An Evidence-based Physical Therapy Prescription for Adults With X-linked Hypophosphatemia

Context: X-linked hypophosphatemia (XLH) is a rare and progressive metabolic phosphate-wasting disorder characterized by lifelong musculoskeletal comorbidities. Despite considerable physical disability, there are currently no disease-specific physical therapy (PT) recommendations for XLH designed to improve engagement and confidence in performing activities of daily living (ADL). Objective: The objective of this patient-centered study was to develop an evidence-based PT program to address gaps in the management of adult XLH without imposing unintended harm. Methods: Creation of the program was informed by a prior controlled clinical study to evaluate the physical and functional effect of XLH on adulthood, and guided by the physical presentation of participants, subjective data and patient goals acquired at intake, and by performance on multiple active range of motion (ROM) movements from the standing position. A weekly standardized interview process was used to assess progression of physical and functional abilities, gains and concerns, and to obtain timely feedback to inform future exercise modifications. Outcomes were evaluated using validated functional tools and subjective data obtained throughout the study. Results: A remote 12-week PT program was created based on collected data. Open and closed kinetic-chain exercises were developed and implemented. Functional improvements were documented, and weekly surveys indicated improved abilities and confidence to engage in ADL. Minimal improvements were observed in active upper and lower extremity ROM, reflective of substantial bony restrictions characteristic of XLH. Conclusion: This study represents the first disease-specific PT recommendations for XLH to mitigate the unique physical challenges of the adult disorder that can be modified to adapt to the current progression status of the adult disorder.