Lead investigator Associate Professor Peter Malliaras outlines his team’s study examining the efficacy of tendon sheath injection for Achilles tendinopathy, and invites you to become involved.

Achilles tendinopathy is a common, painful and disabling musculoskeletal condition characterised by local tissue pathology, swelling, and activity-related pain. The cumulative lifetime prevalence of Achilles tendinopathy in the general population has been reported to be six per cent, meaning that approximately 1.5 million Australians have, or will suffer from, Achilles tendinopathy. Therefore, Achilles tendinopathy is a major healthcare issue as it severely reduces physical capacity, including walking and running. More and more Australians are likely to be affected by Achilles tendinopathy given our ageing population and increasingly popular physical activity campaigns targeting inactive and/or metabolically ill people (ie, people with risk factors for Achilles tendinopathy).

Progressively loaded exercise is recommended as a first line treatment for Achilles tendinopathy; however, there are reports that 44 per cent, or even as high as 75 per cent, of people may not respond to the recommended evidence-based exercise treatments. Further, 60 per cent of people with Achilles tendinopathy are reported to have continued pain and disability after five years despite exercise interventions, and 48 per cent sought additional treatment including injections and surgery. These figures highlight the significant health costs associated with managing Achilles tendinopathy.

It is estimated that hundreds of thousands of Australians fail exercise treatments for Achilles tendinopathy and resort to injection options, as recommended by clinical practice guidelines. Despite this, there are currently no injection treatments with demonstrated long-term efficacy.

Steroid injections demonstrate short-term efficacy in improving tendinopathy pain and function with high chances of recurrence in the longer term. Other injections in clinical use for Achilles tendinopathy, including polidocanol, aprotinin, and platelet-rich plasma injections, have been shown to be no more effective than placebo or no injection.

The tendon sheath injection is a promising new treatment option

A relatively new injection used to manage Achilles tendinopathy is the tendon sheath injection (TSI). The TSI involves 10 mL of local anaesthetic, 25 mg of steroid and 40 mL of saline (total of 50 mL of fluid). The large fluid volume is injected in the interface between Kager’s fat and the Achilles tendon, causing a mechanical separation of these tissues. It is hypothesised that the TSI disrupts neurovascular in-growth from Kager’s fat to the Achilles tendon, which is thought to be a source of pain in Achilles tendinopathy.

The current project builds directly on two double-blind randomised controlled trials conducted by myself and collaborators, which were published in the American Journal of Sports Medicine and the Scandinavian Journal of Medicine & Science in Sports. These trials examined the efficacy of TSI with steroid versus sham, and TSI with steroid versus TSI without steroid over a six-month follow-up in treating Achilles tendinopathy. There is now a need for a high-quality randomised controlled trial examining the long-term efficacy and safety of the TSI with and without steroid compared to sham in Achilles tendinopathy.

Aims

Our research team at Monash University led by myself, in collaboration with researchers from La Trobe University and international researchers from the UK and USA, have secured a $600,000 National Health and Medical Research Council Project Grant (2019–2021), to examine the efficacy of TSI with steroid, and TSI without steroid versus sham injection, to improve pain and function among individuals with Achilles tendinopathy over 12 months. We hypothesise that TSI with steroid and TSI without steroid will lead to superior Victorian Institute of Sport Assessment-Achilles (VISA-A) outcome compared to sham injection at 12 months.

Study design

Our three-arm, parallel group, double-blind, randomised controlled trial will recruit 192 adults, aged over 18 years with more than three months of pain in the mid-portion Achilles area and confirmed diagnosis of mid-portion Achilles tendinopathy with an ultrasound scan. Eligible people need to have already trialled some form of treatment for their Achilles problem (eg, consulted a physiotherapist or doctor). The trial will be based at a large radiology clinic in central Melbourne, Imaging at Olympic Park (IOP). Participants receive $200 travel and time reimbursement in exchange for participation.

Participants will be randomised into sham injection, TSI with steroid or TSI without steroid, groups. All injections will be prepared and delivered by a radiology nurse and experienced musculoskeletal radiologist  under ultrasound imaging. Post-injection, all participants will receive an identical 12-week evidence-based exercise intervention. This includes an evidence-based and progressively loaded exercise protocol for Achilles tendinopathy, education about physical activity modification  and resumption, and advice about progressing and regressing exercise load, based on a pain-monitoring model. Participants will be reviewed by the researchers at IOP at two, six and 12 weeks to modify the exercise as required (eg, progress load, modify technique), and at 12 weeks to provide evidence-based advice about continuing exercise beyond the intervention period. The primary outcome will be pain and function assessed using the VISA-A score at 12 months.

Secondary outcomes include changes in Achilles tendon thickness and vascularity, overall pain intensity, maximum voluntary isometric contraction and rate of force development of the plantarflexor muscles, health-related quality of life and cost-effectiveness of the TSI injections.

Outcomes and significance

If the TSI demonstrates efficacy compared to sham it can be used as a potential option in the future among people with Achilles tendinopathy who do not respond to recommended exercise and advice. Having an evidence-based injection option will ultimately reduce the significant and long-standing pain and disability, as well as costs associated with managing Achilles tendinopathy. Improvement in long-term patient outcomes will enable greater participation in physical, work and social activities, which is integral to healthy ageing.

GET INVOLVED

Recruitment for this clinical trial is now underway. If you or your clinic would like to refer patients to the trial, contact Associate Professor Peter Malliaras at peter.malliaras@monash.edu.au.

Peter Malliaras is an APA Sports and Exercise Physiotherapist who, in 2006, completed his PhD in tendinopathy, identifying novel risk factors. Currently an associate professor at Monash University Physiotherapy Department, he has co- authored more than 100 peer-review publications and is involved in multiple funded tendinopathy research projects in Australia and internationally.