Cyclops Lesions & Nerve Injury
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Let's talk briefly about Cyclops lesions.
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These are referred to as nodular, um, intercondylar,
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localized arthrofibrosis.
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Um, these result in loss of terminal knee extension, um,
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and are considered in quotes, a complication
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of ACL reconstruction.
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And as Dr. Resnick referred to earlier,
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that these can be seen in the absence
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of ACL reconstructions.
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The etiology to this day is often debated, still
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possibly a metastatic, um, metaplastic reaction
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to the exposed ends of the ACL
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or possibly due to abnormal tunnel placement
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or the ACL reconstruction.
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The risks include surgery
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during the active inflammatory phase of the injury,
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so surgeons may elect to wait several weeks for the knee
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to cool off prior to performing an ACL reconstruction.
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Um, the more procedures, uh, you perform in the knee,
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the more likelihood for a cyclops lesion.
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And what are we looking for?
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Usually an intermediate nodular focus along the ant aspect
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of the intercondylar notch.
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And one study suggested that, uh, a
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nodular focus greater than 10 millimeters in at least one
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dimension was fairly accurate for the presence
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of a cyclops lesion.
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So here's what it might look like, sort of intermediate
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and signal intensity, uh, both on your T one
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and your uh, fluid sensitive sequences.
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This one a little bit brighter, uh,
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but sort of intermediate and signal intensity.
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And the reason of course, why it's called a cyclops lesion
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is an arthroscopy.
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It looks sort of like an eye staring at you.
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So this is the reconstructive ligament.
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And then here's the cyclops lesion.
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Kind of looking straight up at us on arthroscopy.
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We'll talk briefly finally, about nerve injuries
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that can occur around the knee.
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These are fairly common,
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at least from a clinical standpoint.
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You probably won't see them as much, uh,
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requiring MRI attention, but in some cases you may.
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And these are the kind of major
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nerves we want to think about.
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The laterals, cutaneous nerve and the saphenous nerve.
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And here is the sensory distribution
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of these nerves along the medial aspect of the knee
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and the lower leg, the saphenous nerve, the lateral aspect
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of the knee, the lateral sal cutaneous knee,
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and a small branch of the saphenous nerve that is the infra
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or infra patella branch of the nerve can be injured,
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particularly during patella tendon harvested harvests.
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So here's an example of an injury to the saphenous nerve.
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Normally this lives right underneath the Sartorius, so one
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of the pez tendons.
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So when they're going to grab the, uh, CEUs
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and the semi tendinosis with their tendon strippers,
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here you can see all the fibrosis.
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And this is a neuroma along the course
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of the saphenous nerve.
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This patient had pain and anesthesia at
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and below the level of this neuroma
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and went on to resection of the neuroma.
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What with resolution of their symptoms.
Donald Resnick, MD
Professor Emeritus, Department of Radiology
University of California, San Diego
Mini N. Pathria, MD, FRCP(C)
Division Chief, Musculoskeletal Imaging
University of California San Diego
Eric Y. Chang, MD
Adjunct Professor, Radiology
University of California, San Diego
Brady K. Huang, MD
Clinical Professor of Radiology
UC San Diego Medical Center
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