Osteoarthritis, Osteophytes, and Enthesophytes Affect Biomechanical Function in Adults With X-linked Hypophosphatemia

Abstract

Context X-Linked hypophosphatemia (XLH) is a lifelong metabolic disease with musculoskeletal comorbidities that dominate the adult clinical presentation. Objective The adult XLH disorder has yet to be quantified on the basis of the physical and functional limitations that can affect activities of daily living. Our goal was to report the impact of the musculoskeletal manifestations on physical function. Design and setting Musculoskeletal function was evaluated by validated questionnaires and in an interdisciplinary clinical space where participants underwent full-body radiologic imaging, goniometric range of motion (ROM) measurements, general performance tests, and kinematic gait analysis. Patients Nine adults younger than 60 years with a diagnosis of XLH and self-reported musculoskeletal disability, but able to independently ambulate, were selected to participate. Passive ROM and gait analysis were also performed on age-approximated controls to account for differences between individual laboratory instrumentation. Results Enthesophytes, degenerative arthritis, and osteophytes were found to be consistently bilateral and diffusely present at the spine and synovial joints across participants, with predominance at weight-bearing joints. Passive ROM in adults with XLH was decreased at the cervical spine, hip, knee, and ankle compared to controls. Gait analysis relative to controls revealed increased step width, markedly increased lateral trunk sway, and physical restriction at the hip, knees, and ankle joints that translated into limitations through the gait cycle. Conclusions The functional impact of XLH musculoskeletal comorbidities supports the necessity for creating an interprofessional health-care team with the goal of establishing a longitudinal plan of care that considers the manifestations of XLH across the lifespan.

Giving Credence to the Experience of X-Linked Hypophosphatemia in Adulthood: An Interprofessional Mixed-Methods Study

“…Key physical and functional findings are reported in the adjunct arm of this study, which was conducted with age-and sexmatched controls. 18 Briefly, these studies confirmed the global and bilateral presence of enthesophytes of mechanically loaded fibrocartilaginous tendon/ ligament insertion sites, significant loss of cartilage, and osteophytes typical of progressive degenerative arthritis. These findings correlated with significant restriction in range of motion and deviations in gait, consistent with a Trendelenburg-like gait.…”

“…Adults with XLH face ongoing and progressive functional limitations and pain as they age, 18 which influences the experience of and decisions around work, travel, physical and mental health, and social and family life. 30 The mixed-methods nature of the study is particularly vital given the correlation of themes emerging from this qualitative analysis with the physical findings from the functional outcome study of adults with XLH, 18 the poorly appreciated pain and fear of falls experienced by this population, and the repeated experience of being shown a lack of credence by health care providers (Figure 2). This disconnect with providers may result in underutilization of available services and therapies and less adequate management of XLH.…”

“…In populations with chronic musculoskeletal changes, the fear of falling itself may be a greater predictor of future falls 36,37 than the Berg balance score. Persistent osteomalacia and a compensatory analgesic gait assumed by these patients to ambulate 18 predisposes individuals to falling and to fall-related fractures. A prior experience with even a single episode of fracture-related fall(s), regardless of origin, emerged as a fear of falling.…”

“…These findings correlated with significant restriction in range of motion and deviations in gait, consistent with a Trendelenburg-like gait. 18 In addition to physical findings, qualitative data were obtained through interviews by social work and OT. While questionnaire data were collected online or by mail via surveys, assessments such as Berg balance score, gait analysis, and interviews were completed in a day-long, on-site visit.…”

“…Physical and radiographical data for adults with XLH and sex/age-matched controls were obtained concurrently. 18 In the current mixed-methods analysis, themes emerging from qualitative analysis of social work and OT interviews were first corroborated with intake surveys, triangulated by confirmation with participants, and then correlated with physical findings (Table 1).…”