Purpose or Case Report: First described by Rathbun in 1948, hypophosphatasia is an inherited metabolic disorder arising from the deficient activity of the tissue-nonspecific isoenzyme of alkaline phosphatase. There are several different types and varying clinical presentations of hypophosphatasia, characterized according to their age of onset by Fraser in 1957. In addition, the severity of the radiographic findings is inversely correlated with the age of presentation, with older patients presenting with less severe forms of the disease. Classically, the radiographic findings resemble rickets/osteomalacia, but in the presence of normal Vitamin D metabolism. Additional findings associated with hypophosphatasia are Bowdler spurs, which are transverse bony spurs in the radius, fibula and ulna and central lucencies or “punched out” lesions in the metaphysis, particularly of the knee (Case 1). In this case series of 3 patients, these characteristic radiographic features as depicted on skeletal surveys, along with their clinical manifestations, diagnostic criteria, management, treatment, and prognosis will be discussed. In particular, the evolution of radiographic changes with treatment in one patient will be assessed (Case 2).
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