Purpose. Tourniquet-induced nerve injuries have been reported in the literature, but even if electromyography abnormalities in knee surgery are frequent, only two cases of permanent femoral nerve palsies have been reported, both after prolonged tourniquet time. We report a case of tourniquet-related permanent femoral nerve palsy after knee surgery. Case Report. We report a case of a 58-year-old woman who underwent surgical treatment of a patella fracture. Tourniquet was inflated to 310 mmHg for 45 minutes. After surgery, patient complained about paralysis of the quadriceps femoris with inability to extend the knee. Electromyography and nerve conduction study showed a severe axonal neuropathy of the left femoral nerve, without clinical remission after several months. Discussion. Even if complications are not rare, safe duration and pressure for tourniquet use remain a controversy. Nevertheless, subtle clinical lesions of the femoral nerve or even subclinical lesions only detectable by nerve conduction and EMG activity are frequent, so persistent neurologic dysfunction, even if rare, may be an underreported complication of tourniquet application. Elderly persons with muscle atrophy and flaccid, loose skin might be in risk for iatrogenic nerve injury secondary to tourniquet.