Bone Loss

Decreased bone mineral density (BMD) in astronauts returning from long-duration spaceflight missions has been well documented, but the altered mechanical loading environment experienced by the musculoskeletal system, which may contribute to these changes, has not been well characterized. The current study describes the loading environment of the lower extremity (LE) during typical days on the International Space Station (ISS) compared to similar data for the same individuals living on Earth. Data from in-shoe force measurements are also used as input to the enhanced daily load stimulus (EDLS) model to determine the mechanical ''dose'' experienced by the musculoskeletal system and to associate this dose with changes in BMD.

Plaque-induced lesions can produce peri-implant bone loss with ultimate implant loss. Although the peri-implant tissues seem to be more resistant than the periodontal ones to plaque and calculus, they can produce a more extensive spread of the infection to the deeper tissues around implants. The case of a 45year-old female patient is presented in which, over a three year period, there was a progressive loss of peri-implant bone and the formation of a periapical radiolucency with an external fistula. The implant was removed and examined with the cutting-grinding system. Microscopy examination showed that most of the hydroxyapatite (HA) was still adherent to the metal. There was a detachment in the area of the HA-titanium interface. The implant surface was almost completely covered by bacteria. Bacteria were also present in the bone medullary spaces surrounding the implant. The infection of the periodontal tissues had progressed into the alveolar bone, thus producing a localized bone infection. The cause of the implant failure is probably related to a defective connection of the abutment or to overloading of the implant due to the presence of interlocks in the prosthetic restoration.

We report the case of a 24 year-old patient who underwent a novel treatment for a lateral femoral condyle fracture. The fracture was associated with extensive joint line depression and not considered suitable for conventional fixation techniques. Existing reconstructive options for such situations include unicondylar osteoarticular allograft, arthrodesis and arthroplasty. However, these techniques all present significant disadvantages, particularly in the management of active patients. We report our medium-term results following reconstruction using a custom-made lateral femoral condyle hemiarthroplasty replacement. Follow-up at 48 months revealed an excellent, pain-free level of function, with an Oxford Knee Score of 46/ 48, a Knee Society knee score of 87/100 and a functional score of 100/100. Radiographs demonstrated no evidence of prosthesis loosening or migration and no erosion of the lateral tibial plateau. The technique allows preservation of the remaining normal joint surface of the femur that may promote earlier and better restoration of function. Furthermore, the isolated condyle hemi-replacement maximises bone preservation, facilitating future anticipated revisions. The procedure presents an attractive alternative to other surgical options and their attendant problems. Further investigation into this technique is required before widespread adoption, though such studies will be compromised by the relative rarity of patients in whom the technique is indicated.

The effects of Spinal Cord Injury (SCI) on bone in paralyzed areas are well documented but there are few data for the importance of the level of injury in the decrease of mechanical strength in paralyzed legs. The aim of the present study was to describe bone loss of the separate compartments of trabecular and cortical bone in spinal cord injured men and to compare possible changes in mechanical properties of tibia with the neurological level of injury. Fifty men were included in this study: 39 had complete SCI in chronic stage. As chronic stage, we considered paraplegia >1.5 years (yrs). Men were separated as follows: Group A (18 men, high paraplegia: Thoracic (T)4-T7 level, mean age: 33 yrs, duration of paralysis: 5.9 yrs) and group B (21 men, low paraplegia: T8-T12 level, mean age: 39 yrs, duration of paralysis: 5.6 yrs) in comparison with 11 healthy men as a control group (C) of similar age, height, and weight. None of the subjects was given bone acting drugs. The neurologica...

Objective: To evaluate the effect of premature ovarian failure on bone mineral density. Materials and methods: Forty-five women with karyotypically normal spontaneous premature ovarian failure underwent hip and spinal bone density measurements by dual energy Xray absorptiometry. Findings were compared with a control group of 61 women of similar age. Results: The median (range) age of the women with premature ovarian failure was 33 (18-39) years. The median (range) time since diagnosis of premature ovarian failure was 2 years (0.5-7). Forty-one of the women (91%) had sought medical advice previously and had taken a variety of estrogen and progestin replacement regimens at least intermittently. Both the femoral neck bone mineral density measurements and the spinal bone mineral density measurements were significantly lower than measurements of the control group (P<0.05). Conclusion: Our study shows that premature ovarian failure has significantly lower levels of bone mineral density than the control group of normal women. We suggest that hormone replacement therapy should be substituted early and consistently in affected patients. Our data also raise questions about whether preservation of bone mass in these patients will require replacement of additional gonadal steroids.

Osteoprotegerin (OPG, osteoclastogenesis inhibitory factor) is a secretory glycoprotein involved as a soluble factor in the regulation of bone mass. OPG and its ligand (RANKL) levels in serum indicate the osteoclast formation activity. Alterations of the RANKL/OPG concentration ratio may be the cause of bone loss in many imbalances including osteoporosis, hypercalcaemia, metastatic osteolytic lesions and rheumatic bone degradation. The interactions of OPG with several antibodies were studied using the piezoelectric quartz crystal sensor. Monoclonal anti-OPG antibodies (5H3, 4E6H9 and OPG1.3) were immobilised on the sensing surface modified with covalently attached monolayer of protein A. Binding of both OPG standard and recombinant OPGFc chimeric protein was followed in real time. All antibodies were able to bind OPG and OPGFc, though in the case of MAb 4E6H9 the immunocomplexes dissociated quickly in the absence of OPG. Alternatively, biorecognition layers with RANKL were used. Two versions of the piezoelectric sensor for OPG were developed. The direct immunosensor was based on the antibody 5H3 and the affinity sensor employed the immobilised RANKL. The RANKL sensor exhibited poor reproducibility of results. For the immunosensor, the measuring range was 1.2-35 U/L of OPG. One analysis was completed within 15 min; the sensors were used repeatedly using regeneration with glycine buffer (pH 2.0). The developed immunosensor seems promising for rapid determination of osteoprotegerin in serum.

Disuse induces rapid and severe bone loss in larger mammals as a result of greatly elevated osteoclastic resorption. In this study, we tested whether risedronate (RIS), a potent inhibitor of osteoclastic activity, would effectively prevent cancellous bone loss in female beagles (5 -7 years old, N = 28) subjected to single forelimb immobilization (IM) for 12 months. Age-matched, non-IM dogs served as controls (Con). Half the animals from each group received RIS 1 mg/kg p.o. daily (Con + RIS, IM + RIS). Remaining dogs received sterile water (Con, IM). Histomorphometry showed that IM caused a dramatic reduction in cancellous bone mass (À71%) of distal 2nd metacarpals, characterized by marked decreases in trabecular width (À51%) and number (À41%), and 4-fold increases in the indices of bone resorption (eroded surface, osteoclast number, and surface). Bone formation indices (calcein-labeled surface, osteoid surface, and bone formation rate) were also significantly higher in IM than in controls. Activation frequency in IM increased about 4-fold beyond control level. RIS treatment reduced, but did not abolish cancellous bone loss due to immobilization. IM animals treated with RIS lost nearly 50% of cancellous bone mass, while trabecular width and number were reduced by 31% and 25%, respectively. In both RIS-treated control and IM animals, overall bone formation parameters (mineralized bone surface fraction and bone formation rate) remained roughly at intact control levels; however, mineral apposition rate relative to intact control was reduced 40% in RIS-treated control and 86% in RIS-treated IM animals. These results indicate that high-dose RIS treatment might suppress osteoblastic function, especially under long-term disuse. Interestingly, bone resorption parameters in RIS-treated IM animals reached levels even higher than in vehicle-treated IM animals; values for eroded surface, osteoclast number, and surface were 84%, 53%, and 83% above vehicle-treated IM values, respectively. Our data indicate that risedronate treatment is partially effective in preventing cancellous bone loss during long-term disuse. Moreover, our results suggest that bisphosphonates can impair the ability of mature osteoclasts to resorb bone, but cannot overcome the strong stimulus for osteoclast recruitment caused by long-term disuse. D

The suitability of a mouse model for host response in the induction of alveolar bone loss by Porphyromonas gingiualis was explored. The mouths of immunocompetent and severe combined immunodeficient (SCID) mice were infected with P. gingivalis ATCC 53977. P. gingiualis was not isolated from the mouths of these mice before infection, but was present at least 42 days after infection. P.

In several studies on patients with rheumatoid arthritis, an association of bone loss with a persistently high disease activity has been found. The aim of our study was to investigate the relation between disease activity and serum levels of vitamin D metabolites, parathyroid hormone (PTH), and parameters of bone turnover in patients with rheumatoid arthritis. A total of 96 patients (83 women and 13 men) were divided into three groups according to disease activity measured by serum levels of C-reactive protein (CRP). In the whole group, serum levels of 1,25dihydroxyvitamin D3 (1,25(OH) 2 D 3 ) (P < 0.001) and PTH (P < 0.05) were negatively correlated to disease activity. The urinary excretion of collagen crosslinks-pyridinoline (Pyd) (P < 0.001) and deoxypyridinoline (Dpd) (P < 0.05)-showed a positive correlation with disease activity. The inverse correlation between serum 1,25(OH) 2 D 3 and disease activity was separately evident in patients with (P < 0.001) and without (P < 0.01) glucocorticoid treatment, in pre-(P < 0.01) and postmenopausal (P < 0.001) women, and in men (P < 0.01). 1,25(OH) 2 D 3 and PTH serum levels were positively correlated to serum bone alkaline phosphatase (ALP) (P < 0.01). The results indicate that high disease activity in patients with rheumatoid arthritis is associated with an alteration in vitamin D metabolism and increased bone resorption. The decrease of 1,25(OH) 2 D 3 levels in these patients may contribute to a negative calcium balance and inhibition of bone formation. Furthermore, low levels of 1,25(OH) 2 D 3 as an endogenous immunomodulator suppressing activated T cells and the proliferation of cells may accelerate the arthritic process in rheumatoid arthritis.

Physical exercise is recommended for the prevention and treatment of osteoporosis. However. its exact role and effectiveness in adulthood IS unclear. While vigorous exercise of long duration enhances bone density, few adult individuals comply with such training programs_ The present srudy evaluates the influence of nonphysiological mechanical stimulation. In the form of low intensity vibration (frequency: 50 Hz. accelerarton: 2 g. 30 min/day for 5 days/week). on the prevention of bone loss in an animal model of postmenopausal osteoporosis. In the ovariectomised groups of rats a statistically significant (p < 0.05) decrease of bone density (femur and tibia) was recorded at 5 weeks postovariecromy. This effect was maintained for the I2 week duration of the study Vibration prevented early bone loss after ovariectomy. Vibrared ovariectomised rats showed statistically significantly higher (p c 0.05) BMD values compared to those of their ovariectomised controls at 5 weeks. Vibration did not influence the bone density of the SHAM-operated rats. Although vibration increased ultimate strength (fracture load of the rat femur) in the ovariectomised rats. this finding was not statistically significant. Our data indicate that this method of safe and easily applicable vibration. in the form of a vibrating platform. is effective in preventing early postovariectomy bone loss in an animal model K e y w o r d s : Vibrationdensity -Strength.

Glucocorticoid-induced osteoporosis is the most frequent cause of sec- ondary osteoporosis. Glucocorticoids cause a rapid bone loss in the first few months of use, but the most important effect of the drug is suppres- sion of bone formation. The administration of oral glucocorticoid is asso- ciated with an increased risk of fractures at the spine and hip. The risk is

The purpose of this study was to evaluate the outcome of trabecular metal (TM) acetabular components used in revision hip arthroplasty with major bone deficiency. We retrospectively reviewed the records of 46 patients undergoing revision hip arthroplasty with severe acetabular bone loss. Clinical outcomes were assessed using Harris Hip Score, Western Ontario and McMaster Universities, and Short-Form 12. Mean follow-up was 50 months. All patients had Paprosky type IIc or III acetabular bone deficiency. Major complications included 1 infection, 2 dislocations, and 1 arterial bleeding. Average Harris Hip Score was 78.2. Short-Form 12 scores were within population-based age-matched averages. Western Ontario and McMaster Universities scores were mainly in the 2 lowest disability categories. Porous tantalum shows promising results in revision arthroplasty with severe acetabular bone loss.

Vitamin K2 may preserve bone strength and reduce fracture risk. In this randomised double-blind placebo-controlled trial among healthy postmenopausal Norwegian women, 1 year supplementation of vitamin K2 in the form of Natto capsules had no effect on bone loss rates. Introduction Japanese studies indicate that vitamin K2 (menaquinone-7 (MK-7)) intake may preserve bone strength, but this has not been documented in Europeans. The aim of this study was to assess the effect of MK-7 on bone mineral density (BMD) changes in postmenopausal Norwegian women.

Chemotherapy for breast cancer causes early-onset menopause for most women older than age 40 and is associated with accelerated bone loss. The primary objective of this study was to compare the effects of intravenous (IV) zoledronic acid versus prescribed physical activity (PA) on changes in bone mineral density (BMD) for women between the ages of 40 and 55 years receiving chemotherapy for breast cancer. A randomized controlled trial of 62 patients with breast cancer during chemotherapy compared IV zoledronic acid and oral calcium/vitamin D (ZO group) versus a PA program and oral calcium/vitamin D (PA group). ZO group participants received zoledronic acid IV every 3 months for 5 treatments. PA group participants were enrolled in a home-based exercise program and received motivational counseling, pedometers, and exercise tapes. BMD measurements from dual-energy x-ray absorptiometry (DEXA) scanning were completed at baseline and at 12 months. BMD significantly decreased in the PA grou...

This paper investigates the process of diagenesis in mammal, bird and fish bone after burial of fresh and freshly cooked specimens in selected soil types for 7 years. Almost all soft tissue had disappeared, but fur, feathers and hoof survived in acidic soil. Examination revealed that the rate of bone loss and modification could not be simply related to soil pH and/or inferred Eh; very different bone preservation occurred in geographically adjacent soils of similar pH and drainage. Bone modification also varied greatly between animals of similar size, with bird bone appearing to be particularly resilient. The state of the remains prior to burial was critically important. While boiling clearly accelerated diagenesis, other forms of cooking did not appear to have this effect. The role of micro-organisms in the degradation process is addressed. It is suggested that routine methods of bone quantification may be inappropriate for such diagenetically altered assemblages.

Glenoid wear following shoulder hemiarthroplasty (HA) has been reported around 80% in long-term follow-up studies. Radiographic analysis is useful to depict glenoid erosion but does not evaluate accurately glenoid bone loss. Multichannel computed tomography (MCCT) allows scanning with submillimeter section thickness through dense areas of glenoid bone, despite the presence of metallic prostheses. In this preliminary study, we performed a MCCT analysis of glenoid erosion, in 15 patients with painful shoulder HA, at an average follow-up of 5.5 years. Clinical scores were retrospectively assessed at an early (1 year), medium (2.5 years), and late (5.5 years) follow-up. We analyzed the following glenoid features: articular line space (ALS), glenoid length (bone stock), glenoid version, morphology of erosion (concentric, superior ed inferior tilt), and gross bone defects. Glenoid was retroversed in 13 patients (minimum 0°maximum 8°), antiversed in 2 patients (2°and 6°). Erosion was described as concentric in 13 patients, eccentric (''superior tilt'') in 1 patient, biconcave in another patient. The mean glenoid length was 19.7 mm (min 16.4 max 22.7). Gross bone defects were described in six patients. The scores registered at latest follow-up showed a significant decrease compared with the values at 1 year (P \ 0.001) and at 2.5 years (P \ 0.001). The patients with glenoid erosion associated with gross defects and ALS B1.2 mm had lower scores for pain and lower scores for ROM (P \ 0.01). Multidetector CT analysis establishes a new frontier in the postoperative management of shoulder arthroplasty, and its application in the glenoid analysis offers a significant contribution for the following reasons: qualitative and quantitative glenoid features are better seen because volume-rendering eliminates most streak artifacts and produces high-quality images; spatial information relative to the prosthetic devices and the relationship among hardware and bone can be better demonstrated; allows an accurate preoperative planning prior to starting with revision surgery.

Osteoporosis (OP) is a well documented complication of some rheumatic diseases. Rheumatoid arthritis (RA) represents the paradigm of bone loss which occurs both locally (iuxta-articular OP and bone erosions) and systemically (generalized osteoporosis and fractures). Both local and systemic bone loss in RA are mainly due to an imbalance in the RANKL/OPG ratio produced by pro-inflammatory cytokines. There is sub- stantial evidence that bone loss does occur also in systemic lupus erythematosus, ankylosing spondylitis and scleroderma. The pathogenesis of bone loss is multifactorial, with disease-dependent and disease-independent factors. Glucocorticoids represent the single most important risk factor for OP, even at low dose, and are associated with a significant increase in fracture risk. Functional impairment, hypovitaminosis D due to lack of sun exposure, disease activity and drugs, such as immunosuppressant and anticoagulants, also play a role.

Objectives: The aim of this study was to histologically assess whether elevation of partial-thickness flaps results in reduced bone alterations, as compared with fullthickness flap preparations. Material and Methods: In five beagle dogs, both mandibular second premolars (split-mouth design) were subjected to one of the following treatments: Tx1: elevation of a partial-thickness flap over the mesial root of P 2 and performing a notch at the height of the bone. Tx2: elevation of a full-thickness flap over the mesial root of P 2 and performing a notch at the height of the bone. After 4 months, sections were evaluated for: (i) vertical bone loss and (ii) osteoclastic activity using histometry. Results: Elevation of both full-and partial-thickness flaps results in bone loss and elevated osteoclastic activity. Partial-thickness flaps can result in less bone loss than full-thickness flaps, but are subject to some variability. Conclusion: Use of partial-thickness flaps does not prevent from all bone loss. The procedure may result most of the times in less bone loss than the elevation of fullthickness flaps. Further research has to evaluate the determinants of effective outcomes of partial-thickness flap procedures.

En dehors des problèmes posés par le risque de rejet, les suites d'une transplantation rénale peuvent être émaillées de diverses complications non immunologiques qui peuvent entre autres mettre en jeu le pronostic fonctionnel du greffon. À la phase précoce, l'insuffisance rénale aiguë ou le retard de récupération fonctionnelle est le plus souvent en rapport avec une néphropathie ischémique liée aux conditions de la transplantation. Les complications tardives peuvent toucher de nombreux organes. La qualité de la surveillance à long terme est de ce fait un élément essentiel du pronostic après transplantation. La néphropathie chronique de l'allogreffe peut être aggravée par la toxicité rénale des immunosuppresseurs ou par des lésions de rejet chronique. La perte du contenu minéral osseux doit être prévenue ou enrayée. Les complications métaboliques et cardiovasculaires tardives sont aujourd'hui la première cause de mortalité après transplantation. Les facteurs de risque cardiovasculaire (diabète, dyslipidémie et surtout hypertension artérielle) doivent être soigneusement contrôlés. Les complications pouvant toucher les autres organes ou systèmes sont également passées en revue. © 2005 Elsevier SAS. Tous droits réservés.

In postmenopausal women, the use of aromatase inhibitors increases bone turnover and induces bone loss at sites rich in trabecular bone at an average rate of 1-3% per year leading to an increase in fracture incidence compared to that seen during tamoxifen use. The bone loss is much more marked in young women with treatment-induced ovarian suppression followed by aromatase inhibitor therapy (average 7-8% per annum). Pre-treatment with tamoxifen for 2-5 years may reduce the clinical significance of the adverse bone effects associated with aromatase inhibitors, particularly if this leads to a shortening in the duration of exposure to an aromatase inhibitor. However, skeletal status should still be assessed at the commencement of aromatase inhibitor therapy. The rate of bone loss in women who experience a premature menopause before the age of 45 or are receiving ovarian suppression therapy is accelerated by the concomitant use of aromatase inhibitors. These patients are considered to be at high risk of clinically important bone loss and should have a baseline dual energy Xray absorptiometry (DXA) assessment of bone mineral density (BMD). (D.M. Reid).

To treat systemic bone loss as in osteoporosis and/or focal osteolysis as in rheumatoid arthritis or periodontal disease, most approaches target the osteoclasts, the cells that resorb bone. Bisphosphonates are currently the most widely used antiresorptive therapies. They act by binding the mineral component of bone and interfere with the action of osteoclasts. The nitrogen-containing bisphosphonates, such as alendronate, act as inhibitors of farnesyl-pyrophosphate synthase, which leads to inhibition of the prenylation of many intracellular signaling proteins. The discovery of RANKL and the essential role of RANK signaling in osteoclast differentiation, activity and survival have led to the development of denosumab, a fully human monoclonal antibody. Denosumab acts by binding to and inhibiting RANKL, leading to the loss of osteoclasts from bone surfaces. In phase 3 clinical studies, denosumab was shown to significantly reduce vertebral, nonvertebral and hip fractures compared with placebo and increase areal BMD compared with alendronate. In this review, we suggest that the key pharmacological differences between denosumab and the bisphosphonates reside in the distribution of the drugs within bone and their effects on precursors and mature osteoclasts. This may explain differences in the degree and rapidity of reduction of bone resorption, their potential differential effects on trabecular and cortical bone, and the reversibility of their actions.

The purpose of this study was to examine the most frequently used criteria to define treatment success in implant dentistry. An electronic MEDLINE/ PubMED search was conducted to identify randomized controlled trials and prospective studies reporting on outcomes of implant dentistry. Only studies conducted with roughened surface implants and at least five-year follow-up were included. Data were analyzed for success at the implant level, peri-implant soft tissue, prosthetics, and patient satisfaction. Most frequently reported criteria for success at the implant level were mobility, pain, radiolucency, and peri-implant bone loss (> 1.5 mm), and for success at the peri-implant soft-tissue level, suppuration, and bleeding. The criteria for success at the prosthetic level were the occurrence of technical complications/prosthetic maintenance, adequate function, and esthetics during the five-year period. The criteria at patient satisfaction level were discomfort and paresthesia, satisfaction with appearance, and ability to chew/taste. Success in implant dentistry should ideally evaluate a long-term primary outcome of an implant-prosthetic complex as a whole.

Background: Implant supported dental prostheses are increasingly used in dental practice. The article describes causes of bone loss around the dental implant. Moreover, properties of different materials are compared and discussed. The advantages, disadvantages, and biomechanical concept of different implant-abutment connections are presented. The location of connections in relation to the bone level and the influence of microgap between the abutment and implant are described. Additionally, the implant abutments for cemented and screwed prosthetic restorations are compared. The influence of implant and abutment surface at the transmucosal level on peri-implant soft tissue is discussed. Finally, the biological aspect of abutment-implant connection is analyzed.

Objective: The aim of this systemic review is to study bone loss factors around oral implants after first year.

Methods and Materials: A systemic research was conducted on PubMed, Google Scholar, and International Journal of Implant Dentistry in Nov. 2021 with the following keywords: oral implants and marginal bone resorption/crestal bone loss/bone loss/bone resorption. This search resulted in a total of one thousand seven hundred fifty-seven papers. Further search and filtering based on inclusion criteria finally resulted in 12 studies, which were reviewed.

Result: Ten publications fulfilled the inclusion criteria. Two studies evaluated the influence of implant surface characteristics and two studies reported on the effect of implant design on MBL changes. Six publications analyzed the combined effect of different implant surfaces and designs on MBL alterations. Meanwhile, these studies fucose on patient characteristics, and clinical handling as well. As revealed from available studies, there is no evidence that modified surfaces are superior to non-modified implant surfaces in marginal bone preservation. One study reported on significantly improved MBL preservation for implants with a conical and micro-threaded marginal collar than implants with a cylindrical and non-threaded marginal portion after 3 years in function. No implant system was found to be superior in marginal bone preservation.
Clinical evidence was presented that the so-called combined factors (implant hardware, clinical handling, and patient characteristics) may lead to marginal bone resorption. However, once tissue damage has been caused by combined factors, inflammation and/or infection may develop secondarily and then result in peri-implantitis that may need particular clinical treatment.

Conclusion: As marginal bone loss primarily depends on numerous background factors, it seems logical that, for example, the use of poorly constructed implants placed and handled by untrained clinicians may result in high numbers of patients with secondary problems in form of peri-implantitis; having said this, control of combined factors may likewise lead to very good clinical results where peri-implantitis would represent a very rare disease indeed even at follow-up times of 10 years or more. So, in short that can be said that all the factors and reasons that lead to bone resorption around dental implants are a matter of several factors that are relevant to both the doctor, the patient, and the implant system and its materials.

Cancer patients are at risk for adverse events involving bone. Metastasis of cancer to bone and primary bone tumors can compromise the integrity of bone. Various cancer therapies cause long-term skeletal disorders, particularly bone loss, osteomalacia, and avascular necrosis. Cancer therapies that include chemotherapy, glucocorticoids, hormonal agents, and newer targeted therapies can affect bone in several ways. With the improved effectiveness of cancer treatment, more cancer patients are surviving longer and may experience fractures as a long-term complication of bone loss. Prevention of bone loss through early detection and appropriate use of anti-osteoporosis treatment may decrease bone loss and fractures. This article reviews causative risk factors, mechanisms, and prevention and treatment strategies for cancer therapy-related bone loss in hematologic and specific solid malignancies.

Spinal muscular atrophy (SMA) is characterized by degenerating lower motor neurons and an increased incidence of congenital bone fractures. Survival motor neuron (SMN) levels are significantly reduced due to deletions/mutations in the telomeric SMN1 gene in these patients. We utilized the Smn −/− SMN2 mouse model of SMA to determine the functional role for SMN in bone remodelling. μCT analysis of lumber vertebrae, tibia and femur bones from SMA mice revealed an osteoporotic bone phenotype. Histological analysis demonstrated a thin porous cortex of cortical bone and thin trabeculae at the proximal end of the growth plate in the vertebrae of SMA mice compared to wild-type mice. Histochemical staining of the vertebrae showed the presence of abundant activated osteoclasts on the sparse trabeculae and on the endosteal surface of the thin cortex in SMA mice. Histomorphometric analysis of vertebrae from SMA mice showed an increased number of osteoclasts. Serum TRAcP5b and urinary NTx levels were elevated, consistent with increased bone resorption in these mice. SMA mice showed a significant decrease in the levels of osteoblast differentiation markers, osteocalcin, osteopontin and osterix mRNA expression; however, there were no change in the levels of alkaline phosphatase expression compared to WT mice. SMA mouse bone marrow cultures revealed an increased rate of osteoclast formation (54%) and bone resorption capacity (46%) compared to WT mice. Pre-osteoclast cells from SMA mice showed constitutive upregulation of RANK receptor signalling molecules critical for osteoclast differentiation. Our results implicate SMN function in bone remodelling and skeletal pathogenesis in SMA. Understanding basic mechanisms of SMN action in bone remodelling may uncover new therapeutic targets for preventing bone loss/fracture risk in SMA.

Osteoporosis, a classical age-related disease and known to be more common in women than in men, has been reported increasingly often in men during the past few years. Although men at all ages after puberty have larger bones than women, resulting in greater bending strength, mortality after a hip fracture, one of the major complications of osteoporosis, is more common in men than in women. Sex hormone deficiency is associated with unrestrained osteoclast activity and bone loss. Even though estrogen deficiency is more pronounced in women, it appears to be a major factor in the pathogenesis of osteoporosis in both genders. In contrast to osteoporosis in postmenopausal women, the treatment of osteoporosis in men has been scarcely reported. Nevertheless, some drugs commonly used for the treatment of osteoporosis in women also appear to be effective in men. The aim of this study is to review primary osteoporosis in the elderly with particular emphasis on gender-related aspects.

Bisphosphonates are primary agents in the current pharmacological arsenal against osteoclastmediated bone loss due to osteoporosis, Paget disease of bone, malignancies metastatic to bone, multiple myeloma, and hypercalcemia of malignancy. In addition to currently approved uses, bisphosphonates are commonly prescribed for prevention and treatment of a variety of other skeletal conditions, such as low bone density and osteogenesis imperfecta. However, the recent recognition that bisphosphonate use is associated with pathologic conditions including osteonecrosis of the jaw has sharpened the level of scrutiny of the current widespread use of bisphosphonate therapy. Using the key words bisphosphonate and clinical practice in a PubMed literature search from January 1, 1998, to May 1, 2008, we review current understanding of the mechanisms by which bisphosphonates exert their effects on osteoclasts, discuss the role of bisphosphonates in clinical practice, and highlight some areas of concern associated with bisphosphonate use.

Background Loosening of acetabular components often leads to bony defects. Management of extensive acetabular bone loss in hip revision arthroplasty can be a tremendous challenge. Questions/purposes We asked whether a reconstruction with impacted bone grafts will provide a durable and painfree function in extensive acetabular defects. We specifically determined the (1) survival rates with the end point of revision for any reason, aseptic revision, and radiographic loosening;

The purpose of this study was the clinical and radiographic comparison of dental implants with surfaces roughened by anodic oxidation (TiUnite), dual acid-etched implants (Osseotite), and machined implants. Seventy-four patients (mean age, 52.8 +/- 14.2 years; range, 23 to 80 years; 41 men and 33 women) received 198 dental implants-58 TiUnite implants (25 patients), 52 Osseotite implants (27 patients), and 88 machined implants (22 patients). Clinical measurements and radiographs were evaluated at the time of surgery, at the restorative phase, and 2 years postloading. To account for statistical correlation among multiple implants in the same subject, a &quot;per patient&quot; mode of analysis was conducted. A 1-way analysis of variance of bone loss was conducted by type of implant as well by area of the mouth. In addition, differences in mean bone loss were tested for bone density category, gender, and smoking status using Student t tests. Eighteen TiUnite implants (31.0%) were place...

The ability of alprazolam to diminish cortisol response and favor ovarian function could make it useful in the prevention of osteopenia in athletes in selected cases. A sample of 45 female Wistar rats, all 93 days old and with a mean initial weight of 267 ± 17 g, were studied. Rats were exposed to a high-performance level of exercise and were divided into two groups-one group received an alprazolam supplement and one did not-and compared with controls to determine the effect of alprazolam on bone mass as measured by dual-energy X-ray absorptiometry (DKA). Exercise consisted of treadmill running on 5 out of 7 days during a period of 11 weeks. A steep grade treadmill inclination was used to stimulate high-intensity muscle activity. Final inclination was 17.5°and treadmill speed was 45 cm/ second. Upon completion of the experiment, all the rats were killed and the femur and 5th lumbar vertebra were dissected and cleaned. Length, weight, bone mineral content (BMC), and density (BMD) of the whole right femur and 5th lumbar vertebra were measured. In the exercise only group (no alprazolam), the length, weight, BMC, BMD, and femur BMC/final rat weight ratio of the femur, and the vertebral weight, vertebral BMD and BMC, and vertebral BMC/final rat weight ratio were lower than in the control and the exercise-alprazolam groups (P < 0.0167 -< 0.0001). Alprazolam preserves bone mass in rats exposed to intense exercise.

Purpose: To assess the clinical effectiveness of immediate nonfunctional loading for single-tooth implants placed in the anterior maxilla following augmentation with cancellous freeze-dried block graft. Materials and Methods: The clinical outcomes of immediately nonfunctionally loaded implants up to 18 months after placement in the anterior maxilla were evaluated in 11 consecutive patients. Implants were immediately restored with unsplinted acrylic resin provisional crowns. Follow-up was monthly, and intraoral radiographs were obtained immediately after implant placement and at 6, 12, and 18 months. Survival rate and radiographic marginal bone loss were evaluated at 0, 6, 12, and 18 months. In the anterior maxilla, 12 implants were placed. Results: Marginal bone loss did not extend beyond the first thread up to 18 months follow-up, and the survival rate was 100%. Conclusion: Within the limits of the present study, immediate nonfunctional loading for single-tooth implants placed in the anterior maxilla following augmentation with cancellous freeze-dried block graft seems a promising treatment alternative. (Case Series) INT J ORAL MAXILLOFAC IMPLANTS 2008;23:709-716