Floating knees occur when there are ipsilateral fractures of both femoral and tibial shafts. These are relatively rare injuries with reported poor outcomes.
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Clinical presentation
The usual presentation is a combined closed midshaft femoral fracture and open midshaft tibial fracture. Vascular injury is present in about 20% of the patients. Due to the high-energy trauma, it is common for the patient to also present associated injuries, such as contralateral limb injury, knee ligament injury, and head trauma.
Pathology
Mechanism
Floating knee injuries are often the result of high-energy trauma, mostly traffic accidents.
Classification
type I: none of the fractures is juxta-articular
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type II: one of the fractures is juxta-articular
type IIA: femoral fracture involves the condylar flare
type IIB: tibial fracture involves the condylar flare
type III: both fractures are juxta-articular
Treatment and prognosis
Floating knee injuries are historically associated with poor functional outcomes.
Some of the possible treatment options are:
non-operative treatment - closed reduction and hinged functional brace
internal fixation of the femur and closed reduction and functional cast bracing of the tibia
intramedullary nailing
external fixation
Amputation
Intramedullary nailing has been reported with better functional outcomes compared to the other treatment methods.