Temperature elevations in orthopaedic cutting operations.

Temperature measurements were made in bovine cortical bone using two cutting burst at 20,000 and 100,000 rpm and two reciprocating saw blades at 20,000 strokes per minute. A combination of feed rates and depths of cuts were investigated for the cutting burs. Cortical temperatures decreased as a result of increases in feed rate, but increased as the depth of cut increased. Temperature increase due to an increase in rotational speed was dependent upon the particular bur. The cutting forces were observed to increase with feed rate and depth of cut, but to decrease with increased rotational speed. The effect of saw design and irrigation had a significant effect on the cortical temperature. Without irrigation, the bone temperature exceeded temperatures reported to produce thermal necrosis. Clinical tests during total joint replacement indicated saw temperatures exceeding 200 degrees C when irrigation was not used.