Medial Supporting Structures of the Knee with Emphasis on the Medial Collateral Ligament.

A) Anatomy:

The medial supporting structures of the knee can be divided into layers,  superficial, intermediate, and deep (Figure 1).

Superficial layer (layer I): formed from deep crural fascia.
Beneath layer I, the gracilis and semitendinosus tendons can be found. 
The anterior portion of the medial supporting structures consists of the medial retinacular ligaments and pes anserinus tendons.The pes anserinus bursa is deep to the pes anserinus tendons and superficial to the TCL; when inflamed, the distended pes anserinus bursa produces a mass along the medial or anteromedial aspect of the proximal portion of the tibia (Figure 2).

Middle layer (layer II):Medial collateral ligament; anterior fuses with superficial layer to form medial patellar retinaculum.

Deep layer (layer III): Deep medial capsular ligament and joint capsule.


B)Grading:
The grade scale includes tibial collateral ligament and deep medial capsular ligament as follow:
-Grade I: Peri-ligamentous fluid collection around tibial collateral ligament.
-Grade II: Complete disruption of TCL with normal DMCL.
-Grade III: Disruption of both ligaments.



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