Misdiagnosis of vertebral fractures on local radiographic readings of the multicentre POINT (Prevalence of Osteoporosis in INTernal medicine) study

BACKGROUND

Osteoporotic vertebral fractures (VFs) are often misdiagnosed because asymptomatic and occurring in the absence of specific trauma. Further, diagnostic assessment of VFs may be suboptimal.

AIM OF THE STUDY

To assess the misdiagnosis of vertebral fractures on local radiographic readings in the cohort of patients enrolled in the POINT study.

METHODS

We enrolled hospitalised patients, admitted for any cause to the Internal Medicine Units of 37 hospitals participating to the cross-sectional previously published POINT study. The assessment of VFs was performed both by local radiologists and by two expert skeletal radiologists, by using semiquantitative method (SQ). To better evaluate mild vertebral deformities, the two central radiologists also used the algorithm-based qualitative assessment (ABQ).

RESULTS

The radiographs of 661 patients (401 females; mean age 75.8±8.0) were evaluated. The inter-reader percent agreement between two central expert radiologists per-vertebra assessment was excellent (99.78%; k=0.984; 95% CI, 0.977-0.991). Central reading identified 318/661 (48.1%) patients with at least one VF. Local and central readings agreed in 502/661 (75.9%) patients, resulting in a fair reproducibility (k=0.52; 95% confidence interval 0.44-0.59). Diagnostic performance parameters of local readings were: sensitivity 76.1%; specificity 75.8%; PPV 74.46%; NPV 77.38%). By examining 9254 vertebrae, central and local readers diagnosed 665 (7.2%) and 562 (6.1%) VFs respectively. Misdiagnosis (102 false positives and 205 false negatives) mainly occurred for mild VFs. Local readings identified correctly 460 out 665 VFs diagnosed by central readings, resulting in sensitivity of 69.2% and PPV of 81.8%.

CONCLUSIONS

Following a standardized protocol of acquisition techniques and of interpretation criteria, an excellent agreement between local and central readings for moderate and severe vertebral fractures resulted. However a significant amount of mild vertebral fractures, that are the most of VFs, were misdiagnosed by local radiologists. In order to improve VFs assessment, the radiologists should be trained and sensitized in relation to the relevant clinical significance of osteoporotic VFs identification.

High prevalence of fragility vertebral fractures in patients hospitalised in Internal Medicine Units. Results of the POINT (Prevalence of Osteoporosis in INTernal medicine) study

BACKGROUND

Osteoporotic vertebral fractures (VFs) often go unrecognised in both healthy individuals and in pathological conditions. Few data exist on VFs in patients hospitalised in Internal Medicine Units (IMUs), who often suffer from multiple concomitant chronic disorders.

AIM OF THE STUDY

This multicentre cross-sectional study was aimed at assessing the prevalence of VFs in an unselected population of patients referring to IMUs. Correlations between VFs and the main coexisting diseases were also investigated.

METHODS

Information on demographic, clinical and laboratory findings, and on the presence of known risk factors for osteoporosis was recorded. The Genant's semi-quantitative method was used to evaluate, in a central reading centre, the presence and severity of VFs in the thoracic and lumbar spine.

RESULTS

A cohort of 995 patients was evaluated. At least one VF of any grade was found in 47.5% of patients, with similar prevalence between females (48.1%) and males (46.7%). Older age, chronic obstructive pulmonary disease, and previous diagnosis of osteoporosis showed a significant association with VFs in multivariable analysis. However, 79.7% of the VFs were observed in patients without previous diagnosis of osteoporosis. Moreover, a VF of grade 2 or greater was found in 20.8% of patients.

CONCLUSIONS

Fragility VFs is a very frequent finding in patients hospitalised in IMUs. Consequently, more attention should be devoted in this clinical setting to this comorbidity, which is known to be an additional factor for mortality and, when localised in the thoracic part of the spine, may negatively influence a concomitant respiratory insufficiency.

Bone integration of new stemless hip implants (proxima vs. nanos). A DXA study: preliminary results

The development of short femoral prostheses has the advantage to preserve bone and soft tissues, restore hip geometry, permit mini-invasive techniques and allow quickly return to an active life, but very few studies described bone reaction to these new designed prostheses. The aim of the present study was to evaluate the osseointegration of two different partial neck retained stemless hip prosthesis at one year after surgery, measured by the changes of periprosthetic bone mineral density (BMD) in 5 regions of interest (ROIs) using a dual-energy X ray absorptiometry (DXA) device. The signs of stress-shielding were evaluated by standard radiographs. Thirty-two uncemented primary total hip arthroplasty (THA) patients allocated into 2 groups were evaluated. In the first group (n=19) a Proxima (De-Puy-J&J) hip stem was implanted. In the second group (n=12) a Nanos (Smith & Nephew) hip stem was used. We found that both the implants preserve metaphyseal bone stock and increase periprosthetic BMD. In Nanos prostheses a significant higher BMD values were observed in region of interest (ROI) 3 and 4 (p<0.05). No differences were found in ROIs 1, 2, and 5. Proxima stem seem to produce a physiological strain distribution in the femur. No signs of stress-shielding were present in both the implants. In conclusion, this preliminary DXA analysis showed a physiological integration of both the stems that reproduces the biomechanical stress of proximal femur. New designed short stem implants showed optimal osseointegration after one year, and therefore appears an excellent alternative to traditional long stem hip prostheses.

Endocrine and physical determinants of bone mass in late postmenopause

To analyze the relative contribution of endocrine and physical factors to bone mineral density (BMD) in late menopause, we studied biochemical markers of bone turnover as well as sex and calciotropic hormones in 53 women (mean age 61 +/- 5.3 years), 5 to 23 years after natural menopause. BMD was measured at the lumbar spine and proximal femur by dual energy radiography. Stepwise regression analysis showed that age and PTH levels were the two major factors that significantly accounted for spinal BMD, with a final r2 = 0.27. Plasma androstenedione was the only other variable that contributed, albeit not significantly, to spine BMD increasing the r2 by 2%. Conversely, body mass was the main contributor to femoral BMD at all sites. While serum calcium and urinary hydroxyproline were significant determinants of neck BMD, urinary hydroxyproline and age provided significant source of variation for trochanteric BMD, and circulating FSH for BMD in the Ward's area. The final models gave r2 values of 0.35, 0.31, and 0.23, for neck, trochanter and Ward's areas, respectively. Thus, determinants of bone density differentially affect the vertebral and proximal femoral sites. While increasing age and PTH, probably reflecting a subclinical vitamin D deficiency, explain a decreased vertebral bone density, body mass appears to affect mostly the proximal femur. Circulating androgens play a secondary role. A persistently increased bone turnover state is conducive to lower bone density in late postmenopausal women.

Periprosthetic DXA after total hip arthroplasty with short vs. ultra-short custom-made femoral stems: 37 patients followed for 3 years

BACKGROUND AND PURPOSE

Dual-energy X-ray absorptiometry (DXA) analysis of the 7 periprosthetic Gruen zones is the most commonly used protocol to evaluate bone remodeling after the implantation of conventional femoral stems. We assessed the value of DXA after cementless primary total hip arthroplasty (THA) by comparing the effect of progressive shortening of the stem of two femoral implants on periprosthetic bone remodeling using a specifically developed protocol of analysis with 5 periprosthetic regions of interest (ROIs).

PATIENTS AND METHODS

Bone mineral density (BMD) was evaluated in 37 patients in the plateau stage, 3 years after THA. Two femoral implants featuring conceptually new designs and surgical technique were tested: types 1 and 2, characterized by extremely short stem and virtual absence of distal stem, respectively.

RESULTS

We found that progressive shortening of the femoral stem produces more proximal loading, which effectively preserves metaphyseal bone stock and increases periprosthetic BMD in the medial ROIs over time. In the type 2 group, higher absolute BMD values were observed in medial ROIs 4 and 5. No differences were found in ROIs 1, 2, and 3.

INTERPRETATION

This study shows the flexibility of DXA in adapting the protocol of periprosthetic analysis to the specific requirements of new implant designs, and it shows its high sensitivity in evaluation of the biological response of bone to changes in implant shape.

Performance of five phalangeal QUS parameters in the evaluation of gonadal-status, age and vertebral fracture risk compared with DXA

The aim of this cross-sectional study was to study the value of five different quantified ultrasound (QUS) parameters-amplitude-dependent speed of sound (AD-SoS), Ultrasound Bone Profile Index (UBPI), fast-wave amplitude (FWA), bone transmission time (BTT) and signal dynamic (SDY)-measured at the phalanges of the hand in discriminating women with vertebral fracture and their relationship with some determinants of bone mass, in particular age and gonadal status compared with lumbar spine and hip dual-energy x-ray absorptiometry (DXA). We included 791 women aged 35-84 y, divided into pre-menopause, early menopause and late postmenopause groups on the basis of gonadal status and years since menopause (YSM). The presence of vertebral fracture was evaluated radiographically. All QUS parameters were very sensitive to changes in early postmenopause, with a doubled decrease in early postmenopausal with respect to late postmenopause. In particular AD-SoS and BTT decreases were markedly high in the early postmenopause group. In the late menopause group, similar decreases were observed for AD-SoS, UBPI and hip bone mineral density (BMD). In the multiple logistic model, DXA and QUS significantly discriminate women with and without fractures (p < 0.0001); odds ratio (OR) was higher at lumbar spine BMD (OR 4.01), FWA (OR 3.88), AD-SoS (OR 3.81) and total hip BMD (OR 3.77). Even adjusting the logistic model for age, height, weight, lumbar spine and total hip BMD, all QUS parameters remained significantly predictive of vertebral fracture. AD-SoS showed the best performances both in terms of OR and ROC analysis. QUS parameters show a different behavior in evaluating the effect on bone mass of the time since menopause; AD-SoS and BTT showed a high sensitivity to first changes in bone tissue after menopause. After correction for potential confounders, AD-SoS showed the same ability of lumbar spine BMD in discriminating women with or without vertebral fractures and in the prediction of fracture risk.

Bone preservation with a conservative metaphyseal loading implant

Proximal load transfer and the absence of distal fixation of the stem are crucial to obtain the best behaviour of the femoral bone after total hip replacement. In this study, dual energy X-ray absorptiometry (DEXA) was employed to understand and compare the bone density changes and thus the re-distribution of mechanical forces in two different extra short stems. Two cohorts of ten patients were included in this retrospective study. Both implants are custom-made and present a well defined lateral flare. The first model is fully coated and presents a short stem (Group A), the second is an unstemmed metaphyseal implant with a polished tip (Group B). DEXA scans were obtained in all patients at the two-year follow-up. A higher BMD was detected in ROIs 1, 2, 4, 5 in Group B confirming a preservation of the proximal bone mass and thus indirectly a more proximal load transfer. The results obtained confirm the importance of the geometry of the implant on proximal bone density. Loading both medial and lateral proximal femoral flares and the complete absence of the diaphyseal portion of the stem provide the optimal bone remodelling of the femur after total hip replacement.

Bone remodelling in THA: A comparative DXA scan study between conventional implants and a new stemless femoral component. A preliminary report

Periprosthetic bone loss is a major cause for concern in patients undergoing total hip arthroplasty (THA). There are many different factors that may determine the pattern of bone loss and bone remodelling following THA, such as the quality of the bone before the hip replacement, skeletal bone mass at the time of the operation, material and method of fixation and implant design. Recent developments in dual-energy X-ray absorptiometry (DXA) have made it possible to quantify bone mineral density (BMD) to evaluate changes around the prosthesis and to measure bone stock and bone density redistribution after a total hip replacement. In this cross-sectional multicentre clinical study the DXA method was used to compare bone mass after uncemented THA of a custom-made stemless design with five groups of conventional cementless implants (Alloclassic, Mayo, CFP, IPS, ABG). The adaptive bone changes of the proximal femur three years after implantation were evaluated. Periprosthetic BMD was measured in 130 subjects in the seven regions of interest (ROI) based on Gruen zones. Significant differences were found between the stemless implant and the other five groups in zones 1, 4 and 7. The CFP, IPS, and ABG groups showed decreased BMD in ROI 1, and the Mayo, IPS and Alloclassic in ROI 7. An increased BMD in ROI 4 was observed in the Mayo, IPS, ABG and Alloclassic groups. The results of the present study suggest that a conservative stemless implant with complete proximal load transfer produces a homogeneous and more physiological redistribution of bone density, allowing maintenance of proximal periprosthetic bone stock.

Clinical applications of body composition measurements using DXA

Dual-energy X-ray absorptiometry (DXA) scanning was primarily developed for the diagnosis of osteoporosis and was initially applied to studies of the clinically important sites of the lumbar spine, femoral neck, and forearm. The rapid adoption of DXA has led to the development of different, competing generations of equipment. Improvements have been achieved through advances in X-ray generation and detection technology, modification of data acquisition protocols, and implementation of more sophisticated image analysis algorithms. As a result, DXA has been extended to allow the study of the total skeleton and its regional parts, as well as soft-tissue composition measurement. The three major components of the body: fat mass, lean mass, and bone mineral mass, can now be easily measured using a single whole body DXA scan with high precision and low scanning time. The comprehensive view of body composition provided by DXA makes it an attractive technique for a variety of clinical applications such as the prevention of cardiovascular and metabolic diseases, clinical management of different chronic diseases, and monitoring of the impact of treatment regimens on body tissues. In this article we review the contribution DXA has made to the understanding of body composition in clinical studies in adults.

Ipriflavone directly inhibits osteoclastic activity

Ipriflavone, an isoflavone derivative, is a new drug used in an attempt to decrease bone loss in osteoporosis. Experimental studies have shown that this compound acts by inhibiting osteoclastic bone resorption both in vivo and in vitro, but the mechanism of its inhibitory action on resorbing cells remains unclear. Using bone resorption assays, video image analysis together with measurements of intracellular free calcium in isolated osteoclasts, we show here that IP directly inhibits osteoclastic activity by the modulation of intracellular free calcium.