Pain Mechanisms in Young Adolescent Females With Longstanding Patellofemoral Pain
Condition: Patellofemoral Pain Syndrome; Pain
MeSH terms: Patellofemoral Pain Syndrome
Study type: Observational

Summary: 
      Patellofemoral pain (PFP) is a highly prevalent musculoskeletal condition in adult females,
      which is associated with decreased quality of life and physical activity levels. PFP is
      highly persistent, with up to 50% of adolescents reporting persistent pain at both one and
      two year follow-ups. Previous research has demonstrated altered pain sensitivity in in older
      individuals with chronic pain, however, less is known about this in conditions such as PFP,
      which is common in younger populations. Additionally it is unknown if these characteristics
      return to similar values as healthy controls, when symptoms resolve.

      The aim of this study will be to compare pain sensitivity in individuals with PFP, compared
      to those with a previous history of PFP who currently are pain-free, and a control group with
      no history of knee pain.
    

Detailed description: 
      Recently it has been demonstrated that females with longstanding PFP demonstrate increased
      pain sensitivity, or hyperalgesia in the peripheral nervous system and impaired conditioned
      pain modulation, which is representative of decreased descending control of pain in the
      central nervous system. This is commonly seen in older adults with chronic longstanding pain,
      such as knee OA.

      Understanding the evolution of pain mechanisms during recovery may yield important insights
      into the highly recurrent nature of this condition. Self-reported recovery appears to be
      associated with increased pressure pain thresholds, in comparison to those with current PFP.
      However, it is unknown whether these characteristics, along with centrally mediated pain
      processing, ever return to 'normal', or to the same levels of those with no history of pain.

      To examine this, the investigation will compare the three groups (PFP versus Recovered versus
      Control), on measures of pain sensitivity (as defined in the primary and secondary outcomes),
      to determine differences between groups.

      Demographic data, regarding age, height and weight will be collected, as well as pain
      frequency (almost daily, several times per week, weekly, monthly, rarely, never), pain
      intensity (measured on numeric rating scale), Knee Injury and Osteoarthritis Outcome score,
      and spatial distribution of pain (using the Navigate pain application). The group that self
      report as recovered, will be asked to report when their symptoms resolved.

      A subgroup analysis will be undertaken in the recovered group, to examine the relationship
      between the time since last knee pain was experienced, (duration they self- report being
      symptom-free), and pain sensitivity, as assessed by the primary and secondary outcome
      measures.

      Participants will be recruited from the Adolescent Pain in Aalborg (APA2011) cohort. In 2011,
      a cohort of 2200 adolescents aged 15 to 19 years answered an online questionnaire on
      musculoskeletal pain. Of these, 504 reported knee pain, and 153 of these were clinically
      diagnosed with PFP. Five years later, the 504 adolescents, as well as 252 randomly selected
      adolescents who did not report knee pain in 2011, completed a follow-up questionnaire
      regarding current pain (clinical trials.gov identifier: NCT02873143). From this group, a
      sample of participants' who were diagnosed with PFP in 2011, and self report with current
      pain, or as 'recovered' will be randomly contacted for inclusion in the current investigation
      (PFP and recovered groups respectively). Additionally, of the control participants from the
      original APA2011 cohort, who reported no pain in 2011, and no pain in 2016, a random sample
      will be drawn and invited to participate as the control group.

      If this cohort is insufficient to reach the required sample size (n = 36 in each group),
      participants will be recruited through other sources such as GP's, and social media.

      Embedded within this cross-sectional study, is a randomized crossover trial (in the group
      with PFP) which has been approved by the local ethical committee under the same approval
      number (N-20160058). This can be accessed on clinicaltrials.gov under the title "The acute
      effects of hip and knee exercises on pain sensitivity in young adult females with
      long-standing patellofemoral pain - a randomized crossover study." with Dr. Michael Rathleff
      as the primary investigator.
    

Intervention name(s): No Intervention
Intervention type(s): Other
Intervention description(s): No intervention
Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        The study population will consist of young females. One group will include participants
        with current longstanding patellofemoral pain, while a second group will include those with
        a history of pain, who self report as recovered, and a control group, who has no previous
        history of knee pain.