title: Somatosensory and Biomechanical Abnormalities in Females With Patellofemoral Pain.
abstract: Chronic patellofemoral pain (PFP) is a common orthopedic condition for which little is understood of the alterations in pain processing such as hyperalgesia, hypoesthesia, and the relationship of altered knee mechanics to hyperalgesia. We assessed pain, pressure pain thresholds (PPT), detection to light touch, and the relationship of pain and PPTs to knee abduction angle during a stair step down task between females with and without PFP.
  
  
  
  Twenty females diagnosed with PFP and 20 age-matched pain-free females participated in this study. Individuals underwent an instrumented assessment of knee mechanics during a stair step down task, PPT and detection of light touch over the center of the patella and lateral retinaculum, and PPT outside painful area over the right elbow.
  
  
  
  The PFP group had significantly lower PPT values at the patella (P=0.02), lateral retinaculum (P=0.001), and at the elbow (P=0.03). There was an elevated threshold to detect light touch over the center of their patella (P=0.04). A significant relationship between both pain (r=-0.49, P=0.03) and PPT values (r=0.65, P=0.004) to the frontal plane knee angle existed in the PFP group which was not present in the control group (r=-0.17, P=0.49) or in the elbow (r=-0.009, P=0.972).
  
  
  
  These results suggest that PFP is characterized by an increase in both localized and centralized pain sensitivity that is related to movement mechanics. Thus, PFP has both biomechanical, nociceptive components as well as inferred aspects of altered central sensitization.
authors.affiliation: Division of Physical Therapy, College of Health Sciences, University of Kentucky Department of Biostatistics, College of Public Health, Lexington, KY Graduate Program in Physical Therapy and Rehabilitation Science, University of Iowa, College of Medicine, Iowa City, IA.
authors.forename: Brian
authors.initials: B
authors.lastname: Noehren
authors.forename: Logan
authors.initials: L
authors.lastname: Shuping
authors.forename: Aron
authors.initials: A
authors.lastname: Jones
authors.forename: David A
authors.initials: DA
authors.lastname: Akers
authors.forename: Heather M
authors.initials: HM
authors.lastname: Bush
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Sluka
mesh_terms: D000293:Adolescent; D000328:Adult; D018771:Arthralgia / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D015331:Cohort Studies; D005260:Female; D005269:Femur / Q000503:physiopathology*; D005542:Forearm / Q000503:physiopathology; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D017288:Pain Threshold; D010329:Patella / Q000503:physiopathology*; D014110:Touch; D055815:Young Adult