Posteromedial Approach to Knee

What it exposes. The posteromedial (Lobenhoffer) approach gives direct access to the posteromedial tibial plateau, the posteromedial corner and the posterior capsule, with the medial head of gastrocnemius interposed as a curtain between the field and the popliteal neurovascular bundle. It is the workhorse exposure for a posteromedial split or shear fragment that cannot be reduced or buttressed from the front. Why posteromedial (and not anterior). A posteromedial fragment sits on a steep shear plane (mean sagittal angle 73 degrees) that a laterally based locking plate does not control; the fragment tends to displace caudally in flexion. A direct posterior buttress or antiglide plate resists this displacement. An anterior or anteromedial approach simply cannot reach or buttress a posterior coronal fragment. Primary indications — trauma

• Posteromedial tibial plateau fractures: Schatzker IV with posteromedial extension, coronal split fractures of the posterior medial plateau, and the posteromedial component of bicondylar Schatzker V to VI patterns.
• Failed reduction via an anteromedial approach, where the posterior fragment is not accessible from the front. Secondary indications
• Posteromedial corner injuries: avulsion of the semimembranosus insertion, posterior oblique ligament (POL) repair, posteromedial capsular repair, combined ligamentous reconstruction.
• Posterior medial meniscus: root tear (open repair), peripheral posterior horn inside-out repair, medial meniscus transplantation. Relative contraindications
• Active infection overlying the incision; severe vascular compromise requiring vascular surgery first.
• Severe peripheral vascular disease (high vessel-injury risk), severe soft-tissue injury (compartment syndrome, degloving), and obesity (BMI greater than 40) — a very difficult exposure. Position & landmarks. Two positions are used. Prone gives the best direct access to the posteromedial corner with gravity-assisted retraction, but cannot be combined with an anterior approach in the same sitting and makes fluoroscopy harder. Supine with the leg hanging off the side of the table (knee flexed 90 degrees over the table edge) allows same-sitting anterior conversion and easier fluoroscopy, but gravity works against you and the field is cramped. Palpate and mark the medial femoral epicondyle and adductor tubercle (proximal landmarks), the posteromedial tibial margin, and the medial head of gastrocnemius and semimembranosus tendon — the interval between them is the line of the approach. Use a radiolucent table and a large C-arm throughout.

Work down through the layers along the posteromedial tibia, protecting the saphenous nerve superficially, then develop the interval between the medial head of gastrocnemius (lateral) and semimembranosus (medial) down to the posterior capsule, keeping the gastrocnemius retracted laterally as a curtain over the popliteal bundle and staying strictly subperiosteal on the posterior tibial cortex.

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Structures at risk, by layer

Posteromedial versus anteromedial

Extensions and the dual-approach strategy. For bicondylar fractures (Schatzker V, VI) the posteromedial incision is usually combined with an anterolateral approach so that the medial and lateral columns are each buttressed. Many units stage fixation — a temporary spanning external fixator first, definitive dual plating once the soft-tissue envelope recovers (often 7 to 14 days); some centres perform same-sitting dual plating in favourable soft tissues. The posteromedial incision can be extended proximally along the medial femoral condyle or distally along the posteromedial tibial border if more exposure is needed. Complications. Popliteal vessel injury is uncommon in reported series but is the highest-stakes complication (limb-loss risk of 10 to 15 percent if repair is delayed beyond 6 hours). Tibial nerve injury occurs in less than 1 percent. Saphenous nerve numbness (5 to 10 percent) is common and often unavoidable — counsel preoperatively. Compartment syndrome runs at 5 to 10 percent in high-energy medial plateau fractures; wound problems and infection are under 2 percent in favourable soft tissues, rising to 10 to 15 percent wound dehiscence and 5 to 8 percent infection in obesity. Late problems include post-traumatic arthritis in 20 to 30 percent despite anatomic reduction, malunion from inadequate reduction, and prominent hardware needing removal in 10 to 15 percent. Postoperative care. Neurovascular checks are mandatory every 1 to 2 hours for the first 24 hours; avoid a femoral nerve block (it masks compartment syndrome); deflate the tourniquet before closure and check pulses. Weight-bearing is toe-touch for 6 to 8 weeks for simple patterns and non-weight-bearing for 8 to 12 weeks for complex or bicondylar patterns. Begin gentle passive ROM early, avoiding varus stress to protect the medial fixation.

• ORIF of posteromedial tibial plateau fractures — Schatzker IV with posteromedial extension, Moore type I posteromedial split fracture-dislocations, and the posteromedial component of bicondylar Schatzker V to VI fractures (often the medial half of a dual-approach strategy).
• Posteromedial corner repair — semimembranosus avulsion fixation, posterior oblique ligament and posteromedial capsular repair, combined ligamentous reconstruction.
• Posterior medial meniscus work — root repair, peripheral posterior horn inside-out repair, medial meniscus transplantation.
• Popliteal vessel exploration — in combination with vascular surgery, for repair of a popliteal injury.

Guidelines, registries & global practice. The posteromedial (Lobenhoffer) approach is a specialised, high-risk exposure for surgeons experienced in periarticular trauma; there is no single national standard exam candidates must quote, but the convergent message across major trauma bodies is CT-driven planning, fragment-specific exposure and a posterior buttress for the unstable posteromedial fragment.