A combined posterolateral corner (PLC) and posterior cruciate ligament (PCL) injury is most likely suggested by a positive dial test at 30 and 90 degrees of knee flexion.
The Dial test may be performed prone or supine and is tested at 30 and 90 degrees of knee flexion. The test is positive if there is an increase in tibiofemoral external rotation by 10-15° compared to the contralateral side. An postive test at 30 degrees that is normal at 90 degrees indicates an isolated PLC injury. A postive test at 30 and 90 degrees indicates a combined PLC and PCL injury.
The review article by Covey states that the PLC is comprised of the ITB, the LCL, the popliteus complex consisting of both dynamic components (the popliteus muscle-tendon unit) and static components (the popliteofibular ligament, popliteotibial fascicle, and popliteomeniscal fascicles), the middle third of the lateral capsular ligament, fabellofibular ligament, arcuate ligament, the posterior horn of the lateral meniscus, the lateral coronary ligament, and the posterolateral part of the joint.
1. Positive Dial test at 30 degs, but not at 90 degs indicates isolated PLC injury.
2. Varus stress (not valgus) is used to test the lateral structures.
3. A posterior drawer test is used to assess degree of PCL instability.
4. A pivot shift test is used for ACL instability. A "reverse pivot shift" test is used for PCL and PLC.
Video A demonstrates how the Dial test can be performed in either the prone or supine position with measurement of tibial external rotation at 30° at 90° of knee flexion.
Covey DC: Injuries of the posterolateral corner of the knee. J Bone Joint Surg Am 2001;83:106-118
PMID:11205847 (Link to Abstract)
Arendt EA (ed): Orthopaedic Knowledge Update: Sports Medicine 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 327-340