Tibiofemoral dislocation after total knee arthroplasty treated successfully with an external fixation device.

Tibiofemoral dislocation after primary total knee arthroplasty (TKA) is a rare but potentially devastating complication with various patient-related and surgeon-related predisposing factors. We present the case of an obese 86-year-old woman who sustained an atraumatic posterior tibiofemoral dislocation 3 days after a primary medial-pivot design TKA. The knee remained unstable after reduction, owing to significant hamstring hypertonia. The administration of botulinum toxin injections in the hamstrings resulted in no clinical improvement. The periprosthetic infection workup was negative and the neurological impairment of the patient was excluded. The patient was reoperated with extensive hamstring release and the application of a lateral external fixator. The external fixator was removed 6 weeks postoperatively, and physical therapy was initiated. At 1-year follow-up, the patient had a painless, stable knee with a 0-100° range of motion, without any neuromuscular impairment.