{"id":181125,"date":"2026-08-17T10:53:23","date_gmt":"2026-08-17T10:53:23","guid":{"rendered":"https:\/\/pabau.com\/?p=181125"},"modified":"2026-08-17T12:17:39","modified_gmt":"2026-08-17T12:17:39","slug":"posterolateral-drawer-test","status":"publish","type":"post","link":"https:\/\/pabau.com\/nl\/blog\/posterolateral-drawer-test\/","title":{"rendered":"Posterolateral drawer test: Technique, grading, and pitfalls"},"content":{"rendered":"
\n
\n \"Key\n

Key takeaways<\/h3>\n <\/div>\n
\n
\n
\n \n \n <\/svg>\n <\/div>\n

The posterolateral drawer test detects posterolateral rotatory instability by adding external tibial rotation to a posterior drawer force at 80 degrees of flexion.<\/p>\n <\/div>\n

\n
\n \n \n <\/svg>\n <\/div>\n

A positive result is judged side to side, comparing the injured knee against the uninjured one rather than counting absolute millimeters.<\/p>\n <\/div>\n

\n
\n \n \n <\/svg>\n <\/div>\n

One prospective MRI study found posterolateral corner damage in 16% of all knee ligament injuries, and isolated injury was rare.<\/p>\n <\/div>\n

\n
\n \n \n <\/svg>\n <\/div>\n

Grading follows the modified Hughston classification, which sorts posterolateral subluxation into less than 5 mm, 5 to 10 mm, and more than 10 mm.<\/p>\n <\/div>\n

\n
\n \n \n <\/svg>\n <\/div>\n

Practice management software like Pabau keeps knee examination findings in one client record, so grading stays consistent between clinicians and visits.<\/p>\n <\/div>\n <\/div>\n <\/div>\n \n\n\n

Some knees give way near full extension, ache along the lateral joint line, and thrust into varus during gait. That combination belongs to the posterolateral corner, or PLC, and a routine knee exam can walk straight past it.<\/p>\n\n\n\n

LaPrade and colleagues<\/a> screened acute knee injuries presenting with a hemarthrosis by MRI. They found posterolateral corner damage in 16% of all knee ligament injuries. Isolated PLC tears made up only 2.1% of cases, and 87% of injured corners sat alongside other torn ligaments.<\/p>\n\n\n\n

The posterolateral drawer test is the maneuver that brings the pattern out. Get the flexion angle, the foot fixation, and the force vector right, and the instability declares itself. <\/p>\n\n\n\n

The posterolateral drawer test detects rotatory instability<\/h2>\n\n\n\n

The test loads the posterolateral corner by combining posterior tibial translation with external tibial rotation. <\/p>\n\n\n\n

Neither force on its own stresses those structures the same way, which is why a plain posterior drawer can look normal on a knee with a torn corner.<\/p>\n\n\n\n

Posterolateral rotatory instability, known as PLRI, behaves differently from straight posterior instability. When the corner fails, the lateral tibial plateau rotates backward and outward relative to the femur under load. Patients describe the knee giving way as it approaches extension, and you can often see a varus thrust in stance phase.<\/p>\n\n\n\n

You will also see the maneuver called the posterolateral rotatory drawer test. Both names describe the same thing. Keep it separate from the standard posterior drawer, which holds the tibia in neutral rotation and reads the PCL instead.<\/p>\n\n\n\n

Four posterolateral corner structures the test stresses<\/h2>\n\n\n\n

The PLC is a three-layer complex on the lateral side of the knee, and four structures do most of the stabilizing work:<\/p>\n\n\n\n