This 1988 cadaveric cutting study by Grood, Stowers, and Noyes applied known forces to 15 unembalmed lower limbs and measured six-degree-of-freedom tibial motion after sequential sectioning of the PCL, LCL, popliteus tendon, and arcuate complex. The study quantified how each posterolateral structure independently and collectively limits posterior tibial translation, external rotation, and varus angulation across 0–90° of flexion. It established the biomechanical rationale for the posterior drawer test at 90° and the dial test at 30°.
Two widely taught clinical rules are directly refuted by this paper. Hughston's teaching that a positive varus stress test in full extension diagnoses PCL rupture is wrong: PCL sectioning adds only 1.7° of varus at 0°, a trivial and clinically undetectable amount. And a positive posterolateral drawer at 90° does not reflect isolated arcuate complex injury — significant external rotation at 90° almost always means the PCL is also torn.
Apply this as a two-step dial test interpretation at every PLC exam: Increased external rotation at 30° only. Isolated PLC injury Increased rotation at both 30° and 90°. Combined PCL + PLC, plan reconstruction of both
When the posterior drawer is positive at 90° but translation is minimal at 30°, the secondary restraints are still partially intact. Consistent with isolated PCL rupture. When posterior laxity is similar at both angles, suspect additional extra-articular restraint failure.
This paper is the foundational reference for all subsequent PLC reconstruction literature. It directly informs the LaPrade anatomic reconstruction, which targets the three structures (LCL, popliteus tendon, popliteofibular ligament) whose combined disruption this study showed is required for clinically significant posterolateral instability.
This 1988 cadaveric cutting study by Grood, Stowers, and Noyes applied known forces to 15 unembalmed lower limbs and measured six-degree-of-freedom tibial motion after sequential sectioning of the PCL, LCL, popliteus tendon, and arcuate complex. The study quantified how each posterolateral structure independently and collectively limits posterior tibial translation, external rotation, and varus angulation across 0–90° of flexion. It established the biomechanical rationale for the posterior drawer test at 90° and the dial test at 30°.
Two widely taught clinical rules are directly refuted by this paper. Hughston's teaching that a positive varus stress test in full extension diagnoses PCL rupture is wrong: PCL sectioning adds only 1.7° of varus at 0°, a trivial and clinically undetectable amount. And a positive posterolateral drawer at 90° does not reflect isolated arcuate complex injury — significant external rotation at 90° almost always means the PCL is also torn.
Apply this as a two-step dial test interpretation at every PLC exam: Increased external rotation at 30° only. Isolated PLC injury Increased rotation at both 30° and 90°. Combined PCL + PLC, plan reconstruction of both
When the posterior drawer is positive at 90° but translation is minimal at 30°, the secondary restraints are still partially intact. Consistent with isolated PCL rupture. When posterior laxity is similar at both angles, suspect additional extra-articular restraint failure.
This paper is the foundational reference for all subsequent PLC reconstruction literature. It directly informs the LaPrade anatomic reconstruction, which targets the three structures (LCL, popliteus tendon, popliteofibular ligament) whose combined disruption this study showed is required for clinically significant posterolateral instability.