Clinical evaluation of posterior cruciate ligament and posterolateral corner insufficiency

Injuries to the posterior cruciate ligament (PCL), and more commonly to the posterolateral corner (PLC), often gounrecognized. If present, posterolateral instability left untreated can compromise the results of anterior cruciate ligament or PCL reconstruction. Disruption of the PCL does not significantly increase internal or external tibial rotation. If increased external tibial rotation is present, there has been an injury to the PLC structures and the correction of the problem cannot be accomplished by cruciate ligament reconstruction alone. Appropriate recognition and treatment of posterolateal instability can restore normal rotatory motion patterns and can also reduce the stresses on cruciate ligament grafts, improving chances for successful results. The detection of posterolateral instability is best accomplished with the Dial test. PCL laxity is best detected by the posterior drawer test at 90° of knee flexion. Magnetic resonance imaging can be useful in delineating injuries to the PCL and PLC and is helpful in surgical planning. To document PCL and PLC laxity and to report the results of treatment, it is important to obtain stress radiography preoperatively for assessing posterior and varus instability and to record a Dial test to document posterolateral laxity.