EN BLOC RESECTION OF THE LATERAL MALLEOLUS FOR MALIGNANT TUMORS OF THE DISTAL FIBULA

Abstract

Background: Amputation of the distal fibula for malignant tumors is accepted practice. Few studies have reported limb salvage surgery for malignant tumors of the distal fibula. After distal fibulectomy, the main concerns are local recurrence of the tumor and ankle instability and deformity related to total resection of the lateral malleolus. Our objective was to analyze the oncologic and functional outcome of lateral malleolus en bloc resection for malignant tumors of the distal fibula, with special attention to operative techniques, reconstruction methods, and postoperative complications.

Methods: The authors identified ten patients who had malignant tumors of the distal fibula requiring total resection of the lateral malleolus. The patients’ medical records, operative reports, radiographs, and the histologic specimens were reviewed. There were four children (mean age, 7.5 years) and six adults (mean age, 42.16 years). The distal metaphysis was involved in seven patients and the epiphysis in three. There were four osteosarcomas, three chondrosarcomas, two Ewing sarcomas, and one adamantinoma. The most common symptoms at presentation were a palpable mass in nine patients, ankle pain in six, and pathologic fracture in one. The mean duration of symptoms before diagnosis and treatment was nineteen months. All patients had operative treatment; two patients with osteosarcoma had perioperative chemotherapy and one patient with Ewing sarcoma had radiotherapy and chemotherapy and another patient with Ewing sarcoma had chemotherapy only. Two types of “en bloc” resection of the distal fibula were performed. Wide (type II) extra-articular resection was performed in seven patients. Marginal (type I) intra-articular resection of the distal fibula was performed in three patients. After resection, a primary ankle arthrodesis was performed in four adults and postoperative bracing without any reconstruction in four children and two adults.

Results: Within a mean follow-up time of 14.4 years (range, three to thirty years), tumor recurred locally in two patients after a marginal type I resection of a chondrosarcoma, and in one after a type II wide extra-articular resection of an osteosarcoma. All ten patients were disease-free at latest follow-up examination. Six patients had reoperation. A below-knee amputation was performed in three patients for chronic osteomyelitis, for local recurrence of chondrosarcoma, and for a late adamantinoma of the tibia. One patient had further soft tissue and bone reconstructive surgery for lateral talus subluxation and cavovarus deformity. Another patient required ankle arthrodesis for recurrent ankle instability and ankle joint degenerative changes. One patient had wide re-resection for local recurrence of an osteosarcoma. All ten patients were ambulatory at latest follow-up evaluation. Four adult patients who underwent primary arthrodesis and one child who had no initial reconstruction and had late ankle arthrodesis had a satisfactory outcome, with an ISOLS functional score of 27.6 (92%). Two adolescents who had postoperative bracing without any soft tissue reconstruction had an ISOLS functional score of 24 (80%) with no ankle pain and satisfactory function; they used an ankle-foot orthosis during sports activities. Three patients who subsequently required below-knee amputation used a below-knee prosthesis for ambulation.

Conclusions: Limb salvage surgery for high-grade malignant tumors of the distal fibula can be achieved by wide extra-articular resection. For low-grade malignant tumors or high-grade tumors responding to adjuvant therapy, a more conservative marginal intra-articular resection may be adequate. Primary arthrodesis is indicated in adults after wide extra-articular resection. In children, repair of the lateral soft tissues and reconstruction of the tibiofibular mortise is necessary after tumor resection to avoid late ankle deformity or instability.