Arteriovenous malformations are defined as congenital lesions of vascular origin with multiple large feeding arteries. When these lesions become symptomatic, they can adversely affect the surrounding soft tissues and osseous structures1,2. Surgical resection with or without embolization therapy is commonly used to treat localized symptomatic arteriovenous malformations. Total surgical resection is necessary to prevent recurrence but may sometimes produce challenging anatomic defects and expose important structures such as bone, joints, tendons, and neurovascular bundles3.
Here, we describe an arteriovenous malformation that infiltrated the extensor hallucis longus tendon, resulting in a checkrein deformity of the great toe. The segmental defect of the extensor hallucis longus was reconstructed with use of a tendon graft consisting of one-third of the nearby anterior tibial tendon.
The patient was informed that data concerning the case would be submitted for publication, and she consented.
A thirty-three-year-old woman presented with a painful, slow-growing soft-tissue mass on the anterior aspect of the distal third of the right leg of ten years' duration. In addition, she had a checkrein deformity of the right great toe of approximately two years' duration. More specifically, she was unable to flex the great toe plantarward when the ankle was in plantar flexion, and the great toe extended during ankle plantar flexion. No previous treatment had been rendered. She reported no recent history of trauma, and the medical history was otherwise unremarkable. Her general health was excellent.
A firm 6 × 4-cm soft-tissue mass was palpable on the anterior aspect of the distal third of the right leg. The mass was slightly mobile and had a nodular, spongy consistency. It was not pulsatile and lacked a bruit or thrill.
Radiographs showed a calcific density just underneath the skin on the anterior aspect of the leg 5 cm proximal to the ankle joint. Magnetic resonance imaging showed a relatively well-defined soft-tissue mass of low signal intensity (similar to that of muscle) on T1-weighted images, mixed intermediate and high signal intensity on T2-weighted images (Fig. 1-A), and high signal intensity on gadolinium-enhanced images (Fig. 1-B). Furthermore, the mass was observed to infiltrate the extensor hallucis longus tendon and a portion of the extensor digitorum longus muscle. However, there was no cortical destruction of bone or bone-marrow change. The mass appeared to be a hemangioma or a vascular malformation.
Surgical resection was attempted to relieve pain and to resolve the checkrein deformity of the great toe because the lesion was relatively well demarcated. When the patient was under general anesthesia, the great toe extended as the ankle was moved plantarward (Fig. 2). A 10-cm-long zigzag incision was made over the anterior aspect of the leg, extending from the ankle proximally (Fig. 3-A). The superficial peroneal nerve was identified and protected. The mass was observed to lie just beneath the superficial fascia, and it was necessary to transect the superior extensor retinaculum and part of the inferior extensor retinaculum to expose the entire mass (Fig. 3-B). The mass infiltrated the extensor hallucis longus tendon from 2 cm to 8 cm proximal to the ankle joint (Fig. 3-C); however, the anterior tibial and extensor digitorum longus tendons were free of the mass. The lesion was completely excised, including a whole 6-cm-long segment of the extensor hallucis longus tendon and some of the extensor digitorum longus muscle (Fig. 3-D). Multiple veins and arteries were encountered and ligated during the excision, and feeding arteries were considered to be branches of the anterior tibial artery. However, the anterior tibial artery and the deep peroneal nerve were readily separated from the mass. To bridge the segmental defect created in the extensor hallucis longus tendon, we harvested 8 cm of one-third of the width of the nearby anterior tibial tendon and grafted it end to end to the extensor hallucis longus tendon ends while adjusting tension (Fig. 3-E). The transected retinacula were primarily repaired without difficulty because of the reduced volume of the anterior compartment of the ankle.
The postoperative pathology report described a lesion of innumerable veins and arteries of various sizes and shapes surrounded by fibrovascular and fibroadipose tissues (Fig. 4). Many of the blood vessels, especially the arteries, showed extensive subintimal fibrosis. Furthermore, smooth-muscle hypertrophy was evident in the walls of many of the vascular structures. These findings are consistent with the diagnosis of an arteriovenous malformation.
The postoperative recovery was uneventful. A short leg splint with neutral dorsiflexion of the ankle and great toe was applied. The closed suction drain was removed at three days postoperatively, and passive dorsiflexion of the great toe was started. The incision healed without complications. The sutures were removed at three weeks postoperatively, and a short leg cast was applied. At six weeks postoperatively, the short leg cast was removed and active motion of the great toe and ankle was permitted. At the one-year follow-up examination, there was no evidence of tumor recurrence and the great toe showed a nearly normal active range of motion (Figs. 5-A and 5-B).