[Metabolic bone diseases : what's new in 2023]. / Maladies osseuses : ce qui a changé en 2023.

The sequential effects of romosozumab and denosumab in osteoporosis are shown in real-life, while the mechanisms of post-denosumab rebound are reviewed extensively. A network meta-analysis confirms the superiority of anabolics vs anti-resorptives on fracture reduction, while the latter shown a reduction of mortality in a large population-based study. Fracture risk prediction by FRAXPlus is improved. New meta-analyses confirm the benefits of Vitamin D on fractures and falls. Finally, multiples trials with new molecules for the treatment of rare bone diseases, including osteogenesis imperfecta, fibrous dysplasia and hypoparathyroidism, shown promising results.

Dans l'ostéoporose, les effets séquentiels du romosozumab et du dénosumab se précisent et les mécanismes du rebond à l'arrêt de ce dernier font l'objet d'une revue détaillée. Une méta-analyse en réseau confirme la supériorité des traitements anaboliques sur les antirésorbtifs, alors que l'effet de ces derniers sur la réduction de la mortalité est démontré dans une large étude populationnelle. La prédiction du risque fracturaire est améliorée par l'outil FRAXPlus. De nouvelles méta-analyses des bénéfices de la vitamine D sur le risque de fractures et de chutes sont également disponibles. Enfin, de nombreuses études encourageantes sur l'efficacité de nouveaux traitements dans de multiples maladies osseuse rares, telles l'ostéogenèse imparfaite, la dysplasie fibreuse et l'hypoparathyroïdie, ont été publiées.

Proposed diagnostic criteria for the diagnosis of hypophosphatasia in children and adolescents: results from the HPP International Working Group.

Hypophosphatasia (HPP) is a rare inborn error of metabolism that presents variably in both age of onset and severity. HPP is caused by pathogenic variants in the ALPL gene, resulting in low activity of tissue nonspecific alkaline phosphatase (TNSALP). Patients with HPP tend have a similar pattern of elevation of natural substrates that can be used to aid in diagnosis. No formal diagnostic guidelines currently exist for the diagnosis of this condition in children, adolescents, or adults. The International HPP Working Group is a comprised of a multidisciplinary team of experts from Europe and North America who have expertise in the diagnosis and management of patients with HPP. This group reviewed 93 papers through a Medline, Medline In-Process, and Embase search for the terms "HPP" and "hypophosphatasia" between 2005 and 2020 and that explicitly address either the diagnosis of HPP in children, clinical manifestations of HPP in children, or both. Two reviewers independently evaluated each full-text publication for eligibility and studies were included if they were narrative reviews or case series/reports that concerned diagnosis of pediatric HPP or included clinical aspects of patients diagnosed with HPP. This review focused on 15 initial clinical manifestations that were selected by a group of clinical experts.The highest agreement in included literature was for pathogenic or likely pathogenic ALPL variant, elevation of natural substrates, and early loss of primary teeth. The highest prevalence was similar, including these same three parameters and including decreased bone mineral density. Additional parameters had less agreement and were less prevalent. These were organized into three major and six minor criteria, with diagnosis of HPP being made when two major or one major and two minor criteria are present.

Unusual phosphaturic mesenchymal tumor mimicking osteoid osteoma.

Phosphaturic mesenchymal tumor is a rare tumor characterized by paraneoplastic osteomalacia. The diagnosis is often delayed because of nonspecific symptoms and difficulty to localize the tumor. In this study we report a case of PMT of the left femur detected by Ga-68-DOTATATE PET-CT with radiological features mimicking osteoid osteoma. We report a 31-year-old female patient who presented to our hospital for evaluation due to progressive bone pain and muscle weakness. Her laboratory data showed hypophosphatemia and increased fibroblast growth factor 23 (FGF-23) together with reduced bone mineral density on bone densitometry. The diagnosis of PMT was suspected and the tumor was identified on Ga-68-DOTATATE PET-CT as a focal uptake in a lucent lesion of the left femoral head with a central sclerotic dot mimicking a nidus as seen in osteoid osteoma. The lesion was treated with percutaneous radiofrequency ablation. Laboratory tests and bone densitometry rapidly improved post-treatment. The present case emphasizes the difficulty to diagnose PMT due to its nonspecific biochemical and clinical presentation and the relevance of functional imaging for locating these tumors despite different radiological presentation.

[New reimbursement criteria for vitamin D measurements: what about our migrant patients?] / Nouveaux critères de remboursement du dosage de la vitamine D : et nos patients migrants ?

Vitamin D deficiency is a global health burden, which has been subject to debate in recent years. Although its consequences on patients' general health are debatable, the association between severe vitamin D deficiency and osteomalacia are clearly established. Since the 1st of July 2022, blood testing in individuals who do not meet the recognized risk factors for deficiency is no longer reimbursed in Switzerland. Being a migrant (or refugee) does not constitute a risk factor even though it has repeated been shown that this population is at high risk of deficiency, in particular sever deficiency. This article aims to establish new recommendations for vitamin D deficiency diagnosis and substitution for this population. It is sometimes necessary to adapt our national recommendations to take into account our cultural diversity.

Le déficit en vitamine D est un problème de santé publique au cœur de l'actualité. Si les répercussions sur la santé générale des patients sont débattues, l'association entre déficit sévère et ostéomalacie est clairement établie. En Suisse, depuis le 1er juillet 2022, l'assurance obligatoire de soins ne rembourse plus son dosage sanguin, sauf si le patient présente des facteurs de risque avérés. Le fait d'être migrant (ou réfugié) n'est pas considéré comme l'un d'eux. Pourtant, plusieurs études attestent que cette population est à haut risque de déficit, notamment sévère. Cet article a pour but d'établir de nouvelles recommandations de dépistage et de substitution qui s'adaptent à cette population. Il est parfois nécessaire d'adapter les recommandations nationales pour prendre en compte la diversité culturelle populationnelle.

Mechanisms underlying the long-term and withdrawal effects of denosumab therapy on bone.

Denosumab, a human monoclonal antibody against receptor activator of nuclear factor-κB ligand (RANKL), is a potent inhibitor of osteoclast differentiation and activity. As the first biologic drug used to treat osteoporosis, denosumab has shown potent anti-resorptive properties and anti-fracture efficacy. The effects of this drug are also unique compared with the effects of bisphosphonates: namely, long-term treatment with this drug results in a continuous gain of bone mineral density, whereas withdrawal of the drug results in a transient overshoot in bone turnover and rapid bone loss. Although the mechanisms for these specific effects remain incompletely understood, emerging experimental and clinical data have started to highlight potential biological and pharmacological mechanisms by which denosumab might affect osteoclasts, as well as osteoblasts, and cause both sustained bone gain and bone loss upon treatment cessation. This Perspective discusses those potential mechanisms and the future studies and clinical implications that might ensue from these findings.

Time for Revival of Bone Biopsy with Histomorphometric Analysis in Chronic Kidney Disease (CKD): Moving from Skepticism to Pragmatism.

Bone Biopsy (BB) with histomorphometric analysis still represents the gold standard for the diagnosis and classification of different forms of renal osteodystrophy. Bone biopsy is the only technique able to provide comprehensive information on all bone parameters, measuring static and dynamic parameters of turnover, cortical and trabecular microarchitecture, and mineralization defects. In nephrological practice, bone biopsy yields relevant indications to support therapeutic choices in CKD, heavily impacting the management and prognosis of uremic patients. Unfortunately, the use of bone biopsy has decreased; a lack of expertise in performing and interpreting, perceived procedure invasiveness and pain, and reimbursement issues have all contributed to this decline. Nevertheless, both bone biomarkers and instrumental images cannot be considered reliable surrogates for histological findings, being insufficiently accurate to properly evaluate underlying mineral and bone disorders. This is a multidisciplinary position paper from the Nephrology and Osteoporosis Italian Scientific Societies with the purpose of restating the role of bone biopsy in CKD patient management and of providing strong solutions to allow diffusion of this technique in Italy, but potentially also in other countries. The Italian approach through the optimization and standardization of bone biopsy procedure, the construction of the Italian Hub and Spoke network, and a request for adjustment and national homogenization of reimbursement to the Italian Health Ministry has led the way to implement bone biopsy and to improve CKD patient management and prognosis.

Pumping the Periosteum: A Feasibility Study.

PURPOSE: Gradual elevation of periosteum from the bone surface is known to promote the adaptation of soft tissues and the formation of hard tissues. The aim of our study was to estimate the benefit of periosteal distraction osteogenesis (PDO) on de novo bone formation in a rat model. MATERIALS AND METHODS: After device placement, animals were allowed for a latency period of 7 days. Animals in the PDO group were subjected to distraction at a rate of 0.1 mm/d for 10 days. In the periosteal pumping (PP) group, the animals were subjected to distraction at a rate of 0.1 mm/d. The direction of distraction was alternated every 2 days. The animals were euthanized at 17, 31, and 45 days after surgery, and the samples were analyzed histologically and by microcomputed tomography. RESULTS: In both groups, the new bone was characterized as primary woven bone that was located at the leading edge of bone apposition. Bone volumes significantly increased throughout the observation period both in the PP group ( P = 0.018) and in the PDO group ( P < 0.001). The new bone was denser and more mature in the PP group than in the PDO group, and the difference was significant at the 31-day time point ( P = 0.024). However, the volume of the new bone was higher in the PDO at the 45-day time point ( P < 0.001). CONCLUSIONS: We propose that the PP may be applied to enhance the osteogenic capacity of periosteum without plate elevation. Because this is only a proof-of-principle study, the alternated protocol of periosteal distraction warrants evaluation in the future studies.

Denosumab in the Treatment of Osteoporosis: 10 Years Later: A Narrative Review.

The fully human monoclonal antibody denosumab was approved for treatment of osteoporosis in 2010 on the basis of its potent antiresorptive activity, which produces clinically meaningful increases in bone mineral density (BMD) and reduces fracture risk at key skeletal sites. At that time, questions remained regarding the long-term safety and efficacy of this receptor activator of nuclear factor kappa-B ligand (RANKL) inhibitor; and with clinical experience, new questions have arisen regarding its optimal use. Here, we examine these questions through the lens of data from the FREEDOM trial program and other studies to determine where denosumab fits in the osteoporosis treatment landscape. Clinical consensus and evidentiary support have grown for denosumab as a highly effective anti-osteoporosis therapy for patients at high risk of fracture. In the 10-year FREEDOM Extension study, denosumab treatment produced progressive incremental increases in BMD, sustained low rates of vertebral fracture, and further reduction in nonvertebral fracture risk without increased risk of infection, cancer, or immunogenicity. There was no evidence that suppression of bone turnover or mineralization was excessive, and rates of osteonecrosis of the jaw (ONJ) and atypical femoral fracture (AFF) were very low. It is now recognized, however, that transitioning to another anti-osteoporosis therapy after denosumab discontinuation is essential to mitigate a transient rebound of bone turnover causing rapid BMD loss and increased risk of multiple vertebral fractures (MVFs). Taken together, the available data show that denosumab has a favorable benefit/risk profile and is a versatile agent for preventing osteoporotic fractures in the short and long term. Video abstract: Denosumab in the Treatment of Osteoporosis-10 Years Later (MP4 62727 KB).

Primary mouse osteoblast and osteoclast culturing and analysis.

Mesenchymal-derived osteoblasts play a key role in bone formation via synthesis and mineralization of the bone and bone remodeling. Osteoclasts are multinucleated cells of hematopoietic origin with a role in bone resorption. Here, we describe a protocol for generating primary cultures of these two cell types from bone tissue including the femur, tibia, and humerus of young mice. We describe methods for addressing their activity and/or differentiation, enabling studying the effects of various treatments during or following differentiation ex vivo. For further practical example of using these protocols, please refer to Chevalier et al. (2020).

Hand grip strength and early mortality after hip fracture.

This research describes the risk of death in elderly after hip fracture according to their strength, measured by hand grip. The result is that the weaker the patient, the greater the risk of death after hip fracture, highlighting the need to assess the force in those patients. For the coming years, most of hip fractures will occur in developing countries. It has been described that low muscular strength, measured by grip strength, increases the risk of mortality in those with hip fracture, in both high-and low- income countries. The objective of this study was to determine the mortality among patients with hip fracture and lower hand grip strength (HGS). MATERIAL AND METHODS: We conducted a cohort and longitudinal study at Hip and Pelvic Surgery Department of a tertiary hospital, in Monterrey, Mexico. The study included patients aged over of 69, admitted for hip fracture surgery from February 1st 2013 to July 31st 2014. HGS measurement was performed by a trained physician at arrival to emergency department prior to surgery; clinimetric variables were asked, and a complete medical history was included. RESULTS: A total of 670 patients were included in the study and grouped in different tertiles according to hand grip strength. During follow-up, there were 112 deaths (17.4%), 61 (27.5%) in tertile 1, 37 (17.1%) in tertile 2, and 14 (6.8%) in tertile 3, p < 0.001. The association remained significant after adjusting for confounding variables. Less than 5% of patients discharged from hospital were identified with osteoporosis. CONCLUSION: Lower hand grip strength in patients with a hip fracture is associated with high mortality after hip fracture.

Osteoporosis in Premenopausal Women: A Clinical Narrative Review by the ECTS and the IOF.

CONTEXT: Consensus regarding diagnosis and management of osteoporosis in premenopausal women (PW) is still lacking due to few studies carried out in this population. DESIGN: The European Calcified Tissue Society and the International Osteoporosis Foundation convened a working group to produce an updated review of literature published after 2017 on this topic. RESULTS: Fragility fractures in PW are rare and mostly due to secondary osteoporosis (ie, in presence of an underlying disease such as hormonal, inflammatory, or digestive disorders). In absence of another disorder, low bone mineral density (BMD) together with fragility fractures qualifies as idiopathic osteoporosis. In contrast, low BMD alone does not necessarily represent osteoporosis in absence of bone microarchitectural abnormalities. BMD increases in PW with osteoporosis when the underlying disease is treated. For example, in celiac disease, an increase of 9% in radius trabecular volumetric density was achieved after 1 year of gluten-free diet, while anti-tumor necrosis factor alpha improved BMD in PW with inflammatory bowel diseases. In amenorrhea, including anorexia nervosa, appropriately delivered estrogen replacement therapy can also improve BMD. Alternatively, antiresorptive or anabolic therapy has been shown to improve BMD in a variety of conditions, the range of improvement (3%-16%) depending on skeletal site and the nature of the secondary cause. No studies were powered to demonstrate fracture reduction. The effects of bisphosphonates in childbearing women have been scantly studied and caution is needed. CONCLUSION: The majority of PW with osteoporosis have an underlying disease. Specific therapy of these diseases, as well as antiresorptive and anabolic drugs, improve BMD, but without evidence of fracture reduction.

RANKL inhibition improves muscle strength and insulin sensitivity and restores bone mass.

Receptor activator of Nfkb ligand (RANKL) activates, while osteoprotegerin (OPG) inhibits, osteoclastogenesis. In turn a neutralizing Ab against RANKL, denosumab improves bone strength in osteoporosis. OPG also improves muscle strength in mouse models of Duchenne's muscular dystrophy (mdx) and denervation-induce atrophy, but its role and mechanisms of action on muscle weakness in other conditions remains to be investigated. We investigated the effects of RANKL inhibitors on muscle in osteoporotic women and mice that either overexpress RANKL (HuRANKL-Tg+), or lack Pparb and concomitantly develop sarcopenia (Pparb-/-). In women, denosumab over 3 years improved appendicular lean mass and handgrip strength compared to no treatment, whereas bisphosphonate did not. HuRANKL-Tg+ mice displayed lower limb force and maximal speed, while their leg muscle mass was diminished, with a lower number of type I and II fibers. Both OPG and denosumab increased limb force proportionally to the increase in muscle mass. They markedly improved muscle insulin sensitivity and glucose uptake, and decrease anti-myogenic and inflammatory gene expression in muscle, such as myostatin and protein tyrosine phosphatase receptor-γ. Similarly, in Pparb-/-, OPG increased muscle volume and force, while also normalizing their insulin signaling and higher expression of inflammatory genes in skeletal muscle. In conclusions, RANKL deteriorates, while its inhibitor improves, muscle strength and insulin sensitivity in osteoporotic mice and humans. Hence denosumab could represent a novel therapeutic approach for sarcopenia.

[Osteoporosis in patients with chronic renal failure : evaluation and management ? Role of bone biopsy]. / Ostéoporose chez l'insuffisant rénal : quelle évaluation et quel traitement ? Place de la biopsie osseuse.

The management of osteoporosis in patients with mild to moderate chronic kidney disease (CKD) can be established as in general population. In severe or terminal CKD, bone densitometry is indicated. Bone-specific alkaline phosphatase is considered a useful marker for distinguishing among the histologic types of renal osteodystrophy. In ambiguous cases, bone biopsy together with quantitative histomorphometry will be necessary. As far as the treatment is concerned, the bisphosphonates, which had been avoided due to their renal excretion as well as the official warnings against using them in case of renal clearance lower than 30 ml/min, seem to be effective even in advanced stages of renal disease. There are limited data, though, regarding the management of osteoporosis in terminal stages of CKD.

La prise en charge des patients en insuffisance rénale légère à modérée peut être calquée sur celle de la population générale. En cas d'insuffisance rénale sévère ou terminale, la densitométrie osseuse reste indiquée. Le type d'ostéodystrophie rénale sera présumé à partir du niveau de phosphatase alcaline osseuse. Dans les cas équivoques, une biopsie osseuse avec histomorphométrie quantitative sera nécessaire. Quant au traitement, les bisphosphonates, longtemps mis à l'écart vu leur élimination rénale et la contre-indication de principe existant pour la plupart d'entre eux pour des niveaux de clairance inférieure à 30 ml/min, sont efficaces même à des stades avancés de l'insuffisance rénale. La prise en charge de l'ostéoporose chez l'insuffisant rénal terminal reste encore un domaine avec des données limitées.

The C-Terminal Intact Forms of Periostin (iPTN) Are Surrogate Markers for Osteolytic Lesions in Experimental Breast Cancer Bone Metastasis.

Periostin is an extracellular matrix protein that actively contributes to tumor progression and metastasis. Here, we hypothesized that it could be a marker of bone metastasis formation. To address this question, we used two polyclonal antibodies directed against the whole molecule or its C-terminal domain to explore the expression of intact and truncated forms of periostin in the serum and tissues (lung, heart, bone) of wild-type and periostin-deficient mice. In normal bones, periostin was expressed in the periosteum and specific periostin proteolytic fragments were found in bones, but not in soft tissues. In animals bearing osteolytic lesions caused by 4T1 cells, C-terminal intact periostin (iPTN) expression disappeared at the invasive front of skeletal tumors where bone-resorbing osteoclasts were present. In vitro, we found that periostin was a substrate for osteoclast-derived cathepsin K, generating proteolytic fragments that were not recognized by anti-periostin antibodies directed against iPTN. In vivo, using an in-house sandwich immunoassay aimed at detecting iPTN only, we observed a noticeable reduction of serum periostin levels (- 26%; P < 0.002) in animals bearing osteolytic lesions caused by 4T1 cells. On the contrary, this decrease was not observed in women with breast cancer and bone metastases when periostin was measured with a human assay detecting total periostin. Collectively, these data showed that mouse periostin was degraded at the bone metastatic sites, potentially by cathepsin K, and that the specific measurement of iPTN in serum should assist in detecting bone metastasis formation in breast cancer.

Osteoporosis drug treatment: duration and management after discontinuation. A position statement from the SVGO/ASCO.

Antiosteoporotic drugs are recommended in patients with fragility fractures and in patients considered to be at high fracture risk on the basis of clinical risk factors and/or low bone mineral density. As first-line treatment most patients are started with an antiresorptive treatment, i.e. drugs that inhibit osteoclast development and/or function (bisphosphonates, denosumab, oestrogens or selective oestrogen receptor modulators). In the balance between benefits and risks of antiresorptive treatment, uncertainties remain regarding the optimal treatment duration and the management of patients after drug discontinuation. Based on the available evidence, this position statement will focus on the long-term management of osteoporosis therapy, formulating decision criteria for clinical practice.

[To where and until when handle the osteoporosis?] / Jusqu'où et jusqu'à quand traiter l'ostéoporose ?

Estrogen replacement therapy, selective modulators of the estrogen receptor (SERMs), bisphophonates and denosumab are antiresorptive therapies which can be used for several years. Teriparatide is still the only bone forming agent available, its use is limited to 24 months. Except the absence of new fragility fractures, there is no well defined target in the treatment of osteoporosis. Nevertheless persistence of high fracture risk (prevalent fractures and/or low BMD) on therapy indicates to maintain or intensify the treatment. On the contrary, if fracture risk is low, a « therapeutic window ¼ could be considered after treatment with bisphosphonates, whereas after denosumab a short course of another treatment may be necessary.

L'œstrogénothérapie substitutive, les modulateurs sélectifs du récepteur aux œstrogènes (SERM), les bisphosphonates et le dénosumab sont des inhibiteurs de la résorption osseuse qui peuvent être utilisés plusieurs années. Le tériparatide est le seul traitement ostéoformateur et son utilisation est limitée à 24 mois. Hormis l'absence de nouvelles fractures de fragilité, il n'y a pas de cible thérapeutique définie dans le traitement de l'ostéoporose. Néanmoins, la persistance sous traitement d'un haut risque de fracture (fractures prévalentes et/ou ostéodensitométrie basse), est une indication à poursuivre, voire intensifier la thérapie. Si le risque de fracture est bas, au contraire, une « fenêtre thérapeutique ¼ est envisagée pour les traitements dont la durée d'action est plus longue que leur période d'administration (bisphosphonates). Pour le dénosumab, un relais thérapeutique de courte durée est nécessaire.

Prepubertal Impact of Protein Intake and Physical Activity on Weight-Bearing Peak Bone Mass and Strength in Males.

Context: Peak bone mass (PBM) and strength are important determinants of fracture risk in later life. During growth, bone is responsive to changes in nutrition and physical activity (PA), particularly before pubertal maturation. Objective: In prepubertal healthy boys, protein intake (Prot-Int) enhances the impact of PA on weight-bearing bone. We hypothesized that the synergism between Prot-Int and PA on proximal femur as recorded at 7.4 years would track until PBM. Methods: A total of 124 boys were followed from 7.4 to 15.2 and 22.6 years. At 7.4 years, they were dichotomized according to the median of both PA and Prot-Int. Results: In boys with PA greater than the median (310 vs 169 kcal ⋅ d-1), higher vs low Prot-Int (57.7 vs 38.0 g ⋅ d-1) was associated with +9.8% greater femoral neck (FN) bone mineral content (BMC) (P = 0.027) at 7.4 years. At 15.2 and 22.6 years, this difference was maintained: FN BMC: +12.7% (P = 0.012) and +11.3% (P = 0.016), respectively. With PA greater than the median, in Prot-Int greater than vs less than the median, differences in FN BMC z scores were +0.60, +0.70, and +0.68 at 7.4, 15.2, and 22.6 years, respectively. Microfinite element analysis of distal tibia at 15.2 and 22.6 years indicated that in the 2 groups with PA greater than the median, cross-sectional area, stiffness, and failure load were greater in Prot-Int greater than vs less than the median. Conclusions: This study demonstrates the crucial influence of Prot-Int on the response to enhanced PA and the importance of prepubertal years for modifying the bone growth trajectory and, thereby, for achieving higher PBM and greater strength in healthy male participants.

Unmet needs and current and future approaches for osteoporotic patients at high risk of hip fracture.

This review provides a critical analysis of currently available approaches to increase bone mass, structure and strength through drug therapy and of possible direct intra-osseous interventions for the management of patients at imminent risk of hip fracture. PURPOSE: Osteoporotic hip fractures represent a particularly high burden in morbidity-, mortality- and health care-related costs. There are challenges and unmet needs in the early prevention of hip fractures, opening the perspective of new developments for the management of osteoporotic patients at imminent and/or at very high risk of hip fracture. Amongst them, preventive surgical intervention needs to be considered. METHODS: A European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO)/International Osteoporosis Foundation (IOF) working group reviewed the presently available intervention modalities including preventive surgical options for hip fragility. This paper represents a summary of the discussions. RESULTS: Prevention of hip fracture is currently based on regular physical activity; prevention of falls; correction of nutritional deficiencies, including vitamin D repletion; and pharmacological intervention. However, efficacy of these various measures to reduce hip fractures is at most 50% and may need months or years before becoming effective. To face the challenges of early prevention of hip fractures for osteoporotic patients at imminent and/or at very high risk of hip fracture, preventive surgical intervention needs further investigation. CONCLUSION: Preventive surgical intervention needs to be appraised for osteoporotic patients at imminent and/or at very high risk of hip fracture.

Romosozumab Treatment in Postmenopausal Women with Osteoporosis.

BACKGROUND: Romosozumab, a monoclonal antibody that binds sclerostin, increases bone formation and decreases bone resorption. METHODS: We enrolled 7180 postmenopausal women who had a T score of -2.5 to -3.5 at the total hip or femoral neck. Patients were randomly assigned to receive subcutaneous injections of romosozumab (at a dose of 210 mg) or placebo monthly for 12 months; thereafter, patients in each group received denosumab for 12 months, at a dose of 60 mg, administered subcutaneously every 6 months. The coprimary end points were the cumulative incidences of new vertebral fractures at 12 months and 24 months. Secondary end points included clinical (a composite of nonvertebral and symptomatic vertebral) and nonvertebral fractures. RESULTS: At 12 months, new vertebral fractures had occurred in 16 of 3321 patients (0.5%) in the romosozumab group, as compared with 59 of 3322 (1.8%) in the placebo group (representing a 73% lower risk with romosozumab; P<0.001). Clinical fractures had occurred in 58 of 3589 patients (1.6%) in the romosozumab group, as compared with 90 of 3591 (2.5%) in the placebo group (a 36% lower risk with romosozumab; P=0.008). Nonvertebral fractures had occurred in 56 of 3589 patients (1.6%) in the romosozumab group and in 75 of 3591 (2.1%) in the placebo group (P=0.10). At 24 months, the rates of vertebral fractures were significantly lower in the romosozumab group than in the placebo group after each group made the transition to denosumab (0.6% [21 of 3325 patients] in the romosozumab group vs. 2.5% [84 of 3327] in the placebo group, a 75% lower risk with romosozumab; P<0.001). Adverse events, including instances of hyperostosis, cardiovascular events, osteoarthritis, and cancer, appeared to be balanced between the groups. One atypical femoral fracture and two cases of osteonecrosis of the jaw were observed in the romosozumab group. CONCLUSIONS: In postmenopausal women with osteoporosis, romosozumab was associated with a lower risk of vertebral fracture than placebo at 12 months and, after the transition to denosumab, at 24 months. The lower risk of clinical fracture that was seen with romosozumab was evident at 1 year. (Funded by Amgen and UCB Pharma; FRAME ClinicalTrials.gov number, NCT01575834 .).