Simultaneous bilateral floating knee: A case report

Abstract

Background: The phrase "floating knee is a flail knee joint," referring to ipsilateral femoral and tibial fractures, was first used by Blake and McBryde in 1975. This condition is often caused by a high-energy trauma with often extensive injury to the soft tissues, and is accompanied by life-threatening systemic complications, including head, chest or abdominal injuries and a high incidence of fat embolism. Floating knee is a severe and uncommon injury pattern.

Case summary: A 27-year-old man sustained multiple injuries when the electric motorcycle he was riding was hit by a van. His injuries included traumatic hypovolemic shock, comminuted and open type II fractures of the left femoral shaft, fracture of the right femoral shaft, comminuted fracture of the bilateral tibial and fibular shaft, and multiple lacerations and abrasions on his forehead, lower lip, neck and limbs. The diagnosis was simultaneous bilateral floating knee complicated with soft tissue injuries. After emergency treatment and the exclusion of life-threating complications, open reduction and internal fixation were successfully performed using plates and screws in the bilateral femoral and tibial shafts.

Conclusion: Simultaneous bilateral floating knee is a rare and severe injury pattern. The treatment is challenging, and complications. We present a case report of a young adult who suffered from bilateral floating knees during road traffic accident. We also offer our treatment experience of this complex injury and review past literature.

Keywords: Case report; Fat embolism syndrome; Femoral and tibial fractures; Floating knee; High-energy trauma; Life-threatening complications.

Figure 1

Initial plain radiographs revealed displaced bilateral femoral, tibial, and fibular midshaft fractures. A and B: Bilateral femoral fractures; C and D: Tibial fracture.

Figure 2

The photographs showed that we punctured hundreds of small holes around the closed wound using an 18-gauge needle in the thigh and leg, imitating a Chinese medicine bloodletting method, to allow the accumulated blood in the tissue to flow out to prevent skin necrosis and compartment syndrome. A: Thigh; B: Leg.

Figure 3

Postoperative X-rays illustrated that the patient received open reduction and internal fixation with one locking plate in the left femoral shaft, one broad dynamic compression plate in right femoral shaft, and two narrow dynamic compression plates in bilateral tibial shafts. A: Left femoral shaft; B: Right femoral shaft; C and D: Two narrow dynamic compression plates in bilateral tibial shafts.

Figure 4

Radiography revealed bone union of bilateral femoral and tibial fracture sites at postoperative 13 mo. A and B: Bone union of bilateral femoral; C and D: Bone union of tibial fracture.