Current Concepts in the Management of Posterolateral Corner Injuries

High-Yield Summary

• Posterolateral corner (PLC) injuries compromise knee stability by disrupting the lateral collateral ligament (LCL), popliteus tendon, and popliteofibular ligament, leading to varus and rotational instability.
• Accurate diagnosis requires a combination of clinical exam maneuvers (dial test, varus stress test) and advanced imaging; missed PLC injuries increase failure rates of cruciate ligament reconstructions.
• Surgical indication hinges on injury grade, chronicity, and concomitant ligament damage; acute grade II/III injuries and chronic instability generally require reconstruction rather than repair.
• Anatomic reconstruction techniques restore native biomechanics more reliably than nonanatomic repairs, reducing varus gapping and rotational laxity.
• Mastery of surgical landmarks and intraoperative assessment of graft tension and knee stability is critical to avoid residual instability or overconstraint.

Clinical Fundamentals

The posterolateral corner of the knee consists primarily of three static stabilizers: the lateral collateral ligament (LCL), the popliteus tendon, and the popliteofibular ligament. These structures resist varus forces, external tibial rotation, and posterior tibial translation, particularly in knee flexion beyond 30 degrees. The LCL originates from the lateral femoral epicondyle and inserts on the fibular head, providing primary varus restraint. The popliteus tendon originates from the lateral femoral condyle and inserts on the posterior tibia, functioning as a dynamic stabilizer and secondary restraint to external rotation. The popliteofibular ligament connects the popliteus musculotendinous junction to the fibular head, reinforcing posterolateral stability.

Biomechanically, the PLC resists varus stress and external rotation, especially at 30° of knee flexion. Injury to the PLC often occurs in high-energy trauma or combined ligamentous injuries, with an incidence of up to 16% in multiligament knee injuries. Missed or inadequately treated PLC injuries lead to chronic instability, accelerated osteoarthritis, and failure of cruciate ligament reconstructions.

Classification & Diagnosis

Diagnostic Pearls:

• The dial test at 30° knee flexion is most sensitive for detecting PLC injury; >10° side-to-side difference indicates injury.
• Varus stress testing at 0° and 30° differentiates isolated LCL injury from combined PLC injury.
• MRI is essential but may underestimate severity; correlate with clinical exam and stress radiographs.
• Common pitfall: failure to assess PLC in the setting of ACL/PCL injuries leads to graft failure.

Decision-Making Algorithm

Surgical approach selection depends on injury chronicity and tissue quality. Acute injuries with good tissue quality may be amenable to repair augmented with reconstruction. Chronic injuries require anatomic reconstruction using grafts (autograft or allograft). Nonanatomic techniques are reserved for salvage or when anatomic reconstruction is not feasible.

Surgical Mastery & Pearls

Stepwise Conceptual Overview:

1. Exposure: Utilize a lateral hockey-stick incision to expose the fibular head, LCL origin, and popliteus tendon insertion. Protect the common peroneal nerve with meticulous dissection.
2. Identification of Landmarks: Palpate the lateral femoral epicondyle, fibular head, and popliteus sulcus to guide tunnel placement.
3. Tunnel Placement: Create femoral tunnels at the anatomic footprints of the LCL and popliteus tendon. The fibular tunnel should be drilled from anterolateral to posteromedial to avoid peroneal nerve injury.
4. Graft Preparation and Passage: Use doubled semitendinosus or allograft tendons sized to match native structures. Pass grafts through tunnels replicating native ligament orientation.
5. Fixation: Fix grafts with interference screws or cortical buttons at 30° knee flexion with slight valgus to avoid overconstraint.
6. Intraoperative Assessment: Perform varus stress and dial tests after fixation to confirm restoration of stability.

Intraoperative Red Flags:

• Excessive varus opening after fixation suggests inadequate graft tension or tunnel malposition.
• Overconstraint causing limited external rotation indicates overtightening; adjust graft tension accordingly.
• Common peroneal nerve injury risk during fibular tunnel drilling mandates nerve identification and protection.

Evidence-Based Synthesis

Recent randomized controlled trials and biomechanical studies have established the superiority of anatomic PLC reconstruction over repair or nonanatomic techniques. LaPrade et al. demonstrated that anatomic reconstruction restores varus and rotational stability more effectively, reducing failure rates in multiligament knee reconstructions. Conversely, repair alone, especially in chronic injuries, shows high rates of residual laxity and reoperation.

MRI sensitivity for PLC injuries remains limited, emphasizing the importance of clinical examination and stress radiographs. Emerging evidence supports early surgical intervention within three weeks to optimize outcomes, as delayed reconstruction is associated with increased technical difficulty and poorer functional results.

Controversy persists regarding graft choice and fixation methods. Autografts provide biological incorporation but may be limited by donor site morbidity, while allografts offer size versatility but carry risks of delayed incorporation. Current consensus favors individualized graft selection based on patient factors and surgeon experience.

Master Class Pro-Tip

When performing anatomic PLC reconstruction, intraoperative dynamic assessment under fluoroscopy or navigation can refine tunnel placement and graft tensioning, minimizing residual instability. Prioritize restoration of the native length-tension relationship of the LCL and popliteus complex by tensioning grafts at 30° flexion with neutral rotation. Avoid overtightening, which can lead to lateral compartment overload and early osteoarthritis. Mastery of the common peroneal nerve anatomy and gentle handling during fibular tunnel creation is paramount to prevent debilitating nerve palsy.

Last Updated on February 1, 2026 by OrthoNet AI