Dolph Houben

41 Vascularized Bone Grafts, a closer look at the free fibula flap 2 Surgical technique recipient Tibia Each recipient site represents different challenges regarding vascular access, fixation, and post-operative management. For tibial defects, the ipsilateral fibula may be used as a pedicled autograft. This significantly reduces operative time, as there is no need for a microsurgical anastomosis [65] . When missing, fractured, or is surrounded by damaged and heavily scarred soft tissue, the use of the contralateral fibula as a free flap is required. Initial vessel dissection in the recipient can be performed either before the fibula harvest or at the same time if two surgical teams are used. Pre-operative planning is most crucial when a free flap is used. Determine where the best suitable recipient vessels are located, how the fibula is going to be orientated (orthograde/antegrade), what type of fixation is needed, and if an additional massive allograft is needed. A pre-operative angiogram can therefore especially useful to determine the right recipient vessels and location. Depending on recipient-site vessel availability, the free fibular flap may be oriented in either orthograde (for anastomosis to the anterior tibial artery) or retrograde fashion (for anastomosis to the posterior tibial artery) [57] . For metaphyseal and diaphyseal reconstruction the fibula can be best placed intramedullary. If it does not fit well inside the tibia, the best alternative is to place an allograft matched to the defect (fixed with an IM-nail) and an onlay fibula spanning the defect secured with lag screws for compression. In case of using a fibula alone, one could center the fibula and ream the medullary canal of the tibia to fit the fibula. Stable internal fixation is crucial to achieve union at both docking sites. Stability can be provided by internal fixation spanning the defect (locked IM nails or spanning locking plates and screws). The type of fixation is depending on the position of the fibula with or without an allograft. Fixation of the fibula only with small fragment plates and screws above and below or with external fixation result in higher complication rates [34, 42, 66] . When bony fixation is achieved vascular repair of the free fibula can be performed by a microanastomosis. Preferably end-to-side anastomoses are used when possible to preserve distal blood supply. Post-operatively, immobilization and non-weight bearing are advised until there is radiographic evidence of healing. Persistent non-union at the docking site 6 months after the initial transfer should be treated with additional cancellous bone graft. After the union of both docking sites, mobilization and weight-bearing can be carefully initiated. Partial or protected weight bearing is advised until radiographic evidence of fibular hypertrophy (Fig. 4D) [57] . In children, non-weight bearing is required following syndesmotic fusion. When an osteocutaneous flap is taken, direct closure of the donor site is ill-advised, due to the risk of a compartment syndrome. A split-thickness skin graft should be used to complete skin closure.