[Minimally invasive osteosynthesis of pilon fractures].

OBJECTIVE: The primary aim of minimally invasive osteosynthesis (MIO) is the anatomical reconstruction of the distal tibial articular surface, with preservation of the soft tissue to allow early functional postoperative management. This should lead to a normal bone healing and recovery without arthrosis.

INDICATIONS: Fractures type Rüedi I + II or AO 43-B1, -B2, AO 43-C1, -C2, rare and relative indications are fractures of type AO 43-B3 and -C3 fractures without IIb and III° soft tissue injuries. It may also be used as an additional technique for osteosynthesis with external fixators.

CONTRAINDICATIONS: Severe comminuted fractures of the pilon with closed or open II and III° soft tissue damage. Severe soft tissue damage (III°).

SURGICAL TECHNIQUE: An intensive preoperative analysis of conventional X-rays and CT images is necessary to support the indication for MIO of pilon fractures. The first step is reduction of the fracture with axial traction, in some cases with a distractor or external fixator. The definitive reduction is performed with K-wire joysticks or reduction clamps. The key step is the intraoperative X-ray control of the reduction in various planes, if possible with 3D reconstruction. An alternative is also arthroscopic control of the articular reduction. All manipulations are performed via small incisions. After incision of the skin, all layers of soft tissue are smoothly divided with scissors allowing the soft tissue including vessels and nerves to be moved out of the working channel. All instruments and implants (e.g., K-wires, drill sleeve, screws) are introduced between the opened scissor branches. After lag screw osteosynthesis with 3.5 or 4.5 mm conventional screws, the articular block is reduced to the diaphysis and fixed with a minimally invasively inserted plate. Under X-ray control in two planes, the plate is adjusted into position and preliminarily fixed with K-wires. The screws are inserted using the minimally invasive technique.

POSTOPERATIVE MANAGEMENT: Immediate mobilization starting on day 1 with partial weight bearing (sole contact or 12-15 kg) for 4-6 weeks, postoperative protection with orthesis or split cast for 2-5 days depending on degree of swelling, early functional physiotherapy, thrombosis prophylaxis with heparin until complete mobilization. Full weight-bearing depending on fracture type after 6-8 weeks.

RESULTS: Advantages of minimally invasive osteosynthesis of pilon fractures compared to conventional open reduction and osteosynthesis, include protection of the soft tissue and no further disturbances of circulation-ideal prerequisites for undisturbed bone healing. In 129 patients after osteosynthesis of pilon fracture, no reoperations were necessary when using MIO, but reoperation was necessary with other techniques in 17.6% of all patients. In addition, no infections were observed with MIO vs. 13.4% of patients with other techniques. The average Olerud/Molander Score was 95 points for the MIO group vs. 58.91 points for all patients treated, while MIO plus an external fixator received a score of 50 points. The average Ankle Hindfoot Score was 64.9 points, for MIO 87.5 points, and for operations consisting of MIO plus an external fixator 58 points.