What predicts functional outcome after treatment for patellofemoral pain?

Med Sci Sports Exerc. 2012 Oct;44(10):1827-33. doi: 10.1249/MSS.0b013e31825d56e3.


Purpose: Although physical therapy is known to be effective in treating patellofemoral pain (PFP), there is considerable individual variation in the treatment response. It is unclear why some patients benefit from a specific treatment while others do not experience improvement. This study, using a prospective study design, aims to identify factors that could predict the short-term functional outcome and account for the variation frequently seen in the outcome after conservative treatment of PFP.

Methods: Thirty-six patients (20 female and 16 male with a mean age of 23.8 ± 6.7 yr) followed a physical therapy rehabilitation program of 7 wk. Before this treatment, all patients were evaluated on subjective symptoms (pain on visual analog scales in millimeters) and functional performance (step test expressed as highest level, single-legged hop test in centimeters, and triple-hop test in centimeters). The concentric and eccentric knee extensor strength at 60°.s(-1) and 240°.s(-1) (N.m) were measured as well as the quadriceps muscle size by calculating the cross-sectional area (cm(2)) with magnetic resonance imaging. The success of the treatment was evaluated by the functional Kujala anterior knee pain scale. A linear regression model was used to identify predisposing factors for the functional outcome.

Results: The total quadriceps cross-sectional area (P = 0.010), the eccentric average peak torque at 60°.s(-1) (P = 0.015), and the frequency of pain at baseline (P = 0.012) have been indicated as predisposing variables in the short-term functional outcome after a physical therapy rehabilitation program for PFP (adjusted R(2) = 0.46).

Conclusion: Patients with a greater quadriceps muscle size, lower eccentric knee strength, and less pain have a better short-term functional outcome after conservative treatment for PFP.

Publication types

  • Clinical Trial

MeSH terms

  • Adolescent
  • Adult
  • Exercise Test
  • Exercise Therapy*
  • Female
  • Humans
  • Knee / physiopathology
  • Magnetic Resonance Imaging
  • Male
  • Muscle Strength / physiology
  • Organ Size
  • Pain Measurement
  • Patellofemoral Pain Syndrome / therapy*
  • Quadriceps Muscle / anatomy & histology
  • Quadriceps Muscle / physiopathology
  • Treatment Outcome
  • Young Adult