Altered fibular growth patterns after tibiofibular synostosis in children

Background: latrogenic synostosis of the tibia and fibula following an oper ation on the leg in a child has been reported rarely in the literature, and the effects of this complication on future growth, alignment, and function are not known. This is a retrospective case series, from one institution, of crossunions of the distal parts of the tibia and fibula complicating ope rations on the leg in children. The purpose is to alert surgeons to this po ssible complication. Methods: The senior author identified eight cases of iatrogenic tibiofibula r synostosis seen in children since 1985. The patients had various diagnose s and were from the practices of four pediatric orthopaedic surgeons. Synos tosis developed in six patients after osteotomies of the distal parts of th e tibia and fibula, in one after internal fixation of distal tibial and fib ular metaphyseal fractures through a single incision, and in one after post erior transfer of the anterior tibialis tendon through the interosseous mem brane combined with peroneus brevis transfer to the calcaneus. Medical reco rds were reviewed, and preoperative and follow-up radiographs were analyzed for changes in the relative positions of the proximal and distal tibial an d fibular physes and in the alignment of the ankle. Results: Five patients were symptomatic after crossunion; they presented wi th prominence of the proximal part of the fibula, ankle deformity, or ankle pain. Three patients were asymptomatic, and a synostosis was identified on routine follow-up radiographs. Intraoperative technical errors caused two of the crossunions; the cause of the others was unknown. Following tibiofib ular synostosis, growth disturbances were noted radiographically in every p atient. The normal growth pattern of distal migration of the fibula relativ e to the tibia was reversed, resulting in a decreased distance between the proximal physes of the tibia and fibula as well as proximal migration of th e distal fibular physis relative to the distal part of the tibia. Shortenin g of the lateral malleolus led to greater valgus alignment of the ankle. Conclusions: Tibiofibular synostosis can complicate an operation on the leg in a child. After crossunion, the normal distal movement of the fibula rel ative to the tibia is disrupted, resulting in shortening of the lateral mal leolus and ankle valgus as well as prominence of the fibular head at the kn ee. The synostosis also interferes with the normal motion that occurs betwe en the tibia and fibula with weight-bearing, potentially leading to ankle p ain.