What is the posterolateral corner?
The posterolateral corner is located on the outside of the knee and functions to stabilize the knee in rotation as well as lateral bending. The posterolateral corner is a complex of three ligaments including the lateral collateral ligament (LCL), the popliteus tendon (PLT) and the popliteofibular ligament. Injuries are often due to a sports impact in sports like soccer, football, or basketball.
What are symptoms of posterolateral corner injuries?
- Instability – the knee will feel unstable when turning or pivoting
- There will be mild swelling on the outside of the knee, generally not associated with intra-articular joint swelling unless there is an accompanying injury.
- Numbness along the outside of the knee, or drop foot can occur from peroneal nerve injuries which are associated with PLC injuries.
How do we diagnose posterolateral corner injuries?
Dr. Cooper will diagnose posterolateral corner injuries based on physical exam and imaging. Specific physical exam test are the varus stress test – bending the knee and stressing the ligaments of the PLC. The dial test assesses knee rotation at thirty degrees and ninety degrees, this can help differentiate if the posterior cruciate ligament is injured with the PLC or not. Many of the exam maneuvers will also assess the cruciate ligaments (anterior cruciate ligament and posterior cruciate ligaments) as these are injured in approximately 72% of patients who have a PLC injury.
How do we classify posterolateral corner injuries?
- Grade I Injury: small partial tear with minimal instability
- Grade II Injury: partial tear with an endpoint to stressing
- Grade III Injury: complete tear with no good endpoint to stressing
How are posterolateral corner injuries treated?
Unlike the medial side of the knee, the injuries to the lateral side of the knee do not heal well without surgery. Surgery is recommended for grade III injuries in order to restore stability and prevent further damage to the knee. Surgical reconstruction involves the use of an allograft or an autograft tendon to rebuild the structures of the PLC. The tendons are fixed into tunnels in the bones of the knee.
Full recovery can take up to a year, depending on the extent of repairs, and begins with immediate physical therapy.
