Chronic Achilles tendinopathy is a prevalent overuse injury, affecting a significant portion of active individuals. The incidence rate stands at approximately 2-3 cases per 1,000 registered adult patients, with the majority of cases (74%) involving midportion Achilles tendinopathy. Athletes, particularly runners, face the highest risk, with an estimated lifetime incidence of 52%.

The exact cause of Achilles tendinopathy remains complex and multifactorial. Repetitive mechanical loading is considered the primary contributor to tendon degeneration. Factors such as age, sex, body mass index (BMI), and foot biomechanics also play a role in the development of the condition. Poor training techniques, inadequate footwear, and sudden increases in activity levels further elevate the risk of Achilles tendon injuries.

Initial treatment strategies indicate exercise and load management as primary approaches to alleviate symptoms and promote recovery. However, the long-term prognosis remains a challenge for many affected individuals.

Long-Term Outcomes of Achilles Tendinopathy

Despite adherence to treatment protocols, the persistence of symptoms remains a concern. Studies indicate that two-thirds of patients continue to experience symptoms one year after diagnosis, highlighting the chronic nature of the condition. Even after a decade, approximately one-quarter of affected individuals report ongoing discomfort.

For those who do not respond to conservative management, surgical intervention becomes necessary. Nearly one-third of patients who fail to find relief through non-surgical methods eventually undergo operative procedures to address the condition. The surgical approaches typically involve tendon debridement, repair, or augmentation techniques to restore tendon structure and function. While surgery has been beneficial for some patients, it carries risks such as prolonged recovery time, potential complications, and inconsistent long-term success rates.

Neovascularisation and Pain Mechanism

A key pathological feature of chronic Achilles tendinopathy is neovascularisation, the formation of new blood vessels within the tendon. This phenomenon is observed in 50-100% of symptomatic patients through Doppler ultrasonography. Alongside neovascularisation, nerve infiltration is also believed to contribute to the persistence of pain.

Research suggests a correlation between increased ultrasonographic Doppler flow and symptom severity. These findings highlight the complex nature of pain mechanisms in Achilles tendinopathy and have led to investigations into targeted treatments aimed at reducing neovascularisation. The presence of excessive neovascularisation may create an environment where pain-generating nerve fibres proliferate, leading to chronic discomfort and impaired function.

High Volume Injections

High volume injections have emerged as a treatment strategy aimed at eliminating neovascularisation by applying mechanical pressure through an injected fluid. However, controversy surrounds the inclusion of corticosteroids in the injection mixture. Research indicates that corticosteroids improve short-term outcomes (6-12 weeks), but their benefits do not extend to intermediate-term effects.

The principle behind high volume injections is to disrupt pathological blood vessels and associated nerve ingrowth, potentially reducing pain and restoring tendon function. The procedure typically involves injecting a saline and local anaesthetic solution under ultrasound guidance to ensure precise delivery. The effectiveness of high-volume injections remains debated, with mixed evidence regarding their long-term benefits.

Clinical Evidence on High Volume Injections

Several cohort studies and a small randomised controlled trial (RCT) have suggested that high volume injections can lead to short-term pain reduction and functional improvement. A recent blinded RCT, involving 19 participants per group, demonstrated significant symptom improvement at six weeks, though these benefits diminished by 24 weeks. These findings have contributed to the increasing clinical adoption of high-volume injections.

While initial studies showed promise, there remains uncertainty about the long-term effects of high-volume injections. Some patients report transient relief, but others experience a return of symptoms, indicating that the procedure may not address the underlying degenerative changes within the tendon. Further research is required to determine whether high volume injections provide sustained functional improvements or merely offer temporary symptom relief.

Findings from the Recent Large Study

A larger study recently compared high volume injection (without corticosteroids) combined with exercise against a placebo injection combined with exercise over 24 weeks. The results showed no significant differences in pain relief and functional outcomes between the two groups. Furthermore, there was no clear evidence of mechanistic effects from high volume injections alone.

These findings suggest that previously observed short-term benefits of high-volume injections may have been attributable to corticosteroids rather than the injection procedure itself. The study also reinforces concerns about the potential long-term detrimental effects of corticosteroids on tendon health. Given the known risks of corticosteroid-induced tendon weakening and rupture, clinicians must weigh the benefits against potential complications when considering injection-based therapies.

Clinical Implications

The growing popularity of high-volume injections as a treatment for Achilles tendinopathy is challenged by these findings. Instead, exercise, patient education, and load management remain the foundation of effective treatment. The evidence continues to support an importance on exercise-based rehabilitation over injection-based interventions.

Exercise therapy, particularly eccentric strengthening programs, has shown strong evidence in improving tendon structure and function. Eccentric exercises involve controlled lengthening of the tendon under load, promoting collagen remodelling and enhancing tendon resilience. Combining structured rehabilitation with biomechanical assessments, footwear modifications, and activity adjustments can improve long-term outcomes.

Future research is needed to explore alternative conservative treatment options, focusing on long-term symptom relief and functional recovery without potential risks associated with corticosteroids or invasive procedures. Platelet-rich plasma (PRP) injections, shockwave therapy, and novel biologic therapies are emerging areas of interest, with ongoing studies investigating their efficacy in Achilles tendinopathy management.

Strengths and Limitations

The study was conducted according to CONSORT guidelines, ensuring rigorous methodology. It also incorporated blinded patients, assessors, and statisticians, with only one participant lost to follow-up, strengthening the reliability of the results.

However, certain limitations must be acknowledged. The doctor performing the injections was not blinded, though they were not involved in data analysis. Additionally, the study lacked a control group receiving exercise therapy alone, making it difficult to isolate the specific effects of injections. Potential confounding factors, such as placebo effects, promoted healing responses, and natural disease progression, could have influenced outcomes. Furthermore, high volume injections require technical expertise, making their general application in clinical settings more challenging.

Future studies should aim to include larger sample sizes, longer follow-up periods, and robust control groups to better understand the role of high-volume injections in Achilles tendinopathy management. Comparative trials evaluating different conservative treatment modalities can help identify the most effective non-invasive interventions.

Conclusion

The latest findings question the efficacy of high-volume injections as a reliable treatment for Achilles tendinopathy, reinforcing the importance of exercise-based rehabilitation. While short-term improvements may be observed, particularly with corticosteroid use, the long-term benefits remain uncertain. Considering the chronic nature of the condition, clinicians should prioritise evidence-based rehabilitation strategies, including structured exercise programs and patient education, to optimise recovery outcomes.

As research continues to progress, the focus should shift toward innovative conservative therapies that address the underlying pathology of Achilles tendinopathy. Understanding the mechanisms driving tendon degeneration and pain will be essential in developing targeted treatments that provide lasting relief and functional improvement. The current evidence highlights the need for a cautious approach to injection-based interventions while advocating for rehabilitation as the foundation of Achilles tendinopathy management.

Reference

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