Lower limb deformity correction in X-linked hypophosphatemia (XLH) with intramedullary nails: A strategy to reduce deformity recurrence and improve limb function.

Purpose: X-linked hypophosphatemia (XLH) is a rare metabolic disorder leading to impaired bone mineralization and rickets. Severely affected patients often develop complex, three-dimensional lower limb deformities, resulting in pain and reduced mobility. Although various surgical approaches have been described, deformity recurrence remains common. This study retrospectively analyzed the outcomes of multilevel deformity correction using intramedullary nails (IN) in patients with XLH.

Methods: Between 2002 and 2022, 45 lower limb reconstructions involving 165 osteotomies were performed in 26 XLH patients using femoral IN (retrograde) and tibial IN (antegrade). Each leg required two to five osteotomies. The age at surgery was 24 ± 13.8 years. Clinical and radiographic evaluations were conducted pre- and postoperatively.

Results: The follow-up was 76.7 ± 49.2 months. Mechanical axis deviation improved significantly from 54.3 ± 31.0 mm to 12.8 ± 8.9 mm (p < 0.0001). The mechanical lateral distal femoral angle improved from 99.0° ± 10.9° to 90.5° ± 4.4° (p < 0.0001), the medial proximal tibial angle from 80.7° ± 8.0° to 87.4° ± 3.1° (p < 0.001), and the posterior proximal tibial angle from 76.7° ± 9.0° to 80.4° ± 4.2° (p = 0.018). Lower Extremity Functional Scale scores improved from 45 ± 12 to 55 ± 12 (p < 0.01). Deformity recurrence occurred in 2/43 limbs (4.7 %), both revised. Complications arose in 17/45 limbs (37.8 %), of which 14 (31.1 %) required revision surgery, primarily screw removal or osteophyte resection (8/45, 17.8 %). Malunion occurred in 2/45 (4.4 %), implant-related infections in 3/45 (6.7 %).

Conclusion: IN-based deformity correction of lower limbs in XLH provides effective, long-term correction with low recurrence. Despite frequent complications, most patients experience functional improvement. Nail retention is recommended to prevent fractures and recurrences.