Is it possible to decrease skin temperature with ice packs under casts and bandages? A cross-sectional, randomized...

There is a general belief that the presence of a cast or a bandage eliminates the lowering effects of skin temperature when local cold therapy applied on the surface of the cast or bandage. The purpose of this study is to determine the magnitude of temperature changes at the skin of the ankle after the application of frozen ice packs to the surface of various casts and bandages both in normal and swollen ankles.

Thirty-two healthy subjects (Group A) and 12 patients with Grade III inversion type acute ankle sprain (Group B) were randomly divided into four groups. The sensor of the digital thermometer was secured to the ankle over the anterior talo-fibular ligament in every subject before placement of a bandage or cast. Robert Jones bandage, elastic support bandage, a below-knee plaster cast and synthetic below-knee cast were applied in groups 1, 2, 3 and 4, respectively. Two frozen ice packs were placed around the cast or bandage at the level of sensor, and skin temperatures were recorded.

The skin temperature under dressings and casts decreased significantly relative to the baseline temperatures with local cold therapy in all groups. The fall in the temperature with cryotherapy in group A showed a three-phase pattern of change between groups 1 and 2, groups 2 and 3 and groups 2 and 4 during the experiment. The fall in the skin temperature with ice packs differed significantly between groups 1 and 3, and also groups 1 and 4 from the beginning till the end of the experiment. There was no significant difference between groups 3 and 4 in terms of skin temperature fall with cryotherapy during the whole experiment. The results were similar in group B.

A bandage or cast does not prevent measurable skin temperature lowering by frozen ice packs both in normal and swollen ankles.