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Joint shape may contribute to relationships between body weight and hip osteoarthritis: Findings from a cross sectional study in peri-menopausal women
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Abstracts / Osteoarthritis and Cartilage 24 (2016) S63eS534
vigorous physical activity was significantly associated with an increase in patella cartilage volume (B ¼ 0.06 [95%CI 0.01 to 0.11], p ¼ 0.032). Some participants demonstrated BML onset/progression at the medial tibia (30%), lateral tibia (23%), medial femur (9%) and lateral femur (19%) while others demonstrated an improvement in BMLs at the medial tibia (33%), lateral tibia (40%), medial femur (9%) and lateral femur (9%). However, there were no other statistically significant relationships between moderate-to-vigorous physical activity and BML change over 2 years. Conclusions: These preliminary findings suggest that 60 minutes of moderate-to-vigorous physical activity is associated with an increase of 3.6% patellar cartilage volume over the subsequent 2 years. This result may be encouraging and reflect a positive response of the patellar cartilage volume to time spent moderate-to-physical activity or conversely, reflect an adverse swelling response. A better understanding of the clinical relevance of an increase in patellar cartilage volume in this population is needed, so that these young individuals can be appropriately advised regarding intensity of exercise participation. 334 JOINT SHAPE MAY CONTRIBUTE TO RELATIONSHIPS BETWEEN BODY WEIGHT AND HIP OSTEOARTHRITIS: FINDINGS FROM A CROSS SECTIONAL STUDY IN PERI-MENOPAUSAL WOMEN B.G. Faber y, D. Baird y, J. Gregory z, R.J. Barr z, R.M. Aspden z, D.A. Lawlor y, C. Gregson y, J. Tobias y. y Univ. of Bristol, Bristol, United Kingdom; z Univ. of Aberdeen, Aberdeen, United Kingdom Purpose: Increased body weight has long been associated with an increased risk of osteoarthritis (OA). Although a direct effect of increased mechanical forces acting on the joint is generally held to be responsible, alterations in hip shape, which is associated with OA at this site, may contribute to this relationship. To address this question, we examined the relationship between body weight and hip shape in a large cohort of women around 50 years of age, in whom hip shape changes which are present are likely to represent risk factors for, rather than consequences of, hip OA. Methods: Avon Longitudinal Study of Parents and Children (ALSPAC) is a population based cohort based in the west of England established in 1991. Hip dual X-ray absorptiometry (DXA) scans were offered to all mothers attending research clinics held between 2008 and 2011. We analysed images using the statistical shape modelling (SSM) software SHAPE developed by the University of Aberdeen. The model used 58 points marking the proximal femur and acetabular eyebrow, followed by Procrustes analysis to adjust for any differences in size, location and rotation of the hip and then performed principal component (PC) analysis on these points. The top ten PCs (hip shape modes (HSM)) were selected. Each mode describes and quantifies a linearly independent variation of hip shape. Linear regression was used to analyse weight (exposure) against all hip shape modes (outcome). We present standardised coefficients adjusted for height and age. Results: Our analyses are based on 4465 females with a mean age of 48 years (range 34 to 61 years). The top ten modes examined demonstrated cumulative variance in hip shape of 80.74%. A strong association was seen between weight and HSM 2 (b 0.22, 95% CI 0.25, 0.19, p-value 1.5x10-46). HSM 2 explains 15% of the total variation in hip shape within our population. HSM 2 describes changes in acetabular coverage of the femoral head, such that greater weight is associated with changes suggestive of a pincer-type deformity (Fig 1). This mode is also associated with other changes including femoral shaft width and neck-shaft angle. In addition, a strong association was seen between weight and HSM 9 (b 0.15, 95% CI 0.18, 0.12, p-value 2.1x10-23). HSM 9 explains 2% of the total variation in hip shape within our population. HSM 9 describes changes in femoral head size and sphericity (Fig 2). Greater weight is associated with a flatter femoral head and a change in curvature to the femoral that resembles a camtype deformity. Conclusions: In women of an age prior to OA onset, greater body weight is associated with a higher risk of pincer and cam deformities, both of which are components of femoro-acetabular impingement which is a recognised risk factor for hip OA. In light of these findings, we speculate that increased body weight is associated with an increased risk of OA not only as a direct result of greater mechanical forces acting on the joint, but also as a consequence of associated alterations in hip shape.
Figure 1. Shape changes described by ±2 standard deviations of HSM 2.
Figure 2. Shape changes described by ±2 standard deviations of HSM 9.Ă
Abstracts / Osteoarthritis and Cartilage 24 (2016) S63eS534
vigorous physical activity was significantly associated with an increase in patella cartilage volume (B ¼ 0.06 [95%CI 0.01 to 0.11], p ¼ 0.032). Some participants demonstrated BML onset/progression at the medial tibia (30%), lateral tibia (23%), medial femur (9%) and lateral femur (19%) while others demonstrated an improvement in BMLs at the medial tibia (33%), lateral tibia (40%), medial femur (9%) and lateral femur (9%). However, there were no other statistically significant relationships between moderate-to-vigorous physical activity and BML change over 2 years. Conclusions: These preliminary findings suggest that 60 minutes of moderate-to-vigorous physical activity is associated with an increase of 3.6% patellar cartilage volume over the subsequent 2 years. This result may be encouraging and reflect a positive response of the patellar cartilage volume to time spent moderate-to-physical activity or conversely, reflect an adverse swelling response. A better understanding of the clinical relevance of an increase in patellar cartilage volume in this population is needed, so that these young individuals can be appropriately advised regarding intensity of exercise participation. 334 JOINT SHAPE MAY CONTRIBUTE TO RELATIONSHIPS BETWEEN BODY WEIGHT AND HIP OSTEOARTHRITIS: FINDINGS FROM A CROSS SECTIONAL STUDY IN PERI-MENOPAUSAL WOMEN B.G. Faber y, D. Baird y, J. Gregory z, R.J. Barr z, R.M. Aspden z, D.A. Lawlor y, C. Gregson y, J. Tobias y. y Univ. of Bristol, Bristol, United Kingdom; z Univ. of Aberdeen, Aberdeen, United Kingdom Purpose: Increased body weight has long been associated with an increased risk of osteoarthritis (OA). Although a direct effect of increased mechanical forces acting on the joint is generally held to be responsible, alterations in hip shape, which is associated with OA at this site, may contribute to this relationship. To address this question, we examined the relationship between body weight and hip shape in a large cohort of women around 50 years of age, in whom hip shape changes which are present are likely to represent risk factors for, rather than consequences of, hip OA. Methods: Avon Longitudinal Study of Parents and Children (ALSPAC) is a population based cohort based in the west of England established in 1991. Hip dual X-ray absorptiometry (DXA) scans were offered to all mothers attending research clinics held between 2008 and 2011. We analysed images using the statistical shape modelling (SSM) software SHAPE developed by the University of Aberdeen. The model used 58 points marking the proximal femur and acetabular eyebrow, followed by Procrustes analysis to adjust for any differences in size, location and rotation of the hip and then performed principal component (PC) analysis on these points. The top ten PCs (hip shape modes (HSM)) were selected. Each mode describes and quantifies a linearly independent variation of hip shape. Linear regression was used to analyse weight (exposure) against all hip shape modes (outcome). We present standardised coefficients adjusted for height and age. Results: Our analyses are based on 4465 females with a mean age of 48 years (range 34 to 61 years). The top ten modes examined demonstrated cumulative variance in hip shape of 80.74%. A strong association was seen between weight and HSM 2 (b 0.22, 95% CI 0.25, 0.19, p-value 1.5x10-46). HSM 2 explains 15% of the total variation in hip shape within our population. HSM 2 describes changes in acetabular coverage of the femoral head, such that greater weight is associated with changes suggestive of a pincer-type deformity (Fig 1). This mode is also associated with other changes including femoral shaft width and neck-shaft angle. In addition, a strong association was seen between weight and HSM 9 (b 0.15, 95% CI 0.18, 0.12, p-value 2.1x10-23). HSM 9 explains 2% of the total variation in hip shape within our population. HSM 9 describes changes in femoral head size and sphericity (Fig 2). Greater weight is associated with a flatter femoral head and a change in curvature to the femoral that resembles a camtype deformity. Conclusions: In women of an age prior to OA onset, greater body weight is associated with a higher risk of pincer and cam deformities, both of which are components of femoro-acetabular impingement which is a recognised risk factor for hip OA. In light of these findings, we speculate that increased body weight is associated with an increased risk of OA not only as a direct result of greater mechanical forces acting on the joint, but also as a consequence of associated alterations in hip shape.
Figure 1. Shape changes described by ±2 standard deviations of HSM 2.
Figure 2. Shape changes described by ±2 standard deviations of HSM 9.Ă