By: 1 March 2011

Achilles tendinitis is a form of repetitive strain injury typically characterised by tight gastrocnemius and soleus complex in association with a typically weak tibialis anterior and extensor hallucis and digitorum longus muscles/tendons.

Legend has it that Achilles was the son of the mortal Peleus and the nymph Thetis. Thetis tried to make her son immortal by dipping him into the River Styx, while holding him by his left ankle. His heel was therefore the only portion of Achilles capable of sustaining a mortal wound, which he received from a goddess-guided arrow shot by Paris of Troy

Achilles Tendonitis
Initial tendon inflammation is usually referred to as tendonitis. It is not entirely clear if this is a denegenerative phase or inflammatory phase. This is usually heralded by vague pain following excessive sporting activity or rarely triggered by poor quality footwear, inappropriate stretching and manipulation or by certain antibiotic (Quinolones)

Achilles Tendinosis
As the tendonitis progresses, the tendon tissue begins to degenerate. This results in the formation of microtears in the tendon tissue, which is the hallmark of tendinosis. Often the degeneration occurs at the attachment of the tendon to the heel bone, producing pain when walking or running.

Achilles Paratenonitis
The Achilles tendon is covered by a paratenon, which acts like a sheath. Paratenonitis usually occurs in association with tendonitis. When the paratenon inflames, it adheres to the tendon adjacent to it and prevents the tendon from gliding smoothly. Tenderness and swelling result, and it is difficult to move the foot without pain.

Rupture and Avulsion
The next phase of severity following Achilles tendonitis and tendinosis, if left untreated, includes two very serious conditions. These are tendon rupture and avulsion. Rupture is a tear completely through the substance of the tendon itself. Avulsion is the condition in which the Achilles tendon actually pulls away from the calcaneal insertion. Pain is severe and walking is usually impossible.

Haglund Deformity
When Retrocalcaneus bursitis exists at the same time as Achilles tendinitis in the same leg, this is known as Haglund's deformity. This may also be accompanied by prominence or bony hypertrophy of the posterosuperior corner of the calcaneus.

Incidence and Prevalence of Achilles Tendonitis
Though the overall incidence of Achilles tendonitis is unknown, it occurs in approximately 6-18% of runners, and also is more common in athletes, especially in sports that involve jumping (e.g., high jumping, sprinting), and in people who do excessive walking. Achilles tendonitis secondary to hindfoot arthritis is more common in people who are middle aged or older.

Functional Anatomy
The morphological characteristics, particularly the rotation structure, of human Achilles tendon have been extensively studied. The tendon fibres of the two muscle groups (gastrocnemius and soleus) intersect each other in a rotating manner. This rotation is from medial to lateral. The rotation starts at 12-15 cm above the calcaneum but becomes most obvious approximately 5cm above the calcaneum. The degrees of rotation vary and can be of three types: light, medium and heavy. The tendon rotation structure has some biomechanical implications for the tendon's adaptation to the tremendous tensile forces developed during special situations Along with common factors known to result in tendon injury; it is believed that structural weakness is one of the most important factors resulting in tendon injury. The most avascular part of the tendon is approximately 44mm above insertion, which is the most obvious position of rotation. Combination of a wringing type of action between the two parts of tendon fibers in addition to the two-joint (knee and ankle) span of the gastrocnemius, causes the stretched tendon to buid up even greater tension and is easily torn when the quadriceps muscle group contracts strongly during knee extension. Tendon histopathology demonstrates (1) Cellular activation and increase in cell numbers (2) increase in the ground substance, (3) collagen disarray, and (4) neovascularisation.

Scoring Systems
There are various scoring systems which have been described for conditions and the functional limitations there from affecting the Achilles tendon. Most scoring systems are too complex or impractical to be used in clinical practice. Only two scoring systems are currently used by foot and ankle surgeons for grading symptoms based on various criteria – the VISA-A questionnaire (Victorian Institute of Sports Assessment - Achilles) and the AO Foot and Ankle Score (AOFAS). The VISA-A is reproduced below.

The VISA-A questionnaire
In this questionnaire the term pain refers specifically to pain in the achilles tendon region.

1. For how many minutes do you have stiffness in the Achilles region on first getting up?

100mins                       0mins
  0 1 2 3 4 5 6 7 8 9 10  

2. Once you are warmed up for the day, do you have pain when stretching the Achilles tendon fully over the edge of a step? (keeping the knee straight)

Strong severe pain                       No pain
  0 1 2 3 4 5 6 7 8 9 10  

3. After walking on flat ground for 30 minutes, do you have pain within the next 2 hours? (If unable to walk on flat ground for 30 minutes because of pain, score 0 for this question).

Strong severe pain                       No pain
  0 1 2 3 4 5 6 7 8 9 10  

4. Do you have pain walking downstairs with a normal gait cycle?

Strong severe pain                       No pain
  0 1 2 3 4 5 6 7 8 9 10  

5. Do you have pain during or immediately after doing 10 (single leg) heel raises from a flat surface?

Strong severe pain                       No pain
  0 1 2 3 4 5 6 7 8 9 10  

6. Do you have pain during or immediately after doing 10 single leg hops?

Strong severe pain/unable                       No pain
  0 1 2 3 4 5 6 7 8 9 10  

7. Are you currently undertaking sport or other physical activity?

  • 0 Not at all
  • 4 Modified training