Should we ice inflamed joints, or not? This question is not as straightforward as it might seem to those of us who have embraced icing and the pain relief it brings. Icing, also known as local cryotherapy, is one of the oldest therapies in rehabilitation and is known to reduce pain, swelling and inflammation. However, some people’s joints react badly to icing (see below) and for them it’s not a good idea. Concerns have also been raised about cold-induced constriction of blood vessels and the resulting reduction of oxygen in tissues. Since hypoxia (lack of oxygen) is a powerful driver of fibrosis this might be a valid cause for concern. But as we know, reducing pain and inflammation is especially important in the context of arthrofibrosis, and the traditional anti-inflammatory medications, consisting of non-steroidal anti-inflammatory drugs and corticosteroids, are associated with well-known toxicities in the long term . We should utilise safe and effective methods where they are available.
To understand the pros and cons of local cryotherapy I turned to recent scientific reviews on the topic. Cryotherapy typically consists of an ice pack, cool gel, cool mud pack, crushed ice or even frozen peas placed on or around a joint. More advanced cryotherapy equipment combines controlled cooling with compression  and is sometimes available in hospitals. Whole-body cryotherapy is also utilised by professional sporting bodies and others, but this is a separate topic.
As mentioned, it’s important to understand that cryotherapy does not suit every joint. A significant proportion of post-traumatic joints react with increased pain, aching and stiffness  and cryotherapy should be completely avoided in these cases. Nerves in these joints have been damaged by a combination of trauma (surgery, injury), inflammation and sometimes compression by scar tissue, and as a result have developed cold hypersensitivity - also known as post-traumatic cold intolerance . A related condition also occurs in which damaged sensory nerves are overly sensitive to heat, and in both cases the end result of stimulated, painful nerves is an increase in inflammation. Cold and heat hypersensitivity are not the same thing as chronic regional pain syndrome (CRPS), but instead is a common reaction by nerves to trauma .
So, if your joint doesn’t like cryotherapy, please avoid it, your body will let you know.
The following information applies to joints that haven’t developed cold hypersensitivity, although they may have heat hypersensitivity. For these joints cryotherapy feels good, and you’ll probably look forward to doing it.
If you have arthrofibrosis you’ll likely be familiar with the massive spike in pain and inflammation after surgery. Cells affected by trauma immediately release substances that activate the immune system, producing an inflammatory burst of cytokines (signalling factors) and growth factors accompanied by oxidative stress and enzymatic changes. The sudden demand to make these factors requires energy and means that cells must ramp up their metabolism, which ramps up their need for oxygen (known as hyper-metabolism) . But at the same time the tissues are dealing with a lack of blood flow caused by cut or damaged blood vessels and constriction from swelling . The reduced blood flow means that less oxygen is delivered to the tissues in the joint (ischemia)  at a time when their need for oxygen is higher than normal . This causes the death of healthy cells in the area and yet more inflammation and oxidative damage. This attracts more immune cells such as neutrophils and macrophages to the injured area  which release more inflammatory cytokines and oxidants that directly damage cell membranes and increase the severity and extent of the injury.
How does cryotherapy help? One of the best-known effects of local cryotherapy is its ability to reduce pain (analgesia). Reducing inflammation is part of this effect, but cooling has more direct effects on nerves at the site of application as well as in the spinal cord . Cryotherapy inhibits nerve firing  and nerve conduction leading to an increased pain threshold and less pain . It also reduces the levels of neurotransmitters that signal pain while reducing the pro-fibrotic effects that these have. The pro-fibrotic effects of certain neurotransmitters are why pain control is important in the treatment of arthrofibrosis (see blog Why pain control is important).
Cooling the operated area has significant benefits for joint health in addition to pain reduction. It decreases the metabolism of cells that have entered a hyper-metabolic state, and by doing so, decreases their oxygen requirement. This enables cells to survive in the surgically-induced, low oxygen environment. The production of stress signalling factors, including hypoxia-induced factors (HIF-1a), is lowered, reducing their pro-fibrotic effects. In addition, cooling decreases levels of inflammatory cytokines and reduces enzyme activity and oxidative damage, which means there is less cell death .
It is true that cryotherapy causes the constriction of blood vessels (vasoconstriction). However, after about 10 minutes of cooling nerves will signal to the body to increase blood flow again and vasodilation (known as cold-induced vasodilation) will take place [2, 7]. The return to normal blood flow re-warms the tissues and restores oxygen levels, and is followed by a new phase of vasoconstriction . These alternating periods of vasoconstriction and vasodilation during cold exposure is known as the Hunting reaction. It occurs in most people and protects against cold-induced hypoxia and cell damage, but it can be diminished in the elderly, people whose core body temperature is low, after alcohol consumption, and in some health conditions . So it seems that overall, cryotherapy results in a reduction of secondary hypoxia (it doesn’t appear to increase hypoxia) and reduced inflammation, swelling, cell death and damage . Studies report that range of motion is improved with cryotherapy and mobilizations can be undertaken with less pain and greater efficacy .
Cryotherapy works in the same way for long-term joint diseases like osteoarthritis and rheumatoid arthritis, reducing pain and chronic low-grade inflammation.
Research suggests that the earlier that cooling is applied post-operatively the greater the benefits will be , but heavy bandaging will prevent effective cooling. Cryotherapy can reportedly reduce the temperature inside joints to 30 oC for 2 hours  and will likely have beneficial effects during this period. While we’ve been discussing cryotherapy for post-operative pain and inflammation it seems that cryotherapy works in the same way for long-term joint diseases like osteoarthritis and rheumatoid arthritis , reducing pain and chronic low-grade inflammation [1, 2]. The levels of major pro-inflammatory cytokines, TNF-α, IL-1β and IL-6 are reduced in the synovial fluid of knees in response to local cryotherapy , in addition to a reduction in damaging enzymes, oxidative stress, histamine levels and immune cell activation . So cryotherapy should also work for chronic arthrofibrosis if the joint is inflamed.
To summarise, there is reasonable evidence that cryotherapy affects our biology at many levels and has a range of benefits for inflamed joints , so long as they don’t have cold intolerance. It’s also cheap and readily available to all, and in our experience it’s a useful tool for treating arthrofibrosis. Professor Klintberg from the Physiotherapy Department, Sahlgrenska University hospital, Sweden, recommended applying cryotherapy for up to 15 minutes three times a day, and in their study the majority of post-operative patients stated they would recommend the treatment to a friend or relative if they were in the same situation. Although cryotherapy methods vary considerably in how the cold is applied, as well as duration, temperature and timing , most methods will deliver benefits, but cold packs must not be in direct contact with the skin because skin burns and nerve damage can occur . Using a soft, conforming cool pack (as opposed to a rigid ice pack that only contacts the body in a small area) is likely to cool the joint more effectively.
Remember that, as with most therapies, going harder is not necessarily better. Too cold for too long can become painful, damaging and pro-inflammatory and should be avoided , so please pay attention to the instructions on your equipment and how your joint is responding. There are some medical conditions in which cryotherapy is not well tolerated, so if you have any concerns please ask your doctor, and if cryotherapy doesn’t feel good, don’t do it.
Guillot, X. et al. Cryotherapy in inflammatory rheumatic diseases: a systematic review. Expert Rev Clin Immunol 10, 281-294 (2014). https://doi.org/10.1586/1744666X.2014.870036
Klintberg, I. H. & Larsson, M. E. Shall we use cryotherapy in the treatment in surgical procedures, in acute pain or injury, or in long term pain or dysfunction? - A systematic review. J Bodyw Mov Ther 27, 368-387 (2021). https://doi.org/10.1016/j.jbmt.2021.03.002
Kambiz, S. et al. Thermo-sensitive TRP channels in peripheral nerve injury: a review of their role in cold intolerance. J Plast Reconstr Aesthet Surg 67, 591-599 (2014). https://doi.org/10.1016/j.bjps.2013.12.014
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Douzi, W. et al. (1)H-NMR-Based Analysis for Exploring Knee Synovial Fluid Metabolite Changes after Local Cryotherapy in Knee Arthritis Patients. Metabolites 10 (2020). https://doi.org/10.3390/metabo10110460