Cold therapy has one of the oldest reputations in recovery care, and one of the more mixed records in the research literature. Some outcomes are well supported. Others are studied far less, or show results that depend heavily on how the cold was applied. This is a plain look at what the evidence currently says, not a sales pitch for ice.
The mechanism, in short
Cold applied to skin and the tissue beneath it causes vasoconstriction, blood vessels narrow, reducing blood flow to the area, and slows local cell metabolism. The pain relief that follows is generally attributed to two things working together: less fluid pressure building up around the healing tissue, and cold’s own effect on how nerves signal pain. Older physiology reviews describe this as a reflex response running through the autonomic nervous system, triggered within seconds of cold contact.
None of this is new or contested. What’s less settled is exactly how much of the pain relief patients report comes from each mechanism, and how that translates into a specific protocol, how cold, how long, how often.
What a 2024 systematic review found for shoulder surgery
A 2024 systematic review pooled six randomized trials, 233 patients total, looking at cryotherapy after shoulder surgery. Most found cryotherapy reduced postoperative pain; one trial found no difference from the control group. Three of the studies also measured joint and skin temperature directly and confirmed cryotherapy lowered both. The review’s own framing was that the evidence is “promising but limited,” citing small sample sizes and inconsistent methods across trials as the reason to stay cautious rather than declare the case closed.
What a review of knee and musculoskeletal surgery trials found
A separate systematic review, ten trials covering 573 patients, looked specifically at cold compression devices after knee and other musculoskeletal surgery. It found a statistically significant reduction in pain scores at 48 hours after surgery compared with no cryotherapy, with no difference in adverse events between groups. The same review noted the evidence for other outcomes, swelling, range of motion, longer-term function, was insufficient to draw firm conclusions either way.
That pattern repeats across much of the literature: pain, especially in the first days after surgery, is the outcome cold therapy is best supported for. Claims beyond that deserve more scrutiny.
Where the evidence is thinner
Two honest caveats worth keeping in mind:
- Trial sizes are small. Many of the available studies run from a few dozen to a few hundred patients. That’s enough to detect a real pain effect reasonably reliably, but not enough to settle finer questions, like the ideal temperature, session length, or whether benefits differ much between a machine and a well-managed ice pack routine.
- Most trials test the general approach, not a specific product. The research supports consistent, controlled cold applied over a planned course of sessions as a concept. It doesn’t single out particular equipment as proven superior, that’s a different, much narrower question the trials mostly don’t ask.
What this means practically
If your care team has included cold therapy in your recovery plan, the research backs that decision, particularly for managing pain in the early days after surgery. The honest summary is: well-supported for pain, less settled for swelling and function, and mostly silent on specific equipment beyond “apply cold consistently, as directed.”
If your plan calls for structured, repeated cold sessions and you’re weighing how to execute it at home, the rental page explains how that looks in practice.
Sources referenced: a 2024 systematic review of cryotherapy after shoulder surgery (six randomized trials); a systematic review of cold compression after knee and musculoskeletal surgery (ten trials, 573 patients); and foundational physiology literature on cold-induced vasoconstriction.