Pain mapping of the anterior knee: injured athletes know best

Background and aims Research investigating differences in pain location and distribution across conditions is lacking. Mapping a patient's pain may be a useful way of understanding differences in presentations, however the use of pain mapping during a pain provocation task has not been investigated. The aim of this study was to assess the reliability of patient and clinician rated pain maps during a pain provocation task for the anterior knee. Methods Participants were recruited from a larger study of professional Australian rules football players (n=17). Players were invited to participate if they reported a current or past history of patellar tendon pain. No clinical diagnosis was performed for this reliability study. Participants were asked to point on their own knee where they usually experienced pain, which was recorded by a clinician on a piloted photograph of the knee using an iPad. Participants then completed a single leg decline squat (SLDS), after which participants indicated where they experienced pain during the task with their finger, which was recorded by a clinician. Participants then recorded their own self-rated pain map. This process was repeated 10 min later. Pain maps were subjectively classified into categories of pain location and spread by two raters. Pain area was quantified by the number of pixels shaded. Intra- and inter-rater reliability (between participants and clinicians) were analysed for pain area, similarity of location as well as subjective classification. Results Test-retest reliability was good for participants (intraclass correlation coefficients [ICC]=0.81) but only fair for clinicians (ICC=0.47) for pain area. There was poor agreement between participants and clinicians for pain area (ICC=0.16) and similarity of location (Jaccard index=0.19). Clinicians had good inter- and intra-rater reliability of classification of pain spread (k=0.75 and 0.67). Conclusions Participant completed pain maps were more reliable than clinician pain maps. Clinicians were reliable at classifying pain based on location and type of spread. Implications Clinicians should ask patients to complete their own pain maps following a pain provocation test, to elicit the most reliable and consistent understanding of their pain perception.