Effect of Arthroscopy and Continuous Cryotherapy on the Intra-articular Temperature of the Knee

Purpose: The purpose of this study was to determine “in vivo” the intra-articular temperature of the knee in baseline situation, to quantify its variation during the arthroscopic surgery and the repercussion on the body temperature, and to quantify the variation of the intra-articular temperature after the application of topic cold postoperatively. Type of Study: Case series. Experimental study in patients who undergo arthroscopic surgery of the knee monitoring their intra-articular temperature. Methods: An intra-articular temperature data acquisition system is used in 30 patients who undergo arthroscopic surgery of the knee using saline solution at room temperature and monitoring their body temperature with a rectal temperature probe. In 23 of these patients, after surgery, a plastic bag with 2 kg of ice is applied on the knee, and the variation of the intra-articular temperature is measured for at least 1 hour. Results: The basal temperature of the knee (32.22° ± 0.28°C) decreases during the intervention using saline fluid at room temperature to nearly equalize it (24.49° ± 0.97°C), and it led to a drop of the body temperature of 0.14° ± 0.04°C. The continuous external application of ice after the arthroscopy produces a drop of the intra-articular temperature directly related to the time, with a magnitude of almost 4°C in the first hour. Conclusions: The intra-articular baseline temperature of the knee is significantly lower than that of the body, and the repercussion of its drop during arthroscopic surgery on the body temperature is insignificant. The external application of ice is an effective and sure method to diminish the intra-articular temperature of the knee. Level of Evidence: Level IV, case series with no control group.