Outcomes of orthopedic surgery in a cohort of 49 patients with X-linked hypophosphatemic rickets (XLHR)

Abstract

Background: X-linked hypophosphatemic rickets (XLHR) is due to mutations in PHEX leading to unregulated production of FGF23 and hypophosphatemia. XLHR is characterized by leg bowing of variable severity. Phosphate supplements and oral vitamin analogs, partially or, in some cases, fully restore the limb straightness. Surgery is the alternative for severe or residual limb deformities. Objective: To retrospectively assess the results of surgical limb correction in XLHR (osteotomies and bone alignment except for 3 transient hemiepiphysiodesis). Methods: We analyzed the incidence of recurrence and post-surgical complications in 49 XLHR patients (29F, 20M) (mean age at diagnosis 6.0 years (± 7.1)). Results: At first surgery, the mean age was 13.4 years (± 5.0). Recurrence was observed in 14/49 (29%) patients. The number of additional operations significantly decreased with age (2.0 (± 0.9), 1.7 (± 1.0) and 1.2 (± 0.4) in children 15 years; P < 0.001). Incidence of recurrence seemed to be lower in patients with good metabolic control of the rickets (25% vs 33%). Complications were observed in 57% of patients. Conclusion: We report a large series of surgical procedures in XLHR. Our results confirm that phosphate supplements and vitamin D analog therapy is the first line of treatment to correct leg bowing. Surgery before puberty is associated with a high risk of recurrence of the limb deformity. Such procedures should only be recommended, following multidisciplinary discussions, in patients with severe distortion leading to mechanical joint and ligament complications, or for residual deformities once growth plates have fused.

Keywords

• X-linked hypophosphatemic rickets
• osteotomy
• PHEX
• hemiepiphysiodesis
• genu varum
• genu valgum