Lateral tibial plateau fractures are very commonly encountered by orthopaedic surgeons. The classic lateral patterns described by Hohl2, Moore3, and Schatzker et al.4 can be treated with lateral buttress plating. Approximately 7% of lateral tibial plateau fractures involve the posterolateral tibial plateau5. This pattern results from a shearing force as the lateral femoral condyle impacts the posterolateral plateau after a valgus force with the knee in flexion6,7. Stable fixation of this segment is required since there is a strong tendency for the fragment to migrate posteriorly and distally with knee motion6,7. This will result in joint instability, pain, and possible neurovascular injury6. The antiglide fracture pattern suggests that the ideal fixation is a buttress plate positioned to reduce the apex of the fracture7,8.
Access to this fragment from a standard lateral approach, however, is difficult because the fibula blocks visualization and reduction. Attempted fixation of posterolateral fractures through an anterolateral approach has resulted in malreduction with unstable fixation9. Described approaches include fibular osteotomy9,10 and fibular-sparing approaches5,8,11,12. Solomon et al. described a transfibular approach between the posterior margin of the iliotibial band and the posterior cruciate ligament to reduce and fix posterolateral fracture patterns in eight patients9. All patients had healed fractures and osteotomies. Yu et al. utilized fibular osteotomy to treat posterolateral tibial plateau fractures in eighty-two patients10. At the three-year follow-up, all had healed with good knee joint function. This approach, however, is extensive and carries potential morbidity, including peroneal nerve injury and posterolateral knee instability9,10.
Posterolateral approaches utilizing the interval between the lateral gastrocnemius and medial aspect of the fibula, without fibular osteotomy, have been described to access the posterolateral aspect of the tibial plateau5,8,12. Dissection is performed between the common peroneal nerve and the lateral sural cutaneous nerve. The soleus is released laterally to medially from the fibula to the proximal part of the tibia to expose the proximal 5 cm of posterolateral tibia. A major disadvantage of this approach is that distal extension of the exposure is blocked by the passage of the anterior tibial artery, which is anterior to the interosseous membrane 5 cm distal to the joint line5,8,12. In the series reported by Chang et al.8, Frosch et al.5, and Tao et al.12, a total of twenty-six patients with posterolateral tibial plateau fractures were treated; stable acceptable reductions were obtained with no complications in twenty-five of these patients. In these cases, the size of the posterolateral fragment was smaller than in our patient. This allowed for safe posterior fixation. In our case, the location of the apex of the posterolateral fracture (7 cm distal to the knee joint) required buttress-plate fixation that extended well distal to the trifurcation as well as passage of the anterior tibial artery into the anterior compartment of the leg.
Our patient had an unusual fracture pattern with a large posterolateral fragment as well as substantial lateral comminution and joint depression with fibular entrapment. Described posterolateral approaches require dissecting laterally to medially across the interosseous membrane; therefore, for large posterolateral fragments with an apex located up to 4 cm distally from the joint, exposure risks injury to the anterior tibial artery. Because direct, safe visualization was required for both components of the fracture, we elected to perform a direct posterior popliteal approach with buttress-plate fixation of the posterolateral fracture, followed by a direct lateral approach to reduce the fracture, bone-grafting, and placement of the buttress plate on the lateral tibial plateau. Prolonged retraction in the popliteal exposure must be avoided to prevent venous thrombosis and tibial nerve neuropraxia. Screws should be placed distal to the apex in an antiglide pattern, with care taken to keep the screws distal to the depressed anterolateral fragments. Otherwise, posterior screws may interfere with elevation of the anterolateral depression. Although more time-consuming, this dual approach allowed for a good reduction and stable fixation of both components of this fracture.
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