This illustration of the posterolateral corner gives an idea that this region has a complicated anatomy.
How does one injure the posterolateral corner?
The posterolateral corner is most commonly injured in an accident involving a blow to the opposite side of the knee, that is to the front of the knee on the medial side. It can also be damaged by hyperextension or by the knee being forced into varus (ie. bowed outwards).
"....Injuries to the posterolateral corner (PLC)....are most commonly associated with athletic trauma, motor vehicle accidents, and falls...."
What are the signs and symptoms of posterolateral corner damage?
Symptoms of posterolateral corner disruption may be vague and confusing.
There may be bruising initially in the posterolateral area, and outward bowing when the person takes weight on that side. There are general feelings that the knee cannot be trusted. Stairs may be a particular problem. Feelings of instability and 'giving way' may be experienced. Damage to the fibular nerve may cause numbness or tingling of the foot and a foot drop and 'slapping' gait.
"....there is commonly a diffuse tenderness over the posterolateral knee and the fibular head due to irritation of the PLC structures, knee capsule, and common fibular nerve...."
"....an abnormal gait pattern may develop which the patient cannot compensate for. During the initial contact and loading phase of gait, the knee may suddenly angulate in a varus direction (known as a varus thrust gait)...."
What posterolateral corner structures are most commonly injured?
Structures in the PLC may be damaged individually or several structures may be damaged at once.
"....Three primary static stabilizing structures form the PLC: the fibular (or lateral) collateral ligament, the popliteus tendon, and the popliteofibular ligament...."
Why is the posterolateral corner an issue with ACL reconstruction?
An ACL reconstruction is highly likely to fail if the surgeon has not addressed PLC laxity due to damage to the structures there.
Diagnosis "....entails a detailed understanding about the posterolateral structures and function. A high level of suspicion is recommended based on the trauma setting and the patient symptoms. Failure to address this condition may place other reconstruction graft at risk...."
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