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Is ice right? Does cryotherapy improve outcome for acute soft tissue injury?
  1. N C Collins
  1. Department of Emergency Medicine, University Hospital Galway, Galway, Ireland
  1. Dr N C Collins, Department of Emergency Medicine, University Hospital Galway, Newcastle Road, Galway, Ireland; nievoc{at}yahoo.co.uk

Abstract

Aims: The use of ice or cryotherapy in the management of acute soft tissue injuries is widely accepted and widely practised. This review was conducted to examine the medical literature to investigate if there is evidence to support an improvement in clinical outcome following the use of ice or cryotherapy.

Methods: A comprehensive literature search was performed and all human and animal trials or systematic reviews pertaining to soft tissue trauma, ice or cryotherapy were assessed. The clinically relevant outcome measures were (1) a reduction in pain; (2) a reduction in swelling or oedema; (3) improved function; or (4) return to participation in normal activity.

Results: Six relevant trials in humans were identified, four of which lacked randomisation and blinding. There were two well conducted randomised controlled trials, one showing supportive evidence for the use of a cooling gel and the other not reaching statistical significance. Four animal studies showed that modest cooling reduced oedema but excessive or prolonged cooling is damaging. There were two systematic reviews, one of which was inconclusive and the other suggested that ice may hasten return to participation.

Conclusion: There is insufficient evidence to suggest that cryotherapy improves clinical outcome in the management of soft tissue injuries.

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Ice is routinely used in the management of soft tissue injuries, from sprains to strains and contusions. A recent personal survey of Irish emergency physician practice indicated that 73% of consultants “always or frequently” advocate the use of ice while only 7% “never” use cryotherapy; 30% were “unsure” if ice therapy is beneficial. Experience (47%) and common sense (27%) were the reasons most frequently cited for using ice, while 17% used scientific reasoning. Two-thirds (66%) of the consultants surveyed occasionally questioned the medical evidence for ice, 17% never questioned it and 17% frequently questioned the evidence. Almost a quarter (23%) had read literature supporting an improved clinical outcome following ice, 17% had not read supporting literature and 60% were unsure. The frequency with which Irish physicians advocate the use of ice echoes the findings of a UK study stating that 80% of emergency department consultants recommend ice in the management of ankle sprains.1 The use of ice in the management of acute soft tissue injuries is firmly established, but is there evidence to support this practice?

A comprehensive review of published scientific literature was undertaken to investigate if ice improves outcome when used in the management of acute soft tissue injuries. Outcome was defined as (1) a reduction in pain, (2) a reduction in swelling/oedema, (3) improved function and (4) reduced time to return to participation in normal activity.

METHODS

A thorough review of the published literature was performed by a single investigator. Search terms for ice included: ice, cryotherapy, thermal treatment, cold and freezing. A second set of search terms for soft tissue injury included: sprain, strain, contusion, bruise, minor injury, ligament, tendon and haematoma. Lastly, for outcome, there were four specific parameters: (1) reduction in pain; (2) reduction in swelling or oedema; (3) improved function; and (4) time taken to return to participation.

Specific exclusion criteria were exercise-induced injury, acute bone injury and the postoperative use of ice. Unlike published systematic reviews,2 3 this comprehensive review was not confined to human studies and animal trials were also considered.

A comprehensive literature search was performed using Medline 1966–2006 (using the MeSH system), EMBASE 1988–2006, the Cochrane Library, Google Scholar and citation tracking. The search sought to identify papers that examined the therapeutic effect of cryotherapy on soft tissue injuries using the search terms above. After a generalised search, limits for “trials” were applied. Exclusion criteria included the terms “exercise-induced injury”, “bone injury”, “postoperative”, “ice hockey” and “ice cream”. No limits were applied to the year of the study or population (animal or human). Non-randomised trials were included in the search. The references of identified articles were examined to identify additional articles that may have been missed during the original search. In several cases direct correspondence with the publisher was required to obtain these articles.

Human trials were then assessed using Jadad4 and PEDro5 scoring systems to assess the internal validity (effect of bias) of the research methods. These scoring systems, while somewhat flawed, do facilitate comparison between clinical trials and allow a crude assessment of quality.

RESULTS

The various search methods yielded 66 potential papers of interest of which either the abstract or complete article was obtained. Several of the older papers68 required direct communication with the journal publishers as they were not available electronically or in otherwise accessible journals. The studies were then subdivided into clinical trials, animal trials and systematic reviews. Selected older reviews were also considered, although they were not strictly systematic.

Human trials

There was significant variation in the quality of the clinical trials with Jadad4 and PEDro5 scores ranging from 0–5 and 2–10, respectively (table 1). A summary of the key papers is given in table 2.

Table 1 Jadad and PEDro scores for clinical trials
Table 2 Summary of cryotherapy trials in human subjects

Clinical outcome measures focused primarily on function and, to a lesser extent, on pain and oedema. In general the study methods used were poor. Basur et al10 used neither randomisation nor blinding and Hocutt et al11 lost almost 40% of patients to follow-up. Two papers describe well conducted studies; the most recent was published in 2003 by Airaksinen et al9 and clearly demonstrates in 74 patients the benefits of a cold gel versus placebo in reducing pain at rest, pain with movement and functional disability. These results were statistically significant with p values <0.001. The principal author works in the Physical and Rehabilitation Centre of a university hospital and it is not stated if the patients presented here directly or through an emergency department. A disclosure statement acknowledges that neither the author nor institution benefited financially from the study.

The well-designed study by Sloan et al12 was conducted in a UK emergency department (1989). One hundred and forty-three patients had a single 30 min cryotherapy session using a cooling anklet applied by a physiotherapist. The results for 116 patients showed reduced soft tissue swelling (p = 0.07), reduced injury severity scores (p = 0.15) and a minimal improvement in weight bearing (p = 0.64) in the cold therapy group. Cryotherapy had no impact on range of movement or analgesia needs and, while these results are not statistically significant, the author comments that a study of more prolonged cooling warrants investigation.

The interpretation of the results by Coté et al8 and Laba and Roestenburg6 show inconsistencies with the conclusions drawn in table 2. Coté et al8 examined the absolute (rather than the percentage) change in ankle volume between their three study groups. This may be acceptable if the baseline volumes of each group are similar. However, no randomisation occurred and significant intragroup differences exist. If they had considered percentage change, then the results would favour heat therapy instead of cooling.8 Laba and Roestenburg6 surmise that there is no difference between the groups but later state that the rate of recovery is faster in the ice group (grade 4 sprains recover 2.9 days more quickly with ice). No statistical calculations were made. The study is fundamentally flawed as 13 of the 30 patients used ice at home before enrolment in the study.

Animal trials

There were four relevant animal studies (table 3). The primary outcome measure was oedema (volume,13 microcirculatory14 and histological changes7). Each study showed a reduction in soft tissue swelling with modest cooling (ice for 20 min,14 cold water 12.8–15.6°C,13 cooling to 30°C for 1 h15). McMaster15 shows that prolonged cooling and cooling to very low temperatures increases tissue damage.

Table 3 Summary of cryotherapy trials in animals

This suggestion is supported in a study of cryotherapy and bony injury by Matsen et al16 (not included in this systematic review as inclusion criteria were soft tissue injuries only). The tibial fractures induced by Matsen et al in rabbits were cooled for either 6 or 24 h with bags of water at 5–25°C. Prolonged subcutaneous swelling occurred in limbs cooled to 5–15°C for 24 h but significant swelling did not occur in limbs cooled to 10°C for 6 h or cooled to 20–25°C for 24 h. An inverse linear relationship exists between temperature and soft tissue oedema.

The major limitation of these animal studies is lack of observer blinding.

Systematic reviews

Two true systematic reviews were included (table 4). The 2004 study by Bleakley et al2 conducts a very broad and thorough review of the literature. Five clinical questions are posed and an attempt is made to draw a meaningful conclusion. Their efforts are limited by the broad inclusion criteria and this hampers any direct comparisons. Hubbard et al3 pose a very focused clinical question as to whether ice therapy hastens return to participation in normal activity. The conclusion drawn is that cryotherapy instituted soon after injury may be effective. The major limitation is that the search was limited to randomised controlled trials in humans and only four papers with weak methodologies were obtained.

Table 4 Systematic reviews

DISCUSSION

Soft tissue injuries form a significant proportion of the work load in the emergency department. Ankle sprains alone are estimated to comprise 3–5% of emergency department attendances or 5600 injuries per day in the UK.1 Ice therapy or cryotherapy is an accepted practice that is perceived by physicians to be cheap, safe and tolerable with only moderate inconvenience to patients. However, the animal studies above show a potential for cold-induced tissue damage with prolonged exposure and very cold temperatures, and there are occasional case reports of burns, nerve injury and frost bite.17 18 The evidence base for cryotherapy, like many other established therapies, is largely unquestioned.

While numerous papers on ice therapy exist, many are set in artificial scenarios (such as exercise-induced injury) which may not represent the cohort of trauma patients presenting to an emergency department. Other studies use surrogate outcome measures (commonly skin or muscle temperature) which do not necessarily correlate with patient-orientated outcomes that matter. This systematic review was designed to be relevant and applicable to patients presenting with acute trauma and to investigate patient-orientated outcomes.

Despite thorough searching, there is a paucity of evidence for such a well-accepted practice, and the evidence available is based on small patient numbers and some inherently weak trials. Only one clinical trial, involving 74 patients, showed a definite benefit of cold therapy in reducing pain and disability. The animal studies do show reduced oedema, but it is not yet known if that corresponds to faster clinical recovery.

Other systematic reviews on ice therapy have been performed. The review by MacAuley19 in 2001 examines the literature for the most effect icing method. That study, however, used skin temperature as a measure of effect and not any of the outcome measures defined by this study.

Two other thorough but not truly systematic reviews are notable. Meeusen and Lievens20 provide a comprehensive review of many animal and human trials and conclude that the effect of cryotherapy, while useful, is probably confounded by other co-existing first aid measures. Cold therapy may reduce pain and can both increase and decrease inflammation. An interesting older study by Olson and Stravino21 in 1972 predates the concept of systematic reviews. Only papers where “systematic study has been pursued” were reviewed. The appraisal had four aims, the second of which was to review the literature and the third to examine the benefits and limitations of cold therapy. Several studies from the 1950s and 1960s are quoted, and the authors conclude that the numbers involved in the studies are too low to allow meaningful analysis and that comparison of techniques is difficult. They conclude that physiological and clinical studies suggest that cold therapy can be valuable in decreasing haemorrhage and oedema in acute injuries and providing analgesia for acute muscle spasm.

Now, over 30 years later, many of these same issues exist in assessing this clinical question; well conducted trials are few, patient numbers are low and direct comparison between studies is not without difficulty.

CONCLUSIONS

This systematic review concludes that cryotherapy may have a possible benefit in the treatment of acute soft tissue injury if it is instituted soon after the injury and care is taken to limit exposure time and to induce only modest cooling, otherwise harm may ensue. The volume and quality of data available for such a prevalent clinical condition, however, are inadequate, and it begets the question “If cryotherapy was a pharmacological therapy, is there an evidence base to support its use?”

Acknowledgments

I would like to thank my colleagues in the emergency department for their support and direction, with particular thanks to the library staff of HSE West Library, University Hospital Galway.

REFERENCES

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Footnotes

  • Competing interests: None declared.

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