The posterolateral corner refers to the structures that lie on the back and outside portion of the knee, around the head of the fibula. This anatomical region is quite complex, with several structures in a small space helping to contribute to lateral and rotational stability of the knee during dynamic tasks (such as playing sport). The posterolateral corner involves multiple structures, including but not limited to: Active stabilisers:
•ITB (iliotibial band) •Biceps femoris tendon (lateral hamstring) •Lateral gastrocnemius (calf muscle) •Popliteus (+ popliteofibular ligament attaching to fibular head) Passive stabilisers:
•Arcuate ligament
•LCL (lateral collateral ligament)
•Posterolateral capsule
These structures are not commonly injured, but when injured happen often with ACL and/or PCL injuries. As a result, they are not the priority in terms of management, and as a result can be missed entirely.
Common mechanisms of injury
Posterolateral corner injuries often occur in the same mechanism as ACL injuries; involving knee valgus (knee caving in), tibial external rotation (foot turning out), hip internal rotation (hip rolling in), non contact. They can also occur from a direct blow to the lateral leg or anteromedial knee, or via direct varus force
Why is it important to not miss?
The posterolateral corner contributes directly to lateral and rotational stability - without this passive support, you may be at greater risk of reinjury. Without this passive support, there may also be a higher possibility of having setbacks during rehabilitation if not addressed as its own issue. Furthermore, if surgery is being considered as a management option (particularly for ACL tears), the presence of posterolateral corner injury may influence the type of surgery being performed e.g. having a lateral extra-articular tenodesis to aid in passive knee support. There is also some evidence to support outcomes being better if PLC injury is managed within 2 to 3 months following injury.
Considerations for rehabilitation
Train with rotation! Strengthening into the rotational plane will help improve capacity with rotational movements. Incorporate this as part of a strength program, as well as with plyometric options in a rehabilitation context. These exercises may not be the absolute priority of the program, but are an important component to include, particularly under fatigue.
Exercise examples
Multidirectional lunges - challenging rotation in multiple planes of motion aids in exposing the knee to multidirectional forces in a more controlled way
Multidirectional hopping - added challenge compared to
References:
Bmj. (2020, October 9). Football ACL injuries reloaded: How, where, and when #knowledgetranslation. BJSM blog - social media’s leading SEM voice. https://blogs.bmj.com/bjsm/2020/10/19/football-acl-injuries-reloaded-how-where-and-when-knowledgetranslation/
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