Successful preservation of below-knee amputation stump wound with vastus lateralis anterolateral thigh flap in a patient with peripheral artery disease

Abstract

The preservation of a below-knee amputation (BKA) stump is essential for maintaining optimal limb function and facilitating future prosthetic use. Salvaging an infected stump is particularly challenging due to the loss of healthy soft tissue necessary to preserve adequate limb length. Patients with peripheral artery disease are often not considered candidates for complex reconstruction given concerns for poor perfusion, active smoking, and medical comorbidities. This case demonstrates a patient who underwent a BKA after failed revascularization for acute limb ischemia. Successful salvage of a BKA stump with a polymicrobial infection was achieved using an anterolateral thigh free flap with vastus lateralis muscle. At 4 months postoperatively, the patient was successfully ambulating with a prosthetic leg. This case demonstrates that advanced reconstruction for preservation of BKA stump may be feasible in patients with underlying peripheral artery disease.

Preservation of a below-knee amputation (BKA) stump is important to preserve limb function for future prosthetic use. Additionally, required energy expenditure and quality of life with a BKA are superior to an above-the-knee amputation.^1,2 Salvage of an infected stump is difficult given the minimal local soft tissue coverage available in addition to often poor wound healing potential in vascular surgery patients. Anterolateral thigh flap with additional vastus lateralis muscle has been previously described as successful for amputation revision in trauma patients.3, 4, 5 The objective of this case report was to demonstrate a successful salvage of the BKA stump using a free flap in a vascular surgery patient with a polymicrobial stump wound infection. The patient has agreed to the publication of this case report.

Case report

The patient is a 62-year-old man who initially presented with Rutherford class 2B acute limb ischemia likely secondary to embolus from his femoral artery aneurysm. He underwent popliteal and dorsalis pedis artery cutdown with thrombectomy, angiogram, and four-compartment fasciotomy. Ultimately, the patient required a BKA due to complete loss of motor sensory function of the foot and ankle, as well as progressive foot necrosis. Unfortunately, the patient developed significant incisional breakdown with an underlying wound infection. Wound cultures grew Escherichia coli and Enterococcus faecalis. He required operative debridement of the devitalized tissue of his BKA stump at 5 weeks after his amputation (Fig 1). At this time, the plastic surgery team was consulted, given exposure of the tibia and inadequate soft tissue available to achieve coverage of the residual limb and maintain a BKA stump. After a multidisciplinary limb preservation meeting, the decision was made to proceed with a free flap 4 days later for BKA stump salvage.

Fig 1.

Below-knee amputation (BKA) stump wound before (A) and after initial debridement (B).

To bring adequate inflow and outflow for the microvascular free tissue transfer, an arteriovenous (AV) loop was created. The contralateral greater saphenous vein was harvested. The ipsilateral distal superficial femoral artery and femoral vein were then exposed at the adductor canal. Inflow was created with an end-to-side anastomosis from the superficial femoral artery to the greater saphenous vein conduit, followed by an outflow anastomosis to a large branch of the femoral vein using a venous coupler (Fig 2). The AV loop was tunneled through the medial subcutaneous tissue, superficial to the deep fascia in the residual limb soft tissue defect. The contralateral limb anterolateral thigh flap was then incised with identification of multiple perforators, and a segment of the vastus lateralis thigh muscle was included with the descending branch of the lateral circumflex femoral artery and associated vena comitans. The flap was then transferred to the residual limb, whereby the lateral circumflex femoral artery and flap vein were anastomosed to the AV loop with nylon sutures and a venous coupler, respectively. The vastus lateralis was then anchored to the distal tibia using bone tunnels and sutures. The tibial nerve was transferred to the vastus lateralis muscle flap. The incisions were closed in standard fashion.

Fig 2.

Intraoperative images demonstrating an arteriovenous (AV) loop graft and free flap to residual limb.

The patient returned to the operating room after a short interval for repair of his 2.1-cm femoral artery aneurysm with an interposition bypass graft to prevent any future embolic events. A planned revision of the amputation was also performed to optimize the contour of the residual limb and better facilitate wound healing. His BKA stump healed well with no phantom pain or hyperesthesia of the stump (Fig 3). At 4 months postoperative, the patient was successfully ambulating with his prosthetic leg (Fig 4).

Fig 3.

Amputation stump 4 months after flap surgery.

Fig 4.

Patient ambulating 4 months postoperatively with excellent metrics.

Discussion

More than 150,000 individuals annually undergo lower extremity amputations due to underlying peripheral artery disease (PAD).⁶ Amputations above the ankle are often life-altering events that impose a tremendous burden on patients and their families. More than one-half of patients undergoing amputations are permanently disabled after the surgery.⁷ Close to 60% of patients undergoing BKA achieve ambulatory status at follow-up compared with approximately 25% of patients undergoing above-the-knee amputation.⁸ The ability to attain ambulatory status and maintain independence is not only a matter of function, but it also directly impacts their overall survival.⁹ Microvascular free tissue transfer flap for limb salvage is a well-described technique in advanced limb salvage. Free flap transfer is especially useful in patients with a large traumatic soft tissue defect when local rotation flap is not feasible. However, this case is unique in that it is typically considered a relative contraindication in patients with PAD due to the concern for viability of the free flap. His case was carefully considered by our multidisciplinary limb salvage group, which consists of vascular surgeons, plastic surgeons, and podiatrists. In this particular case, even though the patient had underlying thromboembolic and aneurysmal disease, his computed tomography angiogram showed that his superficial femoral artery was relatively free of stenoses and could support adequate inflow for the AV loop conduit for the tissue transfer. In addition, on the contralateral side, he had a robust profunda femoris, which we believed it would be a sufficient donor site and that the patient would have adequate ability to heal the wound at the donor site. The femoral artery aneurysm was a concern because it could potentially be a source of another embolic event; however, given the recent wound infection and open BKA stump, a femoral artery aneurysm repair with a prosthetic at this time was not able to be performed. Instead, a decision was made to continue anticoagulation until he was able to undergo repair at a later date.

Using a free flap for the preservation of amputation stump length and knee joint is only described in trauma patients. This report presents a unique case of successful preservation of a BKA stump in an infected wound in a patient with PAD. We believe this result is important to share, because vascular patients are often excluded from undergoing more advanced measures of limb preservation techniques due to concerns for early failure. As evidenced in our patient, these efforts resulted in successful preservation of optimal limb length and thus a return to successful ambulatory status with significant improvement in quality of life and restoration of independent living.

We recognize that there are a number of patients with PAD for whom this technique may not be feasible, depending on the extent of their atherosclerosis, which duly emphasizes the importance of a multidisciplinary approach to limb preservation efforts. Patients with PAD secondary to thromboembolic disease or aneurysmal disease may be more likely to heal a flap as compared with patients with severe atherosclerosis. For patients who are being considered for this procedure, a full assessment of inflow and the donor site by computed tomography angiogram of the bilateral lower extremities or a catheter-based angiogram is of utmost importance. In addition, an adequate vein conduit should be assessed using ultrasound examination.

Conclusions

Microvascular tissue transfer is a viable option in the preservation of BKA stump length and function in patients with PAD. The management of these challenging patients requires a dedicated multidisciplinary team with expertise in both vascular and advanced reconstruction techniques. Although this type of limb salvage may require multiple surgeries, it can effectively restore and/or preserve ambulatory function, quality of life, and mortality outcomes.

Funding

None.

Disclosures

None.

From the Midwestern Vascular Surgical Society