Metabolic and orthopedic management of X-linked vitamin D-resistant hypophosphatemic rickets

Abstract

Purpose Therapy of vitamin D-resistant hypophosphatemic rickets (VDXLR) consists of oral phosphate and vitamin D supplements. Bone deformities, pain, and small stature can occur even in children with good compliance, requiring surgical correction and bone lengthening. However, only few surgical reports are available. Methods Twelve patients (three males) with VDXLR were followed at our institution. Median age at diagnosis was 3 9/12 years (range, birth to 11 10/12) with a follow-up period of 7 8/12 years (1 9/12-30) and age at last follow-up of 13 6/12 years (2-30). Eight patients underwent surgical correction, three of them in combination with bone lengthening. The corrections were performed at the end of growth in three patients. Clinical endpoints were height, leg axis, and pain. Results Single bilateral surgical correction was performed in six patients; one patient each had three and five corrections. Bone lengthening was performed in three patients. At last follow-up, the height of seven operated patients was within normal range. In addition, leg axis was normalized in six patients with mild genua vara in two. Only one patient complained of intermittent pain. Bone healing was excellent; surgical complications were rare. There was no radiological evidence of degenerative arthropathy.Conclusions Medical treatment remains the main pillar of therapy in children with VDXLR. In case of bone deformity, surgery can safely be performed, independent of age or bone maturation. All patients were satisfied with the results of axial corrective surgery and bone lengthening, and in the majority only one corrective intervention was needed.

Results of deformity correction in children with X-linked hereditary hypophosphatemic rickets by external fixation or combined technique

“…Imel et al [3] discovered a significant increase of circulating FGF23 concentrations during phosphate and calcitriol therapy, which can be a cause of resistance of patients with X-linked hereditary hypophosphatemic rickets to conservative treatment. Even after fine deformity correction and supportive therapy which reduces active rickets, osteomalacia persists and can be a cause of deformity relapse [13,32].…”

“…Various methods are used for fixation of bone fragments after performed osteotomies: plaster cast, K-wires, bone plates, external fixators, and intramedullary nails [7,8,13,[16][17][18][19][20]. It goes without saying that application of intramedullary locked nails in pediatric orthopaedics is restricted.…”

“…In all the cases drug-resistant deformities were detected, which induced the lower limb deformities requiring operative correction [13].…”

“…Gradual correction can be initiated on the fourth to sixth postoperative day. In all cases we strived to eliminate the present deformities and to prevent under-or overcorrection, which is known to be fraud with relapse of deformations [13,16,29]. When a homogeneous bone regenerate was seen with radiographic evidence of consolidation of at least three of four cortices, the external fixator was removed in both groups according to being able to walk with partial or full weight-bearing without pain.…”

“…Although, the conservative treatment is not always successful. In such cases, operative procedures for correction of multiplanar bone deformities can be indicated to prevent secondary orthopaedic complications such as pain, pathologic fractures, degenerative arthropathy or for cosmetic reasons [13][14][15].…”