Fig. 12.1
A relatively sharp injury. After proper debridement and bone shortening, direct wound closure could be achieved with minimal wound necrosis. A flap was not needed
Fig. 12.2
A case of Fig. 12.1 after bone lengthening; the final result was good. This is a very unusual situation in the authors’ practice
Indications
The risk-benefit ratio is very delicately balanced in lower limb replantation, and indications should be carefully evaluated [19–22]. Because the staged process is labor-intensive and requires highly committed teams for consistent results, the first consideration should include the ability and willingness of the team to assume such cases. Otherwise, referral to the proper team, if time and general condition of the patient allow, is appropriate.
Given the complexity of the whole process, and the high risk of complications, absolute indications cannot be unequivocally established. A balanced interplay between the type of injury, the general condition of the patient, and the technical capacity and involvement of the surgical team is critical for deciding a particular indication. Complex replantations, as in the case of the lower limb, should not be “attempted.” Instead, a clear plan of reconstruction possibilities, likely complications, and the solution for them should be formulated at the outset, and then, if the chances for success are considered high, replantation should proceed. Absolute contraindications are infrequent and include anatomic destruction of the sole of the foot, massive crushing of the extremity, concurrent destruction of the knee joint in a young patient, sacral root avulsion, and extended ischemia time (over 8–10 h). Ischemia times in the 6–8 h range can be managed with temporary arterial catheter perfusion [23]. While there exists a whole collection of injury severity scores for lower limb trauma, with cutoff numbers for salvage, their usefulness for the experienced surgeon is very limited.
Age, per se, is not a contraindication, but previous ambulatory state is important. A physically fit patient in his or her seventies could benefit from replantation. A previously nonambulatory patient has no indication for replantation regardless of the age. Pediatric injuries have a wider indication for replantation [4, 19–21]. The combination of advanced age, severe peripheral occlusive arterial disease, and/or severe comorbidities contraindicates replantation. A patient’s desire is difficult to assess in the emergency situation. The association of severe, potentially lethal injuries is a general contraindication (life before limb). Surgically treatable conditions can be corrected, and a low-impact temporary ectopic replantation can be considered as a temporizing measure (see below).
Injury-related factors are also important in decision-making. Massive bone loss, either primary or resulting from adequate debridement, is a contraindication. Complication rates of bone lengthening of the tibia abruptly increase when more than 15 cm are elongated [24]. Unilateral defects over 18–20 cm contraindicate replantation, even if a good tibial nerve repair can be done. Significant tibial nerve injury precluding satisfactory repair even after aggressive bone shortening also contraindicates replantation. If the tibial nerve can be directly coapted, the sole is relatively intact, the skeletal defect is manageable, and the anticipated soft-tissue problems are deemed solvable, the replanted limb can be more functional than a prosthesis.
Knee joint preservation is crucial in lower limb infrapopliteal amputations. Unless the joint is massively disrupted, every effort should be made to keep at least a below-knee level of amputation if formal replantation is not indicated. Salvage replantation in the form of replanting portions of the otherwise discardable foot may improve the function of the residual limb. As stated above, the authors have no experience in transfemoral replantation, but under optimal circumstances, it would be reasonable to convert the AK into a BK level through replantation of the knee and proximal third of the tibia, especially in bilateral cases. Theoretically, this approach would be relatively straightforward, with short recovery time before prosthetic fitting (bone healing only). Femoral bone shortening could easily be compensated with the prosthesis, obviating the need of bone lengthening.
Crushing of the stump, contamination, and double-level proximal vascular injuries are not per se contraindications and can be managed with adequate debridement or a temporary ectopic replantation.
Surgical Technique
Although the general surgical steps in lower limb replantation are similar to upper limb replantation, the philosophy is somewhat different. Complications are very frequent, and their treatment is an integral part of the replantation process. Lower limb replantation should be viewed as a three-stage surgical procedure, the urgent replantation being but the first stage. Soft-tissue coverage and bone lengthening are the other two stages.
Stage One: Replantation
Generally, this will be more straightforward than most upper limb cases, although general replantation guidelines apply, with some modifications. Using temporary arterial catheter perfusion and artery-last sequence of repairs allows for optimization of ischemia times [23]. Because of the higher risk of soft-tissue necrosis and the relatively lower functional impact of extensive muscle loss compared to the upper limb, debridement should be very aggressive. Bone shortening should also be very liberal to allow for direct wound closure (if possible) and, most importantly, a high-quality tibial or plantar nerve repair. Bone fixation is performed with K-wires in amputations distal to the ankle joint and with modular external fixation in transtibial amputations for expediency. Perfect anatomic reduction or completely stable constructs are not necessary in above-ankle replantations, since this fixation is temporary. Vessel repair should include as many arteries and deep veins as possible if the amputation is distal to the popliteal trifurcation. The risk of skin necrosis is high, and superficial veins should not be relied upon as the main outflow of the limb. Regarding muscles, at least the tibialis anterior muscle and the triceps surae muscle should be repaired. Other muscles can be repaired only under optimal (and unusual) conditions. Wounds are loosely closed if possible; otherwise, the vascular and neural structures are temporarily covered with skin grafts until definitive closure is performed a few days later [28]. Fasciotomies are rarely necessary and only performed if ischemia time exceeds 6–7 h (Fig. 12.3).
Fig. 12.3
A crushing injury, with double-level tibial injury. The sole of the foot was intact. Tibial nerve was repairable. Replantation was performed, anticipating severe skin necrosis
Stage Two: Definitive Wound Coverage
Because skin-edge necrosis is the rule rather than the exception, early flap coverage will almost always be the second stage of the replantation procedure and should be performed within a few days after the replant. Occasionally, the wounds can be covered with skin grafts (Figs. 12.1 and 12.2), but more frequently a free flap is required (Figs. 12.4, 12.5, and 12.6). If vascular repairs are not directly underneath the necrotic skin, 1 week is allowed for demarcation. The recipient vessels are usually proximal to the amputation level, and end-to-side or double end-to-end “T” constructs are mandatory. Distal vessels within the replanted leg can be used as recipients for flap coverage of associated double-level defects. Workhorse flaps as latissimus dorsi, gracilis, or ALT flaps are recommended to avoid unnecessary complexity. Early delayed definitive coverage is preferable to emergency free flaps in most cases.
Fig. 12.4
A case of Fig. 12.3: Extensive circumferential skin necrosis without deep infection at 4th postoperative day
Fig. 12.6
Healed wounds with 9 cm bone shortening
Stage Three: Skeletal Lengthening
In amputations distal to the ankle, bone shortening is inconsequential and does not need further correction. In transtibial amputations, bone shortening has to be corrected through callus distraction (distraction osteogenesis), especially in unilateral cases (Figs. 12.6, 12.16, and 12.21). It is preferable to place the osteotomy for distraction at the proximal metaphysis rather than the fracture site [29, 30]. Bone lengthening should be performed soon after the wounds are healed, usually by the 3rd month, to reduce overall treatment times. Monorail half-pin frames are easier to manage than ring fixators and are preferable in most cases (Figs. 12.7, 12.8, 12.9, and 12.17). A normal lengthening of 1 mm/day is used, and early exchange of the external fixator for a locked, intramedullary nail is advisable to allow weight bearing and further shorten treatment times (Fig. 12.10, 12.11, and 12.12). The proximal metaphyseal osteotomy for distraction could theoretically be performed initially, during replantation surgery, and the monorail fixator placed primarily to shorten the overall treatment time further. The authors do not use this option for two reasons: firstly, placing the monorail fixator accurately adds complexity and time to the initial procedure, and secondly and most important, in the unlikely case of replant failure, the tibial stump would be compromised unnecessarily.
Fig. 12.7
The tubular external fixator was exchanged for a ring fixator for bone lengthening
Fig. 12.8
The short proximal fragment after metaphyseal osteotomy required a ring fixator
Fig. 12.9
Ring fixator allowed lengthening of 9 cm and distal fracture healing
Fig. 12.10
Stable skeleton after exchange of the ring fixator for a reamed locked nail at postoperative month 15
Fig. 12.11
Postoperative situation at 24 months. Plantar sensation was protective
Fig. 12.12
Postoperative situation at 24 months. The patient could walk without aid
Replantation in Unfavorable Situations
If the injured limb is considered amenable to replantation, but the local or general condition of the patient precludes an immediate replantation, there are three useful techniques, namely, ectopic, heterotopic, and salvage replantation, that help overcome these transient difficulties.
Temporary Ectopic Replantation
This is a low-impact, straightforward technique that allows maintenance of perfusion in the amputated part while the local or general condition of the patient improves enough to permit orthotopic transfer [31, 32]. Severe crushing, contamination or double-level injuries of the stump, and hemodynamic instability or treatable potentially lethal associated injuries are the main indications (Figs. 12.13, 12.14, 12.15, 12.16, 12.17, and 12.18). The recipient vessels for the ectopic replantation can be the contralateral femoral artery and saphenous vein or the distal posterior tibial vessels (Figs. 12.19 and 12.23). The latter have the distinct advantage of allowing simultaneous elevation of a perforator flap with the vascular pedicle upon orthotopic transfer, the possibility of repairing two venae comitantes, and possibly the greater saphenous vein too, and the length of the vascular pedicle if the whole posterior vascular bundle is harvested upon transfer [33] (Figs. 12.20, 12.21, 12.22). The main drawback of using the posterior tibialis vessels as recipients is that, should a free fibular flap be necessary later on for the treatment of complications during bone lengthening in the replanted limb, the contralateral “healthy” leg would be left with only the anterior tibial artery, unless the peroneal artery is simultaneously reconstructed with a vein graft, in this unlikely but possible scenario. The ectopically replanted part should be fixed with a modular external fixator to the contralateral femur or tibia to secure a stable fixation. Once the local condition of the stump improves through sequential debridement and wound care, or the general status of the patient is stabilized, the replanted leg can be transferred to the stump. This typically happens about 1 week after the accident. Longer times make dissection of the scarred vessels and identification of structures more difficult. The ectopic time also allows for the skin-edge necrosis to develop, and definitive debridement can be performed with the orthotopic transfer (Fig. 12.23). Soft-tissue shortage should be anticipated when orthotopic transfer is performed, and simultaneous free or regional flaps are usually necessary. Ectopic replantation, although initially a low-impact, straightforward technique, adds considerable complexity to the overall replantation procedure and should be considered cautiously.
Fig. 12.13
In severe injuries with proximal double-level lesions, if the sole is intact, the tibial nerve is repairable, and the skeletal defect manageable, replantation can be performed as a staged ectopic replantation
Fig. 12.14
Ectopic replantation to the contralateral femoral artery and saphenous vein. The proximal injuries were treated meanwhile. At postoperative day 6 orthotopic transfer was planned. Note the concomitant latissimus dorsi free flap for anticipated soft-tissue shortage
Fig. 12.15
The free flap was connected to the anterior tibial vessels and the replant to the posterior tibial vessels
Fig. 12.16
Healed wounds with 11 cm shortening, before lengthening
