Fifty-three patients diagnosed as having one of several types of extensor mechanism disorders of the knee were randomly assigned to one of four treatment groups to assess the effects of one of four different modalities (ice, phonophoresis, iontophoresis, and ultrasound/ice contrast). Following four physical therapy treatments over a 10-day period, the group treated with the ultrasound/ice contrast demonstrated the greatest subjective improvement (47%). The pre- to post-treatment isometric strength resulted in a 28% improvement in knee extension strength and a 34% improvement in knee flexion strength. The authors emphasize that evaluation should include assessment of quadriceps tone and strength as well as careful palpation to determine the irritable structures. Ultrasound/ice is advocated as the most effective choice of the modalities tested for treatment of pain associated with extensor mechanism disorders. J Orthop Sports Phys Ther 1986;8(5):255-259.