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The role of arthroscopic subacromial decompression in the treatment of subacromial shoulder pain (impingement).

Csaw publication in the lancet

The results of an important surgical trial led by Professor Andrew Carr and Professor David Beard have just been published in The Lancet. This study has been conducted by the CSAW study group and SITU with the support of The British Elbow and Shoulder Society (BESS). 

The study aimed to evaluate a common shoulder operation performed in the UK, arthroscopic subacromial decompression, which has been increasingly undertaken for a specific type of shoulder pain and disability because of its perceived benefits.  The surgery involves removing a spur of bone and associated soft tissue with the aim of preventing rubbing, or impingement, of shoulder tissues during arm movement. The effectiveness of the operation has remained somewhat uncertain and it has never been critically evaluated in a full randomised controlled trial.

The study involved 313 patients suffering persistent pain and symptoms for at least three months who had not responded to physiotherapy and steroid injection. It was conducted by 51 surgeons in 32 hospitals in the UK. Patients were randomised to receive one of three different treatment strategies, which were:

  1. Arthroscopic subacromial decompression surgery (removal of bone spur and soft tissue),
  2. Arthroscopy only without decompression (placebo surgery), or
  3. No surgery (observation and reassessment only). 

At both six months and one year follow up it was found that decompression surgery offered no greater benefit to arthroscopy only (placebo surgery). The group who did not receive surgery also improved over time such that patients undergoing surgery were only slightly more improved than those not undergoing surgery. Importantly, this small difference in improvement was not believed to be clinically significant. Patients and surgeons need to be made more aware of the limitations of this type of surgery for the treatment of subacromial shoulder pain and that improvement can occur without the need for surgery. Patients should consider carefully the potential benefits and risks of surgery during the shared decision making process.

As a consequence of the trial findings BESS and the British Orthopaedic Association are planning to update the NICE national guidelines for the treatment of subacromial pain, which are likely to result in a change of practice. It remains possible that a sub-group of patients with specific characteristics may still improve with decompression surgery but further trials will be required to investigate this. These results do not in any way support denying patients who have different shoulder conditions or other types of shoulder surgery when non-operative measures have failed.

This study was carried out by a large team of BESS surgeons and physiotherapists, trial managers, trial co-ordinators and statisticians in the UK, led from the University of Oxford and supported by the Centre for Statistics in Medicine. It has greatly benefited from the strong support of BESS who have a reputation for delivering ground breaking and internationally recognised clinical trials. Undertaking well designed studies that provide high quality evidence for the effectiveness of surgery is critical to providing the best patient care for the future.

Natalie Carter, head of research liaison and evaluation at Arthritis Research UK comments:

 “Painful shoulders account for 2.4% of all GP consultations in the UK, and can make it difficult to work, drive or get dressed. Many people with shoulder pain are treated with, and will respond to, non-operative treatment alone, however surgery is often used as a treatment. In 2010, over 21,000 people had this type of surgery in England – an increase of nearly 750% in 10 years.

This study suggests that other treatments such as physiotherapy can be just as effective as shoulder surgery, and should be taken into consideration with patients considering surgery and could influence the decisions made by health providers.

Often shoulder pain can be short-lived, but if you’re experiencing shoulder pain which continues for more than two weeks, or gets worse, speak to your doctor or a physiotherapist in case you have a more complex problem.”


This study was funded by Arthritis Research UK, the National Institute for Health Research (NIHR) and the Royal College of Surgeons. It was conducted by researchers from the NIHR Biomedical Research Centres at the University of Oxford and University of Bristol.

The NIHR Oxford Biomedical Research Centre is based at the Oxford University Hospitals NHS Foundation Trust and run in partnership with the University of Oxford, funded by the NIHR.

The NIHR improves the health and wealth of the nation through research. Established by the Department of Health, the NIHR:

  • funds high quality research to improve health
  • trains and supports health researchers
  • provides world-class research facilities
  • works with the life sciences industry and charities to benefit all
  • involves patients and the public at every step

For further information, visit the NIHR website www.nihr.ac.uk.