Assessment of anterior subcutaneous hypersignal on proton-density-weighted MR imaging of the knee and relationship with anterior knee pain.
OBJECTIVE
The purpose of this study was to evaluate the prevalence of anterior subcutaneous hypersignal indicating edema on proton-density (PD)-weighted MRI of the knee and to determine whether reporting anterior edema is clinically relevant.


METHODS
One hundred and ninety-one knee MRIs from 162 patients were reviewed for anterior subcutaneous edema. There were 92 men and 70 women with a mean age of 41.72years±13.92 (SD) (range, 15-80years) years and a mean body weight of 75.94kg±12.54 (SD) (range, 50-130kg). The MRI findings were compared with patient age, gender, body weight, history of repetitive microtrauma and clinical findings. Patellar and trochlear chondropathy, medial plica, joint effusion, synovitis, infrapatellar fat-pad signal intensity, suprapatellar fat-pad signal intensity with mass effect, quadriceps and patellar tendon abnormalities were also reviewed.


RESULTS
An anterior hypersignal on PD-weighted MRI was detected in 158/191 MR examinations (82.7%) and 104 (84.6%) of these cases had histories of anterior knee pain. No correlation between anterior pain and anterior edema was found (P=0.42). Age (P<0.0001), weight (P<0.0001), and repetitive microtrauma (P=0.001) were identified as significant variables associated with anterior edema.


CONCLUSIONS
Anterior edema may be a physiological phenomenon or degenerative change related to patient age, weight, and knee movement or mechanics. It should not be reported as a pathological finding on MRI unless clinical findings support regional infection or inflammation.
Düzce University, Faculty of Medicine, Department of Radiology, Düzce, Turkey. Electronic address: nisaunlu@yahoo.com.
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Unlu
Düzce University, Faculty of Medicine, Department of Orthopaedic Surgery and Traumatology, Düzce, Turkey. Electronic address: yturhan_2000@yahoo.com.
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Turhan
Ankara Occupational Diseases Hospital, Department of Internal Medicine, Ankara, Turkey. Electronic address: mehmetkos@gmail.com.
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Kos
Düzce University, Faculty of Medicine, Department of Radiology, Düzce, Turkey. Electronic address: alpalpersafak@yahoo.com.
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Safak
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000000981:diagnostic imaging*; D002062:Bursitis / Q000000981:diagnostic imaging; D004487:Edema / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000000981:diagnostic imaging*; D007717:Knee / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D012189:Retrospective Studies; D040521:Subcutaneous Tissue / Q000000981:diagnostic imaging*; D055815:Young Adult
Bone edema; Bursitis; Knee; Magnetic resonance imaging (MRI)