Bone Mineral Density Of Proximal Tibia Research Articles

The Effect of Photobiomodulation on Bone Mineral Density, Serum Vitamin D, and Bone Formation Markers in Individuals with Complete Spinal Cord Injuries with Osteoporosis.

Study design: A quasi-experimental study utilized a matched-pair design, administering photobiomodulation at four-sites on one side of the body and assigning control to the other side at corresponding sites. Objectives: This study aimed to assess photobiomodulation treatment effects on bone mineral density (BMD) measurement using dual-energy X-ray-absorptiometry in individuals with complete spinal cord injury (C.SCI) and osteoporosis. Methods: Eight patients received treatment at four-sites: forearm-mid-distal (MID), proximal-femur, distal-femur, and proximal-tibia, totaling 32 sites. Using an 830 nm gallium-aluminum-arsenide semiconductor laser irradiation was administered three times weekly for 8 weeks. Different doses (energy density) were determined depending on bone depth from skin surface, as assessed by sonography and adjusted through irradiation time to be 8, 10, and 12 J/cm2 for depths <1 cm, between 1 and 1.5 cm, and >1.5 cm, respectively, using 200 mW power to deliver the optimal isodose of laser at each depth of bone within each therapeutic site. BMD was measured at baseline, week 8 of treatment, and week 15 of follow-up. Serum 25-(OH)-vitamin D and bone formation markers including osteocalcin and bone-alkaline-phosphatase (B-ALP) were also assessed at baseline and week 8 of treatment. Results: Significant increases in BMD were noted in proximal-femur and forearm-MID at both week 8 and week 15. Serum 25-(OH)-vitamin D levels significantly increased after treatment. However, no notable changes were observed in distal-femur and proximal-tibia BMD or in osteocalcin and B-ALP levels. Conclusions: Photobiomodulation (830 nm) laser demonstrated efficacy in improving BMD at proximal-femur and forearm-MID in individuals with C.SCI. Moreover, the observed positive influence on vitamin D levels suggests a potential photobiomodulation role, warranting further investigation.

Preventing OsteoPorosis in Spinal Cord Injury (POPSCI) Study-Early Zoledronic Acid Infusion in Patients with Acute Spinal Cord Injury.

Accelerated sub-lesional bone loss is common in the first 2-3years after traumatic spinal cord injury (TSCI), particularly in the distal femur and proximal tibia. Few studies have explored efficacy of antiresorptives for acute bone loss prevention post-TSCI, with limited data for knee bone mineral density (BMD) or beyond two years follow-up. An open-label non-randomized study was performed at Royal North Shore Hospital and Royal Rehab Centre, Sydney between 2018 and 2023. An 'acute interventional cohort' (n = 11) with TSCI (duration ≤ 12-weeks) received a single infusion of 4mg zoledronic acid (ZOL) at baseline. A 'chronic non-interventional cohort' (n = 9) with TSCI (duration 1-5-years) did not receive ZOL. All participants underwent baseline and 6-monthly blood tests (including CTx and P1NP) and 12-monthly DXA BMD scans (including distal femur and proximal tibia). Participants were predominantly Caucasian and male (mean age 38.4years). At baseline, the 'acute' cohort had higher serum CTx, P1NP and sclerostin concentrations, while the 'chronic' cohort had lower left hip and knee BMD. Majority with acute TSCI experienced an acute phase reaction after ZOL (9/11; 82%). In the acute cohort, left hip BMD fell by mean ~ 15% by 48months. Left distal femoral and proximal tibial BMD declined by mean ~ 6-13% at 12months and ~ 20-23% at 48months, with a tendency towards greater BMD loss in motor-complete TSCI. A single early ZOL infusion in acute TSCI could not attenuate rapidly declining hip and knee BMD. Prospective controlled studies are required to establish the optimal strategy for preventing early bone loss after acute TSCI.

Student Competition (Knowledge Generation) ID 1985735

Background Individuals with chronic spinal cord injury or disease (SCI/D) are at an increased risk of lower extremity fractures. Novel interventions, including nutraceuticals and pharmacotherapy, are being explored to reduce fracture-related morbidity and mortality. Objective This retrospective cohort study aims to evaluate the effectiveness of Denosumab injections with dietary calcium and vitamin D supplements on proximaltibia bone mineral density (BMD) in adults with low bone mass and chronic SCI/D. Design/Methods Adult patients with SCI/D over age 18 years, with a baseline distal femur or proximal tibia Z-score &amp;lt;-2.0 or T-score &amp;lt;-2.5 exposed to at least three doses of Denosumab 60mcg/1ml vial injections will consent to chart abstraction. The cumulative Denosumab dose will be the exposure variable. Calcium intake and vitamin D serum levels will be recorded as effect modifiers. Age, sex, and BMI will be recorded as potential confounders. The primary outcome will be the change in proximal tibia BMD from baseline and secondarily the incidence of lower extremity fracture(s). Results/Findings Demographic and impairment characteristics of the study population will be reported using appropriate descriptive statistics. The associations between mean BMD change and Denosumab exposure will be calculated and adjusted for confounders using an appropriate univariate/multivariate model based on sample size and data distribution. Conclusion This retrospective cohort study will determine the effectiveness of Denosumab injections (with calcium and vitamin D) for maintaining or increasing proximal tibia BMD among patients with chronic SCI/D. The study findings will have a significant impact on Denosumab prescribing practices.

Denervation impacts muscle quality and knee bone mineral density after spinal cord injury

Cross-sectional study. To compare muscle size, body composition, bone mineral density (BMD), and metabolic profiles in denervated versus innervated individuals with spinal cord injury (SCI). Hunter Holmes McGuire Veterans Affairs (VA) Medical Center. Body composition, bone mineral density (BMD), muscle size, and metabolic parameters were collected in 16 persons with chronic SCI (n = 8 denervated, n = 8 innervated) using dual-energy x-ray absorptiometry (DXA), magnetic resonance imaging (MRI), and fasting blood samples. BMR was measured by indirect calorimetry. Percent differences of the whole thigh muscle cross-sectional area (CSA; 38%), knee extensor CSA (49%), vasti CSA (49%), and rectus femoris CSA (61%) were smaller in the denervated group (p < 0.05). Leg lean mass was also lower (28%) in the denervated group (p < 0.05). Whole muscle intramuscular fat (IMF%; 15.5%), knee extensor IMF% (22%), and % fat mass (10.9%) were significantly greater in the denervated group (p < 0.05). Knee distal femur and proximal tibia BMD were lower in the denervated group, 18-22% and 17-23%; p < 0.05. Certain indices of metabolic profile were more favorable in the denervated group though were not significant. SCI results in skeletal muscle atrophy and dramatic changes in body composition. Lower motor neuron (LMN) injury results in denervation of the lower extremity muscles which exacerbates atrophy. Denervated participants exhibited lower leg lean mass and muscle CSA, greater muscle IMF, and reduced knee BMD compared to innervated participants. Future research is needed to explore therapeutic treatments for the denervated muscles after SCI.

Employment of Neuromuscular Electrical Stimulation to Examine Muscle and Bone Qualities after Spinal Cord Injury.

(1) Background: Resource intensive imaging tools have been employed to examine muscle and bone qualities after spinal cord injury (SCI). We tested the hypothesis that surface neuromuscular electrical stimulation (NMES) amplitude can be used to examine knee extensor muscle quality, distal femur and proximal tibia bone mineral density (BMD) in persons with SCI. (2) Methods: Seventeen persons (2 women) with chronic SCI participated in three weeks of NMES-resistance training twice weekly of 4 sets of 10 repetitions. Participants were classified according to the current amplitude (&gt;100 mA) and the number of repetitions (&gt;70 reps) of leg extension into greater (n = 8; 1 woman; group A) and lower (n = 9; 1 woman; group B) musculoskeletal qualities. Magnetic resonance imaging, dual energy x-ray absorptiometry, isometric peak torque, Modified Ashworth and Penn spasm frequency scales were conducted. (3) Results: In between group comparisons, current amplitude was lower (38-46%) in group A. Whole (27-32%; p = 0.02), absolute (26-33%, p = 0.02) thigh muscle and absolute knee extensor muscle cross-sectional areas (22-33%, p = 0.04) were greater in group A. Right distal femur (24%; p = 0.08) and proximal tibia (29%; p = 0.03) BMDs were lower in group B, and peak isometric torque (p &lt; 0.01), extensor spasticity scorers (p = 0.04) and muscle spasm scores (p = 0.002) were significantly higher in group A. Regression models revealed that amplitude of current, repetitions and body weight can accurately predict musculoskeletal qualities in persons with SCI. (4) Conclusions: Surface NMES amplitude and repetitions of leg extension differentiated between SCI survivors with greater versus lower musculoskeletal qualities. The study may shed the light on the interplay between muscle and bone in persons with SCI.

Cross-Sectional Study of Knee Bone Mineral Density and Fragility Fractures in Patients with Neurological Injuries and Neuromuscular Disorders

Background: Patients with neurological injury and neuromuscular disorders are at increased risk for osteoporosis and fragility fracture. This cross-sectional study investigated whether knee bone mineral density (BMD) correlates with fragility fracture in patients with neurological injury and neuromuscular injuries. Methodology: In this retrospective chart review, 435 participants underwent dual-energy X–ray absorptiometry (DXA) for BMD analysis. Distal femur and proximal tibial BMD measurements were performed as per the Toronto protocol. Spine, hip, and forearm DXA was performed following the standards of the International Society of Clinical Densitometry, 2019. Blinded and independent clinical evaluations and laboratory exams were performed. Participants were divided into groups with and without fracture confirmed by clinical history and radiography. Results: Distal femur and proximal tibial BMD were measured in 288/435 (66.2%) participants. Osteoporosis was noted in 138/288 (47.9%) patients. Fractures occurred in 95/435 participants (21.8%), including one fracture in 64/435 participants (14.7%), two fractures in 24/435 participants (5.5%), and greater than two fractures in 7/435 patients (1.6%). Fractures were noted in 23/54 (42.6%) participants with post-polio syndrome, 21/66 with brain injury (31.8%), 3/10 (30%) with brain injury and spinal cord injury, 24/98 (24.5%) with neuromuscular disorders, 9/52 (17.3%) with nontraumatic spinal cord injury, and 15/155 (9.7%) with traumatic spinal cord injury. The median BMD of the knee and hip was lower in participants with fractures. Distal femur and proximal tibial BMD (odds ratio [OR] = 0.02, 95% confidence interval [CI]: 0.01–0.45) remained independently associated with fragility fracture in multivariable analysis. Conclusion: Proximal tibial and distal femur BMD measurements offered additional information on neurological injury and neuromuscular disorders.

Prediction of Distal Femur and Proximal Tibia Bone Mineral Density From Total Body Dual Energy X-Ray Absorptiometry Scans in Persons with Spinal Cord Injury

Bone density decreases rapidly after spinal cord injury (SCI), increasing fracture risk. The most common fracture sites are at the knee (i.e., distal femur or proximal tibia). Despite this high fracture incidence, knee-specific scans for bone density using dual x-ray absorptiometry (DXA) were not available until 2014 and are still not routinely used in clinical practice today. This has made it difficult to determine the rehabilitation efficacy and hindered understanding of the long-term changes in knee areal bone density. The purpose of this investigation was to compare areal bone mineral density values for the knee from both total-body and knee-specific DXA scans in persons with SCI. A total of 20 participants (16 males) >1 yr-post spinal cord injury received two DXA scans; a total-body scan and a knee-specific scan. Standardized methods were used to create regions of interest to determine bone density of four regions – the epiphysis and metaphysis of the distal femur and proximal tibia – from the total-body scan. Linear regressions and Bland-Altman analyses were conducted to determine the correlation (r2) and agreement (mean bias ± 95% level of agreement) respectively between the two scan types for each region. Linear regression analyses showed strong significant (p < 0.001) relationships between the two scan types for the distal femur epiphysis (r2 = 0.88) and metaphysis (r2 = 0.98) and the proximal tibia epiphysis (r2 = 0.88) and metaphysis (r2 = 0.99). The mean bias ± 95% level of agreement were distal femur epiphysis (0.05 ± 0.1 g/cm2) and metaphysis (0.02 ± 0.04 g/cm2); proximal tibia epiphysis (-0.02 ± 0.1 g/cm2) and metaphysis (0.02 ± 0.03 g/cm2). Results suggest knee-specific bone density can be assessed using a total-body DXA scan. This may allow for more comprehensive use of DXA scans which would reduce the burden of multiple site-specific scans for persons with SCI and enable more widespread adoption of knee bone density assessment in this population.

Does medial-to-lateral tibial bone mineral density ratio change following six weeks of twice weekly neuromuscular exercise in patients with knee osteoarthritis?

Purpose: Knee osteoarthritis (OA) is characterized by increased subchondral bone mineral density (BMD). At the knee joint, proximal tibial BMD is associated with dynamic joint loads, and thereby serves as a surrogate structural marker of altered joint loading patterns. Neuromuscular exercise is an effective means of altering knee joint biomechanics as well as improving pain and function in people with knee OA. However, the mechanisms underlying reductions in pain following exercise therapy are poorly understood.

The effect of table olive wastewater extract administration on the adult ovariectomised rat model of osteoporosis.

Recent efforts for alternative non-pharmaceutical treatments for postmenopausal osteoporosis are focused on nutritional measures. The aim of this study was to investigate the effect of table olive wastewater extract (OE) administration on bone mineral density (BMD) and biomechanical strength in ovariectomised rats. Thirty mature 9-month-old female Wistar rats were separated into three groups of ten: Control, Ovariectomised (OVX) and OVX + OE. BMD was measured before ovariectomy, 3 and 6 months afterwards. At the end of the study, blood, both femurs and tibias, internal organs and abdominal fat were collected. After 3 months, the percentage changes from baseline of the total and proximal tibial BMD of the OVX+OE group were both higher compared with the OVX group (P<0·005). Similar results were found after 6 months, when the percentage changes from baseline of the total and proximal tibial BMD of the OVX+OE group were both higher compared with the OVX group (P<0·005). Biomechanical testing of the femurs did not reveal any statistically significant difference between the groups. Body weights throughout the study, organs' and abdominal fat ratios to final body weight and blood results (alanine aminotransferase (ALT), gamma-glutamyltransferase (γ-GT), total cholesterol, HDL-cholesterol, LDL-cholesterol, Ca and P) were within normal limits and did not show any significant difference between the treated and untreated groups. As a conclusion, the administration of OE for 6 months protected tibial BMD loss in comparison with the untreated OVX group without causing adverse effects.

A Registration Method for Three-Dimensional Analysis of Bone Mineral Density in the Proximal Tibia.

Although alterations in bone mineral density (BMD) at the proximal tibia have been suggested to play a role in various musculoskeletal conditions, their pathophysiological implications and their value as markers for diagnosis remain unclear. Improving our understanding of proximal tibial BMD requires novel tools for three-dimensional (3D) analysis of BMD distribution. Three-dimensional imaging is possible with computed tomography (CT), but computational anatomy algorithms are missing to standardize the quantification of 3D proximal tibial BMD, preventing distribution analyses. The objectives of this study were to develop and assess a registration method, suitable with routine knee CT scans, to allow the standardized quantification of 3D BMD distribution in the proximal tibia. Second, as an example of application, the study aimed to characterize the distribution of BMD below the tibial cartilages in healthy knees. A method was proposed to register both the surface (vertices) and the content (voxels) of proximal tibias. The method combines rigid transformations to account for differences in bone size and position in the scanner's field of view and to address inconsistencies in the portion of the tibial shaft included in routine CT scan, with a nonrigid transformation locally matching the proximal tibias. The method proved to be highly reproducible and provided a comprehensive description of the relationship between bone depth and BMD. Specifically it reported significantly higher BMD in the first 6 mm of bone than deeper in the proximal tibia. In conclusion, the proposed method offers promising possibilities to analyze BMD and other properties of the tibia in 3D.

Protective effect of Glycyrrhiza glabra roots extract on bone mineral density of ovariectomized rats.

Objective: The aim of this study was to evaluate the potential effect of the methanolic extract of plant Glycyrrhiza glabra roots on bone mineral density and femoral bone strength of ovariectomized rats.Methods: Thirty 10-month-old Wistar rats were randomly separated into three groups of ten, Control, Ovariectomy and Ovariectomy-plus-Glycyrrhiza in their drinking water. Total and proximal tibial bone mineral density was measured in all groups before ovariectomy (baseline) and after 3 and 6 months post ovariectomy. Three-point-bending of the femurs and uterine weight and histology were examined at the end of the study.Results: No significant difference was noted in bone density percentage change of total tibia from baseline to 3 months between Control and Ovariectomy-plus-Glycyrrhiza groups (+5.31% ± 4.75 and +3.30% ± 6.31 respectively, P = non significant), and of proximal tibia accordingly (+5.58% ± 6.92 and +2.61% ± 13.62, P = non significant) demonstrating a strong osteoprotective effect. There was notable difference in percentage change of total tibia from baseline to 6 months between groups Ovariectomy and Ovariectomy-plus-Glycyrrhiza (−13.03% ± 5.11 and −0.84% ± 7.63 respectively, P < 0.005), and of proximal tibia accordingly (−27.9% ± 3.69 and −0.81% ± 14.85 respectively, P < 0.001), confirming the protective effect of Glycyrrhiza glabra extract in preserving bone density of the Ovariectomy-plus-Glycyrrhiza group. Three-point-bending did not reveal any statistically significant difference between Ovariectomy and Ovariectomy-plus-Glycyrrhiza groups. Uterine weights of the Ovariectomy-plus-Glycyrrhiza group ranged between the other two groups with no statistically significant difference to each.Conclusions: Glycyrrhiza glabra root extract notably protected tibial bone mineral density loss in Ovariectomy-plus-Glycyrrhiza rats in comparison with ovariectomized rats, but did not improve biomechanical strength.

Calf Muscle Pump Stimulation Increases Lower Limb Bone Density in Perimenopausal Women

Nutrient delivery to bone tissue, as for all tissues in the body, is provided through interstitial fluid flow. This flow is driven by the differential fluid pressures between the intramedullary canal and the tissues outside of the bone. Correspondingly, reductions in tissue fluid pressure should enhance interstitial bone fluid flow, nutrient delivery, and thereby increase bone mineral density. This hypothesis was tested in a one year long pilot clinical study of healthy, employed, perimenopausal women (42 - 68 years). Soleus muscle (calf muscle pump) stimulation was utilized with the intent of increasing lower limb fluid return to the heart, serving to both reduce lower limb tissue pressures and to increase intramedullary pressures by increasing cardiac output. Dual-energy x-ray absorptiometry (DXA) assessments of bone mineral density (BMD) were obtained at 12 month intervals. Muscle stimulation usage ranged from 0.7 to 4.8 hours/work-day. Dose dependent responses between duration of daily soleus muscle stimulation and changes in both proximal femur BMD (+0.5% per hour of daily use; p = 0.05) and proximal tibia BMD (+1.5% per hour of daily use; p = 0.0004), were observed; no significant effect was observed at the lumbar spine. These results are consistent with the hypothesis that calf muscle pump stimulation, which is sufficient to reduce lower limb fluid pooling, is capable of significantly reducing the rate of bone loss in perimenopausal women as well as enhancing new bone formation.

Association between body weight and proximal tibial bone mineral density after bilateral total knee arthroplasty

BackgroundProximal tibial bone mineral density (BMD) has been studied for its potential impact on subsidence and loosening of the tibial component after total knee arthroplasty (TKA). However, no known studies of proximal tibial BMD after TKA have evaluated the effect of major impact factors such as body weight (BW), muscle strength, and level of activity. We aim to determine whether factors such as level of activity, quadriceps strength, BW, gender, age, and prosthetic design affect proximal tibial BMD over the mid- to long-term following TKA. MethodsWe evaluated 36 patients (72 knees) who were undergoing bilateral TKA performed by a single surgeon. Median follow up time was 115months (range, 60–211months) for a minimum of five years. We measured BMD in the proximal tibia and used a hand-held dynamometer to measure quadriceps isometric strength, recording the maximum value of three measurements for each patient. ResultsUnivariate analyses using Spearman's correlation coefficient for continuous variables revealed a weak negative correlation between age and BMD (r=−0.316, P=0.007) and a moderate positive correlation between BW and BMD (r=0.430, P<0.001). However, no significant correlations were found between the other factors above and BMD for continuous and discrete variables. Based on multivariate analyses, only BW had a significant effect on BMD (β=0.342, P=0.003). ConclusionsBW is the most impact factor on the proximal tibial BMD after mid- to long-term follow up TKA. Therefore, the management of BW may contribute to prevention of decline of tibial BMD for TKA patients owing to aging.

Changes in proximal tibial bone mineral density reflect redistribution of knee loads with use of a load reducing intervention over 24 weeks

Changes in proximal tibial bone mineral density reflect redistribution of knee loads with use of a load reducing intervention over 24 weeks

Normal range of BMD in proximal tibia as a different skeletal site at women.

OBJECTIVE:Osteoporosis is progressive metabolic bone disease that decreases bone density and features deterioration of bone structure. Dual-energy X-ray absorptiometry (DXA) is commonly used and reliable method to measure bone mineral density (BMD). Aim of this study was to determine normal ranges of BMD in left proximal tibia.METHODS:Fifty-five females were included in this study. BMD was measured at the lumbar spine and the left proximal tibia using DXA. BMD value of subregions in the left proximal tibia was significantly correlated with BMD value of the total lumbar spine (r=0.111–0.766). New average BMD values of the left proximal tibia were calculated according to age using linear regression formula, leading to average BMD value for the total lumbar spine (L1-L4) in normal population. New simulated T-scores for proximal subregions of the tibia were then calculated.RESULTS:T-scores for proximal subregions were not different from T-scores of total lumbar spine (p>0.05).CONCLUSION:It was concluded that proximal tibia is an ideal region for measurement of BMD in osteoporosis.

The Protective Effect of Amphimas pterocarpoides Plant Extract on Bone Mineral Density and Strength in Estrogen Deficient Ovariectomized Wistar Rats

Background: To assess the potential phytoestrogenic effect of Amphimas pterocarpoides plant extract on the ovariectomy (OVX) induced bone loss in rats. Methods: Thirty nine female (10 month old) Wistar rats were separated into Controls (n=11), OVX (n=13) and OVX+AP groups (n=15). Measurements of Bone Mineral Density (BMD) were performed at baseline, 3 and 6 months after ovariectomy. After 6 months treatment, the rats were euthanized and femurs were extracted. The biomechanical properties were evaluated using the 3-point bending test. Results: The percentage changes of the mean values of the proximal tibia BMD from baseline to 3 months for Control, OVX and OVX+AP group were 6.25%, -21.82% and - 12.73% whereas at 6 months they were 8.108%, -32.134% and -22.410% respectively. The 3-point bending test revealed that the maximal load before fracture and the mean values for stress significantly increased in the treatment group compared with OVX rats. Body and uterine weights were similar between OVX and OVX+AP groups. Conclusion: This study is the first to demonstrate that orally administered Amphimas pterocarpoides extract for 6 months is effective in terms of improving bone quantity (Bone mineral density) and quality (biomechanical parameters), surrogate markers of reduced risk of fracture. Therefore, Amphimas pterocarpoides is a new class of phytoestrogen extract and it presents a remarkable antiosteoporotic activity. These properties make Amphimas pterocarpoides a promising herbal therapy for the prevention of postmenopausal osteoporosis induced by estrogen deficiency.

Changes in Bone Density in Metal-Backed and All-Polyethylene Medial Unicompartmental Knee Arthroplasty

BackgroundProximal tibial strain in medial unicompartmental knee arthroplasty (UKA) may alter bone mineral density and cause pain. The aims of this retrospective cohort study were to quantify and compare changes in proximal tibial bone mineral density in metal-backed and all-polyethylene medial UKAs, correlating these with outcome, particularly ongoing pain. MethodsRadiographs of 173metal-backed and 82 all-polyethylene UKAs were analyzed using digital radiograph densitometry at 0, 1, 2, and 5years. The mean grayscale of 4 proximal tibial regions was measured and converted to a ratio: the GSRb (grayscale ratio b), where GSRb>1 represents relative medial sclerosis. ResultsIn both implants, GSRb reduced significantly to 1year and stabilized with no differences between implants. Subgroup analysis showed less improvement in Oxford Knee Score in patients whose GSRb increased by more than 10% at 1year (40/255) compared with patients whose GSRb reduced by more than 10% at both 1 years (8.2 vs 15.8, P=.002) and 5 years (9.6 vs 15.8, P=.022). Patients with persistently painful UKAs (17/255) showed no reduction in GSRb at 1 year compared with a 20% reduction in those without pain (P=.05). ConclusionsBone mineral density changes under medial UKAs are independent of metal backing. Medial sclerosis appears to be associated with ongoing pain.

Protein malnutrition attenuates bone anabolic response to PTH in female rats.

PTH is indicated for the treatment of severe osteoporosis. Elderly osteoporotic patients frequently suffer from protein malnutrition, which may contribute to bone loss. It is unknown whether this malnutrition may affect the response to PTH. Therefore, the aim of the present study was to assess whether an isocaloric low-protein (LP) diet may influence the bone anabolic response to intermittent PTH in 6-month-old female rats. Six-month-old female rats were either pair fed an isocaloric LP diet (2.5% casein) or a normal-protein (NP) diet (15% casein) for 2 weeks. The rats continued on their respective diet while being treated with 5- or 40-μg/kg recombinant human PTH amino-terminal fragment 1-34 (PTH-[1-34]) daily, or with vehicle for 4 weeks. At the end of this period, areal bone mineral density, bone mineral content, microstructure, and bone strength in axial compression of proximal tibia or 3-point bending for midshaft tibia tests were measured. Blood was collected for the determination of IGF-I and osteocalcin. After 4 weeks of PTH-(1-34), the dose-dependent increase of proximal tibia bone mineral density, trabecular microstructure variables, and bone strength was attenuated in rats fed a LP diet as compared with rats on a NP intake. At the level of midshaft tibia cortical bone, PTH-(1-34) exerted an anabolic effect only in the NP but not in the LP diet group. Protein malnutrition was associated with lower IGF-I levels. Protein malnutrition attenuates the bone anabolic effects of PTH-(1-34) in rats. These results suggest that a sufficient protein intake should be recommended for osteoporotic patients undergoing PTH therapy.

Mediolateral subchondral tibial bone mineral density difference does not predict osteoarthritis progression.

Data on the relationship between osteoporosis and osteoarthritis are conflicting. Most studies report "snapshot" prevalences, and there are few studies evaluating localized knee bone mineral density (BMD) measurements with respect to subsequent osteoarthritis progression. The authors hypothesize that increased mediolateral difference of the proximal tibial BMD may predict progression of knee osteoarthritis. In this study, 246 female volunteers were followed up prospectively over 2 years. Baseline BMD measurements of bilateral proximal (subchondral) tibiae were performed, and the mediolateral BMD ratio was calculated. Precision studies were performed on healthy volunteers to validate the technique. The patients were divided into osteoarthritis progressors and non-progressors based on Kellgren-Lawrence radiographic criteria at 2-year follow-up. Patients who were taking bisphosphonates or who had a history of inflammatory, infectious, or metabolic bone disease and previous hip and knee surgery were excluded. Demographic data, calcium supplementation, physical activity, baseline knee radiographs, and radiographs at 2-year follow-up were obtained. The study was adequately powered to detect an effect size of 0.4. There were 121 progressors and 125 non-progressors. Mean mediolateral BMD ratio was 1.02 among the progressors and 1.01 among the non-progressors (t=0.632, P=.528). Potential confounders were equally distributed among both groups. The data suggest that there is no link between proximal tibial BMD ratio and progression of knee osteoarthritis.

Anabolic steroids reduce spinal cord injury-related bone loss in rats associated with increased Wnt signaling

BackgroundSpinal cord injury (SCI) causes severe bone loss. At present, there is no practical treatment to delay or prevent bone loss in individuals with motor-complete SCI. Hypogonadism is common in men after SCI and may exacerbate bone loss. The anabolic steroid nandrolone reduces bone loss due to microgravity or nerve transection.ObjectiveTo determine whether nandrolone reduced bone loss after SCI and, if so, to explore the mechanisms of nandrolone action.MethodsMale rats with complete transection of the spinal cord were administered nandrolone combined with a physiological replacement dose of testosterone, or vehicle, beginning on day 29 after SCI and continued for 28 days.ResultsSCI reduced distal femoral and proximal tibial bone mineral density (BMD) by 25 and 16%, respectively, at 56 days. This bone loss was attenuated by nandrolone. In ex vivo osteoclasts cultures, SCI increased mRNA levels for tartrate-resistant acid phosphatase (TRAP) and calcitonin receptor; nandrolone-normalized expression levels of these transcripts. In ex vivo osteoblast cultures, SCI increased receptor activator of NF-kB ligand (RANKL) mRNA levels but did not alter osteoprotegerin (OPG) mRNA expression; nandrolone-increased expression of OPG and OPG/RANKL ratio. SCI reduced mRNA levels of Wnt signaling-related genes Wnt3a, low-density lipoprotein receptor-related protein 5 (LRP5), Fzd5, Tcf7, and ectodermal-neural cortex 1 (ENC1) in osteoblasts, whereas nandrolone increased expression of each of these genes.ConclusionsThe results demonstrate that nandrolone reduces bone loss after SCI. A potential mechanism is suggested by our findings wherein nandrolone modulates genes for differentiation and activity of osteoclasts and osteoblasts, at least in part, through the activation of Wnt signaling.