Last reviewed: September 29, 2026

Probably not, compared with ordinary ice. Cold of any kind helps a little in the first few days, and in most studies machines have not done better than ice packs.

Ice machines pump cold water through a pad wrapped around the knee, some with added squeezing. Ice packs and gel packs do the same job more simply.

Compared with no cold at all, cold therapy slightly lowers pain around the second day, reduces blood loss, and helps the knee bend a little farther by the time people leave the hospital. Swelling goes down a little in the first days, but not by six weeks. In the largest review, cold did not reduce pain medicine or shorten the hospital stay, and its authors said the benefits may be too small to matter. The evidence is low quality, partly because people always know whether they are getting cold.

Two pooled reviews of trials comparing machines with ice packs found no difference in pain, pain medicine, swelling, bending, blood loss or hospital stay. A few trials found machines lowered pain medicine use in the first week or two. People using machines tended to like them more.

Many people now go home the same day or the next day. In the few trials of cold used at home, it lowered pain medicine use in the first week or two but did not change how well the knee worked. Only one of those trials compared a machine with plain ice, and the machine mainly reduced pain medicine.

A 2015 American Academy of Orthopaedic Surgeons guideline concluded that cold therapy devices do not improve results after knee replacement.

Cold can also cause harm. Frostbite severe enough to destroy the skin over the kneecap has been reported after knee replacement.

In general:

  • Ice packs or gel packs appear to work about as well as a machine.
  • Keep a cloth between the cold and the skin, and take breaks.
  • Numb skin around the scar gives no warning of cold injury, so check the skin.
  • Skin that turns white, blisters or becomes very painful from cold needs to be looked at promptly.

Drafted with AI assistance from published sources, reviewed and edited by Babak Sheikh, MD.

Sources:

This is general information about what published research shows. It is not medical advice and it is not about your situation. Reading it does not create a doctor-patient relationship with me. I am a retired orthopedic surgeon and I do not see patients. Talk with your own doctor before changing anything about your care. If something feels suddenly or seriously wrong, get medical care promptly rather than waiting.

This page is provided as is. I make no guarantee that it is accurate, complete or current, and medical evidence changes. Use of it is at your own risk.

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