Tibial Bone Area Research Articles

Responsiveness of Magnetic Resonance Imaging-derived Measures Over 2.7 Years

To compare the responsiveness of magnetic resonance imaging (MRI)-derived measures of knee osteoarthritis over 2.7 years. There were 430 community-based participants (mean age 63.0 yrs, range 51-79 yrs; 51% female) measured at baseline and 2.7 years later. MRI of the right knee at both timepoints was performed to assess cartilage volume, cartilage defects, bone marrow lesions (BML), meniscal pathology, and tibial bone area. Global measurements were calculated as the sum of tibial and femoral measures. Standardized response mean (SRM) was calculated as the mean of change divided by the SD of change. Global tibiofemoral cartilage volume and cartilage defects had the best SRM of -0.80 and 0.62, respectively. Site-specific measurements were lower (SRM range for cartilage volume -0.48 to -0.54 and cartilage defects 0.33 to 0.49). The SRM for BML was 0.12, meniscal pathology 0.39, and tibial bone area -0.09. Cartilage volume and/or defects tended to be more responsive in those with knee pain, those who were obese, those who were older, and those with radiographic osteoarthritis. Global cartilage volume demonstrated the best sensitivity to change, suggesting that if we relied solely on SRM to optimize clinical trial design, then cartilage volume would be the best outcome measure. However, clinical trials have shown that cartilage volume may be less responsive to treatment compared to other measures that have lower SRM (such as BML). Therefore, although one can optimize trial efficiency by finding more responsive endpoints, both sensitivity to change and magnitude of benefit should be considered.

History of knee injury and MRI-assessed knee structures in middle- and older-aged adults: a cross-sectional study.

The aim of this cross-sectional study was to describe the associations between history of knee injury and knee structure using magnetic resonance imaging (MRI). This study included two population-based samples: the Tasmanian Older Adult Cohort (TASOAC) study (n = 430; mean age, 63.0 years; range, 51-79 years; 51 % female) and the Offspring study (n = 372; mean age, 45.0 years; range, 26-61 years; 57.5 % female). In both studies, 1.5 T MRI scans of the right knee were performed to measure bone marrow lesions (BMLs), cartilage volume, tibial bone area, cartilage defects and meniscal pathology. History of knee injury was assessed using a self-administered questionnaire. The association between knee injury and knee structure was determined using multiple linear and log binomial regression models. Nineteen percent of the middle-aged and 12 % of the older adults reported a history of knee injury. In middle-aged adults, BML presence (prevalence ratio (PR) = 1.6 (95 % CI, 1.2; 2.1)), tibial bone area (difference of means (DM) = +86 (+23, +149)) and meniscal extrusion presence (PR = 2.7 (1.1, 6.8)) were significantly higher in those with knee injury. In older adults, cartilage defect presence (PR = 1.3 (1.0, 1.7)), lateral (DM = -265 (-439, -92)) and total tibial (DM = -325 (-600, -51)) cartilage volume, BML presence (PR = 1.4 (1.0, 1.9)) and tibial bone area (DM = +140 (+19, +260)) were significantly associated with knee injury. Meniscal tears showed no significant associations in either cohorts. The association between knee injury and MRI-assessed structural pathology in the knee joint is moderate and appears to be stronger in older adults compared to middle-aged adults.

Association between urinary C-telopeptide fragments of type II collagen and knee structure in middle-aged women without clinical knee disease

There is evidence for an association between levels of urinary C-telopeptide fragments of type II collagen (uCTX-II) and risk of knee osteoarthritis (OA). The aim of this cohort study was to examine the association between uCTX-II levels and knee cartilage and bone changes in middle-aged women without clinical knee disease. 140 women, aged 40-67 years, with no significant knee pain, knee injury or any forms of arthritis, underwent knee magnetic resonance imaging (MRI) at baseline and 2 years later. Cartilage volume, cartilage defects, tibial plateau bone area and bone marrow lesions (BMLs) were measured using validated methods. Baseline uCTX-II was measured using enzyme-linked immunosorbent assay (ELISA). For every one unit (natural logarithm transformed) increase in baseline uCTX-II level, there was an increase in the prevalence of medial tibiofemoral cartilage defects (Odds ratio (OR) 4.36, 95% confidence interval (CI) 1.58-12.04), medial (80.2mm(2), 95% CI 9.3-151.1) and lateral (86.0mm(2), 95% CI 33.3-138.7) tibial plateau bone area, and the prevalence of lateral tibiofemoral BMLs (OR 10.62, 95% CI 1.82-61.85). Baseline uCTX-II levels were not significantly associated with baseline tibial cartilage volume or changes in knee cartilage volume or defects or bone area over 2 years, although there was a trend for the deterioration of medial tibiofemoral BMLs (P=0.06). In middle-aged women without clinical knee disease, higher uCTX-II levels were associated with early detrimental structural changes at the knee (cartilage defects, tibial bone expansion and BMLs) at baseline but not over 2 years. Further work will be needed to determine its sensitivity to change and whether it predicts disease progression over longer time periods.

Mass effect and signal intensity alteration in the suprapatellar fat pad: associations with knee symptoms and structure

To describe cross-sectional associations between mass effect or signal intensity alteration of the suprapatellar fat pad (SPFP) with knee symptoms and structure in older adults. A cross-sectional sample of 904 randomly selected subjects (mean 62.4 years, 49.9% female) was studied. T1- or T2-weighted fat suppressed magnetic resonance imaging (MRI) was used to assess mass effect or signal intensity alteration of SPFP, cartilage volume, cartilage defects, and bone marrow lesions (BMLs). Knee pain was assessed by self-administered Western Ontario McMaster Osteoarthritis Index (WOMAC) questionnaire. The Osteoarthritis Research Society International (OARSI) atlas was used to assess knee osteophyte, joint space narrowing (JSN) and radiographic osteoarthritis (ROA). Univariable and multivariable linear or logistic regression analyses were used to examine the associations. After adjustment for confounders including age, sex, body mass index (BMI), disease status, tibial bone area and/or ROA, the presence of SPFP mass effect was significantly associated with any knee pain (OR: 2.39; 95% confidence interval (CI): 1.54, 3.70) and ROA (OR: 2.10; 95% CI: 1.33, 3.31) but not with cartilage volume, cartilage defects or BMLs. The presence of SPFP signal intensity alteration was significantly associated with any knee pain (OR: 1.90; 95% CI: 1.43, 2.53), ROA (OR: 1.83; 95% CI: 1.37, 2.45), any BMLs (OR: 1.55; 95% CI: 1.17, 2.06) but not with cartilage volume and cartilage defects. Significant associations with knee pain and BMLs were more evident in subjects with ROA. Presence of SPFP mass effect and/or signal intensity alteration combined was associated with any tibial cartilage defects (OR: 1.45; 95% CI: 1.04, 2.04). SPFP mass effect and/or signal intensity alterations are deleteriously associated with knee pain, radiographic OA and BMLs in this cross-sectional study, suggesting that SPFP abnormalities may contribute to pain and structural abnormalities in the knee.

Children with nephrotic syndrome have increased tibial bone area but similar volumetric bone mineral density to healthy controls

Children with nephrotic syndrome have increased tibial bone area but similar volumetric bone mineral density to healthy controls

Monitoring time interval for pQCT-derived bone outcomes in postmenopausal women

Evidence of measurement precision, annual changes and monitoring time interval is essential when designing and interpreting longitudinal studies. Despite the precise measures, small annual changes in bone properties led to monitoring time intervals (MTIs) of 2-6 years in peripheral quantitative computed tomography (pQCT)-derived radial and tibial bone area, density, and estimated strength in postmenopausal women. The purpose of the study was to determine the precision error, annual change, and MTI in bone density, area, and strength parameters in postmenopausal women. Postmenopausal women (n = 114) from the Saskatoon cohort of the Canadian Multicentre Osteoporosis Study had annual pQCT scans of the distal and shaft sites of the radius and tibia for 2 years. Median annualized rates of percent change and the MTI were calculated for bone density, area, and strength parameters. Root mean squared coefficients of variation (CV%) were calculated from duplicate scans in a random subgroup of 35 postmenopausal women. CV% ranged from 1.4 to 6.1 % at the radius and 0.7 to 2.1 % at the tibia. MTIs for the distal radius were 3 years for total bone density (ToD) and 4 years for total bone cross sectional area (ToA), trabecular area, and bone strength index. At the diaphyseal radius, MTI was 3 years for ToA, 5 years for cortical density, and 6 years for polar stress strain index (SSIp). Similarly, MTI for total and trabecular density was 3 years at the distal tibia. At the diaphyseal tibia, MTI for ToA was 3 years and SSIp 4 years. MTI for longitudinal studies in older postmenopausal women should be at least 2-6 years at the radius and tibia, with specific monitoring of the total and trabecular area, total density, and bone strength at the radius and total and trabecular density, total area, and bone strength at the tibia.

Aromatase inhibitors associated with knee subchondral bone expansion without cartilage loss

Background The profound estrogen depletion caused by aromatase inhibitors (AIs) is associated with musculoskeletal symptoms, but the underlying pathophysiology remains unclear.Objective To assess the effects of AI therapy on structural changes in knee cartilage and subchondral bone over 2 years in postmenopausal women.Setting and participants Thirty women with breast cancer, mean age 58.5 (standard deviation ± 5.6) years and 62 healthy controls, mean age 56.5 (standard deviation ± 4.6) years.Main outcome measures Annualized changes in tibial cartilage volume and subchondral bone area, and worsening of tibiofemoral cartilage defects from paired knee magnetic resonance imaging 2 years apart were compared between the two groups.Results The AI-treated women had significantly greater expansion of the tibial plateau than the control group. The mean annualized differences, after adjusting for age, body mass index and baseline bone area, were 22.1 mm2 (95% confidence interval (CI) 7.6–36.6, p = 0.003) for the medial tibial plateau and 19.1 mm2 (95% CI 9.6–28.5, p < 0.001) for the lateral tibial plateau. The annual change in tibial cartilage volume and the worsening of cartilage defects did not differ between women taking AI therapy and controls.Conclusions AI therapy is associated with knee subchondral bone expansion knee with no effect on knee cartilage in postmenopausal women without pre-existing joint symptoms. This suggests the effect of severe estrogen depletion on knee is on bone, with the tibial bone expansion most likely a response to mechanical load in the setting of bone loss. Whether this then results in an increased risk of knee osteoarthritis will need to be determined.

High-dose vitamin d intervention in infants--effects on vitamin d status, calcium homeostasis, and bone strength.

Guidelines in Finland recommend 10 μg of vitamin D3 daily for all infants. Recent observations suggest that this may be insufficient to maintain optimal serum 25-hydroxyvitamin D (S-25-OHD). The aim of the study was to evaluate effects of various vitamin D doses and determine a dose ensuring S-25-OHD of at least 80 nmol/liter in infants without signs of vitamin D excess. We conducted a randomized double-blind intervention study. Cord blood was obtained at birth for S-25-OHD; 113 infants were randomized to receive vitamin D3 10, 30, or 40 μg/d from age 2 wk to 3 months. An investigator-initiated study was performed in a single maternity hospital in Helsinki, Finland. S-25-OHD, calcium homeostasis, and skeletal characteristics were evaluated with peripheral quantitative computed tomography at age 3 months. Baseline S-25-OHD was similar in all three groups (median, 53 nmol/liter). At 3 months, the mean S-25-OHD values were 88, 124, and 153 nmol/liter, and the minimum values were 46, 57, and 86 nmol/liter in the groups receiving 10, 30, and 40 μg (ANOVA; P < 0.001). No hypercalcemia occurred; plasma calcium, serum PTH, and urine calcium excretion was similar between the groups. Peripheral quantitative computed tomography showed a trend toward larger tibial total bone and cortical bone area with higher vitamin D doses. Vitamin D3 supplementation with up to 40 μg/d from age 2 wk to 3 months was safe and caused no hypercalcemia or hypercalciuria. The 40-μg dose maintained S-25-OHD above 80 nmol/liter in all infants. More extensive and longer intervention studies are necessary to assess long-term effects.

Body fat is associated with increased and lean mass with decreased knee cartilage loss in older adults: a prospective cohort study

To determine the associations between body composition at baseline and knee cartilage loss over 2.9 years in older adults. A total of 395 randomly selected subjects (mean 62 years, range 51-81, 50% female) were studied at baseline and 2.9 years later. T1-weighted fat-suppressed magnetic resonance imaging of the right knee was performed to determine knee cartilage volume and tibial bone area at baseline and follow-up. Height, weight and radiographic osteoarthritis were measured by standard protocols at baseline. Fat mass and lean mass were measured by dual-energy X-ray absorptiometry at baseline. Tibial cartilage volume decreased by 2.0-2.7% per annum. In multivariable analysis, annual change in medial cartilage volume was negatively and significantly associated with body mass index (β: -0.14% per kg m(-2), 95% confidence interval (CI): -0.25%, -0.02%), percentage total body fat (β: -0.19% per %, 95% CI: -0.30%, -0.07%) and percentage trunk fat (β: -0.10% per %, 95% CI: -0.19%, -0.02%), and positively associated with percentage lean mass (β: 0.20% per %, 95% CI: 0.08%, 0.32%). Change in lateral tibial cartilage volume was also significantly associated with percentage total body fat (β: -0.11% per %, 95% CI: -0.21%, -0.001%) and total lean mass (β: 0.13% per kg, 95% CI: 0.04%, 0.22%). These were independent of sex and age even though both were also significant predictors. Body fat adversely affects tibial cartilage loss over time, whereas lean mass is protective. Strategies aimed at reducing body fat but increasing lean mass may reduce knee cartilage loss in older people.

The association between parity and knee cartilage in young women

There have been no reported studies of the association between parity and cartilage in young individuals. The aim of this study was to describe the association between parity, cartilage volume and cartilage defects in women aged 31-41 years. Cross-sectional study of 144 women, mean age 36 years and BMI 25 kg/m(2), who were participants in an established prospective study. Parity was assessed using a questionnaire. Knee (medial tibial, lateral tibial and patellar) cartilage volume, cartilage defects (grade 0-4 depending on the severity of cartilage thickness loss at tibial and patellar sites) and tibial bone area were assessed using T1-weighted fat-suppressed MRI. The prevalence of cartilage defects (grade ≥2) in this population was 13%. Parity was associated with a higher risk of cartilage defects at the patellar [prevalence ratio (PR) per birth 1.52, 95% CI 1.05, 2.21; PR parous vs nulliparous 1.93, 95% CI 0.66, 5.65], but not tibial sites, after adjustment for confounders including age, BMI, smoking, physical activity, knee injury and tibial bone area. This association between parity and patellar cartilage defects was stronger for those women who had three or more births (vs nulliparous, PR 5.27, 95% CI 1.39, 20.01). There were no significant associations between parity and cartilage volume. Parity was associated with knee cartilage defects primarily at the patellar site in this sample of young women. This association was more apparent with increasing number of live births, suggesting a possible adverse effect of parity on knee cartilage.

The associations between body and knee height measurements and knee joint structure in an asymptomatic cohort

BackgroundIt has been suggested that knee height is a determinant of knee joint load. Nonetheless, no study has directly examined the relationship between anthropometric measures of height and knee joint structures, such as cartilage.Methods89 asymptomatic community-based adults aged 25-62 with no diagnosed history of knee arthropathy were recruited. Anthropometric data (knee height and body height) were obtained by standard protocol, while tibial cartilage volume and defects, as well as bone area were determined from magnetic resonance imaging. Static knee alignment was measured from the joint radiograph.ResultsAll anthropometric height measures were associated with increasing compartmental tibial bone area (p ≤ 0.05). Although knee height was associated with tibial cartilage volume (e.g. β = 27 mm3 95% CI 7- 48; p = 0.009 for the medial compartment), these relationship no longer remained significant when knee height as a percentage of body height was analysed. Knee height as a percentage of body height was associated with a reduced risk of medial tibial cartilage defects (odds ratio 0.6; 95% confidence interval 0.4 - 1.0; p = 0.05).ConclusionThe association between increased anthropometric height measures and increased tibial bone area may reflect inherently larger bony structures. However the beneficial associations demonstrated with cartilage morphology suggest that an increased knee height may confer a beneficial biomechanical environment to the chondrocyte of asymptomatic adults.

Patellofemoral and tibiofemoral articular cartilage and subchondral bone health following arthroscopic partial medial meniscectomy

To examine articular cartilage and subchondral bone changes in tibiofemoral and patellofemoral joints following partial medial meniscectomy. For this cross-sectional study, 158 patients aged 30-55 years, without evidence of knee osteoarthritis at arthroscopic partial medial meniscectomy (APMM), and 38 controls were recruited. MRI was performed once on the operated knee for each subcohort of 3 months, 2 or 4 years post-surgery, and the randomly assigned knee of the controls. Cartilage volume, cartilage defects, and bone size were assessed using validated methods. Compared with controls, APMM patients had more prevalent cartilage defects in medial tibiofemoral (OR = 3.17, 95%CI 1.24-8.11) and patellofemoral (OR = 13.76, 95%CI 1.52-124.80) compartments, and increased medial tibial plateau bone area (B = 143.8, 95%CI 57.4-230.2). Time from APMM was positively associated with cartilage defect prevalence in medial tibiofemoral (OR = 1.02, 95%CI 1.00-1.03) and patellofemoral (OR = 1.04, 95%CI 1.01-1.07) compartments, and medial tibial plateau area (B = 2.5, 95%CI 0.8-4.3), but negatively associated with lateral tibial cartilage volume (B = -4.9, 95%CI -8.4 to -1.5). The association of APMM and time from APMM with patellar cartilage defects was independent of tibial cartilage volume. Partial medial meniscectomy is associated with adverse effects on articular cartilage and subchondral bone, which are associated with subsequent osteoarthritis, in both tibiofemoral and patellofemoral compartments. III.

422 AUTOMATIC SEGMENTATION OF BONE AND CARTILAGE FROM KNEE MRI

greater in healthy women (1.82±1.03mm) than in healthy men (1.19mm±1.26mm; p < 0.01). Conclusions: The ratio between meniscus surface area and (ipsicompartimental) tibial bone area may provide a useful measure for comparing meniscus size across different cohorts with mixed sexes, for instance when testing whether knees with OA display meniscus hypertrophy. Although tibial plateau coverage by the meniscus is similar in healthy men and women, medial meniscus extrusion was greater in women, which may provide potential clues as to why women are at greater risk of symptomatic knee OA than men.

Association of Baseline Knee Bone Size, Cartilage Volume, and Body Mass Index with Knee Cartilage Loss Over Time: A Longitudinal Study in Younger or Middle-aged Adults

To determine the association of knee bone size, cartilage volume, and body mass index (BMI) at baseline with knee cartilage loss over 2 years in younger or middle-aged adults. A total of 324 subjects (mean age 45 yrs, range 26-61) were measured at baseline and about 2 years later. Knee cartilage volume and bone size were determined using T1-weighted fat-saturated magnetic resonance imaging. In multivariable analysis, baseline knee bone size was negatively associated with annual change in knee cartilage volume at medial and lateral tibial sites (ß = -0.62% to -0.47%/cm(2), all p < 0.001). The associations disappeared at medial tibial site after adjustment for baseline cartilage volume and became of borderline statistical significance at lateral tibial site after adjustment for both baseline cartilage volume and osteophytes (ß = -0.29, p = 0.059). Baseline knee cartilage volume was consistently and negatively associated with annual change in knee cartilage volume at all 3 medial tibial, lateral tibial, and patellar sites (ß = -4.41% to -1.37%/ml, all p < 0.001). Baseline BMI was negatively associated with an annual change in knee cartilage volume, but only in subjects within the upper tertile of baseline cartilage volume, even after adjusting for cartilage defects (ß = -0.16% to -0.34%/kg/m(2), all p < 0.05). Our study suggests that both higher baseline tibial bone area and knee cartilage volume (most likely due to cartilage swelling) are associated with greater knee cartilage loss over 2 years. A higher BMI was associated with greater knee cartilage loss only in subjects with higher baseline cartilage volume.

Dynamic knee loading is related to cartilage defects and tibial plateau bone area in medial knee osteoarthritis

To evaluate the relationship between dynamic mechanical loading, as indicated by external knee adduction moment (KAM) measures during walking, and measures of articular cartilage morphology and subchondral bone size in people with medial knee osteoarthritis (OA). 180 individuals with radiographic medial tibiofemoral OA participated. Peak KAM and KAM angular impulse were measured by walking gait analysis. Tibial cartilage volume and plateau bone area, and tibiofemoral cartilage defects were determined from magnetic resonance imaging using validated methods. Both peak KAM (coefficient=0.42, 95% confidence interval (CI) 0.04-0.79, P=0.03) and KAM impulse (coefficient=1.79, 95% CI 0.80-2.78, P<0.001) were positively associated with the severity of medial tibiofemoral cartilage defects. KAM impulse was also associated with the prevalence of medial tibiofemoral cartilage defects (odds ratio 4.78, 95% CI 1.10-20.76, P=0.04). Peak KAM (B=0.05, 95% CI 0.01-0.09, P=0.02) and KAM impulse (B=0.16, 95% CI 0.06-0.25, P=0.002) were positively associated with medial:lateral tibial plateau bone area, and KAM impulse was also associated with medial tibial plateau bone area (B=133.7, 95% CI 4.0-263.3, P=0.04). There was no significant association between KAM measures and tibial cartilage volume. Peak KAM and KAM impulse are associated with cartilage defects and subchondral bone area in patients with medial knee OA, suggesting that increased mechanical loading may play a role in the pathological changes in articular cartilage and subchondral bone that occur with medial knee OA.

Subchondral bone and cartilage damage: A prospective study in older adults

There is limited longitudinal evidence relating subchondral bone changes to cartilage damage and loss. The aim of this study was to describe the association between baseline tibial bone area and tibial subchondral bone mineral density (BMD) with tibial cartilage defect development and cartilage volume loss. A total of 341 subjects (mean age 63 years, range 52-79 years) underwent measurement at baseline and approximately 2.7 years later. Tibial knee cartilage volume, cartilage defects (graded on a scale of 0-4), and bone area were determined using T1-weighted fat suppression magnetic resonance imaging. Tibial subchondral BMD was determined using dual x-ray absorptiometry. In multivariable analysis, baseline bone area positively predicted cartilage defect development at the medial and lateral tibial sites (odds ratio [OR] 1.6 per 1 SD increase, 95% confidence interval [95% CI] 1.0, 2.6, and OR 2.4 per 1 SD increase, 95% CI 1.4, 4.0, respectively) and cartilage volume loss at the medial tibial site (beta = -34.9 per 1 SD increase, 95% CI -49.8, -20.1). In contrast, baseline subchondral BMD positively predicted cartilage defect development at the medial tibial site only (OR 1.6 per 1 SD increase, 95% CI 1.2, 2.1) and was not associated with cartilage loss. The results of this study demonstrated that bone area predicted medial and lateral cartilage defect development and medial cartilage volume loss, while subchondral BMD predicted medial defect development but not cartilage loss. These associations were independent of each other, indicating there are multiple mechanisms by which subchondral bone changes may lead to cartilage damage.

The relationship between knee adduction moment and cartilage and meniscus morphology in women with osteoarthritis

The aim of this cross-sectional study is to investigate the relationship between knee adduction moment and knee adduction angular impulse and meniscus, cartilage and bone morphology in women with knee osteoarthritis (OA). Forty-five women aged >40 years with OA in at least one knee, according to American College of Rheumatology clinical criteria were studied. The knee joint loading was assessed by three-dimensional motion analysis system during gait. Three Tesla magnetic resonance imaging (MRI) with a coronal T2-weighted spin echo sequence was used for evaluating meniscus pathology, and a coronal T1-weighted gradient echo sequence for quantifying cartilage morphology and bone surface size. Cartilage thickness, denuded area and subchondral area in the femorotibial joint was measured using custom software. A higher peak knee adduction moment was observed in participants with medial compared to those with lateral tears (2.92+/-1.06 vs -0.46+/-1.7, P<0.001). Participants with a higher knee adduction moment displayed a larger medial meniscus extrusion (r=0.532, P<0.001) and a lower medial meniscus height (r=-0.395, P=0.010). The inverse relationship was observed for the lateral meniscus. A higher knee adduction moment was also associated with a higher ratio of the medial to lateral tibial subchondral bone area (r=0.270, P=0.035). By contrast, cartilage thickness and denuded areas in the femur and tibia were not related to the knee adduction moment. Similar results were found for the relationship between knee adduction angular impulse and meniscus, cartilage and bone morphology. Dynamic knee joint loading is significantly related to meniscus pathology and bone size, but not to cartilage thickness in women with OA.

Meniscal extrusion predicts increases in subchondral bone marrow lesions and bone cysts and expansion of subchondral bone in osteoarthritic knees

Meniscal extrusion is often present in knees with OA, and has been associated with cartilage changes. It is unknown whether meniscal extrusion is related to subchondral bone. The aim of the study was to examine the relationship between meniscal extrusion and knee cartilage and subchondral bone, and also changes in these structures over 2 years in a cohort with mild to moderate knee OA. One hundred and seventeen subjects with knee OA entered the study and underwent MRI on their symptomatic knee at baseline and approximately 2 years later. Meniscal extrusion was assessed at baseline; tibial cartilage volume and plateau bone area, subchondral bone marrow lesions (BMLs) and bone cysts were measured at baseline and follow-up. At baseline, meniscal extrusion was associated with reduced tibial cartilage volume, increased tibial plateau area, increased prevalence of BMLs and bone cysts in both medial and lateral tibiofemoral compartments (all P < or = 0.001). Baseline medial meniscal extrusion was associated with increased expansion of tibial plateau bone (P = 0.04), increases in BMLs (P = 0.02) and bone cysts (P = 0.003) in the medial tibiofemoral compartment over 2 years. Meniscal extrusion predicts increases in subchondral bone lesions and tibial plateau bone expansion in patients with knee OA. These data suggest that subchondral bone changes are an early consequence of meniscal extrusion. This may reflect the impaired ability of an extruded meniscus to optimally distribute mechanical loading across the tibial plateau.

Endogenous glucocorticoid signalling in osteoblasts is necessary to maintain normal bone structure in mice

The role of endogenous glucocorticosteroids (GC) in bone development is ill-defined. Using the Col2.3-11βHSD2 transgenic (tg) mouse model, we examined the effect of osteoblast-targeted disruption of intracellular GC signalling on bone growth and strength, and its modulation by factors such as age, gender and skeletal site.Tibiae and L3 vertebrae of 3 and 7-week-old, male and female wild type (WT) mice and their tg, age and sex matched littermates were analysed by micro-CT and mechanical testing. Data were analysed separately for 3 and 7-week-old mice by 2-way ANOVA using genotype (WT, tg), gender and their interactions as factors.Transgenic mice were characterised by lower bone volume, lower trabecular number and higher trabecular separation in tibial trabecular bone, as well as lower tibial cortical bone area and periosteal and endosteal perimeters. These changes resulted in a marked decrease in mechanical bone strength and stiffness in sexually mature, 7-week-old mice. In the tibia, the observed transgene effect was present in 3 and 7-week-old animals, indicating that the biological effect of disrupted GC signalling was independent of sexual maturity. This was not the case for the vertebral bones, where significant differences between tg and WT mice were seen in 7 but not in 3-week-old animals, suggesting that the effects of the transgene at this site may be modulated by age and/or changes in circulating sex hormone levels.Taken together, our results demonstrate that endogenous glucocorticoids may be required for normal bone growth but that their effect on bone structure and strength varies according to the skeletal site and sexual maturity of the animals.

Geometric characters of the radius and tibia in Macaca mulatta and Macaca fascicularis

We performed comparative analyses of four cross-sections of the distal radius and tibia in two species of macaque to clarify the relationships between bone morphology and locomotor type. The lengths of bones and five bone geometric properties in each section were examined and compared separately in both female and male Macaca mulatta and Macaca fascicularis. In M. mulatta, there were no significant gender-specific differences in either the radius or the tibia. In contrast, the radius and tibia of male M. fascicularis had greater geometric parameters in the 20% and 40% positions relative to the 5% and 10% positions from the distal end than those of their female counterparts. The radius and tibia of M. mulatta were relatively longer than those of M. fascicularis, and the sectional parameters of the tibia of M. mulatta were relatively larger than those of M. fascicularis. Standardization of the log-transformed bone length between the species revealed larger radial cortical bone areas in M. fascicularis. In contrast, there were minimal differences in the tibial cortical bone areas between the two species. This study suggests that the observed distinctions in bone geometry in female and male M. fascicularis may be due to gender-specific differences in the muscle weights of the forearm and calf, which may underlie the divergence in the leaping abilities of females and males of this species. Taken together, these results of interspecies comparisons may be related to the fact that arboreal primates such as M. fascicularis undergo compressive mechanical stress due to the forelimb lead that occurs as the animal descends a sloping trunk or bridges a tree gap downward, while terrestrial primates such as M. mulatta move on nearly flat substrates. Differences in fore- and hind-limb bone properties between the two species are discussed with regard to functional morphology and locomotor type.