By G. Patrick Thomas, Jr., DC, DACBR
Radiographic examination of the knee is
often unrewarding, despite physical and orthopedic findings that clearly
indicate an abnormality. Much of the supporting anatomy of the knee
is invisible with conventional radiography, but more sophisticated techniques
can be used to demonstrate these important structures. Magnetic resonance
imaging is able to delineate the cruciate ligaments and menisci, providing
the clinician a more complete and accurate view of the patient’s condition.
Meniscal injuries are common, and lead
to symptoms such as crepitus and joint locking. Because of their
lack of a blood supply, injured menisci do not heal well, and tend to progression.
The spectrum of meniscal injuries ranges from mild internal degeneration
to frank tears. A convenient grading system is used to describe meniscal
injuries as seen with MRI.
The normal meniscus is a uniformly dark triangle with a sharp apex directed
I tears are identified as a small focal area of increased signal
intensity on T2-weighted images. The area of abnormality does not
extend to the joint surface. The clinical significance of these injuries
is questionable, but they may progress to more serious tears.
II injuries manifest as linear areas of increased signal intensity,
with no extension to the joint surface. They are similar to Grade
I tears both clinically and in regards to their significance for progression.
III: This meniscal injury extends to the joint surface, and
is associated with overt symptoms such as ‘popping’ and locking.
Untreated, they are likely to progress to Grade IV tears.
IV injuries are characterized by fragmentation of the meniscus,
and like the Grade III tear frequently produce crepitus and joint locking.
Grade I and II meniscal injuries are probably
best treated conservatively. It is important to identify and treat
these injuries. Without proper care they may progress to more advanced
Grade III and IV tears may require surgical
intervention. The alteration of the articular surfaces may precipitate
or hasten the development of degenerative changes in the affected joint.
Meniscal injuries are common, and often
go undiagnosed because of the lack of specific finding seen with conventional
radiography. MRI is a very effective tool for demonstrating lesions
of the menisci, giving the treating clinician much more information about
his patient than radiographs alone.
1. Edelman R and Hesselink J: Clinical
Magnetic Resonance Imaging, Philadelphia, WB Saunders, 1990
This article first appeared in the December
2001 issue of Missouri Chiropractor.
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