(Fig 2-D.07) Mimicking Cyclops Lesion, ACLR with Remnant Preservation, Stump Entrapment

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1️⃣ ACLR with Remnant Preservation: Cyclops-like Mass Lesions

✅ Observations from Arthroscopy

• Findings: Compared to the standard technique, ACLR (Anterior Cruciate Ligament Reconstruction) involving remnant preservation observed more cyclops-like mass lesions.
• Clinical Impact: Despite the increased observation of these lesions, they did not result in clinical symptoms such as extension limitation or pain on extension (Arthroscopy, 2011).

2️⃣ Stump Entrapment of the ACL

✅ Definition and Incidence

• Terminology: Stump entrapment of the ACL has been described as a preoperative cyclops lesion or a bell-hammer tear.
• It occurs more frequently in partial tears with disruption of the anteromedial bundle.

✅ Histological Similarities

• Comparison with Post-Operative Lesions: Many lesions identified in adult studies on stump entrapment showed histological characteristics similar to those seen in post-operative cyclops lesions. The resultant impingement from these lesions leads to inflammation and the deposition of fibrous tissue.

✅ Imaging Characteristics

• MR Imaging Findings: The entrapped ACL stump typically exhibits a hypointense to intermediate signal on intermediate-weighted MR imaging and a heterogeneously hypointense to slightly hyperintense signal on T2-weighted sequences.
• Clinical Consequences: Displacement of a portion of the torn ACL into the intercondylar notch, known as ACL stump entrapment (SE), can cause locking or limitation of knee extension.

 

Pediatr Radiol (2011) 41:1040–1046

Radiology. 2016 Oct;281(1):23-40

Skeletal Radiol. 2016 Sep;45(9):1269-76

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