/cm2). There was a highly significant (P < 0.00001) correlation between SB and FB on the spine (r = 0.99) and hip (r = 0.98) using the QDR2000. Correlations found QDR1000 and QDR2000 were lower on the spine (r = 0.97) and hip (r = 0.93).(ABSTRACT TRUNCATED AT 250 WORDS)

Upper extremity bone mass and osteoarthritis of the knees: data from the Baltimore Longitudinal Study of Aging

To examine the association of upper extremity bone mass with osteoarthritis (OA) of the knee, bilateral standing knee radiographs, taken between 1985 and 1991, in 430 Caucasian male and 266 Caucasian female subjects aged 40 years and above in the Baltimore Longitudinal Study of Aging, were read by one investigator for grade of OA using Kellgren-Lawrence scales. Several measures of upper extremity bone mass, size, and density, including combined cortical thickness (CCT), total width and percentage of cortical area of the second metacarpal, and bone mineral content (BMC), width, and density of the distal third of the left radius measured with single photon absorptiometry, were assessed at the same visit. In univariate analyses, men and women with definite knee OA were significantly older, men had significantly greater radial width, and women had significantly lower bone mass as measured by both CCT and BMC. After adjustment for age and body weight, however, men with knee OA had significantly higher BMC and radial width while neither of these measures of upper extremity bone mass and size was significantly associated with the presence of definite knee OA in women. Neither measure of upper extremity bone density was significantly associated with definite knee OA in either sex. These data suggest that, although men (but not women) with definite knee OA have significantly higher levels of adjusted radial bone mass and size, subjects with knee OA do not have significantly higher levels of adjusted bone mineral density at either upper extremity site.

Reduced femoral neck bone density in the daughters of women with hip fractures: the role of low peak bone density in the pathogenesis of osteoporosis

Low bone density in women with hip fractures ("senile" osteoporosis) may be due to excessive bone loss or low peak bone density. If excessive bone loss is responsible, then no reduction in bone density is expected in their daughters. If low peak bone density is responsible, then bone density should also be reduced in their daughters because genetic and family environmental factors influence the variability in bone density. Bone density was measured using dual-photon absorptiometry and expressed as a standardized deviation or Z score relative to 697 controls, adjusting for age, height, weight, and menopausal status. In 74 women with hip fractures, the Z score (mean +/- SEM) was -0.52 +/- 0.14 (P < 0.001) at the femoral neck, -1.04 +/- 0.17 (P < 0.001) at the femoral shaft, and -0.43 +/- 0.10 (P < 0.001) at the lumbar spine. In their 41 daughters, the Z score was -0.40 +/- 0.17 (P < 0.05) at the femoral neck, -0.41 +/- 0.19 (P < 0.001) at the femoral shaft, and 0.23 +/- 0.13 (NS) at the lumbar spine. We conclude that daughters of women with hip fractures are likely to be at increased risk for hip fractures themselves because they have reduced femoral neck bone density. Femoral neck fractures may not be entirely attributable to trauma; reduced bone density is likely to contribute and may be caused by the attainment of a lower peak femoral neck bone density.

Periarticular bone in rheumatoid arthritis versus arthrosis. Histomorphometry in 103 hip biopsies

Histomorphologic differences of the periarticular bone in rheumatoid arthritis (RA) and osteoarthrosis (OA) may be of importance for long-term prosthetic fixation. We have evaluated bone specimens, obtained during total hip replacement from an acetabular and a femoral biopsy site, in 42 RA-hips and 61 OA-hips. In both groups the bone turnover was increased in the acetabulum compared to that in the femur. In the acetabulums the total trabecular bone volume was equal, but osteoid volume, osteoid surface, resorptive surface, and the appositional rate were increased in RA. On the femoral side, only the osteoid volume was higher in RA. The increased bone turnover with a greater amount of unmineralized tissue, as well as resorptive activity in the acetabulum, may be of importance for the higher rate of acetabular component migration and loosening after total hip replacement in RA.

Periarticular bone mineral content in rheumatoid arthritis and arthrosis of the hip. Dual photon X-ray absorptiometry in 53 cases

The bone mineral content (BMC) was determined by dual photon X-ray absorptiometry prior to hip replacement in 22 patients with rheumatoid arthritis and 31 with arthrosis. Compared with the arthrosis patients, the rheumatoids had approximately 20 percent lower bone mineral content in the proximal femur, the lumbar spine, and in the innominate bone superior to the acetabulum.

Osteoarthritis protects against femoral neck fracture: the MEDOS study experience

The relationship between osteoarthritis and osteoporosis (hip fracture) was studied using the data from the MEDOS study, a large prospective epidemiological study of femoral neck fracture patients and age-matched controls in the Mediterranean area. Osteoarthritis was found to be protective against hip fracture in both men and women, with a significant reduction of the relative risk factor for osteoporosis (relative risk = 0.48 and 0.68, respectively, p < 0.001). The age-adjusted relative risk factor for osteoporosis remains even after adjustment for body mass index, indicating that body mass index and osteoarthritis are independent relative risk factors for hip fracture. The mean age of the group with co-existent osteoarthritis and hip fracture was significantly higher for both men and women, compared to the group with osteoporosis alone. This indicates that if osteoarthritic subjects develop osteoporotic fracture, they do so at a later age. The osteoarthritic cases compared to controls and hip fracture cases were significantly smaller in stature in both sexes, and women had a significantly higher body weight and body mass index. Extra-capsular hip fracture was significantly more frequent in cases with concomitant osteoarthritis. These findings confirm earlier observations that osteoarthritis and osteoporosis are two distinct diseases and not phenomena related solely to aging.