Fidelity of power mobility interventions for young children with disabilities: a systematic review

<b>Purpose:</b> To describe the study characteristics, intervention components, and intervention fidelity measurement of power mobility interventions for children three years and younger with mobility disabilities. <b>Methods:</b> We conducted a systematic review of studies that provided a power mobility device and in-person training over more than one session. PubMed, Web of Science, PsycINFO, and Google Scholar (April 2025) were searched. Data were extracted for study characteristics, intervention components, and intervention fidelity measurement (adherence, dosage, quality of delivery, participant responsiveness, program differentiation), including interventionist training and reliability procedures. When not explicitly measured, intervention fidelity were inferred using An et al. <b>Results:</b> Thirty-six studies met eligibility criteria. Samples were small, most involving children with cerebral palsy. Modified ride-on cars with switch access were common, and training occurred in both clinical and community settings. Intervention frequency and duration varied widely (3-36 sessions, 10-120 min), and device use outside sessions was inconsistently reported. Caregiver education appeared in just over half of studies, and goal-directed activities, exploration, and prompting were the most frequent instructional strategies. Few studies explicitly referenced evidence or theory to guide design. One case report systematically measured intervention fidelity; in the remainder, measurement was limited, most often to dosage (sessions completed) or participant responsiveness (developmental outcomes). <b>Conclusions:</b> Fidelity measurement in power mobility interventions for young children is sparse and inconsistent, limiting interpretation, replication, and clinical translation. Future work should define core intervention ingredients, ground design in evidence and developmental theory, and apply intervention fidelity measurements to improve transparency, rigour, and clinical implementation.