Knee valgus angle during single leg squat and landing in patellofemoral pain patients and controls

Knee. 2014 Mar;21(2):514-7. doi: 10.1016/j.knee.2013.11.011. Epub 2013 Nov 27.


Background: Patellofemoral pain (PFP) is a commonly presenting disorder of the lower limb, frequently effecting young physically active individuals particularly females. The condition has been associated with poor control of limb alignment while undertaking unilateral limb loading tasks. This poor alignment of the limb is believed to alter loading stress within the patellofemoral joint. This study aims to investigate the degree of knee valgus, assessed as 2D frontal plane projection angle (FPPA) during single leg squatting (SLS) and hop landing (SLL) tasks in patients with PFP and compare their performance to controls and the uninjured limb.

Method: Twelve female subjects with unilateral PFP formed the patient group and thirty asymptomatic females formed the control group. They had their 2D frontal plane projection angle (FPPA) assessed during single leg squatting (SLS) and hop landing (SLL) tasks.

Results: In the asymptomatic control group the mean FPPA for SLS was 8.4±5.1° and SLL had a mean FPPA of 13.5±5.7°. In the PFP group the mean FPPA for SLS was 16.8±5.4° and SLL had a mean FPPA of 21.7+/-3.6°, these differences were significant (p<0.01) for both tasks.

Conclusion: Patients with PFP have a greater degree of knee valgus on unilateral limb loading task than either their contralateral asymptomatic limb or an asymptomatic control group. If not corrected this may lead to further PFJ stress and ongoing morbidity.

Keywords: Alignment; Limb load; Pain.

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Case-Control Studies
  • Exercise Test*
  • Female
  • Humans
  • Joint Deformities, Acquired / physiopathology*
  • Knee Joint / physiopathology*
  • Pain Measurement
  • Patellofemoral Pain Syndrome / physiopathology*
  • Young Adult