summary Fibular Deficiency is a congenital condition caused by shortening or absence of the fibula which typically presents with anteromedial bowing of the tibia and a leg length discrepancy. Diagnosis is made with radiographs of the tibia. Treatment may be observation or operative depending on degree of fibular deficiency, presence and severity of bowing, and severity of leg length discrepancy. Epidemiology Anatomic location three types of tibial bowing exist in children anterolateral bowing (neurofibromatosis) posteromedial bowing (physiologic) anteromedial bowing (this topic) Etiology Fibular deficiency consists of shortening or entire absence of the fibula previously known as fibular hemimelia the most common congenital long bone deficiency usually involves the entire limb Genetics no known inheritance pattern linked to sonic hedge-hog gene Associated conditions anteromedial tibial bowing most common cause is fibular hemimelia ankle instability secondary to a ball and socket ankle talipes equinovalgus tarsal coalition (50%) absent lateral rays femoral abnormalities (PFFD, coxa vara) developmental dysplasia of the hip cruciate ligament deficiency genu valgum secondary to lateral femoral condyle hypoplasia significant leg length discrepancy shortening of femur and/or tibia Classification Achterman & Kalamchi based on amount of fibula present Achterman and Kalamchi Classification Characteristics Treatment Type IA A portion of fibula remains present but proximal fibular epiphysis is distal to level of proximal tibial physis while distal fibula is proximal to the talus. Heel lift (if LLD >2cm) Contralateral epiphysiodesis Limb lengthening (at/near maturity) Type IB Partial absence of the fibula (30-50%) Distal portion is unable to support the ankle joint Contralateral epiphysiodesis Limb lengthening Supramalleolar osteotomy (to correct ankle valgus) Corrective foot procedures to achieve stable, plantigrade foot Proximal tibial osteotomy (for genu valgus) Type II Complete absence of fibula Multiple Ilizarov surgeries to equalize limb lengths, achieve stable ankle, plantigrade foot Foot ablation/amputation Birch Classification based on limb length and foot function directs treatment Presentation Physical exam classic findings short limb skin dimpling over midanterior tibia equinovalgus foot other findings often missing lateral toes genu valgum Imaging Radiographs fibula is either absent or shortened tibial spines are underdeveloped intercondylar notch is shallow ball and socket ankle joint secondary to tarsal coalitions Treatment Goals treatment determined by the stability and level of foot and ankle function, as well as the degree of limb shortening not based on amount of fibula present Nonoperative observation shoe lift bracing Operative contralateral epiphysiodesis alone indications mild projected LLD (<5cm or <10%) stable, plantigrade foot limb lengthening procedure alone indications plantigrade, functional foot with a stable ankle LLD < 10% technique involves resection of fibular anlage to avoid future foot problems contralateral epiphysiodesis + limb lengthening procedure indications moderate LLD (10-30%) Syme amputation (preferred to Boyd amputation) Boyd is more bulbous and only about 1cm longer indications nonfunctional, deformed, unstable foot LLD > 30% unable to cope psychologically with multiple limb lengthening procedures cosmesis technique amputation usually done at ~1 year of age to allow early prosthesis fitting, better psychosocial acceptance results 88% satisfaction with amputation vs 55% satisfaction with limb lengthening