Cryotherapy is a common modality used after arthroscopic procedures. The current authors investigated whether regions deeper than the lateral gutter experience similar temperature reductions with cryotherapy, supporting a more global temperature effect on the synovium. Thermocouple probes were arthroscopically placed intraarticularly in the medial gutter and suprapatellar pouch after routine knee arthroscopy. Twelve patients were divided into two groups for temperature measurement during 2 hours. Ice was applied only for the first hour in Group 1 (n = 6) and only for the second hour in Group 2 (n = 6). The medial gutter and suprapatellar pouch had significant decreases (average, 2.7 degrees -5 degrees C) in the temperature when ice was applied and a significant increase (average, 1.7 degrees -3 degrees C) in the temperature without ice. Also, the temperatures in the medial gutter and suprapatellar pouch correlated with each other. At 1 hour, the mean difference between ice versus no ice was on average 6 degrees C. Cryotherapy globally decreased intraarticular temperature in the absence of hemarthrosis.