This study determined the temporal trends and factors associated with the rates of performance of tibial osteotomies from 1985 to 1990 in Ontario, Canada and the United States. The Health Care Financing Administration, Ontario Health Insurance Plan, and National Hospital Discharge Survey databases were used to determine the number of osteotomies from 1985 to 1990. Osteotomy rates decreased in both countries approximately by 11% to 14% per year in patients 65 years and older and by 3% to 4% per year in patients younger than 65 years. Men received twice as many osteotomies as women in both countries. In the United States, the average rate of tibial osteotomies was 2 to 3 times lower than in Ontario.