Psychological and pain profiles in persons with patellofemoral pain as the primary symptom

Abstract

Background Patellofemoral pain (PFP) is defined biomechanically, but is characterized by features that fit poorly within nociceptive pain. Mechanisms associated with central sensitization may explain why, for some, symptoms appear nociplastic. This study compares psychological and somatosensory characteristics between those with persistent PFP and controls. Methods A total of 150 adults with PFP were compared to 61 controls. All participants completed a survey evaluating participant characteristics, PFP‐related constructs and psychological factors: anxiety, depression, pain catastrophizing, kinesiophobia, pain self‐efficacy. Participants also attended a session of somatosensory testing, which included knee and elbow thermal and mechanical detection and pain thresholds, conditioned pain modulation (CPM), and temporal summation of pain (TSP). Differences were evaluated using analysis of covariance (sex as covariate). Multivariate backward stepwise linear regression examined how psychological and somatosensory variables relate to PFP (knee injury and osteoarthritis outcome score‐patellofemoral [KOOS‐PF]). Results The PFP group had multimodal reduced pain thresholds at the knee and elbow (standardized mean difference [SMD], p: 0.86–1.2, <.001), reduced mechanical detection at the elbow (0.43, .01) and higher TSP (0.41, .01). CPM was not different. Psychological features demonstrated small effects (0.47–0.59, 0.01–0.04). The PFP group had a 55% (95% CI: 0.47–0.62) risk of kinesiophobia and an 11% (0.06–0.15) reduced pain self‐efficacy risk. Kinesiophobia, knee pressure pain threshold, pain self‐efficacy and pain catastrophizing explained 40% of KOOS‐PF variance (p = <.001). Conclusions Widespread hyperalgesia and evidence of symptom amplification may reflect nociplastic pain. Clinicians should be aware that kinesiophobia and the nociplastic pain may characterize the condition. Significance (a) Individuals with PFP have widespread reduced pain thresholds to pressure and thermal stimuli. (b) Mechanically induced pain is likely amplified in those with PFP. (c) Pain‐related fear is highly prevalent and helps explain PFP‐related disability.

Exploring the Pain in Patellofemoral Pain: A Systematic Review and Meta-Analysis Examining Signs of Central Sensitization

“…In one study, 49% of the PFP group (total n for PFP group=151) reported stopping normal activity due to their knee pain. 43 Body mass index is reported in eight studies, and the PFP group was only significantly higher in one study. 41 Six of the included studies assessed only females, 28,36-40 while nine assessed mixed-sex cohorts, 27,41-43,47,48,52 and none assessed only males.…”

“…A systematic review was conducted for data obtained that could not be pooled due to a low number of total studies, or differences in methods that did not allow for pooled results. Seven studies were included in the systematic review, two assessed thermal pain thresholds 43,45 and five assessed pain mapping.…”

“…Conflicting evidence has been reported for heat and cold pain thresholds for PFP participants. 43,45,46 SMDs could not be calculated as the data were not normally distributed in one study. One study reported large effect sizes (1. demonstrating lower heat pain thresholds at the knee in the PFP group compared to a pain-free group (n=211), while another reported no significant differences between groups (n=44).…”

“…A number of interpersonal factors can affect central sensitization and pain perceptions. 43,51 27,28,[38][39][40][41]43 and PFP groups report similar or higher activity than pain-free groups. In one study, 49% of the PFP group (total n for PFP group=151) reported stopping normal activity due to their knee pain.…”

“…Only two studies had a mean age below years 28,52 while the mean age was older than years in four studies. 27,39,43,45 Some authors contend that PFP may be a different experience for adolescents than adults, and that onset in adolescence may persist or recur in adulthood. 50,53 The effect of age on QST results should continue to be explored for individuals with PFP.…”