To compare the clinical outcomes of floating knee according to the presence of knee joint injury.

Between March 2004 and March 2009, we investigated 36 patients, who underwent surgical treatment for floating knee injuries. We classified the floating knee into two groups as type I (12 cases) has no knee joint injury and type II (24 cases) has knee joint injury. We compared two groups about combined injury (orthopedics or other part), open fracture or not, neurovascular injury,union time, range of motion, and complication rate.

There is statistically no significant difference between two groups as type I (6 cases, 50%) and type II (13 cases, 54.2%) in orthopedic combined injury (p=0.813), and also same as type I (3 cases, 25%) and type II (12 cases, 50%) in combined injury on the other department (p=0.151), and in floating knee with open fracture as 4 type I (33%) and 12 type II (50%) of 16 cases (44%), and Gustilo-Anderson 3 type I, 4 type II, 1 IIIA, 4 IIIB, and 4 IIIC (p=0.423). There is statistically no significant difference between two groups in neurovascular injury as 1 type I (8.3%), and 3 type II (12.5%) (p=0.708). There is a statistically significant difference between two groups in the mean bone union time as 18.2±5.37 weeks (12~24 weeks) for type I and 24.95±9.85 weeks (16~33 weeks) for type II (p=0.045), and in the mean range of knee joint motion as 133±12.74 degree (120~150 degree) for type I and 105±19.00 degree (80~135 degree) for type II (p=0.012).

Floating knee with knee joint injury is severe itself and related with severe combined injuries, subsequent range of knee joint motion limitation, the delay of union time, and high complication rate. Therefore, we should take care in surgical treatment for this trauma entity.