Here's a further look at Achilles tendinitis, this time from a clinical point of view
Physiologist Owen Anderson wrote about the prevention of Achilles tendinitis in issue 5 of SIB. Here two surgeons describe the current methods of treating Achilles problems
'Achilles tendinitis' is a loose term which in the clinical setting is used to describe the pain, swelling and tenderness usually experienced in the relatively hypovascular area (poor blood supply) 2 to 6cm above the insertion of the tendon into the calcaneus (heel bone).
The terminology in Achilles tendon injuries can be confusing and perhaps all overuse injuries arising in tendons should be termed 'tendinopathies' rather than 'tendinitis', which suggests that the fundamental problem is inflammatory.
It is believed that two-thirds of Achilles tendon injuries in competitive athletes are paratenonitis (inflammation of the paratenon only) and one-fifth are insertional complaints (bursitis and insertional tendinitis). The remaining afflictions consist of pain syndromes of the myotendinous junction and tendinopathies(1).
When the term 'tendinitis' is used in a clinical context, it does not refer to a specific histopathological entity but rather to a group of conditions that are truly 'tendinoses' (tendon degeneration without associated inflammation). This may lead athletes and their coaches to underestimate the chronic nature of the condition(2).
The aetiology remains unclear. Excessive repetitive overload of the Achilles tendon is regarded as the primary stimulus resulting in tendinopathy. In one study, however, 31% of 58 patients with tendinopathies did not participate in vigorous physical exercise(3).
Believed causes of acute Achilles tendinitis include:
(a) inflexibility of the Achilles tendon
(b) insufficient gastrosoleus strength or flexibility
(c) functional over-pronation, producing a whipping action on the Achilles tendon as the heel goes from varus on heel strike to valgus in midstance(4)
(d) number of years running, training pace, stretching habits(5)
(e) recent change in shoe wear and poor running shoes
(f) recent increase in training especially if it includes hill running
(g) eccentric loading of a fatigued muscle-tendon unit from overtraining or running on uneven terrain.
Chronic Achilles tendinosis is a condition of unknown aetiology. It is most commonly seen in male recreational runners aged between 35 and 45 and although believed to be due to overuse, is again also seen in patients with sedentary lifestyles. Pain is often but not always experienced when the Achilles tendon is loaded(6).
The patient may admit to a history of a change in training habits, and complain of localised pain and tenderness over the distal Achilles tendon. The pain is best experienced during the push-off phase of running or jumping. Runners experience pain at the beginning and at the end of a training session with a period of diminished discomfort in between(7).
On examination, there may be localised swelling, a tight Achilles tendon, and heel alignment may be abnormal.
The investigations of choice to confirm and evaluate Achilles tendinopathy are MRI and ultrasound. There is a significant overlap of MRI findings in symptomatic and asymptomatic Achilles tendons(8). However, ultrasound - undertaken by a specialist musculoskeletal radiologist - has been recently shown to provide information that accurately diagnoses clinical Achilles tendinopathy and may help to determine the biomechanical processes involved in the injury(9).
In the acute phase the following non-operative measures are employed:
(a) relative rest (avoiding painful aggravating activities)
(c) non steroidal anti-inflammatory analgesia (local gels and tablets)
(d) customised orthoses and heel lifts (12 to 15mm) to alleviate overpronation caused by tibia varum or subtalar or forefoot varus. Heel lifts are commonly used, especially in runners, with success in up to 75%(10)
(e)stretching by pulling, holding and releasing the gastrocnemius-soleus complex using a wall, stair, or 201Â³4 inclined board (11)
(g) cryotherapy for its analgesic effect
(h) therapeutic ultrasound may reduce swelling in the acute inflammatory phase.
If symptoms are severe and unresponsive to the conservative measures above, a short period (maximum three weeks) of cast immobilisation may be necessary.
Patients with chronic problems are initially treated as for acute injuries, although some researchers suggest that this may be time-consuming and unsatisfactory (12).
It has been generally accepted that if a patient has symptoms persisting for at least six months that interfere with work or athletics, and if he/she has been engaged in a defined physical therapy programme, then surgery may be offered.
The Achilles tendon should be explored, partial tears surgically debrided and remaining tissue repaired. Thickened paratenon should be incised or excised(13). Any bony calcaneal prominence should be excised. Satisfactory results have been reported in approximately two-thirds of patients(14,15). However, a recent study has critically reviewed the outcome of surgery for chronic Achilles tendinopathy stated in 26 publications(16). It suggests that the study methods employed in these publications influenced the reported surgical outcome. The true result of surgery for Achilles tendinopathy is therefore unknown. Surgery must only be contemplated when the surgeon is satisfied that there is an absolute indication for it, and that all the appropriate non-operative measures have been attempted by the correct personnel.
It is not known whether open surgery induces revascularisation, denervation or both, resulting in reduction of pain. Multiple percutaneous longitudinal tenotomies (keyhole partial cuts in the tendon in order to allow it to lengthen) can be performed instead of open procedures with comparable outcome(17). This relatively simple procedure should be reserved for patients who have isolated tendinopathies less than 2.5cm long that have been confirmed by ultrasound and where the paratenon is not involved. Such tenotomies have recently been shown to increase the blood supply to the degenerated area in a rabbit model(18).
Rehabilitation post surgery may be prolonged. It has been reported that six months of postoperative rehabilitation for chronic Achilles tendinitis is not enough to recover concentric and eccentric plantar flexion muscle strength compared with the non-injured side(19). Furthermore, progressive calcaneal bone loss has been shown on the operated side one year after surgery(6).
The use of local corticosteroid injections for the treatment of Achilles tendinitis is controversial as many case reports have implicated them as the cause of subsequent Achilles tendon rupture. The theory is that corticosteroid decreases the metabolic rate of chondrocytes and fibrocytes resulting in a weakening of the structural integrity tendon and articular cartilage. There are no published rigorous studies that evaluate the risk of rupture with or without corticosteroid injection, and the data published is insufficient to determine the comparative risks and benefits(10). Taking all this information into account, however, it is best to avoid the use of corticosteroid injections in the treatment of Achilles tendinitis.
Promising short-term results from a prospective multicentre study have been recently published(20). Chronic Achilles tendinosis was shown to respond well to heavy-load eccentric calf muscle training, significantly better than to concentric training, with 82% of patients satisfied and returning to their pre-injury activity level (see also Owen Anderson's article, page 9). Long-term results are needed to evaluate whether this will reduce the need for surgical intervention for tendinoses located in the mid-portion of the Achilles tendon.
The future may lie in molecular biology. Although many of the molecular factors promoting tendon healing have been identified, delivering them to the damaged tendon is proving difficult. The answer to this problem may lie in gene therapy whereby the transfer of growth factor genes into tenocytes may allow the continuous release of growth factors at the healing site. This has been successfully done in animal studies!(21).
Alex Watson and Fares Haddad
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