Periprosthetic bone loss: diagnostic and therapeutic approaches.

Total joint replacement surgery is being performed on an increasingly large part of the population. Clinical longevity of implants depends on their osseointegration, which is influenced by the load, the characteristics of the implant and the bone-implant interface, as well as by the quality and quantity of the surrounding bone. Aseptic loosening due to periprosthetic osteolysis is the most frequent known cause of implant failure. Wear of prosthetic materials results in the formation of numerous particles of debris that cause a complex biological response. Dual-energy X-ray Absorptiometry (DXA) is regarded as an accurate method to evaluate Bone Mineral Density (BMD) around hip or knee prostheses. Further data may be provided by a new device, the Bone Microarchitecture Analysis (BMA), which combines bone microarchitecture quantification and ultra high resolution osteo-articular imaging. Pharmacological strategies have been developed to prevent bone mass loss and to extend implant survival. Numerous trials with bisphosphonates show a protective effect on periprosthetic bone mass, up to 72 months after arthroplasty. Strontium ranelate has been demonstrated to increase the osseointegration of titanium implants in treated animals with improvement of bone microarchitecture and bone biomaterial properties

Targeted approaches in the treatment of osteoporosis: differential mechanism of action of denosumab and clinical utility

Denosumab is a breakthrough biological drug approved by the Food and Drug Administration and European Medicines Agency for the treatment of osteoporosis in 2010. It is a fully human monoclonal antireceptor activator of nuclear factor kappa-B ligand antibody, which inhibits the activity of osteoclasts, resulting in an antiresorptive effect with a significant increase in bone mineral density. The FREEDOM (Fracture Reduction Evaluation of Denosumab in Osteoporosis every 6 Months) trial, comparing denosumab with no treatment in 7868 women with postmenopausal osteoporosis, showed an important reduction of fracture risk at hip, vertebral, and nonvertebral sites in the treated group, while no statistically significant difference in the incidence of adverse events was detected between denosumab and placebo groups. The specific action of denosumab directed against a key regulator of osteoclasts makes it a valuable tool in preventing the occurrence of skeletal events caused by bone destruction in patients with advanced malignancies. The drug was approved for postmenopausal osteoporosis in women at increased risk of fracture and for the treatment of bone loss associated with androgen deprivation therapy in men with prostate cancer

Peripheral quantitative computed tomography (pQCT) for the assessment of bone strength in most of bone affecting conditions in developmental age: a review.

Peripheral quantitative computed tomography provides an automatical scan analysis of trabecular and cortical bone compartments, calculating not only their bone mineral density (BMD), but also bone geometrical parameters, such as marrow and cortical Cross-Sectional Area (CSA), Cortical Thickness (CoTh), both periosteal and endosteal circumference, as well as biomechanical parameters like Cross-Sectional Moment of Inertia (CSMI), a measure of bending, polar moment of inertia, indicating bone strength in torsion, and Strength Strain Index (SSI). Also CSA of muscle and fat can be extracted. Muscles, which are thought to stimulate bones to adapt their geometry and mineral content, are determinant to preserve or increase bone strength; thus, pQCT provides an evaluation of the functional ‘muscle-bone unit’, defined as BMC/muscle CSA ratio. This functional approach to bone densitometry can establish if bone strength is normally adapted to the muscle force, and if muscle force is adequate for body size, providing more detailed insights to targeted strategies for the prevention and treatment of bone fragility. The present paper offers an extensive review of technical features of pQCT and its possible clinical application in the diagnostic of bone status as well as in the monitoring of the skeleton’s health follow-up

Pharmacogenetics of bisphosphonate-associated osteonecrosis of the jaw.

An undesirable effect associated with bisphosphonates is osteonecrosis of the jaw (ONJ). Case reports discussed ONJ development in patients with multiple myeloma or metastatic cancers receiving bisphosphonates as palliation for malignant bone disease. No causative relationship has been unequivocally demonstrated between ONJ and bisphosphonate therapy. To determine if a higher sensitivity to bisphosphonates could in part explain the development of ONJ, the segregation of A/C rs2297480 polymorphism of gene encoding for the farnesyl pyrophosphate synthase (FDPS) with ONJ was evaluated in a cohort of 68 Caucasian patients treated with zoledronic acid for multiple myeloma and metastatic mammary and prostate cancer. The AA and CC genotypes were highly differently distributed among ONJ patients and controls, matched for sex and type of malignant disease, with a positive correlation between AA carrier status and occurrence of ONJ (p=0.03) after 18-24 months of treatment. Because FDPS gene variants have been associated with bone morbidity, these pharmacogenetic association likely reflect the interaction of amino-bisphosphonates with germline sensitivity to drug actions, and might identify patients at highest risk to develop ONJ

The ever-expanding conundrum of primary osteoporosis: aetiopathogenesis, diagnosis, and treatment.

In recent years, as knowledge regarding the etiopathogenetic mechanisms of bone involvement characterizing many diseases has increased and diagnostic techniques evaluating bone health have progressively improved, the problem of low bone mass/quality in children and adolescents has attracted more and more attention, and the body evidence that there are groups of children who may be at risk of osteoporosis has grown. This interest is linked to an increased understanding that a higher peak bone mass (PBM) may be one of the most important determinants affecting the age of onset of osteoporosis in adulthood. This review provides an updated picture of bone pathophysiology and characteristics in children and adolescents with paediatric osteoporosis, taking into account the major causes of primary osteoporosis (PO) and evaluating the major aspects of bone densitometry in these patients. Finally, some options for the treatment of PO will be briefly discussed

Prevalence of osteoporosis in the Italian population and main risk factors: results of BoneTour Campaign.

BACKGROUND: BoneTour is a campaign conducted throughout the Italian territory for the assessment of Italian people bone status and for the prevention of osteoporosis. METHODS: A total of 7305 sequential subjects of both sexes were screened, collecting clinical data through the FRAX™ questionnaire, and measuring heel bone stiffness by Quantitative Ultrasonography (QUS). The 10-year risk for hip and major osteoporotic fractures was calculated taking into account personal or family history of fragility fracture, smoking, alcohol abuse, rheumatoid arthritis, prolonged steroids assumption. Additional risk factors were evaluated, including early menopause, poor sunlight exposure, low dietary calcium intake, physical inactivity, number of pregnancies, months of lactation, tobacco cigarettes smoked per year, specific causes of secondary osteoporosis. Through a correlation study, the influence of each factor on the development of osteoporosis was analyzed. RESULTS: As many as 18 % of women suffer from osteoporosis, as defined by QUS T-score. The calculation of FRAX™ confirmed the weight of the already known risk factors. The correlation study revealed the significance of some additional factors, such as hyperthyroidism, nephrolithiasis, Crohn disease, ulcerative colitis, celiac disease, poor sun exposure, and oophorectomy before age 50. CONCLUSIONS: The high prevalence of secondary osteoporosis in the Italian population clearly indicates the importance of additional risk factors not yet included in the FRAX™ algorithm, for which preventive measures should be considered. Screening campaigns may allow both early diagnosis and access to treatment

Bone mass and quality in patients with juvenile idiopathic arthritis: longitudinal evaluation of bone mass determinants using dual energy X-ray absorptiometry, peripheral quantitative computed tomography, and quantitative ultrasonography.

INTRODUCTION: Our objective was to evaluate longitudinally the main bone-mass and quality predictors in young juvenile idiopathic arthritis (JIA) patients by using lumbar spine dual-energy X-ray absorptiometry (DXA) scan, radius peripheral quantitative computed tomography (pQCT), and phalangeal quantitative ultrasonography (QUS) at the same time. METHODS: In total, 245 patients (172 females, 73 males; median age, 15.6 years: 148 oligoarticular, 55 polyarticular, 20 systemic, and 22 enthesitis-related-arthritis (ERA) onset) entered the study. Of these, 166 patients were evaluated longitudinally. Data were compared with two age- and sex-matched control groups. RESULTS: In comparison with controls, JIA patients, but not with ERA, had a reduced spine bone-mineral apparent density (BMAD) standard deviation score (P < 0.001) and musculoskeletal deficits, with significantly lower levels of trabecular bone mineral density (TrabBMD) (P < 0.0001), muscle cross-sectional area (CSA) (P < 0.005), and density-weighted polar section modulus (SSIp) (P < 0.05). In contrast, JIA showed fat CSA significantly higher than controls (P < 0.0001). Finally, JIA patients had a significant reduced amplitude-dependent speed of sound (AD-SoS) (P < 0.001), and QUS z score (P < 0.005). Longitudinally, we did not find any difference in all JIA patients in comparison with baseline, except for the SSIp value that normalized. Analyzing the treatments, a significant negative correlation among spine BMAD values, TrabBMD, AD-SoS, and systemic and/or intraarticular corticosteroids, and a positive correlation among TNF-α-blocking agents and spine BMAD, TrabBMD, and AD-SoS were observed. CONCLUSIONS: JIA patients have a low bone mass that, after a first increase due to the therapy, does not reach the normal condition over time. The pronounced bone deficits in JIA are greater than would be expected because of reduction in muscle cross-sectional area. Thus, bone alterations in JIA likely represent a mixed defect of bone accrual and lower muscle forces

Increased phospho-mTOR expression in megakaryocytic cells derived from CD34+ progenitors of essential thrombocythaemia and myelofibrosis patients

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