Distal tibial osteotomy to address internal tibial torsion: Should the fibula be cut?

Background Rotational tibial osteotomy seeks to address pathologic tibial torsion. Inclusion of fibular osteotomy during this procedure remains controversial. This study aimed to determine how external rotation through a tibial osteotomy, with or without a fibular osteotomy, would influence tibiofibular joint congruity. Methods Eight cadaveric legs underwent distal tibial osteotomies. Pins were placed to designate neutral, 10°, 20°, 30° of external rotation. Computed tomography (CT) imaging was performed at each rotation without, then with a fibular osteotomy. Magnetic Resonance Imaging was performed prior to fibular osteotomy to confirm that ligaments remained intact. Custom software calculated tibial torsion using CT scan 3D reconstructions. Proximal tibiofibular joint rotation, distal tibiofibular gapping and ankle mortise were measured on each CT exam. Groups without and with fibular osteotomy were compared. Findings There was no difference between tibial osteotomy rotation magnitude with or without the fibular osteotomy (P = 0.2). The group without the fibular osteotomy had greater proximal fibular rotation at the tibiofibular joint at 20°, 30° (P < 0.05), greater posterior distal tibiofibular gap at 10°, 20°, 30° (P < 0.05) and less anterior distal tibiofibular gap at 20°, 30° (P < 0.05). The medial tibiotalar space was narrowed without the fibular osteotomy at 20°, 30° (P < 0.05) compared to pre-rotation. Interpretation Deformity at the proximal tibiofibular and ankle joints become most pronounced at >20° of tibial rotation without a fibular osteotomy. The first joint to be affected is the distal tibiofibular joint. To limit ankle and proximal tibiofibular articular deformation during tibia rotational osteotomy, a fibular osteotomy is recommended when correcting over 20° of rotation.