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1.  Meniscal pathology - the evidence for treatment 
Whilst arthroscopic surgery for the treatment of meniscal tears is the most commonly performed orthopaedic surgery, meniscal tears at the knee are frequently identified on magnetic resonance imaging in adults with and without knee pain. The evidence for arthroscopic treatment of meniscal tears is controversial and lacks a supporting evidence base; it may be no more efficacious than conservative therapies. Surgical approaches to the treatment of meniscal pathology can be broadly categorised into those in which partial menisectomy or repair are performed. This review highlights that the major factor determining the choice of operative approach is age: meniscal repair is performed exclusively on younger populations, while older populations are subject to partial menisectomy procedures. This is probably because the meniscus is less amenable to repair in the older population where other degenerative changes co-exist. In middle-aged to older adults, arthroscopic partial menisectomy (APM) may treat the meniscus tear, but does not address the degenerative whole organ disease of knee osteoarthritis. Thus far, there is no convincing evidence that operative approaches are superior to conservative measures as the first-line treatment of older people with knee pain and meniscal tears. However, in two randomised controlled trials (RCTs) approximately one-third of subjects in the exercise groups had persisting knee pain with some evidence of improvement following APM, although the characteristics of this subgroup are unclear. From the available data, a first-line trial of conservative therapy, which includes weight loss, is recommended for the treatment of degenerative meniscal tears in older adults. The exception to this may be when mechanical symptoms, such as knee locking, predominate. Although requiring corroboration by RCTs, there is accumulating evidence from cohort studies and case series that meniscal repair rather than APM may improve function and reduce the long-term risk of knee osteoarthritis in young adults. There is no clear evidence from RCTs that one surgical method of meniscal repair is superior to another.
doi:10.1186/ar4515
PMCID: PMC4060175  PMID: 25167471
2.  Physical inactivity is associated with narrower lumbar intervertebral discs, high fat content of paraspinal muscles and low back pain and disability 
Introduction
Although physical inactivity has been associated with numerous chronic musculoskeletal complaints, few studies have examined its associations with spinal structures. Moreover, previously reported associations between physical activity and low back pain are conflicting. This study examined the associations between physical inactivity and intervertebral disc height, paraspinal fat content and low back pain and disability.
Methods
Seventy-two community-based volunteers not selected for low back pain underwent magnetic resonance imaging (MRI) of their lumbosacral spine (L1 to S1) between 2011 and 2012. Physical activity was assessed between 2005 and 2008 by questionnaire, while low back pain and disability were assessed by the Chronic Pain Grade Scale at the time of MRI. Intervertebral disc height and cross-sectional area and fat content of multifidus and erector spinae were assessed from MRI.
Results
Lower physical activity levels were associated with a more narrow average intervertebral disc height (β −0.63 mm, 95% confidence interval (CI) −1.17 mm to −0.08 mm, P = 0.026) after adjusting for age, gender and body mass index (BMI). There were no significant associations between physical activity levels and the cross-sectional area of multifidus or erector spinae. Lower levels of physical activity were associated with an increased risk of high fat content in multifidus (odds ratio (OR) 2.7, 95% CI 1.1 to 6.7, P = 0.04) and high-intensity pain/disability (OR = 5.0, 95% CI 1.5 to 16.4, P = 0.008) after adjustment for age, gender and BMI.
Conclusions
Physical inactivity is associated with narrower intervertebral discs, high fat content of the multifidus and high-intensity low back pain and disability in a dose-dependent manner among community-based adults. Longitudinal studies will help to determine the cause and effect nature of these associations.
Electronic supplementary material
The online version of this article (doi:10.1186/s13075-015-0629-y) contains supplementary material, which is available to authorized users.
doi:10.1186/s13075-015-0629-y
PMCID: PMC4422596  PMID: 25947906
3.  Bone geometry of the hip is associated with obesity and early structural damage – a 3.0 T magnetic resonance imaging study of community-based adults 
Introduction
The mechanism by which obesity increases the risk of hip osteoarthritis is unclear. One possibility may be by mediating abnormalities in bony geometry, which may in turn be associated with early structural abnormalities, such as cartilage defects and bone marrow lesions.
Methods
One hundred and forty one older adults with no diagnosed hip osteoarthritis had weight and body mass index measured between 1990 and 1994 and again in 2009 to 2010. Acetabular depth and lateral centre edge angle, both measures of acetabular over-coverage, as well as femoral head cartilage volume, cartilage defects and bone marrow lesions were assessed with 3.0 T magnetic resonance imaging performed in 2009 to 2010.
Results
Current body mass index, weight and weight gain were associated with increased acetabular depth and lateral centre edge angle (all P ≤ 0.01). For every 1 mm increase in acetabular depth, femoral head cartilage volume reduced by 59 mm3 (95% confidence interval (CI) 20 mm3 to 98 mm3, P < 0.01). Greater acetabular depth was associated with an increased risk of cartilage defects (odds ratio (OR) 1.22, 95% CI 1.03 to 1.44, P = 0.02) and bone marrow lesions (OR 1.29, 95% CI 1.01 to 1.64, P = 0.04) in the central region of the femoral head. Lateral centre edge angle was not associated with hip structure.
Conclusions
Obesity is associated with acetabular over-coverage. Increased acetabular depth, but not the lateral centre edge angle, is associated with reduced femoral head cartilage volume and an increased risk of cartilage defects and bone marrow lesions. Minimising any deepening of the acetabulum (for example, through weight management) might help to reduce the incidence of hip osteoarthritis.
doi:10.1186/s13075-015-0631-4
PMCID: PMC4440504  PMID: 25925369
4.  Early cartilage abnormalities at the hip are associated with obesity and body composition measures – a 3.0T MRI community-based study 
Introduction
Although obesity is a risk factor for hip osteoarthritis (OA), the role of body composition, if any, is unclear. This study examines whether the body mass index (BMI) and body composition are associated with hip cartilage changes using magnetic resonance imaging (MRI) in community-based adults.
Methods
141 community-based participants with no clinical hip disease, including OA, had BMI and body composition (fat mass and fat free mass) measured at baseline (1990 to 1994), and BMI measured and 3.0 T MRI performed at follow-up (2009–2010). Femoral head cartilage volume was measured and femoral head cartilage defects were scored in the different hip regions.
Results
For females, baseline BMI (β = −26 mm3, 95% Confidence interval (CI) -47 to −6 mm3, p = 0.01) and fat mass (β = −11 mm3, 95% CI −21 to −1 mm3, p = 0.03) were negatively associated with femoral head cartilage volume. Also, while increased baseline fat mass was associated with an increased risk of cartilage defects in the central superolateral region of the femoral head (Odds Ratio (OR) = 1.08, 95% CI 1.00–1.15, p = 0.04), increased baseline fat free mass was associated with a reduced risk of cartilage defects in this region (OR = 0.82, 95% CI 0.67–0.99; p = 0.04). For males, baseline fat free mass was associated with increased femoral head cartilage volume (β = 40 mm3, 95% CI 6 to 74 mm3, p = 0.02).
Conclusions
Increased fat mass was associated with adverse hip cartilage changes for females, while increased fat free mass was associated with beneficial cartilage changes for both genders. Further work is required to determine whether modifying body composition alters the development of hip OA.
doi:10.1186/s13075-015-0618-1
PMCID: PMC4462003  PMID: 25897761
5.  Occupational risk factors for hip osteoarthritis are associated with early hip structural abnormalities: a 3.0 T magnetic resonance imaging study of community-based adults 
Introduction
Occupational exposure to heavy lifting and stair climbing are associated with radiographic hip osteoarthritis (OA). This study examined whether these activities are associated with early structural hip joint changes in a community-based population.
Methods
In total, 198 community-based people with no history of hip disease, including OA, had 3.0 T-magnetic resonance imaging (MRI) to assess hip cartilage volume, defects and bone marrow lesions (BMLs). Recall of occupational exposure to heavy lifting and stair climbing aged 18 to 30 years and in the previous 10 years were collected. A persistence score was defined as exposure at neither time point (0), at one time point (1) or at both time points (2).
Results
Exposure to heavy lifting when aged 18 to 30 years was associated with BMLs of the central superolateral femoroacetabular region (odds ratio (OR) 3.9, 95% confidence interval (CI) 1.6 to 9.8, P <0.01), with persistence score associated with cartilage defects in the central superolateral region of the femoral head (OR 1.6, 95% CI 1.0 to 2.5, P = 0.04). Exposure to stair climbing aged 18 to 30 years and persistence score were associated with an increased risk of cartilage defects in the central superolateral femoral head and BMLs in the central superolateral and posterior femoroacetabular regions (OR range 2.1 to 3.2, all P ≤0.03).
Conclusions
Occupational exposure to heavy lifting and stair climbing are associated with hip structural abnormalities. If confirmed by longitudinal data, such associations may explain how occupational activities affect the hip joint and may identify new targets for the prevention of hip OA.
doi:10.1186/s13075-015-0535-3
PMCID: PMC4342869  PMID: 25627648
6.  Structural changes of hip osteoarthritis using magnetic resonance imaging 
Introduction
Few data are available concerning structural changes at the hip observed by magnetic resonance imaging (MRI) in people with or without hip osteoarthritis (OA). The aim of this study was to compare cartilage volume and the presence of cartilage defects and bone marrow lesions (BMLs) in participants with and without diagnosed hip OA.
Methods
Femoral head cartilage volume was measured by MRI for 141 community-based persons with no diagnosed hip OA, and 19 with diagnosed hip OA. Cartilage defects and BMLs were regionally scored at the femoral head and acetabulum.
Results
Compared with those without diagnosed hip OA, people with diagnosed hip OA had less femoral head cartilage volume (1763 mm3 versus 3343 mm3; p <0.001) and more prevalent cartilage defects and BMLs (all p ≤0.05) at all sites other than the central inferomedial region of the femoral head. In those with no diagnosed hip OA, cartilage defects in the anterior and central superolateral region of the femoral head were associated with reduced femoral head cartilage volume (all p ≤0.02). Central superolateral BMLs at all sites were associated with reduced femoral head cartilage volume (all p ≤0.003), with a similar trend occurring when BMLs were located in the anterior region of the hip (all p ≤0.08).
Conclusions
Compared with community-based adults with no diagnosed hip OA, people with diagnosed hip OA have less femoral head cartilage volume and a higher prevalence of cartilage defects and BMLs. For people with no diagnosed hip OA, femoral head cartilage volume was reduced where cartilage defects and/or BMLs were present in the anterior and central superolateral regions of the hip joint. Cartilage defects and BMLs present in the anterior and central superolateral regions may represent early structural damage in the pathogenesis of hip OA.
doi:10.1186/s13075-014-0466-4
PMCID: PMC4212104  PMID: 25304036
7.  Does an increase in body mass index over 10 years affect knee structure in a population-based cohort study of adult women? 
Arthritis Research & Therapy  2010;12(4):R139.
Introduction
Although obesity is a modifiable risk factor for knee osteoarthritis (OA), the effect of weight gain on knee structure in young and healthy adults has not been examined. The aim of this study was to examine the relationship between body mass index (BMI), and change in BMI over the preceding 10-year period, and knee structure (cartilage defects, cartilage volume and bone marrow lesions (BMLs)) in a population-based sample of young to middle-aged females.
Methods
One hundred and forty-two healthy, asymptomatic females (range 30 to 49 years) in the Barwon region of Australia, underwent magnetic resonance imaging (MRI) during 2006 to 2008. BMI measured 10 years prior (1994 to 1997), current BMI and change in BMI (accounting for baseline BMI) over this period, was assessed for an association with cartilage defects and volume, and BMLs.
Results
After adjusting for age and tibial plateau area, the risk of BMLs was associated with every increase in one-unit of baseline BMI (OR 1.14 (95% CI 1.03 to 1.26) P = 0.009), current BMI (OR 1.13 (95% CI 1.04 to 1.23) P = 0.005), and per one unit increase in BMI (OR 1.14 (95% CI 1.03 to 1.26) P = 0.01). There was a trend for a one-unit increase in current BMI to be associated with increased risk of cartilage defects (OR 1.06 (95% CI 1.00 to 1.13) P = 0.05), and a suggestion that a one-unit increase in BMI over 10 years may be associated with reduced cartilage volume (-17.8 ml (95% CI -39.4 to 3.9] P = 0.10). Results remained similar after excluding those with osteophytes.
Conclusions
This study provides longitudinal evidence for the importance of avoiding weight gain in women during early to middle adulthood as this is associated with increased risk of BMLs, and trend toward increased tibiofemoral cartilage defects. These changes have been shown to precede increased cartilage loss. Longitudinal studies will show whether avoiding weight gain in early adulthood may play an important role in diminishing the risk of knee OA.
doi:10.1186/ar3078
PMCID: PMC2945030  PMID: 20626854
8.  The association between subchondral bone cysts and tibial cartilage volume and risk of joint replacement in people with knee osteoarthritis: a longitudinal study 
Introduction
To examine the natural history of subchondral bone cysts and to determine whether knee cartilage loss and risk of joint replacement is higher in knees with cysts, compared with those with bone marrow lesions (BMLs) only or those with neither BMLs nor cysts.
Methods
The symptomatic knee in 132 subjects with knee osteoarthritis (OA) was imaged by using magnetic resonance imaging at baseline and 2 years later. Tibial cartilage volume, subchondral bone cysts, and BMLs were measured by using validated methods. Knee arthroplasty over a 4-year period was ascertained.
Results
Bone cysts were present in 47.7% of subjects, 98.1% of whom also had BMLs. Over a 2-year period, 23.9% of subjects had cysts progress, 13.0% developed new cysts, and 11.4% had cysts regress. Bone cysts at baseline were associated with lower medial and lateral tibial cartilage volume compared with those with BMLs only or those with neither (P for trend 0.004 and <0.001, respectively). Annual medial cartilage volume loss was greatest in those with bone cysts compared with those with BMLs only or those with neither (9.3%, 6.3%, and 2.6%, respectively; P for trend, <0.001). As the severity of bone abnormality in the medial compartment increased from no BMLs or cysts present, to BMLs only, to subchondral bone cysts present, the risk of knee replacement was increased (odds ratio, 1.99; 95% confidence interval (CI), 1.01 to 3.90; P = 0.05).
Conclusions
When cysts are present, cartilage loss and risk of knee replacement are higher than if only BMLs are present, suggesting that cysts identify those most likely to benefit from prevention of disease progression. As cysts can regress, they may also provide therapeutic targets in knee OA.
doi:10.1186/ar2971
PMCID: PMC2888209  PMID: 20356405
9.  Development of bone marrow lesions is associated with adverse effects on knee cartilage while resolution is associated with improvement - a potential target for prevention of knee osteoarthritis: a longitudinal study 
Introduction
To examine the relationship between development or resolution of bone marrow lesions (BMLs) and knee cartilage properties in a 2 year prospective study of asymptomatic middle-aged adults.
Methods
271 adults recruited from the Melbourne Collaborative Cohort Study, underwent a magnetic resonance imaging scan (MRI) of their dominant knee at baseline and again approximately 2 years later. Cartilage volume, cartilage defects and BMLs were determined at both time points.
Results
Among 234 subjects free of BMLs at baseline, 33 developed BMLs over 2 years. The incidence of BMLs was associated with progression of tibiofemoral cartilage defects (OR 2.63 (95% CI 0.93, 7.44), P = 0.07 for medial compartment; OR 3.13 (95% CI 1.01, 9.68), P = 0.048 for lateral compartment). Among 37 subjects with BMLs at baseline, 17 resolved. Resolution of BMLs was associated with reduced annual loss of medial tibial cartilage volume (regression coefficient -35.9 (95%CI -65, -6.82), P = 0.02) and a trend for reduced progression of medial tibiofemoral cartilage defects (OR 0.2 (95% CI 0.04, 1.09), P = 0.06).
Conclusions
In this cohort study of asymptomatic middle-aged adults the development of new BMLs was associated with progressive knee cartilage pathology while resolution of BMLs prevalent at baseline was associated with reduced progression of cartilage pathology. Further work examining the relationship between changes and BML and cartilage may provide another important target for the prevention of knee osteoarthritis.
doi:10.1186/ar2911
PMCID: PMC2875638  PMID: 20085624
10.  Total cholesterol and triglycerides are associated with the development of new bone marrow lesions in asymptomatic middle-aged women - a prospective cohort study 
Arthritis Research & Therapy  2009;11(6):R181.
Introduction
Given the emerging evidence that osteoarthritis (OA) may have a vascular basis, the aim of this study was to determine whether serum lipids were associated with change in knee cartilage, presence of bone marrow lesions (BMLs) at baseline and the development of new BMLs over a 2-year period in a population of pain-free women in mid-life.
Methods
One hundred forty-eight women 40 to 67 years old underwent magnetic resonance imaging (MRI) of their dominant knee at baseline and 2.2 (standard deviation 0.12) years later. Cartilage volume and BMLs were determined for both time points. Serum lipids were measured from a single-morning fasting blood test approximately 1.5 years prior to the MRI.
Results
The incidence of BML at follow-up was associated with higher levels of total cholesterol (odds ratio [OR] 1.84, 95% confidence interval [CI] 1.01, 3.36; P = 0.048) and triglycerides (OR 8.4, 95% CI 1.63, 43.43; P = 0.01), but not high-density lipoprotein (HDL) (P = 0.93), low-density lipoprotein (LDL) (P = 0.20) or total cholesterol/HDL ratio (P = 0.17). No association between total cholesterol, triglycerides, HDL, LDL or total cholesterol/HDL ratio and presence of BMLs at baseline or annual change in total tibial cartilage volume was observed.
Conclusions
In this study of asymptomatic middle-aged women with no clinical knee OA, serum cholesterol and triglyceride levels were associated with the incidence of BMLs over 2 years. This provides support for the hypothesis that vascular pathology may have a role in the pathogenesis of knee OA. Further work is warranted to clarify this and whether treatments aimed at reducing serum lipids may have a role in reducing the burden of knee OA.
doi:10.1186/ar2873
PMCID: PMC3003521  PMID: 19961577
11.  Reduced rates of primary joint replacement for osteoarthritis in Italian and Greek migrants to Australia: the Melbourne Collaborative Cohort Study 
Introduction
Racial and ethnic disparities in rates of total joint replacement have been described, but little work has been done in well-established migrant groups. The aim of this study was to compare the rates of primary joint replacement for osteoarthritis for Italian and Greek migrants to Australia and Australian-born individuals.
Methods
Eligible participants (n = 39,023) aged 27 to 75 years, born in Italy, Greece, Australia and the United Kingdom, were recruited for the Melbourne Collaborative Cohort Study between 1990 and 1994. Primary hip and knee replacement for osteoarthritis between 2001 and 2005 was determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry.
Results
Participants born in Italy and Greece had a lower rate of primary joint replacement compared with those born in Australia (hazard ratio [HR] 0.32, 95% confidence interval [CI] 0.26 to 0.39, P < 0.001), independent of age, gender, body mass index, education level, and physical functioning. This lower rate was observed for joint replacements performed in private hospitals (HR 0.17, 95% CI 0.13 to 0.23), but not for joint replacements performed in public hospitals (HR 0.96, 95% CI 0.72 to 1.29).
Conclusions
People born in Italy and Greece had a lower rate of primary joint replacement for osteoarthritis in this cohort study compared with Australian-born people, which could not simply be explained by factors such as education level, physical functioning, and weight. Although differential access to health care found in the population may explain the different rates of joint replacement, it may be that social factors and preferences regarding treatment or different rates of progression to end-stage osteoarthritis in this population are important to ethnic disparity.
doi:10.1186/ar2721
PMCID: PMC2714137  PMID: 19505315
12.  Dietary fatty acid intake affects the risk of developing bone marrow lesions in healthy middle-aged adults without clinical knee osteoarthritis: a prospective cohort study 
Introduction
Fatty acids have been implicated in osteoarthritis (OA), yet the mechanism by which fatty acids affect knee structure and consequently the risk of knee OA has not been fully elucidated. Higher intakes of fatty acids have been shown to be associated with the risk of bone marrow lesions (BMLs) in a healthy population. The aim of this study was to examine the association between fatty acid consumption and the incidence of BMLs in healthy middle-aged adults without clinical knee OA.
Methods
Two hundred ninety-seven middle-aged adults without clinical knee OA underwent magnetic resonance imaging (MRI) of their dominant knee at baseline. BMLs were assessed. Of the 251 participants with no BMLs in their knee at baseline, 230 underwent MRI of the same knee approximately 2 years later. Intakes of fatty acids were estimated from a food frequency questionnaire.
Results
Increased consumption of saturated fatty acids was associated with an increased incidence of BMLs over 2 years after adjusting for energy intake, age, gender, and body mass index (odds ratio of 2.56 for each standard deviation increase in dietary intake, 95% confidence interval 1.03 to 6.37, P = 0.04). Intake of monounsaturated or polyunsaturated fatty acids was not significantly associated with the incidence of BMLs.
Conclusions
Increased fatty acid consumption may increase the risk of developing BMLs. As subchondral bone is important in maintaining joint integrity and the development of OA, this study suggests that dietary modification of fatty acid intake may be one strategy in the prevention of knee OA which warrants further investigation.
doi:10.1186/ar2688
PMCID: PMC2714108  PMID: 19426478
13.  Relationship between body adiposity measures and risk of primary knee and hip replacement for osteoarthritis: a prospective cohort study 
Introduction
Total joint replacement is considered a surrogate measure for symptomatic end-stage osteoarthritis. It is unknown whether the adipose mass and the distribution of adipose mass are associated with the risk of primary knee and hip replacement for osteoarthritis. The aim of the present investigation was to examine this in a cohort study.
Methods
A total of 39,023 healthy volunteers from Melbourne, Australia were recruited for a prospective cohort study during 1990 to 1994. Their body mass index, waist circumference, and waist-to-hip ratio were obtained from direct anthropometric measurements. The fat mass and percentage fat were estimated from bioelectrical impedance analysis. Primary knee and hip replacements for osteoarthritis between 1 January 2001 and 31 December 2005 were determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry. Cox proportional hazards regression models were used to estimate the hazard ratios (HRs) for primary joint replacement associated with each adiposity measure.
Results
Comparing the fourth quartile with the first, there was a threefold to fourfold increased risk of primary joint replacement associated with body weight (HR = 3.44, 95% confidence interval (CI) = 2.83 to 4.18), body mass index (HR = 3.44, 95% CI = 2.80 to 4.22), fat mass (HR = 3.51, 95% CI = 2.87 to 4.30), and percentage fat (HR = 2.99, 95% CI = 2.46 to 3.63). The waist circumference (HR = 2.77, 95% CI = 2.26 to 3.39) and waist-to-hip ratio (HR = 1.46, 95% CI = 1.21 to 1.76) were less strongly associated with the risk. Except for the waist-to-hip ratio, which was not significantly associated with hip replacement risk, all adiposity measures were associated with the risk of both knee and hip joint replacement, and were significantly stronger risk factors for knee.
Conclusions
Risk of primary knee and hip joint replacement for osteoarthritis relates to both adipose mass and central adiposity. This relationship suggests both biomechanical and metabolic mechanisms associated with adiposity contribute to the risk of joint replacement, with stronger evidence at the knee rather than the hip.
doi:10.1186/ar2636
PMCID: PMC2688176  PMID: 19265513
14.  Vastus medialis cross-sectional area is positively associated with patella cartilage and bone volumes in a pain-free community-based population 
Arthritis Research & Therapy  2008;10(6):R143.
Introduction
Although vastus medialis and lateralis are important determinants of patellofemoral joint function, their relationship with patellofemoral joint structure is unknown. The aim of this study was to examine potential determinants of vastus medialis and lateralis cross-sectional areas and the relationship between the cross-sectional area and patella cartilage and bone volumes.
Methods
Two hundred ninety-seven healthy adult subjects had magnetic resonance imaging of their dominant knee. Vastus medialis and lateralis cross-sectional areas were measured 37.5 mm superior to the quadriceps tendon insertion at the proximal pole of the patella. Patella cartilage and bone volumes were measured from these images. Demographic data and participation in vigorous physical activity were assessed by questionnaire.
Results
The determinants of increased vastus medialis and lateralis cross-sectional areas were older age (P ≤ 0.002), male gender (P < 0.001), and greater body mass index (P ≤ 0.07). Participation in vigorous physical activity was positively associated with vastus medialis cross-sectional area (regression coefficient [beta] 90.0; 95% confidence interval [CI] 38.2, 141.7) (P < 0.001) but not with vastus lateralis cross-sectional area (beta 10.1; 95% CI -18.1, 38.3) (P = 0.48). The cross-sectional area of vastus medialis only was positively associated with patella cartilage volume (beta 0.6; 95% CI 0.23, 0.94) (P = 0.001) and bone volume (beta 3.0; 95% CI 1.40, 4.68) (P < 0.001) after adjustment for potential confounders.
Conclusions
Our results in a pain-free community-based population suggest that increased cross-sectional area of vastus medialis, which is associated with vigorous physical activity, and increased patella cartilage and bone volumes may benefit patellofemoral joint health and reduce the long-term risk of patellofemoral pathology.
doi:10.1186/ar2573
PMCID: PMC2656248  PMID: 19077298
15.  Association between meniscal tears and the peak external knee adduction moment and foot rotation during level walking in postmenopausal women without knee osteoarthritis: a cross-sectional study 
Introduction
Meniscal injury is a risk factor for the development and progression of knee osteoarthritis, yet little is known about risk factors for meniscal pathology. Joint loading mediated via gait parameters may be associated with meniscal tears, and determining whether such an association exists was the aim of this study.
Methods
Three-dimensional Vicon gait analyses were performed on the dominant knee of 20 non-osteoarthritic women, and the peak external knee adduction moment during early and late stance was determined. The degree of foot rotation was also examined when the knee adductor moment peaked during early and late stance. Magnetic resonance imaging was used to determine the presence and severity of meniscal lesions in the dominant knee.
Results
The presence (P = 0.04) and severity (P = 0.01) of medial meniscal tears were positively associated with the peak external knee adduction moment during early stance while a trend for late stance was observed (P = 0.07). They were also associated with increasing degrees of internal foot rotation during late stance, independent of the magnitude of the peak external knee adduction moment occurring at that time (P = 0.03). During level walking among healthy women, the presence and severity of medial meniscal tears were positively associated with the peak external knee adduction moment. Moreover, the magnitude of internal foot rotation was associated with the presence and severity of medial meniscal lesions, independent of the peak knee adductor moment during late stance.
Conclusion
These data may suggest that gait parameters may be associated with meniscal damage, although longitudinal studies will be required to clarify whether gait abnormalities predate meniscal lesions, or vice versa, and therefore whether modification of gait patterns may be helpful.
doi:10.1186/ar2428
PMCID: PMC2483448  PMID: 18492234
16.  High sensitivity C-reactive protein is associated with lower tibial cartilage volume but not lower patella cartilage volume in healthy women at mid-life 
Introduction
Elevated serum high sensitivity C-reactive protein (hsCRP) has been reported in established osteoarthritis (OA). The aim of this study was to determine whether serum levels of hsCRP are associated with the variation in tibial and patella cartilage volumes in women without evidence of OA.
Methods
Participants were recruited from a database established from the Australian electoral roll, and were aged 40 to 67 years, were not hysterectomized and had no significant knee pain or knee injury in the last 5 years. Tibial and patella cartilage volumes were measured from magnetic resonance imaging (MRI) of each woman's dominant knee and hsCRP measured in serum. Linear regression models were used to explore the major determinants of variation in both tibial and patella cartilage volume and to assess whether serum hsCRP made an independent contribution to variation in the volumes of cartilage in the two knee compartments.
Results
The mean age of the 176 participants was 52.3 ± 6.6 years. Compared with a standard model for tibial cartilage volume that included bone area, age, smoking and alcohol status, the addition of an hsCRP term made an independent negative contribution to variation in tibial cartilage volume, irrespective of whether body mass index (BMI) was included in the model or not. By contrast, using a similar approach, hsCRP did not contribute independently to variation in patella cartilage volume.
Conclusion
In asymptomatic women aged 40 to 67 years, serum hsCRP is independently negatively associated with the volume of tibial but not patella cartilage suggesting that subclinical inflammation may predispose to knee cartilage loss in the tibial compartment. This should be further assessed by a longitudinal study.
doi:10.1186/ar2380
PMCID: PMC2374464  PMID: 18312679
17.  What is the clinical and ethical importance of incidental abnormalities found by knee MRI? 
Introduction
Magnetic resonance imaging (MRI) is increasingly used to examine joints for research purposes. It may detect both suspected and unsuspected abnormalities. This raises both clinical and ethical issues, especially when incidental abnormalities are detected. The prevalence of incidental, potentially clinically significant abnormalities identified by MRI and their clinical significance in a population undergoing knee MRI in research studies are unknown.
Methods
We examined the prevalence of such lesions in healthy asymptomatic adults and those with symptomatic knee osteoarthritis (OA) undergoing knee MRI with limited sequences for the purpose of research. The MRI findings in 601 asymptomatic subjects and 132 with knee OA who underwent at least one limited knee MRI scan for cartilage volume measurement were examined by an MRI radiologist for the presence of potentially clinically significant abnormalities.
Results
These were present in 2.3% of healthy and 2.3% of OA subjects. All required further investigation to exclude non-benign disease, including four with bone marrow expansion (0.7%), requiring further investigation and management. A single potentially life-threatening lesion, a myeloma lesion, was identified in a subject with symptomatic knee OA on their second MRI scan in a longitudinal study.
Conclusion
As musculoskeletal MRI is increasingly used clinically and for research purposes, the potential for detecting unsuspected abnormalities that require further investigation should be recognized. Incorporating a system to detect these, to characterize unexpected findings, and to facilitate appropriate medical follow-up when designing studies using this technology should be considered ethical research practice.
doi:10.1186/ar2371
PMCID: PMC2374445  PMID: 18252003
18.  Factors that may mediate the relationship between physical activity and the risk for developing knee osteoarthritis 
Studies investigating the effect of physical activity on risk for developing osteoarthritis at weight-bearing joints have reported conflicting results. We examine evidence to suggest that this may be due to the existence of subgroups of individuals who differ in their response to physical activity, as well as methodological issues associated with the assessment of knee joint structure and physical activity. Recommendations for future studies of physical activity and the development of knee osteoarthritis are discussed.
doi:10.1186/ar2343
PMCID: PMC2374461  PMID: 18279536
19.  Effect of antioxidants on knee cartilage and bone in healthy, middle-aged subjects: a cross-sectional study 
The aim of the present study is to examine the effect of dietary antioxidants on knee structure in a cohort of healthy, middle-aged subjects with no clinical knee osteoarthritis.
Two hundred and ninety-three healthy adults (mean age = 58.0 years, standard deviation = 5.5) without knee pain or knee injury were selected from an existing community-based cohort. The intake of antioxidant vitamins and food sources by these individuals was estimated from a food frequency questionnaire at baseline. The cartilage volume, bone area, cartilage defects and bone marrow lesions were assessed approximately 10 years later using magnetic resonance imaging.
In multivariate analyses, higher vitamin C intake was associated with a reduced risk of bone marrow lesions (odds ratio = 0.50, 95% confidence interval (CI) = 0.29–0.87, P = 0.01) and with a reduction in the tibial plateau bone area (β = -35.5, 95% CI = -68.8 to -2.3, P = 0.04). There was an inverse association between fruit intake and the tibial plateau bone area (β = -27.8, 95% CI = -54.9 to -0.7, P = 0.04) and between fruit intake and the risk of bone marrow lesions (odds ratio = 0.72, 95% CI = 0.52–0.99, P = 0.05). Neither fruit intake nor vitamin C intake was significantly associated with the cartilage volume or cartilage defects. Lutein and zeaxanthin intake was associated with a decreased risk of cartilage defects (odds ratio = 0.71, 95% CI = 0.51–0.99, P = 0.04), and vitamin E intake tended to be positively associated with the tibial plateau bone area (β = 33.7, 95% CI = -3.1 to 70.4, P = 0.07) only after adjusting for vitamin C intake. The β-cryptoxanthin intake was inversely associated with the tibial plateau bone area after adjusting for vitamin E intake (β = -33.2, 95% CI = -63.1 to -3.4, P = 0.03). Intake of vegetables and other carotenoids was not significantly associated with cartilage or bone measures.
The present study suggests a beneficial effect of fruit consumption and vitamin C intake as they are associated with a reduction in bone size and the number of bone marrow lesions, both of which are important in the pathogenesis of knee osteoarthritis. While our findings need to be confirmed by longitudinal studies, they highlight the potential of the diet to modify the risk of osteoarthritis.
doi:10.1186/ar2225
PMCID: PMC2206367  PMID: 17617909
20.  Knee cartilage loss in symptomatic knee osteoarthritis over 4.5 years 
The objective of this study was to describe the rate of change in knee cartilage volume over 4.5 years in subjects with symptomatic knee osteoarthritis (OA) and to determine factors associated with cartilage loss. One hundred and five subjects were eligible for this longitudinal study. Subjects' tibial cartilage volume was assessed by magnetic resonance imaging (MRI) at baseline, at 2 years and at 4.5 years. Of 105 subjects, 78 (74%) completed the study. The annual percentage losses of medial and lateral tibial cartilage over 4.5 years were 3.7 ± 4.7% (mean ± SD; 95% confidence interval 2.7 to 4.8%) and 4.4 ± 4.7% (mean ± SD; 95% confidence interval 3.4 to 5.5%), respectively. Cartilage volume in each individual seemed to track over the study period, relative to other study participants. After multivariate adjustment, annual medial tibial cartilage loss was predicted by lesser severity of baseline knee pain but was independent of age, body mass index and structural factors. No factors specified a priori were associated with lateral cartilage volume rates of change. Tibial cartilage declines at an average rate of 4% per year in subjects with symptomatic knee OA. There was evidence to support the concept that tracking occurs in OA. This may enable the prediction of cartilage change in an individual. The only significant factor affecting the loss of medial tibial cartilage was baseline knee pain, possibly through altered joint loading.
doi:10.1186/ar1962
PMCID: PMC1779368  PMID: 16704746
21.  The determinants of change in tibial plateau bone area in osteoarthritic knees: a cohort study 
Arthritis Research & Therapy  2005;7(3):R687-R693.
Bone is integral to the pathogenesis of osteoarthritis (OA). Whether the bone area of the tibial plateau changes over time in subjects with knee OA is unknown. We performed a cohort study to describe this and identify factors that might influence the change. One hundred and twenty-six subjects with knee OA underwent baseline knee radiography and magnetic resonance imaging on their symptomatic knee. They were followed up with a repeatmagnetic resonance image of the same knee approximately 2 years later. The bone area of the tibial plateau was measured at baseline and follow-up. Risk factors assessed at baseline were tested for their association with change in tibial plateau bone area over time. One hundred and seventeen subjects completed the study. The medial and lateral tibial plateau bone areas increased by 2.2 ± 6.9% and 1.5 ± 4.3% per year, respectively. Being male (P = 0.001), having a higher body mass index (P = 0.002), and having a higher baseline grade of medial joint-space narrowing (P = 0.01) were all independently and positively associated with an increased rate of enlargement of bone area of the medial tibial plateau. A larger baseline bone area of the medial tibial plateau was inversely associated with the rate of increase of that area (P < 0.001). No factor examined affected the rate of increase of the bone area of the lateral tibial plateau. In subjects with established knee OA, tibial plateau bone area increases over time. The role of subchondral bone change in the pathogenesis of knee OA will need to be determined but may be one explanation for the mechanism of action of risk factors such as body mass index on knee OA.
doi:10.1186/ar1726
PMCID: PMC1174962  PMID: 15899054

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