Patellofemoral pain syndrome (PFPS) is defined as idiopathic pain arising from the anterior knee that is of otherwise unknown origin. PFPS is characterized by diffuse pain at the front of the knee that is exacerbated by activities that load the knee in flexion or sustain the knee in flexion (running, stairclimbing, squatting, or prolonged sitting). Some describe a feeling of giving way or crepitation in the knee.
Prevalence and Impact
PFPS is highly prevalent among active individuals. The pain and disability resulting from this condition not only affect short-term participation in daily and physical activities but can have a significant long-term impact, with symptoms shown to persist in 1 in 4 sufferers for up to 20 years after initial presentation. As regular physical activity is highly recommended for the prevention of conditions such as cardiovascular disease and type II diabetes, PFPS may have important implications for the long-term health of affected individuals.
Causes
According to theory, PFPS is a result of compressive and shearing forces on the patella’s underside (the knee cap), excessive lateral pressure on the patella, lateral maltracking of the patella, and instability of the patella that results in recurrent subluxation. These factors are thought to cause softening, thinning, and degeneration of the cartilage underneath the patella.
Risk Factors
Risk factors for the development of PFPS are:
- Female gender
- maltracking patella
- tight iliotibial bands/lateral retinaculum
- various lower extremity malalignments
- weak vastus medialis obliquus (VMO)
- weak hip abductors
- weak hip external rotators
- training errors
- history of trauma or degenerative changes in the cartilage
Treatment
Medical intervention, including NSAID drugs, has not been shown to be effective in managing the symptoms of PFPS. Unless the underlying biomechanical problems are changed, the majority of people with PFPS do not experience relief.
Effectiveness of Exercise
The only undisputed form of relatively effective treatment for PFPS is exercise. Within this realm, however, there are many ideas as to what is best. Some advocate the use of taping techniques or custom foot orthoses to decrease symptoms and improve patellar tracking in conjunction with exercise.3 Others use specific equipment and exercises to isolate activation of the VMO.
Some clinicians promote using unloaded exercises for treatment. Others use loaded exercises almost exclusively. In other words, the mechanism for why exercises are effective is unclear.
Recommended Treatment Approach
My management of PFPS involves stretching any tight tissues in the lower limb and strengthening the quadriceps and hip abductor muscle groups. Occasionally, we utilize patellar mobilization and/or taping techniques. We believe strengthening exercises must primarily be done in a weight-bearing and dynamic manner. Mini squats and lunges on the affected leg, step-down exercises, and other simple closed-chain exercises are prescribed.
Generally, we seek to produce some degree of symptoms with the exercises in order to remodel dysfunctional tissue; however, repetition should never worsen the symptoms or cause symptoms to last for more than a few minutes following the exercise. Lingering pain on any exercise is a contraindication to that particular exercise, and modification of the routine is indicated.
Outcomes Data
We have documented outcomes in 64 patients with non-specific knee pain. The average score on the LEFS for patients with non-specific knee pain was 44/80 initially.After treatment, the average score rose to 66/80. This is a significant change of 22 points. The average number of visits for this group of patients was 10 over a 5-week period.
From these results, it is apparent that physical therapy that primarily utilizes mechanical therapy and general exercise can be effective at reducing pain and increasing function associated with nonspecific anterior knee pain, such as PFPS.
References
- Dressendorfer, R., & Granado, M. (2010).Clinical Review: Patellafemoral pain syndrome (PFPS). Cinahl.
- Mckenzie, R., & May, S. (2000). The Human Extemities: Mechanical Diagnosis and Therapy. Wellington: Spinal Publications New Zealand Ltd.
- Vicenzino, B., Collins, N., Crossley, K.,Beller, E., Darnell, R., & McPoil, T.(2008). foot orthoses and physiotherapy in the treatment of patellofemoral pain syndrome: A randomised clinical trial. BMC Muskuloskeletal disorders , 1-12.
- Binkley, J.M., Stratford, P.W., & Lott, S.A.(1999). The lower extremity functional scale(LEFS): Scale development, measurement properties,and clinical application. Physical Therapy,79, 371-383.
