Learning objectives
Review the anatomy andfunction of the knee extensor mechanism in detail.
Identify common pathology involving the knee extensor mechanism.
Discuss imaging andpathology associated with the knee extensor mechanism.
Background
The extensor mechanism of the knee allows us to extend our knee joint,
which is crucial for maintaining a standing position,
rising from a sitting position,
and ascending/descending stairs.
The extensor mechanism consists of various anatomical structures such as the quadriceps muscle,
patella,
patellar tendon,
anterior fat pad,
and medial and lateral retinaculum complexes.
Pathology involving the extensor mechanism can be due to pathologic conditions of the patella (such as fractures or dislocations), avulsion fractures of the patellar tendon attachments (such as Osgood-Schlatter syndrome),
disruptions...
Imaging findings OR Procedure Details
Quadriceps Injury
The anterior thigh is comprised of 4 muscles: the rectus femoris,
vastus medialis,
vastus lateralis,
and vastus intermedius.
These muscles insert in the patella by the quadriceps tendon.
Tear of the quadriceps occurs when any of these four muscles or its conjoined tendon are involved.
Injuries present as tendinopathy,
intramuscular injury,
partial or complete disruption of the distal myotendinous units of the quadriceps muscle.
Involves most commonly the vastus intermedius and usually occurs at or proximal to the patellar insertion.
Presentation
Patient presents...
Conclusion
The extensor mechanism is a vital component of our knee joint and is involved in our biomechanics.
It is susceptibleto different pathologic processes.
Understanding extensor mechanism pathology will aid radiologists in diagnosing knee injuries accurately.
References
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Displaced Patella Fractures.
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Dupuis C,
Westra S,
Makris J,
Wallace E.
Injuries and Conditions of the Extensor Mechanism of the Pediatric Knee.
RadioGraphics.
2009;29(3):877-886.
doi:10.1148/rg.293085163.
Gao G,
Mahadev A,
Lee E.
Sleeve Fracture of the Patella in Children.
Journal of Orthopaedic Surgery.
2008;16(1):43-46.
doi:10.1177/230949900801600111.
Gilmore J,
Clayton-Smith Z,
Aguilar M,
Pneumaticos S,
Giannoudis P.
Reconstruction techniques and clinical results of patellar tendon ruptures: Evidence today.
The Knee.
2015;22(3):148-155.
doi:10.1016/j.knee.2014.10.007.
Hak D,
Sanchez A,
Trobisch P.
Quadriceps...