Self-Reported Anxiety Symptoms Are Associated With Knee Pain Severity In Individuals With ACL Reconstruction

Individuals with ACL reconstruction (ACLR) frequently experience psychological responses to injury that have been linked to knee-related pain and function. However, it is unknown whether anxiety symptoms are associated with knee pain severity among individuals with ACLR. Investigating this association may help to identify a need for psychologically informed treatment approaches to improve knee pain in this population. PURPOSE: To examine the association between anxiety symptoms and knee pain severity in individuals with ACLR. METHODS: 160 individuals with primary, unilateral ACLR (time since surgery [TSS] = 5.8 ± 1.7 mo; age = 22.7 ± 10.5 yrs; 38% male) were included from an ongoing longitudinal study. Participants completed the Patient Reported Outcomes Measurement Information System (PROMIS) Anxiety short form (4a) and the Knee Injury and Osteoarthritis Outcome Score Pain (KOOS-Pain) subscale. The PROMIS Anxiety (4a) includes 4-items that measure emotional distress caused by hyperarousal, fear, stress, and related somatic symptoms in the past 7 days. PROMIS Anxiety scores range from 40.3 to 81.6 where higher scores indicate more anxiety symptoms. The KOOS-Pain subscale includes 9-items that assess knee pain severity. KOOS-Pain scores range from 0-100, where higher scores indicate less or no knee pain. Descriptive statistics (median [IQR]) were calculated for PROMIS Anxiety and KOOS-Pain scores. A multiple hierarchical regression analysis was conducted to determine the association between self-reported anxiety symptoms and knee pain severity. Age and TSS were entered in the first step of the analysis due to their potential influence on knee pain severity. PROMIS Anxiety scores were entered in the second step and the change in R-squared was examined. A-priori α was set at p < 0.05. RESULTS: Age and TSS explained 5% of the variance in KOOS-Pain scores (median = 97.2[13.9]) (F2,157 = 4.22, R2 = 0.051, p = 0.016). PROMIS Anxiety scores (median = 48[14.3]) accounted for an additional 17.9% of the variance in KOOS-Pain scores (F3,156 = 15.56, ΔR2 = 0.179, p < 0.001). CONCLUSIONS: Self-reported anxiety symptoms are a significant predictor of knee pain severity after controlling for age and TSS in individuals with ACLR. Future research should explore interventions to address anxiety throughout ACLR rehabilitation.