POSTERIOR CRUCIATE LIGAMENT TEAR

Posterior cruciate is intraarticular but extrasynovial ligament. It has important function to prevent posterior translation. Though PCL injury is not as common as ACL, but PCL deficiency complicates instability.
PCL can get injured by severe rotational injury (external or internal with valgus) or hyperextension.
During acute episode,
There is severe pain and inability to walk. Often, there is swelling due to haemarthrosis.
After the acute episode subsides, Patient complains of giving away

Signs
There is quadriceps wasting due to disuse. Flexion attitude occurs due to hamstring spasm. Incomplete extension is a common feature of painful unstable knee.

Stress tests
Posterior Drawers test
The manoeuvre tests for inadequacy of PCL. Knee is kept at 90 degrees.
A posterior sag is appreciated. Patient’s foot is stabilised. Upper end of tibia is grasped and glided posteriorly. Abnormal displacement of 5 mm means test is positive.

External Rotation Recurvatum test
Then manoeuvre tests stability of posterolateral corner. Knee is moved from 10 degrees of flexion to full extension. Knee is allowed to fall in hyperextension.
Triad of recurvatum, varus and external rotation makes test positive.

Investigation
Radiographs are usually negative. Some times small avulsions are seen. The OPD diagnosis is clinical. MRI shows clear and accurate images. PCL can be seen better, ACL. Diagnostic arthroscopy can be done.

Management
Posterior cruciate injury can be partial or complete tear. When diagnosed knee should be protected in cast. Though complete tear requires to be reconstructed , in young athletic man. The treatment of partial tear is still conservative.