title: Lower mechanical pressure pain thresholds in female adolescents with patellofemoral pain syndrome.
abstract: METHODS
  Cross-sectional study.
  
  
  OBJECTIVE
  To compare pressure pain thresholds (PPTs) between adolescent females diagnosed with patellofemoral pain syndrome (PFPS) and gender- and age-matched controls without musculoskeletal pain.
  
  
  BACKGROUND
  PFPS is prevalent among adolescents and may be associated with reduced PPT both locally and remotely from the site of reported pain. This may indicate altered central processing of nociceptive information. However, this has never been investigated in adolescents with PFPS.
  
  
  METHODS
  Adolescents with PFPS and a comparison group without musculoskeletal pain were recruited from a population-based cohort of students from 4 upper secondary schools, aged 15 to 19 years. All 2846 students within that age range were invited to answer an online questionnaire regarding musculoskeletal pain. The students who reported knee pain were contacted by telephone and offered a clinical examination by an experienced rheumatologist, who made a diagnosis. PPTs were measured at 4 sites around the knee and 1 site on the tibialis anterior in the 57 female adolescents diagnosed with PFPS and in 22 female adolescents without musculoskeletal pain.
  
  
  RESULTS
  Adolescents with PFPS, compared to controls, had significantly lower PPTs (26%-37% [100-178 kPa]) at each of the 4 sites around the knee, suggesting localized hyperalgesia. On the tibialis anterior, adolescents with PFPS had a 33% (159 kPa) lower PPT (distal hyperalgesia) compared with controls.
  
  
  CONCLUSIONS
  These findings suggest that adolescent females with PFPS have localized and distal hyperalgesia. These findings may have implications for treating PFPS, as both peripheral and central mechanisms may be driving the pain. Registered at clinicaltrials.gov (NCT01438762).
authors.affiliation: Aalborg University Hospital, Research and Innovation Centre, 15 Søndre Skovvej, DK-9000 Aalborg, Denmark. misr@rn.dk
authors.forename: Michael S
authors.initials: MS
authors.lastname: Rathleff
authors.forename: Ewa M
authors.initials: EM
authors.lastname: Roos
authors.forename: Jens L
authors.initials: JL
authors.lastname: Olesen
authors.forename: Sten
authors.initials: S
authors.lastname: Rasmussen
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology*; D017288:Pain Threshold; D046788:Patellofemoral Pain Syndrome / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D011312:Pressure; D015995:Prevalence; D011788:Quality of Life; D055815:Young Adult