DISCUSSION
Most reported cases of lower extremity amputation are below the knee level [
1]. We have described two cases of ankle/foot amputations, with a focus on differences in presentation and management. Traumatic amputations from road traffic accidents have more damage than clean-cut wounds. The bone edges are less viable, and bone shortening is usually required during debridement, as in our case.
One week post-replantation, we noted wound edge necrosis in the patient who had experienced a road traffic accident. In general, this is expected for avulsion and crush injuries [
2], as in the second case. The incidence of soft tissue necrosis and deep infections at the wound edges has been reported to be 83%–90% and 17%, respectively [
1]. Nonetheless, rates of bone nonunion or malunion are not different from non-amputation cases [
2]. A second operation for wound coverage is common for this kind of injury [
2]. In our case, we used a free anterolateral thigh flap with the vastus lateralis muscle. The flap vessels were anastomosed to the anterior tibial artery and its vena comitans in an end-to-side manner, to allow distal foot flow. In contrast, the patient in the first case, in whom the amputation occurred via a cut wound inflicted by a sharp sword, only sustained minimal wound edge damage and did not require any secondary procedures.
Every effort should be made to salvage the amputated part of the limb. In the past, attempts at lower limb replantation resulted in many complications [
1]. Noticeable improvements have occurred in the survival rate and outcomes of replanted lower limbs from past to present. This may reflect advances in surgical skills and facilities, resulting in improved ischemic times, as more resources are available in modern healthcare. Likewise, trends have shifted from a tendency to primarily amputate [
3] to a more favourable view towards replanting the limb at all costs. In 1983, Kutz et al. [
4] reported a 33% success rate in his case series of nine patients who underwent replantation of the leg. In contrast, in 2002, Battiston et al. [
5] reported a 100% success rate of lower extremity replantation in nine patients, of whom 78% achieved functional success (Chen grade I or II). In 2005, Hierner et al. [
6] reported a 62.5% success rate in 15 total and subtotal amputated replantations, of which 92.7% were classified as showing functional success (Chen grade I and II). In a 2009 study by Cavadas et al. [
1] in Spain, the survival rate was 100% in 12 patients with 13 lower leg amputations who underwent replantation.
In the second case (caused by a road traffic accident), the amputated part of the extremity endured 10 hours of ischemic time. Nonetheless, we achieved a good replantation outcome. Although the generally accepted rule is that the ischemic time should be less than 6 hours [
5], Kutz [
4] also reported a similar case with ischemic time of 10 hours, in which replantation was successful.
The indications for replantation or amputation of the lower extremity are still not clearly defined. The outcomes predicted by the Limb Salvage Index or Mangled Extremity Severity Score [
3] cannot be applied universally to all cases, and there does not seem to be an accurate prediction method [
3,
5].
It was previously believed that the feasibility of tibial nerve repair to achieve plantar sensation was the most important factor when considering replantation [
1]. However, Bosse et al. [
3] concluded that, in cases of severe lower extremity trauma, with an insensate plantar surface, the functional outcomes did not differ between salvaged limbs and amputated limbs. In most cases of limb salvage with standard tibial nerve repair, the chances of regaining plantar sensation remain good [
1,
4]. Noticeable improvements have occurred in the survival rate and outcomes of replanted lower limbs from the past to present [
1]. In our patient with the sword slash injury, we intended to repair the tibial nerve at a later stage, due to the burdens imposed by microsurgery. However, due to technical and legal issues, the patient was discharged early and did not return for follow-up. A phone conversation with the patient’s mother revealed that the patient was walking actively and had resumed daily activities, albeit with a slight limp.
The sequence of vessel repair is controversial. Traditionally, when prolonged ischemia occurs, the artery is repaired first, allowing blood flow to flush out the build-up of toxic metabolites. However, in our case, the foot was deemed to be too small to have accumulated many toxic substances. The sequence of vessel repair also reflects the surgeon’s preference, as some surgeons prefer repairing the more difficult vessel while fresh and alert. In other studies, the artery-last sequence has been advocated as a way to promote cleaner and more rapid surgery [
2]. Using a two-team approach, as in our cases, also shortens the ischemic time [
2]. As a rule, as many vessels as possible should be repaired under microscopy [
2].
We used rush rods to achieve both ankle fusion and fracture stabilization. An external fixator was added after wound closure for more structural strength. Perfect rigidity or anatomical correctness of the bone is not as important as vessel repair, and the latter should not be sacrificed for the former [
2].
It is advocated to repair at least the tibialis anterior muscle and triceps surae muscle [
2]. In our case, it was only possible to repair the tibialis anterior and extensor hallucis longus. However, in a fused joint, as occurred in our case, this step is not the highest priority. The wound should be closed without tension [
2], with care not to disturb the underlying fragile neurovascular repairs that have just been done.
With improved survival and functional outcomes of replanted limbs, replantation should be a high priority as opposed to primary amputation in cases of total or subtotal lower extremity amputation. All efforts must be directed towards decreasing the ischemic time to achieve the best survival and functional outcomes. No adequate evidence exists for clear guidelines on the decision of whether to salvage a limb.