Posterior Malleolar Open Reduction and Internal Fixation Through a Posterolateral Approach for Trimalleolar Fractures.

Fixation of the posterior fragment in trimalleolar fractures remains a matter of debate. Recent studies have shown that a persistent step-off in the tibiotalar joint is the most important factor in the development of osteoarthritis and therefore the functional outcome. The disadvantages of the regularly performed indirect reduction by ligamentotaxis or percutaneous reduction followed by percutaneous screw fixation of the posterior fragment in an anterior-to-posterior direction are that an anatomical reduction is more difficult to achieve because of the interposition of soft tissue or loose osseous fragments, it is hard to assess reduction satisfactorily using an image intensifier, and fixation of small or comminuted fragments is technically difficult. Therefore, we favor an open, anatomical reduction of the posterior malleolar fragment using a posterolateral approach. DESCRIPTION: The patient is prone for the operation. A longitudinal incision is made between the lateral border of the Achilles tendon and the posteromedial border of the fibula. The posterior aspect of the fibula is easily reached through the interval just lateral to the peroneal muscle. After debridement of the fracture, it can be reduced and is fixed with either (1) a buttress plate or (2) lag screw(s) with a neutralizing plate. The belly of the flexor hallucis longus is bluntly dissected off of the interosseous membrane and the lateral side of the tibia through the interval medial to the peroneal muscle. Retracting the muscle belly medially allows the posterior aspect of the tibia to be seen. The periosteum is incised to expose the posterior malleolar fracture. Loose fragments can be removed by levering the posterior fragment distally. Reduction is performed and is held temporarily by Kirschner wires. Fixation is undertaken using either lag screws or a slightly prebent 3-hole buttress plate. Placement of a lag screw through the most distal hole of the plate can help to close any possible gaps. Slight internal rotation of the lower leg allows the medial malleolus to be approached and fixed. ALTERNATIVES: Percutaneous anterior-to-posterior screw fixation is an alternative, but it frequently leads to a nonanatomical reduction of the fragment. RATIONALE: This technique provides an adequate view of the fracture, an anatomical reduction in most cases, and sound fixation of the posterior malleolar fragment. Other advantages are that small fragments are easier to fix and small intra-articular fragments can be removed from the site of the fracture.