Vascularized composite allotransplantation (VCA) is becoming an accepted treatment option for bilateral upper extremity amputees, with good mid-term results [1-3]. The indications for upper extremity transplantation are expanding, with excellent results recently reported in a transhumeral case . Bilateral transfemoral (above knee, AK) traumatic amputation causes a profound functional impairment. Prosthetic adaptation may be impossible in some cases, despite aggressive rehabilitation protocols, rendering these patients confined to a wheelchair . Lower extremity transplantation has typically been contraindicated, assuming the theoretical risks would outweigh the benefits. Classically, even lower limb replantation after traumatic amputation has been discouraged , although good results have been reported in below-knee (BK) replantations recently .
Extrapolating the experience of the authors in upper extremity transplantation and in lower limb replantation, a transfemoral bilateral transplantation was performed in July 2011 and reported herein at 12 months of follow-up. To the best of the authors' knowledge, no similar cases have been reported in the literature.
The recipient was a 22-year-old male that suffered a bilateral traumatic AK amputation in a car crash 2 years before (Figure 1). The femur stump was 32-cm long on the right side and 41-cm long on the left (Figure 2). Blood group was O negative, CMV IgG– and EBV IgG+. HLA typing was A1 A24 B15 B44 DRB1*1406 DRB1*15. After an extensive rehabilitation program at a large university hospital, the patient was unable to walk with prostheses and used a wheelchair. Pain and socket instability prevented conventional prosthetic fitting. The patient refused osseointegrated prostheses because of perceived bad results communicated by rehabilitation peer patients. Tinel's sign of the sciatic nerves was located 10 cm above the amputation level. IRB approval was obtained from the hospital and the Spanish organ procurement organization (ONT).
The donor and the transplantation procedure
The donor was a 26-year-old female multiorgan donor with brain death. Blood group was O negative, CMV and EBV IgG–. HLA typing was A2, B44, BW4, DR15 , DR17 , DR51, DR52, DQ6  and DQ2. Crossmatching was negative. Transplantation was performed on July 11, 2011. The quadriceps and hamstring muscles, external iliac vessels and sciatic nerves were dissected and tagged bilaterally at the stumps in the recipient.
The procurement of the legs was performed after cardiac and liver retrieval at the same hospital. The lower extremities were cold perfused in situ. Thirty liters of University of Wisconsin solution were used for simultaneous liver, kidney and lower limbs perfusion without cross clamping. This large amount of solution was used to completely flush the vascular bed of the lower half of the body. No pressure control was used. The femoral vessels were dissected up to the common iliac artery and vein. Femoral osteotomies were performed 22- and 12-cm proximal to the knee joint line in the right and left sides, respectively. This level was estimated based on the previous recipient's height. The sciatic nerves were cut proximally at the sciatic notch. Cosmetic prostheses were affixed to the donor. The right limb was retrieved first, and was immediately transferred to the recipient's OR in a sterile plastic bag without additional cooling means. The left limb was retrieved afterwards, simultaneous with right limb transplantation, and was kept cooled in crushed ice in the meanwhile.
The right leg was transplanted first. The sequence of repairs was the same in both sides. Bone fixation was performed first with 4.5-mm locking plates and screws. Hamstring muscles were then repaired. The sciatic nerve was repaired using epineural interrupted suture. The quadriceps was sutured under tension with heavy absorbable material. No intraoperative cooling was used for the right limb. The iliac artery of the VCA was then flushed with warm (37°C) Ringer's solution. The vascular tree of the leg was filled with warm Ringer's solution and clamped. End-to-side anastomoses were performed to the recipient's external iliac vessels. The vein clamp was released first and then the arterial clamps, allowing revascularization. No significant adverse events took place upon revascularization. The left leg was kept cooled in crushed ice, without temperature measurement, during the right side reattachment, and the same sequence of surgical maneuvers was followed on the left side (Figures 3 and 4). Reperfusion of the second limb was performed 2 h after the first limb and it was well tolerated by the patient. A total of 12 units of packed red cells, six units of fresh frozen plasma and three units of platelets were transfused during and after the surgery. Total ischemia time was 3.5 h on the right side and 5.5 h on the left side. No fasciotomies were performed. An external fixator was inserted in the tibia bilaterally for postoperative suspension. Figure 5 shows patient 4 weeks postoperatively, a single-pin T scab scar is visible in the pretibial region (Figure 5).
Immunosuppressive treatment consisted on induction with alemtuzumab 30 mg IV, and maintenance with mycophenolate mophetyl (MMF) 1 g/12 h, tacrolimus (Tac) for trough levels of 10–17 ng/mL during the first month and 7–12 ng/mL thereafter, and tapering methylprednisolone (1 g on reperfusion, 250 mg for 2 days, 100 mg on POD3, 60 mg from POD 4–14 and progressive reduction thereafter; Figure 6). No CMV prophylaxis was instituted, given the D–/R– matching . CMV replication was monitored weekly. The risk of deep venous thrombosis because of denervation of the calf veins was addressed with prophylaxis using Clopidogrel.
No significant complications developed in the early postoperative period. At POM 4, the patient developed hypertriglyceridemia and was treated with gemfibrocil. At POD 90, Tac was changed for rapamycin in order to reduce Tac exposure and long-term risk of malignancy. Coincident with this, the patient developed CMV primary infection (CMV syndrome) and skin acute rejection (AR; Figure 7). IV valgancyclovir (Val) was started and IV methyl prednisolone (500 mg/day) was given for 5 days. Histology revealed a Banff grade I acute rejection (Figure 8), with positive C4d staining. DSA (flow cytometry) were negative. The AR was resistant to steroids. Intravenous immunoglobulin (IVIg) was given for 7 days and rapamycin was changed for Tac with rapid clinical and histological resolution of the skin changes (Figure 9). Neutropenia occurred at POD 95 (leucocyte counts 4500 per mL at POD 90, 660 per mL at POD 104) and responded to treatment with G-CSF (leucocyte counts 2680 per mL at POD 105 and 5810 per mL at POD 106). CMV replication became negative after 37 days of treatment. Val was stopped on day 307 after verification of cellular CMV immunity (CD8 T cell response against CMV, QuantiFERON-CMV; Ref. 8).
A second AR occurred on POM 9, Banff grade I (Figure 10), related to dose reduction of Tac and MMF because of transient diarrhea (Tac level 6.5 ng/mL and MMF level 3.4 mg/mL). Treatment with dose adjustment reversed the AR (Tac 8.6 and MMF 7.2 mg/mL at 10 days). Two episodes of deep abscess, unrelated to the bone fixation, developed at POM 6 within the left quadriceps, probably because of ischemic areas of distal muscle around the heavy muscular sutures. Acinetobacter spp., and enterococcus spp. were isolated from the exudates, both sensible to aztreonam. Treatment with surgical debridement and intravenous aztreonam for 6 weeks was curative. Bone healing occurred in the right side, but was delayed in the left side (Figure 11). The patient is using local ultrasound (EXOGEN Express, Ultrasound Bone Healing System, Smith & Nephew, Barcelona, Spain) and surgical revision (autologous bone grafting with or without fixation revision) will be performed depending on radiographic response. Renal function, blood pressure and glucose levels have remained normal. CMV replication and DSA have remained negative. Chimerism tests were not performed in this patient.
Passive ankle exercises were started from POD 1. Passive knee range of motion (ROM) was started on POD 15. Active quadriceps contraction was allowed on POD 21, with progressive strength exercises. Hip extension and abduction active exercises were also performed. Ambulation with partial weight bearing was started in swimming pool on POM 4. Ambulation between parallel bars was started on POM 9 with rigid walking boots. Progressive weight bearing was allowed with partially healed osteotomies to stimulate bone healing.
Active ankle plantar flexion started at POM 7 on the left side and POM 8 on the right. Strengthening exercises were performed accordingly. Pressure compression stockings were used during the first 4 months for edema control.
At 1-year follow-up, the patient had full passive ROM in both knees (0°–150°), with active knee extension. There was an extension lag of 30° and 45° on the left and right knees, respectively. Quadriceps strength was better on the left side. There was active flexion of both knees. Foot (ankle) plantar flexion was M4 (MRC score) on the left side and M3+ on the right. Tinel's sign was advancing at plantar level. At the time of this writing (POM 14) there is early recovery of dorsal ankle flexion at the left side. The patient had fully incorporated the transplanted legs into his body image. Walking between parallel bars was improving, although there was mild hip flexion to compensate for the knee extension lag (video S1). The ankles were not stable enough yet and rigid ankle–foot orthoses were used for walking exercises.