Seasonality of hip fracture and haemorrhagic disease of the newborn.

The objective is to examine and compare the seasonalities of fractured neck of femur and haemorrhagic disease of the newborn. The data are from two sources. Admissions for fractured neck of femur in Scotland over five years (1983-87) are examined by age, sex, mortality, operative intervention and source of admission. Data from the United States (1927-36) are examined for infant death rates from suspected haemorrhagic disease of the newborn 3-14 days after birth. The sine curves are examined. The rhythms, while not identical, have similarities. The peaks are in January-February and the troughs in July-August. Amongst hip fractures the peak is one month earlier and the seasonal excess around 20-25 per cent in both conditions. Rickets, haemorrhagic disease of the newborn and fractured neck of femur have comparable seasonal rhythms. Vitamin D regulates the synthesis of the vitamin K dependent bone protein osteocalcin, which is functionally abnormal in postmenopausal women. This may be a significant factor in the seasonal variation of hip fracture.