Bone biopsy in patients with osteoporosis

Utility of iliac crest tetracycline-labelled bone biopsy in osteoporosis and metabolic bone disease: An evaluation of 95 cases over a period of 25 years

Background

Metabolic bone diseases (MBD) are typically diagnosed by non-invasive imaging and clinical biomarkers. However, imaging does not provide structural information, and biomarkers can be transiently affected by many systemic factors. Bone biopsy and pathologic evaluation is the gold standard for diagnosis of MBD, however, it is rarely utilized. We describe our technique for iliac crest tetracycline-labelled bone using a cannulated drill and assess the utility of bone biopsies to provide diagnostic and therapeutic guidance.

Methods

In the 25-year period between March 1998 and January 2023, a total of 95 bone biopsies were performed on 94 patients for an osteological indication at Vanderbilt University Medical Center (VUMC). Patient demographics, bone biopsy indications, complications, diagnostic utility, and subsequent therapeutic guidance were retrospectively reviewed and analyzed.

Results

The procedure had minimal complications and was well tolerated by patients. This technique provided good quality specimens for pathology, which helped establish a diagnosis and treatment change in most patients. Patients that had biopsy-guided treatment alterations showed significant increases in Dual-Energy X-ray Absorptiometry (DEXA) bone mineral density (BMD) scores post-biopsy and subsequent treatment.

Conclusion

Despite scientific and technological progress in non-invasive diagnostic imaging, clinical biomarkers, and procedures for MBD, there remains a small but significant subset of patients who may benefit from inclusion of tetracycline-labelled bone biopsy into the diagnostic and therapeutic picture. Future prospective comparison studies are warranted.

Mini abstract

Tetracycline-labelled bone biopsies are under-utilized. Biopsy led to a histological diagnosis and ensuing treatment alteration in most patients with significant increases in bone mineral density. The biopsy procedure used herein provided good specimens with low pain/adverse events. Bone biopsy remains a valuable tool in a small, though significant, subset of patients.

Trabecular bone microcrack accumulation in patients treated with bisphosphonates for durations up to 16 years

This study quantified the length, number, and density of microcracks in bone from patients treated with bisphosphonates as a function of duration. Anterior iliac crest bone samples from 51 osteoporotic Caucasian females continuously treated with oral bisphosphonates for 1-16 years were obtained by bone biopsy. Samples were histologically processed and analyzed for bone area, microcrack number, and microcrack length. The analyses used statistical modeling and considered patient age, bone mineral density, bone volume/total volume, trabecular thickness, and bone turnover as potential covariates. Microcrack density (number of microcracks/total examined bone area) was linearly related (p = 0.018) to bisphosphonate treatment duration. None of the analyzed covariates contributed significantly to the observed relationship between microcrack density and bisphosphonate treatment duration. Observed increases in microcrack density with increasing bisphosphonate treatment duration is important because increasing levels of microcracks may not only affect bone remodeling but also reduce elastic modulus and are suspected to adversely affect other mechanical properties that may influence fracture risk. The present findings add to our prior results showing changes in bone material properties and modulus with bisphosphonate treatment duration and thereby provide a more comprehensive assessment of the relationship between bisphosphonate treatment duration and bone quality. Statement of Clinical Significance: The present findings provide information guiding clinical use of oral bisphosphonates for post-menopausal osteoporosis therapy.

Novel Radiomics-Clinical Model for the Noninvasive Prediction of New Fractures After Vertebral Augmentation

PURPOSE

To investigate the noninvasive prediction model for new fractures after percutaneous vertebral augmentation (PVA) based on radiomics signature and clinical parameters.

METHODS

Data from patients who were diagnosed with osteoporotic vertebral compression fracture (OVCF) and treated with PVA in our hospital between May 2014 and April 2019 were retrospectively analyzed. Radiomics features were extracted from T1-weighted magnetic resonance imaging (MRI) of the T11-L5 segments taken before PVA. Different radiomics models was developed by using linear discriminant analysis (LDA), multilayer perceptron (MLP), and stochastic gradient descent (SGD) classifiers. A nomogram was constructed by integrating clinical parameters and Radscore that calculated by the best radiomics model. The model performance was quantified in terms of discrimination, calibration and clinical usefulness.

RESULT

Four clinical parameters and 16 selected radiomics features were used for model development. The clinical model showed poor discrimination capability with area under the curves (AUCs) yielding of 0.522 in the training dataset and 0.517 in the validation dataset. The LDA, MLP and SGD classifier-based radiomics model had achieved AUCs of 0.793, 0.810, and 0.797 in the training dataset, and 0.719, 0.704, and 0.725 in the validation dataset, respectively. The nomogram showed the best performance with AUCs achieving 0.810 and 0.754 in the training and validation datasets, respectively. The decision curve analysis demonstrated the net benefit of the nomogram was higher than that of other models.

CONCLUSION

Our findings indicate that combining clinical features with radiomics features from pre-augmentation T1-weighted MRI can be used to develop a nomogram that can predict new fractures in patients after PVA.

Management of Osteoporosis and Spinal Fractures: Contemporary Guidelines and Evolving Paradigms

Physicians involved in treating spine fractures secondary to osteopenia and osteoporosis should know the pathogenesis and current guidelines on managing the underlying diminished bone mineral density, as worldwide fracture prevention campaigns are trailing behind in meeting their goals. This is a narrative review exploring the various imaging and laboratory tests used to diagnose osteoporotic fractures and a comprehensive compilation of contemporary medical and surgical management. We have incorporated salient recommendations from the Endocrine Society, the American Association of Clinical Endocrinology (AACE), and the American Society for Bone and Mineral Research (ASBMR). The use of modern scoring systems such as Fracture Risk Assessment Tool (FRAX®) for evaluating fracture risk in osteoporosis with a 10-year probability of hip fracture and major fractures in the spine, forearm, hip, or shoulder is highlighted. This osteoporosis risk assessment tool can be easily incorporated into the preoperative bone health optimization strategies, especially before elective spine surgery in osteoporotic patients. The role of primary surgical intervention for vertebral compression fracture and secondary fracture prevention with pharmacological therapy is described, with randomized clinical trial-based wisdom on its timing and dosage, drug holiday, adverse effects, and relevant evidence-based literature. We also aim to present an evidence-based clinical management algorithm for treating osteoporotic vertebral body compression fractures, tumor-induced osteoporosis, or hardware stabilization in elderly trauma patients in the setting of their impaired bone health. The recent guidelines and recommendations on surgical intervention by various medical societies are covered, along with outcome studies that reveal the efficacy of cement augmentation of vertebral compression fractures via vertebroplasty and balloon kyphoplasty versus conservative medical management in the elderly population.

Bone Phenotyping Approaches in Human, Mice and Zebrafish - Expert Overview of the EU Cost Action GEMSTONE ("GEnomics of MusculoSkeletal traits TranslatiOnal NEtwork")

A synoptic overview of scientific methods applied in bone and associated research fields across species has yet to be published. Experts from the EU Cost Action GEMSTONE ("GEnomics of MusculoSkeletal Traits translational Network") Working Group 2 present an overview of the routine techniques as well as clinical and research approaches employed to characterize bone phenotypes in humans and selected animal models (mice and zebrafish) of health and disease. The goal is consolidation of knowledge and a map for future research. This expert paper provides a comprehensive overview of state-of-the-art technologies to investigate bone properties in humans and animals - including their strengths and weaknesses. New research methodologies are outlined and future strategies are discussed to combine phenotypic with rapidly developing -omics data in order to advance musculoskeletal research and move towards "personalised medicine".

Low bone mineral density due to secondary hyperparathyroidism in the GlatmTg(CAG-A4GALT) mouse model of Fabry disease

Low bone mineral density (BMD)-diagnosed as osteoporosis or osteopenia-has been reported as a new characteristic feature of Fabry disease; however, the mechanism underlying the development of low BMD is unknown. We previously revealed that a mouse model of Fabry disease [GlatmTg(CAG-A4GALT)] exhibits impaired functioning of medullary thick ascending limb (mTAL), leading to insufficient Ca2+ reabsorption and hypercalciuria. Here, we investigated bone metabolism in GlatmTg(CAG-A4GALT) mice without marked glomerular or proximal tubular damage. Low BMD was detected by 20 weeks of age via micro-X-ray-computed tomography. Bone histomorphometry revealed that low BMD results by accelerated bone resorption and osteomalacia. Plasma parathyroid hormone levels increased in response to low blood Ca2+-not plasma fibroblast growth factor 23 (FGF-23) elevation-by 5 weeks of age and showed progressively increased phosphaturic action. Secondary hyperparathyroidism developed by 20 weeks of age and caused hyperphosphatemia, which increased plasma FGF-23 levels with phosphaturic action. The expression of 1α-hydroxylase [synthesis of 1α,25(OH)2D3] in the kidney did not decrease, but that of 24-hydroxylase [degradation of 1α,25(OH)2D3] decreased. Vitamin D deficiency was ruled out as the cause of osteomalacia, as plasma 1α,25(OH)2D3 and 25(OH)D3 levels were maintained. Results demonstrate that secondary hyperparathyroidism due to mTAL impairment causes accelerated bone resorption and osteomalacia due to hyperphosphaturia and hypercalciuria, leading to low BMD in Fabry model mice.

Structural and Metabolic Assessment of Bone

The assessment of bone structure and metabolism should focus on the bone strength. Many factors are involved, and although bone density is an important component, it is not the same as bone strength. Other aspects of bone quality include bone volume, micro-architecture, material composition, and ability to repair damage. This chapter briefly reviews some of the methods that can be used to assess both density and quality of bone. Non-invasive measurements of density or structure include dual X-ray absorptiometry (DXA), quantitative computed tomography, ultrasound, and magnetic resonance imaging. DXA is most widely used and has advantages of safety and accessibility, but there are limitations in the interpretation of the results, and in clinical practice positioning errors are frequently seen. Invasive methods are used primarily for research. Samples of bone can be used to measure structure by histology as well as micro-computed tomography and infra-red spectroscopy or backscattered electron microscopy. Force can be directly applied to bone samples to measure the bones strength. Impact microindentation is a new minimally invasive technique that measures bone hardness. Metabolic assessment includes blood and urine tests that reflect diseases that cause bone loss, particularly problems with mineral metabolism. Tetracycline-labelled bone biopsies are the standard for measuring bone formation. Non-invasive biochemical tests of bone formation and resorption can evaluate a patient's skeletal physiology.

Young's modulus and hardness of human trabecular bone with bisphosphonate treatment durations up to 20 years

Bone modulus from patients with osteoporosis treated with bisphosphonates for 1 to 20 years was analyzed. Modulus increases during the first 6 years of treatment and remains unchanged thereafter.

INTRODUCTION

Bisphosphonates are widely used for treating osteoporosis, but the relationship between treatment duration and bone quality is unclear. Since material properties partially determine bone quality, the present study quantified the relationship between human bone modulus and hardness with bisphosphonate treatment duration.

METHODS

Iliac crest bone samples from a consecutive case series of 86 osteoporotic Caucasian women continuously treated with oral bisphosphonates for 1.1-20 years were histologically evaluated to assess bone turnover and then tested using nanoindentation. Young's modulus and hardness were measured and related to bisphosphonate treatment duration by statistical modeling.

RESULTS

All bone samples had low bone turnover. Statistical models showed that with increasing bisphosphonate treatment duration, modulus and hardness increased, peaked, and plateaued. These models used quadratic terms to model modulus increases from 1 to 6 years of bisphosphonate treatment and linear terms to model modulus plateaus from 6 to 20 years of treatment. The treatment duration at which the quadratic-linear transition (join point) occurred also depended upon trabecular location. Hardness increased and peaked at 12.4 years of treatment; it remained constant for the next 7.6 years of treatment and was insensitive to trabecular location.

CONCLUSIONS

Bone modulus increases with bisphosphonate treatment durations up to 6 years, no additional modulus increases occurred after 6 years of treatment. Although hardness increased, peaked at 12.4 years and remained constant for the next 7.6 years of BP treatment, the clinical relevance of hardness remains unclear.

Technique, Safety, and Yield of Bone Biopsies for Histomorphometry in Children

PURPOSE

To evaluate image-guided bone biopsy for bone histomorphometry to assess osteoporosis in children with respect to safety and yield.

MATERIALS AND METHODS

A single-center retrospective review was performed of 79 bone biopsies in 73 patients performed between 2007 and 2015. Biopsies of the iliac bone were performed under general anesthesia, after tetracycline labeling, using a Rochester needle (Medical Innovations International, Inc, Rochester, Minnesota). Ultrasound and fluoroscopic guidance were used in all procedures. Biopsy technique, technical success, safety, and histomorphometry results (complete, incomplete, none) were analyzed.

RESULTS

There were 41 male patients (51.8%). Technical success was achieved in 76/79 (96%) procedures. Of 79 biopsies, 75 (95%) were uneventful. Unplanned overnight observation was required in 3 (minor SIR grade B), and prolonged hospital stay owing to hematoma causing nerve compression pain was required in 1 (major SIR grade D). Complete histomorphometric reports were obtained in 69 (87%) procedures, incomplete reports were obtained in 7 (9%), and no reports were obtained in 3(4%). Incomplete reports were insufficient to provide a definitive diagnosis or guide treatment. Histomorphometry impacted subsequent therapy in 69 (87%) biopsies.

CONCLUSIONS

Image-guided bone biopsy for osteoporosis using the Rochester needle is a valuable and safe technique for establishing the diagnosis of osteoporosis and directing treatment based on histomorphometry results.

Quantitative imaging methods in osteoporosis

Osteoporosis is characterized by a decreased bone mass and quality resulting in an increased fracture risk. Quantitative imaging methods are critical in the diagnosis and follow-up of treatment effects in osteoporosis. Prior radiographic vertebral fractures and bone mineral density (BMD) as a quantitative parameter derived from dual-energy X-ray absorptiometry (DXA) are among the strongest known predictors of future osteoporotic fractures. Therefore, current clinical decision making relies heavily on accurate assessment of these imaging features. Further, novel quantitative techniques are being developed to appraise additional characteristics of osteoporosis including three-dimensional bone architecture with quantitative computed tomography (QCT). Dedicated high-resolution (HR) CT equipment is available to enhance image quality. At the other end of the spectrum, by utilizing post-processing techniques such as the trabecular bone score (TBS) information on three-dimensional architecture can be derived from DXA images. Further developments in magnetic resonance imaging (MRI) seem promising to not only capture bone micro-architecture but also characterize processes at the molecular level. This review provides an overview of various quantitative imaging techniques based on different radiological modalities utilized in clinical osteoporosis care and research.

Stiffness and strength of bone in osteoporotic patients treated with varying durations of oral bisphosphonates

Apparent modulus and failure stress of trabecular bone structure from 45 women with osteoporosis treated with bisphosphonates for varying durations were studied using finite element analyses and statistical modeling. Following adjustments for patient age and bone volume, increasing bisphosphonate treatment duration for up to 7.3 years was associated with treatment-time-dependent increases in bone apparent modulus and failure stress. Treatment durations exceeding 7.3 years were associated with time-dependent decreases in apparent modulus and failure stress from the peak values observed.

INTRODUCTION

The purpose of this study was to clarify the relationship between bisphosphonate (BP) treatment duration and human bone quality. This study quantified changes in the apparent modulus and failure stress of trabecular bone biopsied from patients with osteoporosis who were treated with BPs for widely varying durations.

METHODS

Forty-five iliac crest bone samples were obtained from women with osteoporosis who were continuously treated with oral BPs for varying periods of up to 16 years. Micro-CT imaging was used to develop three-dimensional virtual models of the trabecular bone from these samples. Apparent modulus and failure stress of these virtual models were determined using finite element analyses (FEA). Polynomial regression and cubic splines, adjusted for relevant (age and BV/TV) covariates, were used to statistically model the data and quantify the relationships between BP treatment duration and apparent modulus or failure stress.

RESULTS

Second-order polynomial models were needed to relate apparent modulus or failure stress to BP treatment duration. These models showed that these bone quality parameters (a) increased with increasing BP treatment duration up to approximately 7.3 years, (b) reached a maximum at this (~7.3 years) time, and then (c) declined with BP treatment durations exceeding ~7.3 years. A similar result was obtained by modeling with cubic splines.

CONCLUSIONS

Changes in FEA-derived apparent stiffness and failure stress are attributable to changes in trabecular bone structure, which in turn are related to the duration of BP treatment. These relationships are evident even after adjustments are made in the statistical models for changes in age and BV/TV. According to these models, increases in trabecular bone apparent stiffness and failure stress linked to BPs cease and appear to reverse after approximately 7.3 years of treatment. Conclusions regarding optimal BP therapy duration await study of additional bone quality parameters.

Effects of Ovariectomy and Corticosteroid-Induced Osteoporosis on the Osteoinductivity of rhBMP-2 in a Segmental Long-Bone Defect Model

This study used the segmental long-bone defect model to assess the effects of osteoporosis on the formation of new bones and the osteoinductivity of recombinant human bone morphogenetic protein-2 (rhBMP-2). Seventy-two female Sprague-Dawley rats were divided into two groups: an osteoporosis group with ovariectomies and dexamathasone intramuscular injections and a sham group. When they reached 22 weeks in age, each group was further divided into two groups and a 5-mm defect was made in both fibular mid-shafts of each rat. One fibula in each rat was picked randomly and was injected with 0.05 mL of hydrogel carrier; the opposite fibula was injected with the same carrier mixed with rhBMP-2 (10 μg). After rearing for a further 5 and 9 weeks, the ratios of the lengths of the newly formed bones in the fibular defects were determined using micro-CT and undecalcified histology. The sham rhBMP-2-injected group-in all of the 5- and 9-week-kept groups-showed a significantly higher bridging bone formation ratio than the other three groups. The osteoporosis rhBMP-2-injected group showed a significantly higher ratio than both the non-rhBMP-2-injected sham hydrogel and the osteoporosis hydrogel groups. The comparison of the micro-CT parameters of the newly formed bones showed that the sham rhBMP-2 group at both 5 and 9 weeks compared with the osteoporosis rhBMP-2 group had significantly higher percentage bone volumes, trabecular thicknesses, and trabecular numbers, in addition to significantly lower specific surfaces, trabecular pattern factors, and structural model indices. The histology results showed that the sham-rhBMP-2 group began forming bridging bones in the defect areas at 5 weeks, and at 9 weeks, trabeculae and marrow spaces were observed. However, the osteoporosis rhBMP-2 group exhibited a relatively minor level of new bone and trabecula formation. Consequently, the rhBMP-2 group showed significantly increased bone formation in the osteoporosis rat fibular defect model compared with the hydrogel group, whereas the new bone quantities, qualities, and remodeling in the osteoporosis rhBMP-2 group were less effective than those in the sham-rhBMP-2 group, signaling that ovariectomy and corticosteroid-induced osteoporosis significantly undermines rhBMP-2 osteoinductivity.

Vertebral bone density by quantitative computed tomography mirrors bone structure histomorphometric parameters in hemodialysis patients

Diagnosing low bone mass is of clinical importance for hemodialysis (HD) patients due to its association with fractures and cardiovascular disease. We investigated whether bone density obtained by quantitative computed tomography (QCT) is associated with the histologically determined bone volume and microarchitecture parameters in HD patients. Twenty-six HD patients were studied. Bone biopsy samples were obtained from the iliac crest and trabecular bone volume, thickness, number and separation were evaluated by histomorphometry. Vertebral trabecular bone density (VTBD) was evaluated by QCT. VTBD correlated positively with trabecular bone volume (r = 0.69, p < 0.001), trabecular thickness (r = 0.45, p = 0.022) and trabecular number (r = 0.62, p < 0.001), and negatively with trabecular separation (r = -0.50, p < 0.01). In the multiple linear regression analysis adjusting for age, gender and diabetes, VTBD remained associated with bone volume by histomorphometry (β = 0.06; 95 % CI 0.02-0.11; p = 0.006; R² = 0.49). VTBD measured by QCT mirrored bone volume and microarchitecture parameters obtained by histomorphometry in HD patients.