Radiologists more accurately identify damage to knee cartilage by using four radiologic 'signs'

Feb 21 2006

Radiologists can make a more accurate preoperative diagnosis of damage to knee cartilage by using four radiologic 'signs', a recent study found.

Using the four signs to identify the extent and type of damage to knee cartilage makes interpreting MRIs with higher degrees of accuracy easier for any radiologist, regardless of their level of expertise.

During the course of this study, reviewers correctly identified 17 (89%) of 19 radial meniscal tears using the four radiologic signs: the truncated triangle, cleft, marching cleft, and the ghost meniscus. Each of these signs describes a unique type of tear and damage to the cartilage of the knee. These types of tears are categorized based upon the easily recognizable patterns which show up on MRIs.

A meniscal tear exposes the underlying cartilage of the knee and can lead to accelerated wear and arthritis from the decreased structural integrity of the knee joint. Fortunately some types of meniscal tears can be repaired. However, "radial tears are significant in that they frequently are irreparable, and even a relatively small tear can lead to advanced wear," said Keith Harper, MD, lead author of the study.

"It is advantageous to preoperatively identify potentially non-repairable meniscal tears, such as radial tears," said Dr. Harper. "When possible and practical, repairing the damaged cartilage is significantly preferred to its removal." Since treatment of meniscal tears is dependent on their configuration, size, and location, the characterization of the tear can help the surgeon and patient decide what type of surgery is necessary as well as what type of rehabilitation will be needed.

"Radiologists can look for and easily recognize the four radiologic 'signs' in order to prospectively identify radial tears. Using these four radiologic 'signs' increased the prospective characterization and sensitivity for the detection of radial tears from 37% to 89%," said Dr. Harper.

"We feel that by using the four signs, most radiologists who interpret knee MRIs should have a high degree of success of prospectively identifying radial meniscal tears," said Dr. Harper. "Since using the four signs is fairly easy, similar degrees of accuracy can be achieved by radiologists who may not be experts in the field of musculoskeletal radiology."

"Actually, we were surprised to find in the study that the knowledge of specific and more objective signs for radial tears was a great help for even musculoskeletal radiologists with extensive experience interpreting knee MRIs," said Dr. Harper.

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