Chronic ankle instability following minor avulsion fractures of the fibula in children

M. Puthiya Veettil, V. Spitteri, H. Prem

Introduction: Paediatric avulsion fractures of the lateral malleolus, may go into non-union resulting in a detached ATFL (anterior talofibular ligament) and recurrent ankle instability with pain. As paediatric ankle instability is uncommon, advice is usually sought from those surgeons in adult practice, who need to be aware of this condition.

Materials and methods: Six girls aged between 7 to 10 years at the time of injury presented with recurrent ankle instability and pain. All had been treated with a below knee plaster cast for four weeks, followed by physiotherapy for proprioception exercises but had recalcitrant symptoms. Sequential radiographs showed a small avulsion fracture of the lateral malleolus epiphysis, which remained ununited in all cases. When there was no improvement with an ultrasound guided anterolateral ankle injection, they underwent surgical exploration with a lateral approach. Intra operatively ankle instability was confirmed by comparing both sides with an Anterior Drawer Test. At surgery, the bony fragment was found to be attached to the ATFL in all cases. The fragment was excised and the ligament was reattached to the tip of the fibula epiphysis with resorbable suture anchors. A modified Brostrom technique was used. Post operatively, a below knee cast for applied for 6 weeks followed by physiotherapy.

Results: All the patients had an uneventful recovery without complications and had a stable ankle at final follow up. All the children went back to pre-injury level of sporting activities, including gymnastics after 6 months.

Conclusion: Avulsion fractures of lateral malleolus epiphysis in children are actually larger than their radiological size and should be recognised as an injury to the ATFL, which could result in chronic ankle instability and pain. Caution should be exercised when reporting such fragments as a benign Os Subfibulare. Surgical stabilisation using resorbable implants in the epiphysis is safe and successful.