To define the natural history of bone loss around a femoral prosthesis, the bone mineral content and bone mineral density were measured for each femur in 28 patients with unilateral total hip arthroplasty, 18 age-matched controls, and seven patients with unilateral osteoarthritis. The areas measured were inside the lesser trochanter and 4.8 cm distal to it. The contralateral hip served as the control. Three years after arthroplasty there was 40% loss in average bone mineral content inside the lesser trochanter, and 28% loss in average bone mineral content 4.8 cm distally in the medial cortex. At seven to 14 years after operation, patients had lost 40% of bone proximally and 49% distally. The data suggest that this may progress in a proximal-to-distal fashion, and could account for a 50% decrease in bone mass seven to 14 years after surgery.
Authoritative data show conclusively that irradiation with ultraviolet light is of definite beneficial effect in preventing and in curing rickets. The antirachitic range of the solar spectrum, the wave lengths influencing the deposition of calcium in rickets, is from 290 to 313 millimicrons. That the ultraviolet rays of the sun's spectrum cannot be depended on, however, either to cure or to prevent the development of rickets in all latitudes and at all seasons of the year has also been established, as they vary in intensity during the different seasons of the year, the intensity being highest during the summer months and lowest during the winter months. The ultraviolet rays vary in intensity according to the geographic location, being more intense in the torrid zone than in the temperate zone and at high altitudes than at sea level. The intensity of the short rays is to a large extent dependent on the amount of moisture and dust particles in the air.In the latitude of 42°21' (Boston) under the usual winter condi¬ tions of housing and climate, the direct radiations which reach the growing baby, especially when properly clothed, do not suffice to prevent the development of rickets. On account of the cold and consequent loss of body heat during the winter months, direct exposure of naked infants to the sun's rays is not a practical or safe measure in the prevention or cure of this disease.One of the agents which has received attention in the prevention of rickets in the winter has been the ultraviolet transmitting glass. The types of ultraviolet transmitting glasses which have been more frequently used for this purpose are fused quartz glass, Vitaglass and Helioglass. Window panes made from fused quartz transmit ultraviolet light better than any other known product. The cost of producing it, however,
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