Achilles Tendon Injection

Indications and Clinical Considerations

The Achilles tendon is susceptible to developing tendinitis both at its insertion on the calcaneus and at its narrowest part, at a point approximately 5 cm above its insertion ( Fig. 185.1 ). It is also subject to repetitive motion, which may result in microtrauma that heals poorly because of the tendon’s avascular nature. Running is often implicated as the inciting factor of acute Achilles tendinitis. Tendinitis of the Achilles tendon frequently coexists with bursitis of the associated bursae of the tendon and ankle joint, creating additional pain and functional disability. Calcium deposition around the tendon may occur if the inflammation continues, making subsequent treatment more difficult. Continued trauma to the inflamed tendon ultimately may result in tendon rupture ( Fig. 185.2 ).

The onset of Achilles tendinitis usually is acute, occurring after overuse or misuse of the ankle joint. Inciting factors may include activities such as running and sudden stopping and starting, as when playing tennis. Improper stretching of the gastrocnemius and Achilles tendon before exercise as well as the use of quinolone antibiotics have also been implicated in the development of Achilles tendinitis, as well as acute tendon rupture. The pain of Achilles tendinitis is constant and severe and is localized in the posterior ankle. Significant sleep disturbance often is reported. The patient may attempt to splint the inflamed Achilles tendon by adopting a flat-footed gait to avoid plantarflexing the affected tendon. Patients with Achilles tendinitis exhibit pain with resisted plantarflexion of the foot. Creaking or grating may be palpated when passively plantarflexing the foot ( Fig. 185.3 ). As mentioned earlier, the chronically inflamed Achilles tendon may suddenly rupture with stress or during vigorous injection procedures into the tendon itself.

Plain radiographs are indicated for all patients with posterior ankle pain. On the basis of the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging and/or ultrasound imaging of the ankle is indicated if Achilles tendinitis or joint instability is suggested ( Figs. 185.4 and 185.5 ). Radionuclide bone scanning is useful for identifying stress fractures of the tibia not seen on plain radiographs. The injection technique described later serves as both a diagnostic and a therapeutic maneuver.

Clinically Relevant Anatomy

The Achilles tendon is the thickest and strongest tendon in the body, yet it is also very susceptible to rupture. The common tendon of the gastrocnemius muscle, the Achilles tendon begins at midcalf and continues downward to attach to the posterior calcaneus, where it may become inflamed (see Figs. 185.1 and 185.5 ). The Achilles tendon narrows during this downward course, becoming most narrow at approximately 5 cm above its calcaneal insertion. It is at this narrowest point that tendinitis also may occur. A bursa is located between the Achilles tendon and the base of the tibia and the upper posterior calcaneus. This bursa also may become inflamed as a result of coexistent Achilles tendinitis and may confuse the clinical picture.