Abstract
BACKGROUND: There is concern that the prolonged symptom duration commonly observed in Achilles tendinopathy may alter pain processing and lead to development of central sensitization. If true, presence of altered pain processing could explain why nearly one third of individuals with Achilles tendinopathy do not respond to gold standard treatment. Currently, the relationship between symptom duration, symptom severity, pain, and central sensitization in Achilles tendinopathy is unclear. PURPOSE: The purpose of this study was assess the proportion of individuals with midportion Achilles tendinopathy who may have central sensitization, as defined by the Central Sensitization Inventory (CSI) part A questionnaire. A secondary aim was to assess the relationship between symptom duration, pain intensity, symptom severity and CSI scores. STUDY DESIGN: Cross-Sectional Study. METHODS: Individuals diagnosed with midportion Achilles tendinopathy were included (n=182, 57% female (47.3±12.7 years). Bivariate correlations were used to evaluate relationships between symptom duration (time between date of symptom onset and date of study enrollment), symptom severity (assessed by Victorian Institute of Sport Assessment-Achilles, VISA-A), and pain intensity (assessed by Patient-Reported Outcomes Measurement Information System 29, PROMIS-29) with CSI scores. RESULTS: Nine of 182 individuals (4.9%, 9 females) scored above the clinical cut off for CSI, indicating likely presence of central sensitization. Duration of symptoms did not correlate with CSI score (r = 0.037, 95% CI [-.109, .181] p=0.622). VISA-A had a significant negative correlation with CSI score (r=-0.293, [-.420, -.154] p<0.001), and pain intensity had a significant positive correlation with CSI score (r=0.195, [.051, .331] p=0.008). CONCLUSION: Less than five percent of individuals with midportion Achilles tendinopathy met criteria for likely presence of central sensitization as defined by the CSI screening questionnaire. The study findings suggest prolonged symptom duration among those with midportion Achilles tendinopathy is unlikely to increase the occurrence of symptoms associated with central sensitization. LEVEL OF EVIDENCE: Level 4.