A prospective study of the use of transcutaneous neural stimulation (TNS) in 90 arthroscopic knee surgery patients was performed to determine: if TNS is as effective as traditional pain medication in treating postoperative knee pain; and if patients that had received TNS regain preoperative motion and strength quicker than the control population. The patients were divided into three equal groups. Group I consisted of patients with no TNS unit, Group II had a "placebo" unit, and Group III had a "live" unit. Preoperatively, each patient received an isokinetic muscle examination, orientation to the TNS unit, leg circumference measurements, and exercise instruction. An isokinetic muscle examination and leg circumference measurements were repeated at 1, 3, and 7 weeks postoperatively. Additionally, the amount of pain and medication required was analyzed. The results of the study indicated that the use of a TNS unit is an effective adjunct in decreasing postoperative pain in 93% of patients. The amount of pain and total pain medication required was greatest in the control group, less in the placebo, and markedly reduced in the TNS group. A comparison among the three groups revealed that the TNS group regained the following preoperative values 1 month sooner than the other two groups (3 as opposed to seven weeks postoperatively): isokinetic power in flexion and extension (P less than 0.05), range of motion (P less than 0.02), and leg volume (P less than 0.05). There was no correlation between the pain and irregular wave forms on the isokinetic graph. The only complication noted was skin irritation at the electrode sites.(ABSTRACT TRUNCATED AT 250 WORDS)