The ACL posterolateral bundle is tightest in extension when the pivot shift test is most provocative. Its reconstruction in double-bundle ACL surgery specifically addresses the rotational laxity that produces the pivot shift phenomenon — the bucket-handle subluxation of the lateral tibial condyle that produces the giving way sensation in ACL-deficient knees.
| Origin | Posterolateral portion of the ACL femoral footprint |
|---|---|
| Insertion | Posterolateral portion of the ACL tibial footprint |
| Actions | Tight in knee extension; primary restraint against anterior tibial translation and rotation in the extended knee; reproduced in double-bundle ACL reconstruction |
|---|
The pivot shift test (valgus, internal rotation of the leg while extending from flexion) primarily stresses the PL bundle. Residual pivot shift after single-bundle AM reconstruction explains persistent rotational instability in some patients. Adding an anterolateral ligament reconstruction (ALL reconstruction) or double-bundle surgery reduces pivot shift in high-demand athletes.
PL bundle deficiency producing rotational instability addressed by anterolateral ligament reconstruction or double-bundle ACL surgery.
