Aneurysms of the foot arteries

Introduction

Aneurysms of arteries of the foot have been reported as either true aneurysms or pseudoaneurysms. True aneurysms tend to occur in the elderly with atherosclerosis as the underlying etiology. Pseudoaneurysms of the foot arteries, on the other hand, mostly occur in younger patients secondary to trauma to either the dorsum or plantar surface of the foot.

In this report, we present four cases of aneurysms of the foot: one true dorsalis pedis artery (DPA) aneurysm and three cases of post-traumatic plantar artery pseudoaneurysms with arteriovenous fistulas (AVFs). This case series is followed by a discussion on the etiologies, clinical presentations and management options for aneurysms of the foot arteries. Patient consent for publishing was obtained.

Case 1: True dorsalis pedis artery aneurysm

A 60-year-old man presented with a three-year history of an enlarging pulsatile mass located on the dorsal aspect of the right foot (Figure 1(a)). Clinical examining revealed no signs of toe ischemia. A pre-operative arterial duplex ultrasound (DUS) confirmed a 2.6 × 2.0 cm aneurysm of the right DPA with normal right foot toe pressures. The patient was recommended surgical resection of the aneurysm. The saccular-shaped aneurysm was exposed and controlled proximally and distally (Figure 1(b)). To assess distal foot circulation prior to aneurysm resection, a trial of intraoperative clamping of the DPA was carried out distal and proximal to the aneurysm. This revealed decreased Doppler signals in the digital arteries. The aneurysm was resected, and the vessel was reconstructed via an end-to-end anastomosis (Figure 1(c)). Histology demonstrated a true aneurysm given all three layers (intima, media and adventitia) of the arterial wall were affected. ¹ The patient had an uncomplicated post-operative course and remained well at 6-month, 12-month and 2-year follow-up visits. OPEN IN VIEWER

Case 2: Post-traumatic medial plantar artery pseudoaneurysm

A 28-year-old woman presented with a six-month history of pain and swelling on the plantar surface of the foot. She reported a history of trauma to the foot that resulted from stepping on a piece of glass one year prior to the presentation. A deep lacerated wound at that time required multiple interrupted sutures to control the bleeding. The foot was edematous with prominent subcutaneous veins visible in the distal third of the leg. A pulsatile mass with palpable thrill was present on the plantar surface of the foot. Radiographic work-up included magnetic resonance angiography (MRA) of the foot, which revealed a 3.0 × 3.0 cm medial plantar artery pseudoaneurysm deep to the abductor hallucis, flexor hallucis longus and plantar fascia with an associated AVF (Figure 2). The patient underwent successful surgical excision of the medial plantar artery pseudoaneurysm and ligation of AVF with resolution of foot edema and venous dilatation. She remained asymptomatic at 6-month, 12-month and 2-year follow-up visits. OPEN IN VIEWER

Cases 3 and 4: Post-traumatic lateral plantar artery pseudoaneurysms

A 26-year-old woman and an 18-year-old man presented with a new onset painful mass on the plantar surface of the foot. Both of these patients reported a background history of trauma to the plantar surface of the foot six and eight months prior to presentation, respectively. Both patients had undergone local wound exploration and primary repair of the laceration with interrupted stitches as initial management. On clinical assessment, a pulsatile mass on the plantar surface of the foot was visible with a palpable thrill in both patients. Both patients underwent uneventful surgical excision of the lateral plantar artery pseudoaneurysm with AVF ligation (Figure 3), and remained asymptomatic at 6-month, 12-month and 2-year follow-up visits. OPEN IN VIEWER

Discussion

The etiology of foot aneurysms can be divided into two broad categories: true aneurysms and pseudoaneurysms. True foot aneurysms tend to occur in the elderly with atherosclerosis as the underlying etiology. These patients usually present with a painless pulsatile mass in the dorsum of the foot much like how the patient presented in our first case. ¹ However, more serious presentations such as ruptured aneurysm and acute ischemia of the forefoot have also been reported.^2,3 Pseudoaneurysms of the foot arteries, on the other hand, generally occur secondary to a traumatic injury, and are therefore more likely to be underreported.

To determine the rates of all primary foot aneurysms and pseudoaneurysms reported in literature, we conducted a computerized literature in MEDLINE (up to 1 October 2014) using the following keywords: foot artery, dorsalis pedis artery, posterior tibial artery, plantar artery, foot, aneurysm and pseudoaneurysm. No limitations were set for article type, publication date, language, gender or age group. We found 41 total cases of foot aneurysms reported in literature; 18/41 (44%) of the patients had true foot aneurysms, whereas 26/41 (56%) had pseudoaneurysms of the foot arteries with or without AVFs. Only 7/26 (27%) of the pseudoaneurysms involved the plantar artery of the foot.^4–9

Locations of foot artery pseudoaneurysms depend on the type and mechanism of injury sustained. For instance, pseudoaneurysms of the anterior tibial artery and its lateral malleolar branches tend to occur following an injury to the vessels during passage of an arthroscope for ankle arthroscopy.^10–12 Pseudoaneurysms of plantar arteries, on the other hand, generally occur due to trauma to the plantar surface of the foot, often secondary to a local injury.

Most traumatic plantar artery pseudoaneurysms occur in the lateral plantar artery, as it is more superficial and larger than medial plantar artery. Furthermore, the medial plantar artery is protected by the abductor hallucis, flexor hallucis longus and quadrates plantar muscles making injury to this artery uncommon and more difficult to treat surgically. Two out of the three cases of plantar artery pseudoaneurysms presented in this report involved injuries to the more commonly affected lateral plantar artery.

Clinical presentation of patients with foot aneurysms is diverse, and includes: asymptomatic, pulsatile mass that may grow in size over time, foot swelling secondary to venous hypertension caused by an AVF, acute foot ischemia or rupture. Three out of the four cases of foot aneurysms presented in our report were symptomatic; the two patients with a lateral plantar artery pseudoaneurysm presented with persistent foot pain, which was likely associated with increasing size of the pseudoaneurysm. The patient with a medial plantar artery pseudoaneurysm, on the other hand, presented with symptoms secondary to venous hypertension (foot edema, dilated foot and leg veins) caused by the associated AVF.

Several potential management strategies should be considered during the preoperative assessment of foot aneurysms, including: percutaneous embolization of the aneurysm, intact ligation and surgical excision of the aneurysm with reconstruction. Which strategy is selected depends on several factors, such as the vascular anatomy of the foot, presence or absence of collateral arteries, and if there is an associated AVF. Preoperative imaging with MRA, computed tomography angiography (CTA) or catheter-directed angiography can delineate the vascular anatomy of the foot and help guide management.

From an anatomical perspective, the “classic” anastomosis between the medial and lateral plantar arteries is present in only about 20% of individuals and 5% of individuals have no junction between dorsalis pedis and lateral plantar arteries. ¹³ Individuals with good collateral circulation of the foot evidenced by the presence of these vascular anastomoses can likely tolerate embolization or ligation of the aneurysm without the need for reconstruction. However, if the foot perfusion is inadequate, arterial reconstruction is mandatory – this was the case in our first reported patient who exhibited inadequate toe perfusion after excluding the aneurysm from the foot circulation as documented by poor Doppler signals in all digital arteries. Furthermore, the presence of an associated AVF mandates open surgical resection, ¹⁴ as was the case in the second, third and fourth presented patients.

Risk of perioperative complications during surgical excision of foot aneurysms is low. However, the space-occupying effect of a plantar pseudoaneurysm may damage the adjacent nerves if not released properly, which can lead to tarsal tunnel syndrome. ⁹ Other potential complications include arterial/graft thrombosis or distal embolism causing acute ischemia if vascular reconstruction is required. No study has directly compared the outcomes of endovascular and surgical therapy for foot aneurysms, and current evidence for the treatment approach to foot aneurysms is limited to small case series.

Conclusion

Although aneurysms of arteries of the foot are rare, they can lead to complications such as venous hypertension, rupture and acute ischemia if left untreated. Furthermore, the continual emergence of technological leaps in the form of endovascular techniques affords a greater diversity of therapeutic options available for the management of foot aneurysms. A better understanding of the various etiologies, clinical presentations and treatment strategies through cases such as those presented in this report can help clinicians with early diagnosis and management of this rare clinical problem.