Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose: Past investigations into risk factors for patellofemoral joint (PFJ) osteoarthritis (OA) have been limited by the use of radiography, which is insensitive to identify PFJ OA and have focused on only a few risk factors. MRI offers a unique opportunity to directly visualize tissue damage in the PFJ, and risk factors related to medial PFJ damage, which was recently reported as common (Gross, ARD, 2012), can be distinguished from those related to lateral damage. The purpose of this study is to evaluate the association between PFJ structural damage on MRI with a wide spectrum of risk factors including: demographic, modifiable, structural, and biomechanical factors.
Methods: We analyzed data from the baseline exam of MOST, a NIH-funded cohort study of persons aged 50-79 years with or at risk for knee OA. Knees for this study came from persons with x-ray OA in tibiofemoral joint and/or PFJ. Demographic risk factors included age, sex, and race. Modifiable risk factors included BMI, occupational history, quadriceps strength, and hamstring-quadriceps strength ratio. Structural risk factors included Insall-Salvati ratio (measure of patella alta), lateral trochlear inclination (measure of trochlear morphology), and femur length. Biomechanical risk factors included varus and valgus alignment (from long limb x-rays). Cartilage damage and bone marrow lesions (BMLs) were assessed on MRI using the WORMS scale in 4 regions (medial and lateral patella and trochlea). PFJ structural damage was defined in two ways: 1) full-thickness cartilage loss (WORMS 2.5; ³5 on a 0-6 scale) and 2) full-thickness cartilage loss in addition to a BML (³1 on a 0-3 scale). We examined the cross-sectional association between risk factors and PFJ structural damage using logistic regression with GEE to account for the correlation between regions from the same knee. We performed analyses in the PFJ overall (damage in any of the four regions) and for the medial and lateral PFJ separately.
Results: 1268 regions from 317 knees were studied (mean age 63.5 years, mean BMI 30.5 kg/m2, 67% female). Full-thickness cartilage damage was present in any PFJ region, medial, and lateral in 20%, 16%, and 25% of regions, respectively. The hamstring-quadriceps ratio, Insall-Salvati ratio, and lateral trochlear inclination demonstrated the strongest associations with overall and lateral PFJ damage (see table). Females and older subjects were more likely to have medial but not lateral PFJ damage. Femur length was strongly associated with lateral PFJ damage. Similar results were seen for the PFJ damage definition including a BML.
Conclusion: PFJ structural damage is more strongly related to structural and demographic factors than to modifiable ones. Risk factors may be different for medial and lateral PFJ structural damage. Future studies should evaluate risk factors separately for medial and lateral PFJ damage.
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Association between demographic, modifiable, structural, and biomechanical risk factors and full-thickness cartilage damage (WORMS 2.5; ³5) in the PFJ |
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Any PFJ
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Medial PFJ
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Lateral PFJ
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OR (95% CI) |
OR (95% CI) |
OR (95% CI) |
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Demographic risk factors
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Age (per 10 years) |
1.3 (1.1, 1.7)
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1.7 (1.2, 2.4)
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1.2 (0.8, 1.8) |
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Sex (Reference=Male) |
1.4 (0.9, 2.1) |
2.9 (1.5, 5.6)
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0.9 (0.5, 1.7) |
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Race |
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Other (Reference) |
1.0 |
1.0 |
1.0 |
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African American |
0.9 (0.4, 1.7) |
0.6 (0.2, 1.4) |
1.1 (0.4,2.9) |
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Modifiable risk factors
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BMI (per 5 units) |
1.1 (0.9, 1.3) |
1.2 (0.9, 1.5) |
1.0 (0.7, 1.3) |
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Occupational history |
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No labor (Reference) |
1.0 |
1.0 |
1.0 |
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Labor |
1.0 (0.6, 1.5) |
1.2 (0.7, 2.2) |
0.8 (0.4, 1.7) |
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Other |
1.0 (0.6, 1.5) |
0.7 (0.4, 1.4) |
1.3 (0.7, 2.4) |
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History of knee injury (Reference=none) |
0.4 (0.3, 0.7)
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0.4 (0.2, 0.7)
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0.4 (0.2, 0.9)
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History of knee surgery (Reference=none) |
0.8 (0.5, 1.5) |
1.0 (0.5, 2.2) |
0.6 (0.3, 1.5) |
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Quadriceps strength |
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Tertile 1 (Weak) |
1.5 (1.0, 2.4)
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1.4 (0.7, 2.9) |
1.9 (0.9, 3.7) |
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Tertile 2 |
1.6 (1.0, 2.4)
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1.8 (1.0, 3.4)
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1.6 (0.8, 3.2) |
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Tertile 3 (Reference) |
1.0 |
1.0 |
1.0 |
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Hamstring-quadriceps strength ratio |
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Tertile 1 (Reference; Low) |
1.0 |
1.0 |
1.0 |
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Tertile 2 |
0.8 (0.5, 1.3) |
0.8 (0.5, 1.5) |
0.8 (0.4, 1.6) |
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Tertile 3 (High) |
1.8 (1.2, 2.6)
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1.1 (0.6, 1.9) |
2.9 (1.5, 5.6)
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Structural risk factors
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Insall-Salvati Ratio |
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Tertile 1 (Reference) |
1.0 |
1.0 |
1.0 |
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Tertile 2 |
1.2 (0.8, 1.8) |
1.2 (0.7, 2.1) |
1.3 (0.7, 2.6) |
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Tertile 3 (Patella alta) |
1.5 (1.0, 2.4)
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1.1 (0.6, 2.0) |
2.2 (1.1, 4.1)
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Lateral trochlear inclination |
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Tertile 1 (Flat trochlea) |
1.0 (0.6, 1.5) |
0.7 (0.4, 1.4) |
4.4 (2.1, 9.4)
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|
Tertile 2 |
1.8 (1.1, 2.7)
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0.9 (0.5, 1.7) |
1.1 (0.5, 2.2) |
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Tertile 3 (Reference) |
1.0 |
1.0 |
1.0 |
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Femur length |
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Tertile 1 (Reference; Short) |
1.0 |
1.0 |
1.0 |
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Tertile 2 |
1.3 (0.9, 2.1) |
0.8 (0.5, 1.4) |
2.5 (1.2, 5.3)
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|
Tertile 3 (Long) |
1.3 (0.8, 2.0) |
0.6 (0.3, 1.2) |
2.8 (1.3, 6.0)
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Biomechanical risk factors |
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Frontal plane knee alignment |
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Neutral (Reference) |
1.0 |
1.0 |
1.0 |
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Valgus |
1.5 (0.97, 2.4) |
1.1 (0.5, 2.4) |
2.2 (1.1, 4.3) |
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Varus |
0.9 (0.6, 1.3) |
1.3 (0.7, 2.4) |
0.6 (0.3, 1.1) |
Disclosure:
J. J. Stefanik,
None;
K. Wang,
None;
K. D. Gross,
None;
F. Roemer,
Boston Imaging Core Lab,
1,
National Institute of Health,
5,
Merck Serono,
5;
J. A. Lynch,
None;
N. Segal,
None;
C. E. Lewis,
None;
M. C. Nevitt,
None;
A. Guermazi,
BICL, LLC,
4,
AstraZeneca, Genzyme, Novartis, and MerckSerono,
5;
D. T. Felson,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-association-of-demographic-modifiable-structural-and-biomechanical-risk-factors-with-medial-and-lateral-patellofemoral-joint-structural-damage-on-mri-the-multicenter-osteoarthritis-study/