Posterolateral Corner(PLC) Injury of Knee.
* PLC Injury is Injury to the structures wich support and provides stability to PLC of knee
– Ligaments arising from posterolateral joint capsule
– Popliteus tendon and popliteofibular ligament (PFL)
– Fabellofibular ligament (FFL)
– Lateral gastrocnemius muscles and tendon
– fibular collateral ligament (FCL) and biceps femoris (BF) and their common insertion (conjoined tendon).
* Arcuate complex: Group of ligaments with common attachment to tip of fibular styloid: Arcuate, PFL, FFL
* Accounts for approximately 2% of all acute ligamentous injuries about the knee (2).
* T2WI FS MR in sagittal, axial and coronal planes with thin sections. Oblique coronal Plan parallel to long axis of popliteal tendon as seen on sagittal images improve the detection of posterolateral structures.
* Arcuate Ligament, FFL, PFL not always seen. BF, FCL, popliteus tendon constantly identifiable.
* Best diagnostic signs: Edema in PLC on T2WI FS MR. Obvious disruption of main ligamentous or tendinous structures in PLC
* Injury may manifest as only vague edema in PLC on T2WI FS MR .
* Arcuate sign on RG: Thin, curved cortical rim of bone avulsed from tip of fibular styloid, Insertion of arcuate complex.
* Biceps femoris/FCL/conjoined tendon injury: Avulsed fragment much larger than that associated with arcuate complex.
* Low-grade injury: Increased signal around tendon ± tendon thickening
* High-grade injury: Partial or complete tear or osseous avulsion from fibula
* Often, Associated abnormalities may dominate and Failure to recognize injury to the posterolateral structures in the acute setting can result in long-term disability.
– Cruciate ligament injury: If PCL injury overlooked, can result in ACL/PCL reconstruction failure and chronic posterolateral instability.
– Knee dislocation
– Impaction contusions in anterior aspects of medial femoral condyle and medial tibia
– Concomitant peroneal nerve damage: Axial FSE T2-weighted MRI Imaging may demonstrate abnormal signal (Hemorrhagic) about the peroneal nerve.
* Failure to recognize or not repaired High-grade injury to the posterolateral structures in the acute setting can result in long-term disability. Isolated Low-grade PLC injuries usually do well without surgical intervention.
Bibliography
1- Kirkland W. Davis, MD; Andrew Sonin, MD, FACR. Posterolateral Corner Injury in StatDx: Musculoskeletal > Diagnosis > Trauma > Knee > Ligamentous Pathology.
https://my.statdx.com/document/posterolateral-corner-injury/eec8209c-c225-4abb-925f-da5065ab377d
2- David A. Pacholke and co. MRI of the Posterolateral Corner Injury: A Concise Review. JOURNAL OF MAGNETIC RESONANCE IMAGING 26:250–255 (2007).
3- Posterolateral Corner Injury in Radiology Notes website:
http://radnotes.co.nz/musculoskeletal-imaging/knee_and_leg/#Posterolateral_Corner_Injury
4- Dr Amir Rezaee et al. Posterolateral corner injury of the knee in Radiopaedia website
https://radiopaedia.org/articles/posterolateral-corner-injury-of-the-knee