Large distal tibia osteochondroma with deformed fibula: Excision and anatomical reconstruction of ankle syndesmosis

• Main Authors: Goh, Kian Liang, Mohammad Amin, Mohammad Azril, Sharifudin, Mohd Ariff, Anwarali Khan, Mohammed Harris
• Format: Conference or Workshop Item
• Language: English
• Published: 2016
• Subjects: RD701 Orthopedics
• Online Access: http://irep.iium.edu.my/50897/7/50897.pdf; http://irep.iium.edu.my/50897/
• Institution: Universiti Islam Antarabangsa Malaysia

INTRODUCTION Osteochondroma is a benign cartilaginous disease of the bone. Its exophytic growth can occasionally result in periarticular deformity and pain. We describe a case of large osteochondroma of the lateral malleolus causing deformity and pain in a growing child. METHODS A 12 year-old boy with multiple hereditary exostosis, presented with a huge left ankle osteochondroma which became painful for the past 1 year with worsening deformity of the lateral malleolus. He could not participate in sport activities due to the ankle deformity and pain. Examination revealed multiple small bony swelling over both wrists, knees and scapulae. Local examination revealed a bony swelling at the left lateral malleolus measuring 8X8 cm with varus deformity of the ankle. However, the range of ankle motion was full. Radiograph revealed a large sessile bony outgrowth on the distal lateral tibia compressing the lateral malleolus with thinning of the bone and widening of the syndesmotic joint (Figure 1). He underwent excision of the tumour and anatomical reconstruction of the syndesmotic ligament via anterior approach. Multiple drill holes were made at the base of the lesion and the tumour was osteotomized. The ankle syndesmosis had 2 cm widening and reconstruction was performed using tightrope(Arthrax) with endobuttons. Postoperatively, he was immobilised with backslab for 2 weeks and allowed full-weight bearing after 6 weeks. RESULTS At one year follow-up, the lateral malleolus has remodelled and the syndesmotic joint has anatomically reduced with the tightrope (Figure 2). No recurrence was detected. The pain resolved and he had no residual deformity. DISCUSSIONS Multiple osteochondromas is an autosomal dominant disorder with a very high penetrance. The lesions usually develop within the first two decades of life and cease to grow with the closure of the physeal plate [1]. Most are asymptomatic throughout their lives but they may present with ankle pain, a palpable mass and unrestricted ankle motion [2]. Pain in osteochondromas are commonly caused by compressive effect, bursitis, arthritis and tendon, nerve or vessel impingements [3,4]. Ankle involvement is not uncommon and has been reported from 25% to 54% in patients with multiple hereditary exostosis [5]. Untreated or partially excised lesions may potentially lead to plastic deformation of the distal tibia and fibula and pronation deformity of the ankle in skeletally immature patients [2]. Lateral malleolus erosion and impending fracture has been reported which required excision and cast immobilisation [6]. From our literature review, this is the first reported case of syndesmotic reconstruction in an ankle osteochondroma with syndesmotic widening. Syndesmotic reconstruction should be considered if widening is significant. If left untreated, syndesmotic instability may lead to early ankle pain and osteoarthritis. Due to the high growth potential in children, the lateral malleolus and the distal tibia have high propensity to remodel to normal alignment. CONCLUSION Excision of osteochondroma and anatomical reconstruction of the syndesmotic joint with tightrope suture has a good outcome with no complications. This method is particularly advantageous in a growing child as no removal of hardware is required.