Description of the condition
The Achilles tendon is the thickest and strongest tendon in the human body. It attaches the powerful calf muscles (gastrocnemius and soleus) to the heel bone (calcaneus). Rupture of the Achilles tendon is one of the most common tendon injuries in the adult population, with an estimated mean annual incidence ranging from 5.5 to 9.9 ruptures per 100,000 people in Canada (Suchak 2005), and values in Europe ranging from 6 ruptures per 100,000 people in Scotland (Maffulli 1999a) to 18 ruptures per 100,000 people in Finland (Leppilahti 1996). Most acute ruptures occur in people in their thirties or forties during sports activities; however, a smaller peak incidence in older non-athletic people should not be overlooked (Maffulli 1999a). The incidence of this injury is increasing, possibly as a result of the continuing participation in recreational sports activities in later life by the ageing population (Jozsa 1989; Nandra 2012).
The aetiology of spontaneous rupture of the Achilles tendon is not yet fully understood. It is generally considered that primary abnormalities have been present before the ruptures occur (Arner 1959; Maffulli 2000). Multiple causative factors such as tendon degeneration and collagen alteration (Jarvinen 1997), a reduction in blood supply to the midportion of the tendon (Ahmed 1998), conditions comorbid with systemic diseases (Leppilahti 1998), previous administration of steroids or fluoroquinolone antibiotics (Maffulli 1999b; Tsai 2011) and exercise-induced hyperthermia (Wilson 1994) may predispose the Achilles tendon to spontaneous rupture from microtrauma.
Acute Achilles tendon rupture is a debilitating injury, often resulting in prolonged disability and rehabilitation (Willits 2010). Providing patients with a prompt and accurate diagnosis and appropriate treatment is essential to avoid permanent disability and loss of function. A detailed history and physical examination (presence of a palpable gap, decreased ankle plantar flexion strength, and positive Thompson test or other physical tests) is generally sufficient for establishing a clinical diagnosis of acute Achilles tendon rupture (Maffulli 1998). In addition, ultrasonography and magnetic resonance imaging (MRI) can be helpful in some cases (Nandra 2012).
Description of the intervention
Primary treatment of acute Achilles tendon ruptures can be either conservative, generally involving full or partial immobilisation of the ankle, or surgical, generally involving the operative repair of the ruptured tendon. Although surgery tends to have a lower risk of re-rupture compared with non-surgical (conservative) treatment, the risk of infection and other complications are significantly higher (Bhandari 2002; Khan 2010; Lo 1997; Lynch 2004). Currently, conservative treatment is an option for all patients, including those declining surgery, and those for whom an operation or anaesthesia is contraindicated because of impaired healing potential (Maffulli 1999b; Willits 2010). Traditionally, conservatively treated patients usually wear a below-knee cast in equinus for four weeks without weight-bearing, followed by a second cast with the foot in neutral position allowing weight-bearing for another four weeks (Cetti 1993). Differences may exist in terms of the casting materials and techniques used (e.g. use of a heel raise), the duration of immobilisation, the duration of non-weight-bearing and the rehabilitation protocol. More recently, a combination of cast immobilisation and functional bracing (which allows immediate weight-bearing and active plantar flexion but restricts dorsiflexion of the ankle (McComis 1997)), or immediate functional bracing alone, have been introduced to minimise the complications associated with a long period of immobilisation, such as joint stiffness and muscle atrophy (Khan 2010; McComis 1997; Saleh 1992).
Similarly, conservative management after surgical repair of the ruptured Achilles tendon usually entails full or partial immobilisation. The postoperative rehabilitation protocol after surgery has evolved from using rigid immobilisation in a below-knee cast without weight-bearing for four to nine weeks (Cetti 1994) to an early functional protocol involving immediate mobilisation with early weight-bearing using functional bracing (a walking boot or modified orthosis) instead of a cast (Costa 2006; Kangas 2003; Suchak 2008). Physiotherapy for people with acute rupture of the Achilles tendon currently comprises a combination of different individual components of a specific rehabilitation regimen involving the type of cast or orthosis used, the degree of plantar flexion of the ankle, the timing of removal of the orthosis and the implementation of daily range of motion exercises, which have all been identified as variables to be evaluated in further research (Kearney 2012).
How the intervention might work
Conservative treatment, which initially immobilises the patient in a below-knee cast with non-weight-bearing in equinus, can reduce iatrogenic damage to normal tissue and protect the blood supply to the injured tendon, thus facilitating healing. However, prolonged immobilisation in a plaster cast may lead to a series of complications including joint stiffness, calf muscle atrophy, tendocutaneous adhesion and deep venous thrombosis (Mortensen 1999; Saleh 1992). Casting, which has also been the standard postoperative regimen after repair of a ruptured Achilles tendon, can make rehabilitation after surgery more difficult (Kangas 2003). With the merits of avoiding the risks of immobilisation, reducing rehabilitation time, and facilitating an early return to work and sporting activity, functional bracing has been promoted as a viable alternative to the use of a plaster cast (McComis 1997). Experimental studies have demonstrated that early loading of the ruptured tendon leads to benefits in improved tendon characteristics and decreased muscle atrophy (Kjaer 2005; Rantanen 1999). Additionally, some comparative clinical studies have suggested that appropriately implemented functional bracing combined with a rehabilitation protocol that allows early mobilisation and weight-bearing gives comparable results in terms of re-rupture and functional outcomes to those found for surgical repair (Costa 2006; Metz 2008; Twaddle 2007); however, concerns still remain about increased discomfort and pain while the patient walks, and an increased re-rupture rate from damage to the healing tendon caused by early loading of the tendon (Khan 2010 ; Suchak 2008).
Why it is important to do this review
There is no consensus regarding either the optimal primary conservative management of acute Achilles tendon ruptures or optimal management after surgery. Traditionally, plaster cast with prolonged immobilisation has been the standard treatment in both situations. However, the need for prolonged rigid immobilisation has been questioned, especially as satisfactory results have been reported for early mobilisation involving functional bracing. This points to the need to systematically appraise the current evidence of the effects and harms of different conservative interventions for treating acute Achilles tendon ruptures.