Do patients that fracture with normal DXA-measured BMD have normal bone?

Development and validation of a predictive model for vertebral fracture risk in osteoporosis patients

OBJECTIVE

This study aimed to develop and validate a predictive model for osteoporotic vertebral fractures (OVFs) risk by integrating demographic, bone mineral density (BMD), CT imaging, and deep learning radiomics features from CT images.

METHODS

A total of 169 osteoporosis-diagnosed patients from three hospitals were randomly split into OVFs (n = 77) and Non-OVFs (n = 92) groups for training (n = 135) and test (n = 34). Demographic data, BMD, and CT imaging details were collected. Deep transfer learning (DTL) using ResNet-50 and radiomics features were fused, with the best model chosen via logistic regression. Cox proportional hazards models identified clinical factors. Three models were constructed: clinical, radiomics-DTL, and fusion (clinical-radiomics-DTL). Performance was assessed using AUC, C-index, Kaplan-Meier, and calibration curves. The best model was depicted as a nomogram, and clinical utility was evaluated using decision curve analysis (DCA).

RESULTS

BMD, CT values of paravertebral muscles (PVM), and paravertebral muscles' cross-sectional area (CSA) significantly differed between OVFs and Non-OVFs groups (P < 0.05). No significant differences were found between training and test cohort. Multivariate Cox models identified BMD, CT values of PVM, and CSAPS reduction as independent OVFs risk factors (P < 0.05). The fusion model exhibited the highest predictive performance (C-index: 0.839 in training, 0.795 in test). DCA confirmed the nomogram's utility in OVFs risk prediction.

CONCLUSION

This study presents a robust predictive model for OVFs risk, integrating BMD, CT data, and radiomics-DTL features, offering high sensitivity and specificity. The model's visualizations can inform OVFs prevention and treatment strategies.

Using advanced imaging to measure bone density, compression fracture risk, and risk for construct failure after spine surgery

Low bone mineral density (BMD) can predispose to vertebral body compression fractures and postoperative instrumentation failure. DEXA is considered the gold standard for measurement of BMD, however it is not obtained for all spine surgery patients preoperatively. There is a growing body of evidence suggesting that more routinely acquired spine imaging studies such as computed tomography (CT) and magnetic resonance imaging (MRI) can be opportunistically used to measure BMD. Here we review available studies that assess the validity of opportunistic screening with CT-derived Hounsfield Units (HU) and MRI-derived vertebral vone quality (VBQ) to measure BMD of the spine as well the utility of these measures in predicting postoperative outcomes. Additionally, we provide screening thresholds based on HU and VBQ for prediction of osteopenia/ osteoporosis and postoperative outcomes such as cage subsidence, screw loosening, proximal junctional kyphosis, and implant failure.

Postmenopausal women with normal BMD who have fractures have deteriorated bone microarchitecture: A prospective analysis from The OFELY study

Most postmenopausal women who sustain fragility fracture (Fx) have their areal bone mineral density (BMD) above the osteoporosis threshold. A sizeable proportion of them have normal aBMD. This study aimed to prospectively investigate the association of fragility Fx with bone microarchitecture (MA) assessed by high-resolution peripheral computed tomography (HR-pQCT) in postmenopausal women without low BMD. At the 14th annual follow-up of the OFELY study, we measured bone MA at the distal radius and tibia with HR-pQCT in addition to areal BMD with DXA, in 586 postmenopausal women. Among them, 166 (29 %) women, mean (SD) age 65 (8) yr, had normal BMD defined as a T score ≥ -1 at the lumbar spine, femoral neck, and total hip. During a median [IQR] 15 [14-15] yr of follow-up, 46 of those women sustained incident fragility Fx, including 19 women with a major osteoporotic Fx (clinical spine, forearm, proximal humerus, hip). Women who sustained Fx did not differ for age, BMI, tobacco and alcohol use, diabetes, falls, FRAX®, aBMD, and TBS compared with women without incident Fx. In contrast, they had significant impairment of volumetric densities, cortical area (Ct. Ar) and thickness (Ct. Th), stiffness (K), and estimated failure load (FL) at the radius compared with women without incident Fx. At the radius, each SD decrease of volumetric densities, Ct.Ar, Ct.Th, K, and estimated FL were significantly associated with an increased risk of all fragility fractures with hazard ratios (HR) from 1.44 to 1.56 and of major osteoporotic fractures (HR from 1.66 to 2.57). Lesser impairment of bone MA was seen at the tibia. We conclude that even in women with normal areal BMD fragility fractures are associated with deterioration of bone microarchitecture.

Twelve-month resistance and impact exercise program or risedronate provides a relative benefit to hip bone structure in postmenopausal women: results from a randomized controlled trial

Bone strength estimates are important for fracture prevention. This study compared bone strength changes in postmenopausal women with low bone mass who were assigned to 12 months of exercise, a bone medication, or control. Exercise and bone medications benefited structure at the hip. Structure should be considered in fracture prevention research.

PURPOSE

Exercise and bisphosphonates reduce fracture risk, but their impact on estimates of bone strength remains uncertain. This study compared changes in tibial bone strength using peripheral quantitative computed tomography (pQCT) and hip structure analysis (HSA) outcomes from dual-energy X-ray absorptiometry (DXA) scans in postmenopausal women with low bone mass assigned to 12 months of exercise, risedronate, or control.

METHODS

In this RCT, 276 postmenopausal women within 6 years of menopause were randomly assigned to three groups: exercise (92), risedronate (91), or control (93). Exercise included weighted jogging and progressive resistance exercises; risedronate treatment was 150 mg monthly; all groups received calcium and vitamin D. pQCT and DXA images were obtained at baseline and 6 and 12 months and compared between groups over time.

RESULTS

Participants had a mean (± SD) age of 54.5 (± 3.2) years with an average of 36.7 (± 40.7) months postmenopause. No significant differences were found between groups for the change in pQCT outcomes (volumetric bone mineral density, area, and strength estimates). At 12 months, mean percent differences (95% CI) in HSA measures between exercise and controls were as follows: intertrochanteric, cross-sectional area 2.25% (0.28, 4.12) (p = .03), cross-sectional moment of inertia (CSMI) 5.67% (1.47, 9.87) (p < .01), and section modulus (SM) 4.38% (1.02, 7.74) (p = .01), and narrow neck, average cortical thickness 2.37% (-0.08, 4.83) (p = .031). Mean percent differences (95% CI) in HSA measures between risedronate and control were as follows: intertrochanteric, CSMI 4.28% (-0.24, 8.81) (p = .03) and SM 3.35% (-0.21, 6.91) (p = .03), and shaft, subperiosteal width 0.82% (0.05, 1.58) (p = .047), CSMI 2.53% (0.88, 4.18) (p = .004), and SM 1.57% (0.34, 2.8) (p = .008). Exercise maintained neck-shaft angle compared to both control 1.27% (0.13, 2.41) (p = .04) and risedronate 1.31% (0.23, 2.39) (p = .03). All other differences for changes in HSA outcomes over time were not significantly different between the exercise and risedronate groups.

CONCLUSION

Exercise and bisphosphonates may influence structural and strength estimates at the hip, but not at peripheral sites (tibia). Neither exercise nor bisphosphonates were found to be superior in improving estimates of hip bone strength.

Clinical Use of Trabecular Bone Score: The 2023 ISCD Official Positions

Osteoporosis can currently be diagnosed by applying the WHO classification to bone mineral density (BMD) assessed by dual-energy x-ray absorptiometry (DXA). However, skeletal factors other than BMD contribute to bone strength and fracture risk. Lumbar spine TBS, a grey-level texture measure which is derived from DXA images has been extensively studied, enhances fracture prediction independent of BMD and can be used to adjust fracture probability from FRAX® to improve risk stratification. The purpose of this International Society for Clinical Densitometry task force was to review the existing evidence and develop recommendations to assist clinicians regarding when and how to perform, report and utilize TBS. Our review concluded that TBS is most likely to alter clinical management in patients aged ≥ 40 years who are close to the pharmacologic intervention threshold by FRAX. The TBS value from L1-L4 vertebral levels, without vertebral exclusions, should be used to calculate adjusted FRAX probabilities. L1-L4 vertebral levels can be used in the presence of degenerative changes and lumbar compression fractures. It is recommended not to report TBS if extreme structural or pathological artifacts are present. Monitoring and reporting TBS change is unlikely to be helpful with the current version of the TBS algorithm. The next version of TBS software will include an adjustment based upon directly measured tissue thickness. This is expected to improve performance and address some of the technical factors that affect the current algorithm which may require modifications to these Official Positions as experience is acquired with this new algorithm.

Distinct Metabolites in Osteopenia and Osteoporosis: A Systematic Review and Meta-Analysis

Multiple studies have indicated that distinct metabolites are involved in the occurrence and development of osteopenia (ON) and osteoporosis (OP); however, these metabolites in OP and ON have not yet been classified and standardized. This systematic review and meta-analysis included 21 articles aiming to investigate the distinct metabolites in patients with ON and OP. The quality of the included articles was generally high; seventeen studies had >7 stars, and the remaining four received 6 stars. This systematic review showed that three metabolites (phosphatidylcholine (PC) (lipid metabolites), galactose (carbohydrate metabolites), and succinic acid (other metabolites)) increased, four (glycylglycine (gly-gly), cystine (amino acids), sphingomyelin (SM) (lipid metabolites) and glucose (carbohydrate metabolites)) decreased, and five (glutamine, hydroxyproline, taurine (amino acids), lysophosphatidylcholine (LPC) (lipid metabolites), and lactate (other metabolites)) had conflicting directions in OP/ON. The results of the meta-analysis show that gly-gly (MD = -0.77, 95%CI -1.43 to -0.11, p = 0.02) and cystine (MD = -5.52, 95%CI -7.35 to -3.68, p < 0.00001) decreased in the OP group compared with the healthy control group. Moreover, LPC (MD = 1.48, 95%CI 0.11 to 2.86, p = 0.03) increased in the OP group compared with the healthy control group. These results indicate that distinct metabolites were associated with ON and OP, which could be considered a predictor for OP.

Fracture in Patients with Normal Bone Mineral Density: An Evaluation of the American Orthopaedic Association's Own the Bone Registry

BACKGROUND

Fractures often occur in patients with normal dual x-ray absorptiometry (DXA)-measured bone mineral density (BMD). DXA does not consider clinical fracture risk factors or bone quality. We hypothesized that patients with normal BMD who sustain a fracture have other characteristics suggesting abnormal bone and an elevated fracture risk requiring additional bone health evaluation and potential anti-osteoporotic treatment.

METHODS

A total of 7,219 patients who were ≥50 years of age, had sustained a fracture from July 2016 to July 2021, and had DXA data in the American Orthopaedic Association's Own the Bone (AOA OTB) registry were included in this study. The index and prior fracture site data were obtained. BMD status was classified by the World Health Organization T-score criteria. The Fracture Risk Assessment Tool (FRAX) scores with and without BMD were calculated in patients with normal BMD. An elevated risk was defined as a major osteoporotic fracture risk of ≥20% or a hip fracture risk of ≥3%.

RESULTS

The mean patient age (and standard deviation) was 70.8 ± 9.71 years, 84% of patients were female, and 92% of patients were Caucasian. Normal BMD was present in 8.6% of patients. The index fracture was a major osteoporotic fracture in 68.6% of patients with normal BMD and 75.6% of patients with osteoporosis. The most common site for index and prior fractures other than major osteoporotic fractures was the foot and ankle; of patients with normal BMD, 13.9% had this as the most common index site and 17.4% had this as the most common prior site. The FRAX risk calculated without BMD was elevated in 72.9% of patients with normal BMD, and the FRAX risk calculated with BMD was elevated in 12.0% of patients.

CONCLUSIONS

Most patients with a fracture and normal BMD met indications, including a prior fracture or elevated FRAX risk, for anti-osteoporotic therapies. Most patients were Caucasian and therefore potentially had a higher baseline fracture risk. The FRAX risk calculated without BMD was elevated more often than the FRAX risk with BMD, implying that clinical risk factors, which highlight multiple opportunities for non-pharmacologic secondary fracture prevention, should be considered along with DXA. Fractures other than major osteoporotic fractures were more common in patients with normal BMD, suggesting that minor fractures in adults who are ≥50 years of age should be considered sentinel events warranting further evaluation. Surgeons must recognize that other important risk factors apart from BMD may help to guide further bone health evaluation.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Computed Tomography-Based L1 Bone Mineral Density in 624 Dutch Trauma Patients—Are North American Reference Values Valid in Europe?

Opportunistic screening for bone mineral density (BMD) of the first lumbar vertebra (L1) using computed tomography (CT) is increasingly used to identify patients at risk for osteoporosis. An extensive study in the United States has reported sex-specific normative values of CT-based BMD across all ages. The current study aims to validate North American reference values of CT-based bone mineral density in a Dutch population of level-1 trauma patients. All trauma patients aged 16 or older, admitted to our level-1 trauma center during 2017, who underwent a CT scan of the chest or abdomen at 120 kVp within 7 days of hospital admission, were retrospectively included. BMD measurements in Hounsfield Units (HU) were performed manually in L1 or an adjacent vertebra. Student’s t-tests were performed to compare the Dutch mean BMD value per age group to the North American reference values. Linear regression analysis and Pearson’s correlation coefficient (ρ) calculations were performed to assess the correlation between BMD and age. In total, 624 patients were included (68.4% men, aged 16–95). Mean BMD decreased linearly with 2.4 HU per year of age (ρ = −0.77). Sex-specific analysis showed that BMD of premenopausal women was higher than BMD of men at these ages. Dutch mean BMD values in the age groups over 35 years were significantly lower than the North American reference values. Our findings indicate that using North American BMD thresholds in Dutch clinical practice would result in overdiagnosis of osteoporosis and osteopenia. Dutch guidelines may benefit from population-specific thresholds.

Frequency of normal bone measurement in postmenopausal women with fracture: a registry-based cohort study

This registry-based cohort study assessed the percentage of women with prior or incident fracture who had normal bone defined as a normal bone mineral density T-score and normal trabecular bone score (TBS). Inclusion of TBS reduced the percentage with normal bone. Normal bone measurement is rare in women with fracture.

INTRODUCTION

Some fractures occur in women with normal BMD. We hypothesized that adding trabecular bone score (TBS) to DXA would (1) demonstrate that few women with fracture have normal bone, i.e., normal BMD T-score and TBS and (2) increase the percentage of women with fracture that have abnormal bone defined as a BMD T-score ≤ - 2.5 or low TBS.

METHODS

The public healthcare system in Manitoba, Canada, makes it possible to link clinical DXA data to population databases. This study included all women age 50+ with a first DXA from February 1999 to March 2018 with valid BMD, TBS, and fracture data. Bone status was defined as Normal = BMD T-score of the spine, femoral neck, and total femur ≥ - 1.0 AND TBS > 1.31; Abnormal = BMD T-score ≤ - 2.5 OR TBS < 1.23; and borderline = all others. Analyses were stratified by age decade.

RESULTS

Among women with prior (n = 4649) or incident (n = 2547) fracture, bone status assessed by both BMD and TBS was normal in only 6% and 4%, respectively. In women with prior or incident hip fracture, normal bone was present in < 1%. The prevalence of normal bone declined (p trend < 0.001) with age as expected. BMD T-score osteoporosis was present in 40% with any prior and 46% with any incident fracture. BMD T-score osteoporosis was present in 65% and 60% with prior and incident hip fracture, respectively. Including TBS with BMD increased the percentage of women with abnormal bone to 61% and 68% for any prior or incident fracture and to 80% and 81% for prior or incident hip fracture, respectively (all p < 0.001).

CONCLUSION

Including TBS with BMD increases identification of abnormal bone in women with fracture compared with BMD alone. Normal bone is present in < 6% of women with any fracture and < 1% of those with hip fracture. What is thought to be normal bone in women with fracture is rarely normal.