PCL is the primary restraint to posterior drawer and secondary restraint to external rotation. This information is critical for diagnostic purposes, as well as for the restoration of normal knee stability after PCL injury.
Posterior cruciate ligament injuries may be classified with respect to timing (acute versus chronic) and severity of injury (isolated or combined), and both variables will directly affect the treatment and prognosis. Generally speaking, isolated PCL injuries may be treated nonoperatively and have an excellent prognosis. Combined ligament injuries involving the PCL, however, have a more guarded prognosis. In general, surgical repair or reconstruction in combined injuries within the first 3 weeks has superior results to conservative management.
Hyperflexion of the knee, the most common mechanism for an isolated PCL injury. A patient who is seen with a swollen, painful knee after a traumatic incident in which one cannot perform a complete examination should have a PCL injury ruled out by other diagnostic techniques (for example, MRI). The patient will usually also have discomfort with flexion and the posterior drawer examination will be relatively straightforward with a positive posterior tibial subluxation of various degrees.