Achilles tendinopathy is a common overuse condition affecting the adult population. The incidence is on the rise because of greater participation of people in recreational or competitive sports [2]. The general population has an incidence of 2.35 per 1000 people, which is roughly equivalent to more than 150,000 people in the United Kingdom every year [4]. It is a clinical triad of pain, impaired performance and swelling [5]. The main stimulus to cause tendinopathy is excessive repetitive overload; however, about one-third of the studied group did not participate in the vigorous physical activities [6]. During running, forces up to 12.5 times body weight passes through the Achilles tendon which may contribute to tendinopathy [7].

Tendinopathies have been linked to poor vascularity, poor flexibility, genetic make-up, endocrine and metabolic factors [2]. Use of quinolone antibiotic has also been linked [8]. The pathological stimulus is excessive loading of the tendon during physical activity. Various intrinsic factors include poor vascularity, dysfunction of the gastrocnemius-soleus, age, gender, body weight, pes cavus and lateral instability of the ankle [2]. Changes in training pattern, poor technique, previous injuries, footwear and environmental factors such as training on hard, slippery or slanting surfaces are extrinsic factors [2]. The term “tendinopathy” is a description of a clinical condition which includes both pain and pathological process associated with overuse in and around the tendon. “Tendinosis” and “tendonitis” are histopathological descriptive terms and should ideally be used after the histopathological confirmation [9]. The pathological process of Achilles tendinopathy is considered to be a degenerative rather than inflammatory [10].

It is categorised into two types, insertional or non-insertional. Insertional type is less common and affects 20–25% of cases [11]. The predisposing factors for insertional type include increasing age, inflammatory arthropathies, corticosteroid use, diabetes, hypertension, obesity, gout, hyperostotic conditions, lipidaemias and quinolone antibiotics [12]. Symptoms are more proximal in the non-insertional type [13]. It accounts for 70–75% cases presenting, and it affects 9% of recreational runners. It can end the careers of 5% of professional runners [5].

Dry needling involves repeated needling in the abnormal tendon to promote an inflammatory response. Repeated passage of the needle produces physical trauma to the tendon which in turn causes internal haemorrhage leading to an inflammatory response which causes the formation of granulation tissue. This granulation tissue strengthens the tendon [15]. The local anaesthetic is injected around the area before performing the dry needling. There have been early reports of good results of ultrasound-guided needle tenotomy with corticosteroid injection for the treatment of common extensor tendons [16]. Jeffrey et al. evaluated the safety and short-term effectiveness of ultrasound-guided needle tenotomy in other tendons without the use of corticosteroids, because of the fear of tendon rupture [17]. Their study included 14 tendons, but only 4 of them were Achilles tendons.

High-volume image-guided injection (HVIGI) consists of normal saline, local anaesthetic and corticosteroids. It tends to improve amount of pain and improve function in patients suffering with Achilles tendinopathy [20]. The procedure is described as using an aseptic technique, a 21-gauge needle is inserted under real-time ultrasound guidance between the anterior aspect of the Achilles tendon and Kager’s fat pad, targeting the area of maximal neovascularisation. Then a mixture of 10 mL 0.5% bupivacaine hydrochloride and 25 mg of hydrocortisone acetate is injected, followed by 4 × 10 mL of injectable normal saline [20, 21, 22]. Some authors have described using more volume and without adding corticosteroids [23].

There are few closely related procedures that are used for this condition. Sclerotherapy is a procedure that involves injecting a chemical into a blood vessel. The theory behind its use is to sclerose the vessels and eradicate the pain generating nerve fibres [2]. Autologous blood injection involves reinjection of patients own blood. The proposed mechanism of action of this is that the cytokines and growth factors within the injected blood help to stimulate tissue healing and production of type 1 collagen, promoting tendon repair [18].

The aim of this literature review was to find out the evidence for the use of high-volume injections in the treatment of chronic mid-substance Achilles tendinopathy.