Wyndow N, et al. - In this four-month, parallel, two-arm pilot trial that took place in Brisbane, Queensland, and Hobart, Tasmania (August 2014 to October 2016), 46 persons with patellofemoral OA (PFOA) were randomized via concealed allocation to foot orthoses plus prescribed footwear (n = 24), or prescribed footwear (n = 22) in order to examine the feasibility of conducting a randomized clinical trial 26 (RCT) of adding foot orthoses (FO) to footwear in individuals with PFOA and investigate outcomes of pain, 27 physical function and quality of life. Of 782 volunteers, 47 were eligible and 46 took part in it. For both groups (9-10 hours wear per day), intervention adherence was high. No serious adverse events were noted. At 4 months, more than 80% of questionnaires were finished. Between-group impact sizes for patient-reported outcome measures were typically minute, whereas moderate to large within-group response influences were seen in both groups. In conclusion, with modifications to eligibility criteria, a full-scale RCT for PFOA is feasible. Nevertheless, the observed small between-group impact sizes, combined with moderate to large within-group responses for both interventions, designate that a full-scale trial is unlikely to discover clinically significant variations. Secondary outcomes imply that for individuals with PFOA, both interventions could be advised.