How can we strengthen the quadriceps femoris in patients with patellofemoral pain syndrome?

The prescription of quadriceps-strengthening exercise for patients with patellofemoral pain syndrome must be well-designed because the contact area between the patella and the femur changes throughout knee flexion and extension. Total quadriceps strengthening has been shown to be effective for patients with patellofemoral pain syndrome. Quadriceps weakness, specifically vastus medialis obliquus weakness in comparison to the vastus lateralis, can lead to lateral displacement of the patella causing the articulating pressure to be on the lateral facet. Pain-free quadriceps exercise is an important point of the successful treatment program in patients with patellofemoral pain syndrome. Isometric quadriceps exercises such as straight leg raises can facilitate quadriceps activation without stressing the patellofemoral joint and minimizes patellofemoral joint reaction forces, because the patella has no contact with the femoral condyles in the full extension position. Results from literature verified that patients with patellofemoral pain syndrome can benefit from isokinetic exercises if the patients perform all exercises in a pain-free range of knee motion. Closed kinetic chain exercises for patients with patellofemoral pain syndrome were shown more tolerable than open kinetic chain exercises. In addition, both weight-bearing and non-weight-bearing exercises are considered appropriate for strengthening the quadriceps and a key element in the treatment of patellofemoral pain syndrome.