Clin Orthop Surg.  2016 Jun;8(2):232-236. 10.4055/cios.2016.8.2.232.

Pathologic Femoral Neck Fracture Due to Fanconi Syndrome Induced by Adefovir Dipivoxil Therapy for Hepatitis B

• Lee YS
• Kim BK
• Lee HJ
• Dan J

• KMID: 2412353
• DOI: http://doi.org/10.4055/cios.2016.8.2.232

Abstract

In Fanconi syndrome, hypophosphatemic osteomalacia is caused by proximal renal tubule dysfunction which leads to impaired reabsorption of amino acids, glucose, urate, and phosphate. We present a rare case of a 43-year-old Korean male who was found to have insufficiency stress fracture of the femoral neck secondary to osteomalacia due to Fanconi syndrome. He had been receiving low-dose adefovir dipivoxil (ADV, 10 mg/day) for the treatment of chronic hepatitis B virus infection for 7 years and he subsequently developed severe hypophosphatemia and proximal renal tubule dysfunction. The incomplete femoral neck fracture was fixed with multiple cannulated screws to prevent further displacement of the initial fracture. After cessation of ADV and correction of hypophosphatemia with oral phosphorus supplementation, the patient's clinical symptoms, such as bone pain, muscle weakness, and laboratory findings improved.

Keyword

Chronic hepatitis B; Adefovir dipivoxil; Fanconi syndrome; Osteomalacia; Spontaneous fractures

MeSH Terms

Adenine/adverse effects/*analogs & derivatives/therapeutic use
Adult
Antiviral Agents/*adverse effects/therapeutic use
*Fanconi Syndrome/chemically induced/complications
*Femoral Neck Fractures/diagnostic imaging/etiology/physiopathology/therapy
*Fractures, Spontaneous/diagnostic imaging/etiology/physiopathology/therapy
Hepatitis B, Chronic/*drug therapy
Humans
Male
Organophosphonates/*adverse effects/therapeutic use
*Osteomalacia/diagnostic imaging/etiology/physiopathology/therapy
Antiviral Agents
Organophosphonates
Adenine

Figure

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  Fig. 1 Plain radiograph of the pelvis and both femoral heads shows no evidence of fracture or pathologic lesions.

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  Fig. 2 The 99mTc-hydroxymethylene diphosphonate whole body bone scintigraphy displays increased uptake in the right sixth rib and left femoral neck area. Hot uptake in the right sixth rib was due to rib fracture which was diagnosed 3 years ago.

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  Fig. 3 Magnetic resonance imaging revealing abnormal signals in both femoral neck areas. (A) Coronal T1-weighted image of both femoral neck areas. (B) Axial T1-weighted image of both femoral neck areas. Dark line and signal changes were seen in both femoral neck areas, especially on the left side of the hip. (C) Coronal T1-weighted image of the left femoral neck area. (D) Coronal T2-weighted image of the left femoral neck area.

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  Fig. 4 Plain radiographs after operation show normal anatomical relation in hip without pathologic lesion. (A, B) Immediate postoperative radiographs of the left femoral neck. Three cannulated screws were inserted in a reverse triangular pattern. (C, D) Radiographs of the left femoral neck at 8 months after surgery.

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  Fig. 5 Follow-up X-ray of both femoral heads at 14 months after initial treatment. The radiograph shows no signs of avascular osteonecrosis in both femoral neck areas and no loosening of screws in the left femoral neck.

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