A number of MRI signs are now associated with so-called "bucket-handle" meniscus tears in the knee, but researchers are continuing to look at which are the most frequent and accurate indicators of these often obscure yet debilitating injuries.
"Bucket-handle tears may not present at first in less severe tears, but can flip or present as locking later on, necessitating hasty surgical intervention," said Dr. Rosemary Klecker, a clinical instructor at Ohio State University in Columbus, OH, after presenting at the American Roentgen Ray Society meeting earlier this year. "These tears are serious and need to be diagnosed early in the injury."
To determine the incidence of five different MR signs of bucket-handle tears in the sagittal plane, Ohio State researchers identified all patients who had a knee MR exam during a five-year period. Patients who had prior surgery, meniscal anomalies, and penetrating trauma were excluded from the study. Only patients with an arthroscopic diagnosis of a bucket-handle tear were included.
In 40 of the 50 patients included in the study, the medial meniscus was torn; the lateral meniscus was torn in 10 cases. Two osteoradiologists retrospectively reviewed each MR exam for the following signs of a bucket-handle tear -- a double posterior cruciate ligament (PCL) sign, an intercondylar notch fragment, a flipped fragment sign, an absent meniscus sign, and an absent bow tie sign.
The combined sensitivity of all five signs was 96%. Three studies had one sign, while 13 had two findings. Nineteen exams had three signs, and 13 studies had four of the five signs. Two studies did not demonstrate a bucket-handle tear finding in the sagittal plane.
A double PCL sign was the most specific sign for a bucket-handle tear of the medial meniscus, while a displaced intercondylar notch fragment was the most specific for a lateral meniscal tear, Klecker said.
In a related presentation at the ARRS meeting, researchers from Asan Medical Center and Samsung Medical Center in Seoul, South Korea found that the intercondylar tibial cap sign on a sagittal MR image was particularly sensitive and fairly specific for the diagnosis of bucket-handle tears.
The South Korean researchers retrospectively reviewed 51 arthroscopically confirmed diagnoses (37 with bucket-handle tears and 14 without) that had been perceived as bucket-handle tears by MR and/or arthroscopy.
Two radiologists retrospectively reviewed the MR images and reached a conclusion by consensus. Evaluation of MR findings was focused on the presence of double PCL sign, flipped meniscus sign, fragment within intercondylar notch on coronal imaging, intercondylar tibial cap sign on sagittal imaging.
Double PCL sign was 29.7% sensitive, flipped meniscus sign was 43.2%, fragment within intercondylar notch was 91.9%, and intercondylar tibial cap sign was 94.6%, according to the study team. Double PCL sign was 100% specific, flipped meniscus sign was 71.4%, fragment within intercondylar notch was 14.3%, and intercondylar tibial cap sign was 71.4%.
The double PCL sign was observed only in lateral bucket-handle tears, according to Dr. Jeong Hyun Lee of Asan Medical Center. In the other three signs, the frequency between medial and lateral tears was not significantly different, she said.
By Erik L. Ridley
AuntMinnie.com staff writer
July 10, 2000
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