Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose:
Osteoarthritis (OA) commonly occurs in the patellofemoral joint (PFJ) and knee pain in subjects with knee OA often emanates from the PFJ rather than the tibiofemoral joint (TFJ). Despite this, research into risk factors and mechanisms for PFJ OA is limited compared to that of the TFJ. Mediopatellar plica (MPP) is often observed in conjunction with patello-femoral structural damage and plica syndrome is a common cause of knee pain. However, it is unclear if MPP is an independent risk factor for structural PFJ damage or if MPP is an incidental finding of questionable relevance. Our aim was to describe the frequency of different types of MPP in a cohort of subjects with knee pain and to assess the cross-sectional association of MPP with cartilage damage and bone marrow lesions (BMLs) in the PFJ.
Methods:
177 subjects aged 35-65 with chronic, frequent knee pain were included. 3T MRI of both knees was performed and a total of 342 knees were included. MPP was scored as Types A, B, and C according to a grading system modified from the Sakakibara arthroscopic classification, which takes into account the relative size of the plica in relation to the osteochondral junction of the anterior medial trochlea. Using the Whole Organ Magnetic Resonance Imaging Score (WORMS) system, cartilage (graded 0 to 6) and BMLs (graded 0 to 3) were semiquantitatively assessed for the medial patella, medial trochlea, lateral patella, and lateral trochlea. In addition Hoffa-synovitis and effusion-synovitis were scored from 0 to 3. Anatomical measurements of the PFJ that are potential risk factors for cartilage loss included the patellar length ratio (PLR), lateral patellar tilt angle (LPTA), bisect offset (BO), and sulcus angle (SA) on MR images. The frequencies of each type of MPP were recorded. Further, presence of MPP (any type) and its cross-sectional association with cartilage damage (defined as WORMS score ≥2) and BMLs (defined as WORMS score ≥1) in the PFJ was assessed using logistic regression. Adjustment was made for age, gender, body mass index (BMI), PLR, LPTA, BO, SA, and Hoffa- and effusion-synovitis.
Results:
The mean age of subjects was 52 (SD±6) years, 95 (53.7%) were men, 160 (90.4%) were white and 144 (81.4%) had a BMI ≥25. Altogether 163 (47.7%) knees exhibited MPP (76 knees (22.2%) were Type A, 69 knees (20.2%) were Type B, and 18 knees (5.3%) were Type C). Significant cross-sectional associations between MPP and cartilage damage were observed for the medial patella (adjusted odds ratio (aOR) 2.12, 95% CI 1.23-3.64), but not for the medial trochlea or the lateral PFJ. No associations were found for MPP and presence of BMLs in the medial and lateral patellofemoral compartments.
Conclusion:
Type A and B plicae were common while type C plicae were less common. The presence of MPP is cross-sectionally associated with medial patellar cartilage damage. No increased risk was observed for presence of MPP and cartilage damage at the medial trochlea or the lateral compartment. No associations were found between MPP and BMLs in any of the PF subregions. The latter finding might be explained by different loading conditions in the PFJ in comparison to the TFJ.
Disclosure:
L. Xu,
None;
D. Hayashi,
None;
A. Guermazi,
Boston Imaging Core Lab,
1,
Stryker,
5,
Merck Serono,
5,
Genzyme Corporation,
5,
AstraZeneca,
5,
Novartis Pharmaceutical Corporation,
5;
C. K. Kwoh,
AstraZeneca,
2,
Beverage Institute,
2,
Novartis Pharmaceutical Corporation,
5,
Pfizer Inc,
5;
M. J. Hannon,
None;
M. Jarraya,
None;
C. E. Moore,
None;
J. M. Jakicic,
None;
S. M. Green,
None;
F. Roemer,
Boston Imaging Core Lab,
1,
National Institute of Health,
5,
Merck Serono,
5.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/frequency-of-mediopatellar-plica-in-persons-with-chronic-knee-pain-and-its-cross-sectional-association-with-patellofemoral-cartilage-damage-and-bone-marrow-lesions-data-from-the-joints-on-glucosamine/