Lateral Approach to the Knee (Iliotibial Band, LCL and Posterolateral Corner)

What it exposes. The lateral approach gives direct access to the iliotibial band and its insertion on Gerdy's tubercle, the lateral collateral ligament (LCL), the popliteus tendon, the popliteofibular ligament and the fibular head, and through the internervous interval it opens the whole posterolateral corner (PLC). It is the workhorse exposure for posterolateral corner and LCL reconstruction, acute PLC repair, open lateral meniscal work, iliotibial band release or lengthening, and Gerdy's tubercle osteotomy or transfer. Indications

Contraindications - Active infection of the skin or deep tissues over the lateral knee

• Severe soft tissue compromise or previous incisions that conflict with the planned approach
• Where an arthroscopic alternative exists and gives equivalent access (for example, isolated meniscal resection)
• A patient medically unfit for the planned reconstructive procedure Alternative approaches - Anterolateral approach to the proximal tibia: preferred for lateral tibial plateau fractures (Schatzker I to III)
• Posterolateral approach to the knee: for isolated posterior structures accessed prone
• Arthroscopic-assisted PLC reconstruction: combines arthroscopy with limited lateral open incisions
• Medial approach: when the pathology is on the medial side Position and landmarks. The lateral approach is most often performed supine with a bolster or sandbag under the ipsilateral buttock to roll the leg into internal rotation and bring the lateral aspect of the knee uppermost. The knee is flexed over a bolster to relax the iliotibial band and the common peroneal nerve. For isolated posterolateral corner work, the lateral decubitus position with the affected side up gives excellent access to the fibular head and biceps femoris. A thigh tourniquet is used and the limb is prepared from hip to ankle so it can be moved during surgery. Palpable landmarks are Gerdy's tubercle (the prominence on the anterolateral proximal tibia where the ITB inserts), the fibular head (biceps and LCL insertion), the lateral femoral epicondyle (LCL and popliteus origin), the patella and patellar tendon, the lateral joint line (palpated with the knee flexed), and the biceps femoris tendon traced distally to the fibular head. Incision planning. A curvilinear or lazy-S ("hockey-stick") incision is used. It begins posterior to the lateral femoral condyle, passes over the lateral joint line and curves distally and anteriorly over Gerdy's tubercle onto the anterolateral tibia. For posterolateral corner reconstruction the incision is centred over the interval between the fibular head and Gerdy's tubercle, and it must be long enough to expose both the femoral and fibular attachment sites of the LCL without retraction under tension on the skin.

Work down through the layers between the iliotibial tract and biceps femoris, protecting the common peroneal nerve before any fibular head dissection, then open the three-layer posterolateral anatomy to the LCL, popliteus and the popliteofibular ligament. Internervous plane. The safe surgical plane is between the iliotibial tract anteriorly (tensor fascia lata and gluteus maximus, supplied by the superior gluteal nerve) and the biceps femoris posteriorly (long head from the tibial part of the sciatic nerve, short head from the common peroneal part). Retracting the iliotibial band anteriorly and the biceps femoris posteriorly opens the interval without denervating muscle and exposes the LCL, the popliteus tendon and the posterolateral corner.

Layer I is the superficial fascial layer, formed anteriorly by the iliotibial band and posteriorly by the biceps femoris; the common peroneal nerve runs just deep to the biceps tendon within this layer. Layer II contains the lateral retinaculum anteriorly and, posteriorly, the lateral collateral ligament (fibular collateral ligament) spanning from the lateral femoral epicondyle to the fibular head. Layer III is the true joint capsule and the deepest stabilisers: the arcuate ligament, the popliteus tendon and its aponeurosis, the popliteofibular ligament, the fabellofibular ligament and the lateral meniscus. The lateral inferior genicular artery crosses this layer between the LCL and the arcuate ligament.

Structures at risk, by layer

Common peroneal nerve injury management - Document pre-operative dorsiflexion and eversion as a baseline

• If the nerve is transected intra-operatively, consider primary repair or grafting
• For a post-operative neurapraxia, remove constrictive dressings, fit an ankle-foot orthosis to prevent equinus, and arrange electromyography at three weeks
• If there is no clinical or electrodiagnostic recovery by three months, consider nerve exploration

Extending the approach Proximal extension (toward the distal femur): extend the incision proximally along the lateral femur and split the interval between vastus lateralis (retracted anteriorly, femoral nerve) and the lateral intermuscular septum with the short head of biceps posteriorly. This allows access to the distal femur for osteotomy, fixation or supracondylar work; the common peroneal nerve becomes less at risk as you move proximally, but the superior lateral genicular artery is encountered. Distal extension (toward the tibia and fibula): extend distally along the anterolateral tibia into the anterior compartment for access to the tibial diaphysis, or carry the incision posteriorly onto the fibula for the fibular shaft and the proximal tibiofibular joint. Beware the anterior tibial recurrent vessels and the deep peroneal nerve as you approach the anterior compartment. Closure - Copious irrigation and meticulous haemostasis, with particular attention to the lateral inferior genicular artery

• Re-attach the iliotibial band to Gerdy's tubercle if it was released, and re-fix a Gerdy's tubercle osteotomy with small-fragment screws or suture
• Close the deep fascia and the iliotibial band with absorbable suture to restore extensor mechanism tension
• Consider a drain if extensive dissection was performed, exiting it away from the common peroneal nerve
• Close subcutaneous tissue and skin in layers; apply a splint or brace appropriate to the reconstruction

• Posterolateral corner and LCL reconstruction - the principal indication; anatomic reconstruction restores the LCL, popliteus and popliteofibular ligament
• Acute PLC repair - direct repair of avulsed structures in the first two to three weeks
• Lateral meniscectomy or open meniscal repair
• Iliotibial band release or lengthening (Z-lengthening or pie-crusting) for recalcitrant iliotibial band syndrome or fixed flexion-abduction contracture
• Gerdy's tubercle osteotomy and transfer
• Lateral retinacular release or reconstruction for patellar maltracking
• Lateral-based distal femoral osteotomy
• Access to the proximal tibiofibular joint for resection or stabilisation

Biomechanics. The posterolateral corner resists varus angulation, external tibial rotation and posterior tibial translation (in concert with the posterior cruciate ligament). The lateral collateral ligament is the primary restraint to varus at all angles of flexion, while the popliteus and popliteofibular ligament resist external rotation, particularly near full extension. A deficient posterolateral corner places increased stress on a reconstructed posterior cruciate or anterior cruciate ligament and is a recognised cause of graft failure if not addressed.

Guidelines, Registries & Global Practice Management of posterolateral corner injuries is guided by anatomic and biomechanical studies that have defined the attachments and function of the LCL, popliteus and popliteofibular ligament. Principles converge across examination systems: recognise PLC injury clinically (varus at 30 degrees, positive dial test at 30 degrees, reverse pivot shift), confirm on MRI, correct any varus malalignment, and reconstruct the LCL, popliteus and popliteofibular ligament anatomically, often combined with cruciate reconstruction.

Global practice variation. In well-resourced settings, anatomic PLC reconstruction with autograft or allograft and intra-operative imaging is standard. In resource-limited settings, the same anatomic principles are applied using locally available graft and fluoroscopy, with extra-articular tenodesis-type procedures used when anatomic reconstruction is not feasible. The clinical examination (varus opening at 30 degrees and the dial test) is universal and costs nothing. Consent (globally applicable): discuss common peroneal nerve injury (the principal approach-specific risk, mostly transient but occasionally permanent), infection, stiffness, failure of reconstruction (higher in uncorrected varus knees), and the need for protected rehabilitation.