Contributing factors influencing the functional outcome of floating knee injuries

The purpose of the present study was to retrospectively review the floating knee injuries treated at our institute and to determine various factors, such as severity of soft-tissue or skeletal injuries, site of fractures, and treatment methods that may significantly influence the final functional result in these injuries. Between 1986 and 1996, 65 patients with 66 floating knee injuries were treated in our institution. Among 66 fractures of the femur, 19 (29%) were open. There were 43 open tibial fractures. Fifty cases were Fraser type I floating knee fractures, 7 were type IIa, 2 were type IIb, and 7 were type IIc. In 63 cases (95%), both bones had been surgically stabilized with interlocked nails, Ender pins, plates, screws with/without pinning, or external fixations. Final functional results were evaluated according to Karlström and Olerud's criteria. Satisfactory results were rated as cases with excellent or good results. The mean follow-up time was 16.6 months range, (12-50 months). We assessed various factors influencing functional results, including Fraser type, severity of open injury grade (Gustilo) in both fractures, combination of open/closed injuries, fracture types (AO/ASIF type), existence of multiple trauma, neurovascular injuries, polyskeletal trauma, and stabilizing method or operation timing of both fractures. Satisfactory rates in Fraser type I and type II were 64% and 25%, respectively (P= .02). The satisfactory rate in closed, grade I+II, and grade III injuries of the femoral fractures was 53.2%, 81.8%, and 25%, respectively (grade I+II vs. grade III: P < .03). There were no significant correlations between the functional result and the following factors: soft-tissue injuries of the tibia; the fracture pattern of both fractures; the combination of open/closed injuries in each fracture; injury severity score; the existence of neurovascular injuries and double femoral fractures; treatment methods; and operation timing. Severity of damage to the knee joint and open injuries in the thigh were found to be significant factors contributing to the functional outcome in floating knee injuries.