Postoperative weakness of quadriceps function following knee arthrotomy has often been attributed to pain inhibition or lack of motivation. However, the delayed recovery may be the result of a slowly resolving axonal compression syndrome caused by the pneumatic tourniquet. Forty-eight patients who underwent knee arthrotomy were evaluated including postoperative electromyographic testing and clinical follow-up. Thirty of these patients (62.5%) developed postoperative EMG changes. Abnormalities were noted in various muscle groups but most commonly involved the quadriceps alone or quadriceps and gastrocnemius. An effort was made in 20 patients to substantially decrease the duration of tourniquet compression by limiting tourniquet inflation to intracapsular portions of the procedures. Fewer EMG changes and more rapid clinical recovery were noted in patients with decreased tourniquet times, suggesting that it is beneficial to minimize the duration of tourniquet compression. In all patients who returned for serial testing, the EMG abnormalities eventually resolved.