Case Author(s): Gregg D. Schubach, MD and Tom R. Miller, MD, PhD , 10/13/95 . Rating: #D3, #Q4

Diagnosis: Hypophosphatemia/X-linked Vitamin D-resistant Rickets (osteomalacia)

Brief history:

25-year old woman with complaints of low back and left knee pain for one year.


Anterior and Posterior Whole Body Images

View main image(bs) in a separate image viewer

View second image(bs). Lateral images of the left and right knee, respectively.

View third image(xr). Radiographs of the left knee

View fourth image(xr). Spot image of the proximal left femur

Full history/Diagnosis is available below

Diagnosis: Hypophosphatemia/X-linked Vitamin D-resistant Rickets (osteomalacia)

Full history:

25-year old woman with a history of vitamin D-resistant rickets. The patient has undergone spinal fusion and multiple osteotomies to the lower extremities bilaterally. The most recent surgery was approximately nine years ago. The patient now complains of low back and left knee pain for one year.


Tc-99m MDP


Bone scintigraphy demonstrates focal regions of increased radiopharmaceutical uptake in the proximal right femoral diaphysis medially and the left proximal femoral diaphysis laterally. This corresponds to the Looser's zones (pseudofractures) on the plain radiographs of the femora. There is scintigraphic evidence of Harrington rods in the thoracolumbar region in this patient with a lower thoracic dextroscoliosis and short stature. Note is also made of the suboptimally positioned gonadal shield on the plain radiographs. There is shortening and bowing deformities of multiple long bones, including the humeri and femora, which is corroborated on the plain radiographs of the knees. No scintigraphic abnormality is identified in the distal left femur, proximal left tibia, or proximal left fibula to correspond with the foci of periosteal reaction on the radiographs. The radiographic abnormalities, some of which have scintigraphic correlates, likely represent Looser1s zones in various phases of healing. The short stature, bone deformities, and Looser1s zones are characteristic of osteomalacia.


Several rachitic and osteomalacic syndromes, which share one or several renal tubular abnormalities, are collectively known as Fanconi syndromes. X-linked hypophosphatemia (also known as familial vitamin D-resistant rickets) is the most common form of renal tubular rickets and osteomalacia. This syndrome, which is characterized by life-long hypophosphatemia secondary to renal tubular phosphate loss, decreased intestinal absorption of calcium, and normal serum levels of calcium, usually appears between 12 and 18 months of age. Afflicted individuals are short, bowlegged, stocky, and usually men (X-linked dominant trait). The development and severity of rachitic changes differ from patient to patient and systemic symptoms, such as muscle weakness and hypotonia, are absent. Although remission typically follows growth plate closure, recurrence of symptoms is common in adulthood. Radiographic features include bowing of long bones (especially lower extremities), rachitic changes at the growth plates, and minimal osteopenia. Coarsening of the trabecular pattern along with Looser1s zones are identified with aging. The latter may be complicated by complete fractures. The skeleton shows multiple sites of new bone formation at various tendinous and ligamentous attachments. These enthesopathic calcifications/ossifications may be identified in the annulus fibrosis, paravertebral ligaments, apophyseal joints, acetabulum, iliolumbar ligaments, and sacroiliac ligaments. Also, periarticular ossicles may develop as small separate entities, especially about the carpus. Treatment of hypophosphatemia includes phosphate infusion and large doses of vitamin D.

References: Resnik D. Bone and Joint Imaging.

Major teaching point(s):

The short stature, bone deformities, and Looser's zones are characteristic of osteomalacia.

ACR Codes and Keywords:

References and General Discussion of Bone Scintigraphy (Anatomic field:Skeletal System, Category:Metabolic, endocrine, toxic)

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Case number: bs041

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