PATIENT-REPORTED AND OBJECTIVE MEASURES OF PHYSICAL ACTIVITY ARE NOT RELATED 6-MONTHS AFTER ACL RECONSTRUCTION
Authors: Kuenze Christopher , Lisee Caroline , Triplett Ashley , Birchmeier Thomas , Straus Michael W. , Wilcox Christopher L. , Schorfhaar Andrew , Joseph Sheeba , Shingles Michael 
Published: April 2020

Background: When measured objectively, adults with ACL reconstruction (ACLR) are 2.5 times less likely to be physically active than by their healthy counterparts. Currently, it is unclear if patient-reported physical activity (PA) is related to objectively-measured PA among high school-aged individuals with ACLR. Purpose: To evaluate the relationship between patient-reported and objectively-measured moderate-to-vigorous PA (MVPA) among high school-aged individuals 6-months after ACLR. Methods: Seventeen participants (age= 15.9±1.3 years, BMI= 24.7±5.1 kg/m2, months since surgery= 6.3±0.7, graft source= 13 hamstring autograft, 3 patellar tendon autograft, and 1 quadriceps tendon autograft, ACL-RSI= 71.3±24.3) with primary unilateral ACLR were enrolled 6±1 months after surgery as part of a prospective cohort study. Participants completed the Tegner Activity and Marx Activity Scales to assess current physical activity level. Participants also completed the International Physical Activity Questionnaire Short Form (IPAQ-SF) to assess patient-reported MVPA (min/day). Objectively-measured MVPA (min/day) and step count (steps/day) were assessed using ActiGraph GTX9-Link accelerometers worn at the hip over a period of no less than 7 days. Wear time (min/day) was validated using recommendations of Choi et al and Evenson’s child cutpoints were utilized to categorize PA as light, moderate, vigorous, or very vigorous. Relationships between objectively-measured and patient-reported measures of physical activity were assessed using partial correlations ( r) while controlling for total monitor wear-time. We also compared the number of participants who met physical activity guidelines (60 min/day MVPA) via patient-report and objective monitoring using a Fischer’s exact test. Results: Participants reported median Tegner activity levels of 5 [range: 5,9] and Marx activity scores of 16 [range: 4,16], and average IPAQ-SF MVPA of 130±80 [range: 0,300] min/day. Objectively, partipants engaged in 26±14 [9,60] min/day of MVPA and took 6140±1691 [range: 3613,9147] steps/day. Current Tegner activity level was moderately correlated to objectively-measured MVPA ( r = 0.65) but Marx Activity Score ( r= 0.14) and IPAQ-SF MVPA ( r= 0.01) were not related to objectively-measured MVPA (Figure 1). Individuals who reported meeting MVPA guidelines were no more likely to actually meet objectively-measured MVPA guidelines as compared to participants who reported not meeting guidelines (OR= 1.08, CI= 0.93,1.25, p= 0.99). Conclusion: Objectively, 5.9% of participants were categorized as physically active 6-months following ACLR despite the fact that 82.4% of participants reported meeting PA guidelines. The relationship between objective and patient-reported measures of PA among high school-aged participants months post-ACLR is limited and utilization of patient-reported PA measures in this population should be done with caution. [Figure: see text]