A forty-nine-year-old man presented with a one-year history of pain in the right ankle and no history of any traumatic causative event. Physical examination revealed a slight but diffuse swelling in the right ankle, which was painful with movement and during weight-bearing. All laboratory data, including the serum alkaline phosphatase level, were within normal limits. A plain radiograph demonstrated an ill-defined lucent lesion with cloudy mineralization from the head of the talus to the anterior one-third of the body of the talus (Fig. 1).
A T1-weighted sagittal magnetic resonance image (Fig. 2, A) revealed a lesion that had low signal intensity and that extended from the talar head to the talar neck. Low signal area also extended beyond what seemed to be the posterior margin of the tumor. A short tau inversion recovery (STIR) image (Fig. 2, B) revealed high signal intensity throughout the entire talus (suggesting bone marrow edema) and the presence of an effusion (suggesting inflammation about the tumor). Extraosseous tumor was seen in the anterior aspect of the talar neck. A plain computed tomographic scan revealed cortical destruction of the anterior aspect of the talar neck with an associated soft-tissue mass. As most of the tumor seemed to have arisen from inside the bone and extended into the soft tissues, it was thought to be a conventional osteosarcoma rather than a surface variant. A bone scan and positron emission tomography with use of [18F]-2-fluoro-2-deoxy-D-glucose (FDG-PET) showed uptake only in the right ankle.
An open biopsy revealed that the lesion was a high-grade fibroblastic osteosarcoma (Fig. 3). Preoperative systemic chemotherapy, consisting of two courses of cisplatin, two courses of high-dose methotrexate, and two courses of ifosfamide plus doxorubicin, was administered intravenously over the course of twelve weeks. After chemotherapy, the pain and swelling disappeared. The posterior part of the body of the talus demonstrated normal bone-marrow intensity on repeat magnetic resonance imaging. In addition, extraosseous tumor in the anterior aspect of the talus had shrunk, and the ankle joint effusion was no longer visible on magnetic resonance imaging. Uptake of FDG-PET also decreased after chemotherapy. From these physical and radiographic findings, preoperative chemotherapy was believed to have been effective. Two methods of surgery were proposed to the patient after completing chemotherapy: below-the-knee amputation and a limb-salvage procedure. After thorough discussion, the patient gave his informed consent for the limb-salvage procedure.
The operation was begun by making bilateral parallel skin incisions along the medial neurovascular bundle and laterally along the peroneus longus muscle. The biopsy scar was resected with a 2-cm margin.
The distal parts of the tibia and fibula were transected just above the attachment of the joint capsule. Distally, an osteotomy of the calcaneus was done just below the sustentaculum tali along the groove for the flexor hallucis longus. The anterior resection line was between the navicular and the medial cuneiform. Thus, the talus was resected together with its surrounding tissues (Fig. 4). After a wide resection, ankle arthrodesis was performed with use of an intramedullary nail and autogenous bone graft from the ipsilateral ilium. Two blocks of iliac bone were inlaid on the medial and lateral sides of the nail with the cancellous surfaces of the graft facing the cancellous bone in the cut surface of the tibia and calcaneus. Supplementary cancellous bone chips were added around the host-graft junction. To fill the dead space and skin defect, a free latissimus dorsi musculocutaneous flap was harvested and placed over the iliac bone graft. A vascular anastomosis to the anterior tibial artery and vein was performed so that the grafted bone would be covered by a vascularized muscle. Histological examination of the surgical specimen revealed clear resection margins and chemotherapy-induced tumor necrosis of 90%.
A below-the-knee splint was worn by the patient for four weeks postoperatively, at which point he was permitted to walk with a patellar tendon-bearing brace. After completing seven courses of postoperative chemotherapy, the patient was able to return to work.
Union between the distal part of the tibia and the grafted iliac bone was not achieved after one year. Consequently, dynamization of the nail by removal of the proximal locking screws was done, and two months later, bone union was achieved (Fig. 5). The result of surgical treatment, as measured with use of the functional rating system of the Musculoskeletal Tumor Society (MSTS)6, was 90%. The numerical values achieved by our patient in the six categories included in this rating system were 5 points for the category of pain (none), 4 points for function (heavy labor being restricted but no restriction in patient's lifestyle), 5 points for emotional acceptance (enthused), 4 points for supports (a shoe-type orthosis was necessary only outdoors), 4 points for walking ability (continuous outdoor walking was possible for more than an hour but walking uphill was a bit difficult), and 5 points for gait (no alteration). Disability was measured with use of the Toronto Extremity Salvage Score (TESS), which ranges from 0 to 100, with higher scores indicative of less disability7. The patient had a score of 89. The patient continued to be disease-free forty-seven months after surgery and was able to walk with an orthotic device in his shoe.