Undisplaced “subtle Lisfranc injuries” may resolve with casting and non-weightbearing, probably for about 8 weeks to allow the ligaments to heal. However, there is a risk of displacement and we would recommend percutaneous screw fixation of these injuries.
Surgery
Exposure
The TMT joints are usually accessed through longitudinal incisions designed to give access to as many rays as necessary, to be extensile and to protect the intervening skin bridges. A single incision can give access to the 1st and 2nd rays and another to the 3rd, 4th and 5th or a medial or dorsomedial approach can give access to the first ray, another to the 2nd/3rd and another to the 3rd/4th. A transverse dorsal approach has been described (Vertullo 2002).
Some Lisfranc dislocations can be reduced closed and stabilisation achieved with percutaneous screws, but most require formal open reduction.
Any approach needs to respect the cutaneous nerves, mostly branches of the superficial peroneal, the extensor and tibialis anterior tendons and the deep peroneal/dosalis pedis neurovascular bundle – the total nerve injury rate in the three elective series summarised below was 7.2%.
Techniques
The key to the Lisfranc joint is the 2nd TMT joint and it is usually best to start by reducing this first. The other joints can then be reduced around it. A few papers start from medial or lateral and work across. If there is impaction of the cuboid, this needs to be reduced and stabilised first. It is important to get the metatarsal heads into the correct plane to avoid transfer lesions. Temporary stabilisation can be achieved with K-wires or guide wires and definitive stabilisation with screws. Gaines (2009) showed that repeated passes with guidewires substantially increases the damage to the remaining joint surface, and that wires placed in the plantar half of the articular surface had a significant risk of fracturing the metatarsal, cuneiform or both. In our experience, many fracture-dislocations are so comminuted that screw fixation is not possible and compact foot plates in bridging mode are the only option. If primary fusion is chosen joint preparation is by standard methods and bone graft is often required.
Ly and Coetzee (2006) reported a randomised controlled trial comparing ORIF and primary fusion of pure dislocations. The fusion group had significantly better AOFAS midfoot scores and return to function; five patients in the ORIF group required secondary fusion. However, this only accounts for a small proportion of Lisfranc injuries.
Henning (2009) reported an RCT comparing primary fusion with ORIF in a wider range of injuries including fracture-dislocations, although “major intra-articualr fracture patterns” were excluded. Fourth and 5th TMT joints were not fused and were stabilised only with wires. The trial was underpowered, and this appears to be because of problems with recruitment. The putcome measure of most interest seems to be the need for further surgery, but as in Ly’s trial this is complicated by the standard practice of routine removal of fixation screws. It is not surprising to find that 79% of ORIF patients but only 17% of fusion patients had further surgery. There was a trend towards better SMFA scores in the fusion group but no difference in SF36 scores, complications, pain or return to work or to wearing normal shoes.
Raikin (2009) compared screw fixation and suture/endobutton stabilisation in their cadaver model of subtle Lisfranc injury. Both fixation methods reduced abnormal movement on loading almost to normal, and there was no difference between them. A clinical RCT comparing these methods would be valuable.
Aftercare
Most series protect both trauma + elective cases with 6-12 weeks casting and 1-2 months nonweightbearing. The lever arm of the metatarsal shafts is substantial and dorsiflexion malunion a concern. However, Kazzaz (2009) found no increased risk of malunion or non-union with weightbearing in a heel-wedge shoe without plaster after Lapidus procedures.
If Lisfranc dislocations are stabilised with screws it is normally recommended to remove these electively 2-3 months post-operatively to allow motion to be regained at the injured joints. The argument is similar to that around syndesmosis screws in the ankle and there is no convincing evidence that removing either is necessary.
Outcome, complications and salvage
Displaced injuries require closed or open reduction and stabilisation with K-wires or screws. Most older series used wire fixation but a cadaver study by Lee (2004) showed that screw fixation, at least of the three medial joints, gives more rigidity. However, there has been no comparative clinical trial of wire versus screw fixation. If screws are used, most authors recommend removal about 3 months after injury, although there is no clear evidence this is necessary.
There has also been a controversy between temporary screw fixation and primary arthrodesis of the TMT joints. Mulier et al (2002) found more complications in patients who underwent arthrodesis, although they may have had more severe injuries.
Whatever method of reduction and fixation is used, functional outcome is mainly determined by the quality of reduction and the maintenance of that reduction (Myerson 1986, Mulier 1997). Direct injuries probably do worse than indirect injuries and pure ligament injuries than fracture-dislocations.
Almost all patients will develop some degenerative changes but these have little effect on the overall result. About 10-20% will develop symptomatic arthritis requiring arthrodesis (Myerson 1986, Mulier 1997, Kuo et al 2000) and this may be reduced but not avoided by initial ORIF.
Late arthrodesis produced satisfactory results in 70% of patients in Sangeorzan’s series (1990). Poor results were associated with delay in reconstruction. Other causes of poor results from reconstruction include severe soft tissue injuries and regional pain syndromes.
Calder et al (2004) found that delay in diagnosis and the presence of a compensation claim were associated with poorer outcome.