HAPPi Kneecaps! A double‐blind, randomised, parallel group superiority trial investigating the effects of sHoe inserts for adolescents with patellofemoral PaIn: phase II feasibility study

Background Patellofemoral pain (PFP) affects one‐third of adolescents and can persist into adulthood, negatively impacting health and quality of life. Foot orthoses are a recommended treatment for adults with PFP, but have not been evaluated in adolescents. The primary objective was to determine the feasibility of conducting a full‐scale randomised controlled trial (RCT) evaluating effects of contoured, prefabricated foot orthoses on knee pain severity and patient‐perceived global change, compared to flat insoles. The secondary objective was to describe outcomes on a range of patient‐reported outcome measures. Methods We recruited adolescents aged 12–18 years with PFP of ≥2 months duration into a double‐blind, randomised, parallel‐group feasibility trial. Participants were randomised to receive prefabricated contoured foot orthoses or flat shoe insoles, and followed for 3 months. Participants and outcome assessors were blinded to group allocation. Primary outcomes were feasibility of a full‐scale RCT (number of eligible/enrolled volunteers; recruitment rate; adherence with the intervention and logbook completion; adverse effects; success of blinding; drop‐out rate), and credibility and expectancy of interventions. Secondary outcomes were patient‐reported measures of pain, symptoms, function, quality of life, global rating of change, patient acceptable symptom state, and use of co‐interventions. Results 36 out of 279 (12.9%) volunteers (27 female, mean (SD) age 15 (2) years, body mass 60 (13) kg) were eligible and enrolled, at a recruitment rate of 1.2 participants/week. 17 participants were randomised to receive foot orthoses, and 19 to flat insoles. 15 participants returned logbooks; 7/15 (47%) adhered to the intervention. No serious adverse events were reported. 28% (10/36, 4 pandemic‐related) of participants dropped out before 3 months. Blinding was successful. Both groups found the inserts to be credible. Conclusions Based on a priori criteria for feasibility, findings suggest that a full‐scale RCT comparing contoured foot orthoses to flat insoles in adolescents with PFP would not be feasible using the current protocol. Prior to conducting a full‐scale RCT, feasibility issues should be addressed, with protocol modifications to facilitate participant retention, logbook completion and shoe insert wear. Trial registration Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12619000957190. Date registered: 8/07/2019.