A Double Blind, Randomised Controlled Trial of High Volume Saline Injections for Chronic Midportion Achilles Tendinopathy

Hypothesis: High volume saline injections are an effective pain relieving treatment for people with longstanding pain in the achilles tendon which has not improved with a physiotherapy programme.

Objective 1: To establish whether high volume saline injections are an effective treatment in decreasing pain for people with achilles tendinopathy

Objective 2: To investigate whether high volume saline injections can improve day to day functioning, quality of life and the ultrasound appearances of the tendon for people with achilles tendinopathy

Objective 3: To assess the tolerability of the procedure and levels of patient satisfaction using a simple questionnaire.

Objective 4: To follow up the cohort of people who have received the injection for 9 months and ascertain whether any benefits persisted, or if the symptoms recurred.

Background: Achilles tendon disorders are a common problem for athletes with a lifetime risk of around 50%. They are also common for less active people with a lifetime risk of around 6%.

Tendinopathy is a condition which is characterised by pain, difficulty with weight bearing and swelling of the tendon. Symptoms may occur with exercise at first but can progress to occurring at rest and interfering with day to day activities. When the problematic tendon is examined under the microscope, it usually shows signs of degeneration rather than inflammation - especially when symptoms have been persistent. An ultrasound scan will usually show that the tendon is swollen with an increased water content and a disorganised tendon structure.

A special type of ultrasound scan which looks at fluid flows, called a doppler ultrasound, often shows areas of increased blood flow around the tendon. Studies have shown that when these areas of increased blood flow are present, the patient tends to be experiencing more pain and stiffness in the tendon. Under the microscope, these blood vessels are often accompanied by nerve fibres and it has been suggested that these newly growing nerve endings are responsible for the persistent pain that patients experience.

There is robust evidence that a particular type of exercise programme (eccentric loading) is an effective treatment for achilles tendinopathy. These exercises involve taking weight on the tendon whilst it is being compressed rather than stretched - heel lowering exercises. Nevertheless after completing a 3 month eccentric loading exercise programme, around 24-45% of patients will still have symptoms. There is no clear consensus amongst doctors as to what is the best second line treatment to try for this group of people.

A number of different treatments have been described in research literature to try to treat this group of people with persistent symptoms, although no firm conclusion can be reached. There have been 2 small trials of high volume saline injections which showed some promising potential for the treatment. The aim of this injection is to destroy the blood vessels and nerve endings that grow into the swollen tendon to reduce pain and allow people to move and exercise more normally using the tendon. These studies simply looked at before and after injection results and did not compare the injections to a placebo or other treatment. The aim of this project is to conduct a high quality comparison of this new type of injection against a more common steroid and local anaesthetic injection around the tendon sheath. The design of the trial is a double blind, randomised controlled trial. This means that neither the patient, nor the doctor collecting data on pain scores knows which treatment the participant has been given, allowing a fair comparison of the interventions.

The main comparisons between the 2 groups will take place at a 6 week follow up appointment. Once outcome measures have been recorded by the blinded assessor, the participant will then be told which arm of the study they are on. If they previously received the control injection (steroid and local anaesthetic only)and they still have symptoms, they will at this stage be offered the high volume saline injection as well. The investigators will then follow all of the study participants up for 9 months to ascertain whether people show a persistent benefit from the treatment, or whether symptoms subsequently return.

The full study protocol is available on request from the Principle Investigator, along with information leaflets, ethical approvals etc.