You may be describing a device used to apply compression with cold to control swelling, pain, and bleeding into the joint. The pump exchanges warm water for cold.
Intermittent pressure (cycling on and off) helps mimic the muscle action to keep the blood circulating and to keep fluid from pooling or collecting.
The cuff is easy to put on right in the operating room. No time is lost controlling pain and swelling. The device is designed to allow some motion while wearing the cuff. It's easy to put on and take off for full motion.
Many patients wear the Cryocuff for the first 48 hours after surgery for best results.