82 THE JOURNAL OF BONE AND JOINT SURGERY ORTHOPAEDIC PROBLEMS IN ADULT HYPOPIIOSPHATASIA A REPORT OF TWO CASES

Hypophosphatasia in adults is rare. Two elderly sisters presenting with pathological fractures of the femur are reported to illustrate the difficulties in orthopaedic management of this disease. All patients with a history of repeated fractures, especially from minor trauma and with generalised radiological bony abnormality, should be screened for this rare disease. A consistently low level of serum alkaline phosphatase with the presence of phosphoethanolamine in the urine is diagnostic. Despite numerous reports of the disease in children (Rathbun 1948; Fraser 1957), hypophosphatasia pre-senting in adult life is rare with only thirteen cases so far reported in the literature. There are two previous reports of the condition in adult siblings (Macey 1940; Bethune and Dent 1960). The disease is thought to be an inborn error of metabolism transmitted as an autosomal recessive trait (Rathbun er a!. 1 96 1). It causes weakening of the bones, giving rise to multiple fractures often after minor trauma. There may be a history of early loss of teeth and late walking in childhood. The radiographic appear-ances are similar to those of osteomalacia with coarsening of trabeculae, Looser’s zones. subperiosteal bone formation and anterolateral bowing of the femur (Jardon, Burney and Fink 1970). Biochemical investiga-tions show a consistently low level of serum alkaline phosphatase, and normal serum calcium and phosphate with the presence of phosphoethanolamine in the urine. The renal function is normal. After a fracture, there is considerable delay in the rate of healing as illustrated in the following case reports. CASE REPORT