Cryotherapy: an effective modality for decreasing intraarticular temperature after knee arthroscopy

Cryotherapy is a modality commonly used after arthroscopic procedures. We divided 17 patients into two groups after routine knee arthroscopy: 12 patients were immediately treated with ice and 5 control patients were treated without ice for the first hour. In all patients, thermocouple probes were placed intraarticularly into the lateral gutter of the knee. Ice was placed on the operative knees of the treatment group for 2 hours. The control group had no intervention for the 1st hour and then had ice applied for the 2nd hour. Temperatures were continually recorded every minute for 2 hours. The temperature in the treatment group declined significantly, by 2.2 degrees C (95% confidence interval [-3.6 degrees C, -0.72 degrees C]) over the 1st hour and by 0.79 degrees C (95% CI [-1.8 degrees C, 0.18 degrees C]) over the 2nd hour (P = 0.008). The temperature in the control group increased significantly, by 5.0 degrees C (95% CI [2.4 degrees C, 7.5 degrees C]) over the 1st hour (P = 0.006). After ice was applied, the temperature fell significantly, by 4.0 degrees C (95% CI [-8.3 degrees C, 0.26 degrees C]) (P = 0.06). The difference between the temperature decrease in the treatment group and the increase in the control group at 60 minutes was 7.1 degrees C. This is the first rigorously conducted study in human patients that documents a statistically significant decline in intraarticular knee temperature with the application of ice and compression to the skin. The mechanism by which cryotherapy acts must therefore include the cooling effect on the intraarticular environment and synovium.