History and Physical Examination
Floating knee injuries must be included in assessment and treatment protocols for patients with polytrauma.
Damage to the vessels (mainly the popliteal and posterior tibial arteries) and lesions of the nerves (eg, peroneal nerve) are common. Vascular injury is common and may be limb-threatening if not recognized and addressed. Often, the vascular injury is to the anterior tibial artery and does not result in ischemia and is not treated with vascular repair or reconstruction. However, vascular status must be assessed and addressed as appropriate. Traction usually causes neurapraxia, which often resolves, but complete resolution cannot always be anticipated.
The incidence of open fractures is high, approaching 50-70%, at one or both fracture sites. The most common combination is a closed femoral fracture with an open tibial fracture.
A well-documented finding is injury to the knee ligaments that occur in association with ipsilateral femoral and tibial fractures. Anterolateral rotatory instability is the most common pattern of instability. Knee ligament injury is not always suspected, and joint swelling due to hemarthrosis should not be mistaken for a sympathetic effusion. The ipsilateral femoral and tibial shaft fractures and knee ligament injury appear to be part of a continuum of combined injuries resulting from complex, high-energy forces. [16]
In skeletally immature patients, floating knee is uncommon. Few studies of this injury have been conducted in children. Data from available studies have shown that findings observed in children are comparable to those in adults in terms of the mechanism of fracture, the incidence of associated major injuries, and the complexity of treatment.
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Fraser classification of floating knee injuries.
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Karlstrom and Olerud's criteria for assessing functional outcomes after a floating knee injury.
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Letts and Vincent classification system for floating knee injuries in children.
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Treatment protocol for floating knee injuries. Ex-Fix = external fixation; IM = intramedullary; ORIF = open reduction and internal fixation.
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Floating knee injury.
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Positioning for surgery to treat a floating knee injury.
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Conservative management of the femur in an ipsilateral injury of this type is likely to result in malunion of the femoral fracture and shortening.
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Early joint mobilization determines the patient's functional outcome after treatment of floating knee injuries. Nailing of both the tibial and the femoral fractures, as shown, is the best method for enabling early mobilization.
