The posterolateral knee capsule is the primary containment structure of the posterolateral corner, reinforced by the arcuate ligament, LCL, popliteus, and popliteofibular ligament. Its contribution to posterolateral stability means that isolated capsular laxity from stretch injury can produce chronic posterolateral instability even when the discrete ligamentous structures appear intact on MRI.
| Origin | Lateral femoral condyle and posterior tibia |
|---|---|
| Insertion | Arcuate ligament, fibular head, and posterior tibial condyle |
| Actions | Posterolateral knee stability — resists external tibial rotation and posterior translation in combination with the PLC structures |
|---|
The posterolateral capsule is assessed by the external rotation recurvatum test — the patient lies supine and the examiner lifts the great toe; a positive test shows the knee recurvating with external tibial rotation indicating posterolateral capsular laxity. Combined with the dial test, posterolateral capsular assessment guides surgical reconstruction planning.
Posterolateral knee capsule attenuation producing external rotation recurvatum assessed by the ER recurvatum and dial tests.
