Abstract
Acquired pilon deformities are often a combination of axial deviation, translation, rotational defects and leg length discrepancy. Correction of a deformity pattern with a percutaneous rectilinear supramalleolar osteotomy and an external fixation by Ilizarov apparatus aims to reduce misalignment progressively, simultaneously and minimally invasively.
From 1994 to 2004, 27 patients were treated for pilon tri-planar deformity of the leg. The mean age was 27 years (range 16 to 49 years); 15 were males and 12 females. Type and level of the deformity were determined by preoperative X-rays. For the procedure, two rings of Ilizarov apparatus are positioned in the segment of the limb proximal to the osteotomy: one at the level of the proximal tibial metaphysis and the other 3–4 cm beyond the osteotomy. A third ring is positioned at the level of the tibial pilon, parallel to the articular edge of the ankle. In order to maintain stability of the ankle, a half ring or horseshoeshaped component should be placed on the calcaneus and metatarsals with opposing olive wires. The positions of the mobile joints between the rings depend on the location of the correction axis. Closed metaphyseal osteotomy is performed in order to correct tri-planar deformities in a progressive way, through angulations and translation in an oblique plane. The half ring on the foot maintains distraction in the ankle, which is necessary to reduce articular compression and to avoid soft tissue damage and muscular contractures in this region.
In all cases we achieved correction of the angular or rotational deformities. Bleeding was never over 100 ml. We have not observed any soft tissue damage. Controlled weight-bearing was practised on the first day postoperatively, and the mean hospitalisation time was 4 days. Time required to reach the correction was in a range of 3–6 weeks. In 20 patients the total leg discrepancy was in a range of 1.5–6 cm. We reported no case of infection nor union. The devices were removed after a mean time of 11 weeks (range 8–15 weeks). Corrections of tri-planar deformity of the pilon by the Ilizarov apparatus are progressive and minimally invasive. In addition, it is possible to treat misalignment and lengthening by a single operation. With the apparatus layout combining foot fixation and ankle distraction soft tissue and secondary deformities can be corrected and finally a rapid recovery of weight bearing is possible.
