Objective: Patellofemoral pain has high recurrence rates and minimal long-term treatment success. Central sensitization refers to dysfunctional pain modulation that occurs when nociceptive neurons become hyper responsive. Research in this area in PFP has been increasingly productive in the past decade. The aim of this review is to determine whether evidence supports manifestations of central sensitization in individuals with PFP.
Data sources: MeSH terms for quantitative sensory testing (QST) pressure pain thresholds, conditioned pain modulation, temporal summation, sensitization, hyperalgesia, and anterior knee pain or PFP were searched in PubMed, SportDiscus, CINAHL, Academic Search Complete, and Ebscohost.
Study Selection: Peer reviewed studies written in English, published between 2005–2020 which investigated QST and/or pain mapping in a sample with PFP were included in this review.
Data Extraction: The initial search yielded 140 articles. After duplicates were removed, 78 article abstracts were reviewed. Full-text review of 21 studies occurred, with 11 studies included in the meta-analysis and eight studies included in the systematic review.
Data Synthesis: A random-effects meta-analysis was conducted for four QST variables (local pressure pain thresholds, remote pressure pain thresholds, conditioned pain modulation, temporal summation). Strong evidence supports lower local and remote pressure pain thresholds, impaired conditioned pain modulation, and facilitated temporal summation in individuals with PFP compared to pain-free individuals. Conflicting evidence is presented for heat and cold pain thresholds. Pain mapping demonstrated expanding pain patterns associated with long PFP symptom duration.
Conclusions: Signs of central sensitization are present in individuals with PFP, indicating altered pain modulation. PFP etiological and treatment models should reflect the current body of evidence regarding central sensitization. Signs of central sensitization should be monitored clinically and treatments with central effects should be considered as part of a multi-modal plan of care.
Registration Number: This review is registered with Prospero (CRD42019127548)
Pain persistence in patellofemoral pain may be the result of central sensitization.
Individuals with PFP demonstrate altered pressure pain thresholds, central pain inhibition, and central pain facilitation compared to pain-free individuals.
Clinicians should incorporate quantitative sensory tests into the examination process to track improvement over time.