Development of Spinal Enthesopathies in Adults With X-linked Hypophosphatemia

Abstract

Context: Musculoskeletal complications are the main manifestations in adults with X-linked hypophosphatemia (XLH). Enthesopathy significantly impairs quality of life.

Objective: To identify the risk factors associated with the development and progression of spinal enthesopathies in adults with XLH.

Design and setting: We conducted a retrospective study in the French Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism.

Patients: Adults XLH patients with 2 EOS® imaging performed at least 2 years apart at the same center between June 2011 and March 2022. The progression of enthesopathies was defined as a new enthesopathy at least 1 intervertebral level in patients with or without presence of enthesopathy at baseline.

Main outcome measures: Demographic, treatment, PHEX mutation with the progression of enthesopathies.

Results: Fifty-one patients (66.7% of women, mean age 42.1 ± 13.4 years) underwent 2 EOS imaging with an average interval of 5.7 (± 2.31) years.Progression of spinal enthesopathies was observed in 27 (52.9%) patients. In univariate analysis, patients with a progression of spinal enthesopathies were significantly older (P < .0005), were significantly older at treatment initiation (P = .02), presented with dental complications (P = .03), received less frequently treatment during childhood with phosphate and/or vitamin D analogs (P = .06), and presented more frequently with hip osteoarthritis (P = .002) at baseline. In multivariate analysis, none of these factors was associated with a progression of spinal enthesopathies.

Conclusion: This study confirms the high proportion of patients with a progression of spinal enthesopathies. Age seems to be the main factor associated with progression.

Keywords: EOS® imaging; X-linked hypophosphatemia; XLH; enthesopathies; osteomalacia.