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The Spinal Fusion Indications and Outcomes Randomised Trial (SpInOuT)


As people age, there is increasing wear on the bones (vertebrae) in the spine. The spine responds by producing extra bone in some areas, changing its shape in others and sometimes with one vertebra slipping on another. All these changes can narrow the normal spaces where the nerves pass from the spinal cord. When the nerves get pressed, back and leg pain occurs with substantial interference on daily life and on mental and physical well-being. When severe, surgery may be necessary to relieve that pressure.

This is now the most common spinal disorder requiring surgery. 18,000 operations are performed each year in the NHS. Surgery can involve removing the bone that presses on the nerves. Or it could involve, in addition, the insertion of screws and rods (called an instrumented fusion) to make the spine straighter and stronger to achieve long term benefit. There is no agreement between surgeons as to which is better. The instrumented fusion operations are more complex and take into consideration the varying affect on individual patient spines. Unfortunately, there is very limited evidence for patients and surgeons to make an informed choice.

Ultimately a research study called a randomised trial is needed to inform this decision but such a trial will not be easy to conduct.


This proposal outlines a pilot trial which will assess critical aspects of conducting the study to determine if running the larger trial will be practicable. The key issues are:

  1. Whether patients and surgeons are willing to participate in such a trial
  2. Rates of patient recruitment and completion of questionnaires
  3. Which outcomes matter most to patients

The pilot trial will be undertaken across five NHS hospitals in the UK over 21 months.

trial publications

The primary publication can be found here.

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Selected publications

Related research themes