Prospective, controlled, randomized, single blind study in patients undergoing rehabilitation following anterior cruciate ligament reconstruction. 96 patients were randomly assigned to one of three groups. Group Group KH (Kneehab n=33)trained with a new type of NMES with multipath activation for 20 minutes, 3 times per day, 5 days per week for 12 weeks; Group PS (Poli-Stim n=29) trained with standard neuromuscular electrical stimulation (NMES) for 20 minutes per day, 5 days per week for 12 weeks; Group CO (Control - n=34), which did not use muscle stimulation, performed voluntary isometric quadriceps muscle contractions. Patients receiving either form of NMES treatment were instructed to isometrically contract the quadriceps muscle voluntarily with each electrical muscle stimulation. All three groups superimposed this training schedule on the standard post-ACL reconstruction rehabilitation protocol used at the clinic.

The study design corresponded to a two-way variance analysis with three groups and 4 examination times (Baseline, 6 weeks, 12 weeks and 24 weeks post ACL reconstruction). The level of significance was set at 5%. The key indicators of the quadriceps muscle training intervention were the isokinetic strength development of the extensors of the injured leg at 90 degrees/second and 180 degrees/second and the distance achieved by participants performing the single-leg hop and the time to complete the shuttle run. The target was to show a difference of 10% in the relative distance jumped for the single-leg hop and for the isokinetic strength tests and a 1.2 second difference in the time to complete the shuttle run. The target of 3 weeks was set for participants to achieve full weight-bearing capability without use of a walking aid. A comparison between the groups of the time for return to usual work activities was planned.