Chou: OKU: Foot and Ankle 7

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CHAPTER

Disorders of the Achilles Tendon

AJAY N. GURBANI, MD

medial to midline insertion allows the tendon to provide some inversion in addition to its primary role of plantar flexion of the ankle. The tendon does not have a true synovial sheath; instead, it is surrounded by a paratenon, a thin gliding membrane continuous proximally with the fascial envelope of the muscle. The paratenon is a highly vascular structure that, along with the surrounding mus cle complex, provides blood flow to the tendon. An area that is relatively hypovascular within the tendon 2 to 6 cm from the calcaneal insertion may be predisposed to degenerative changes and rupture. The Achilles tendon is subjected to forces as high as 6 to 10 times the body weight during activities such as running. These factors, combined with the function of the gastrocnemius-soleus complex in crossing the knee, ankle, and subtalar joint, may help explain the high incidence of degenerative changes and injuries to the Achilles tendon. ACUTE ACHILLES TENDON RUPTURES Achilles tendon rupture is most common in men between the ages of 30 to 50 years. A retrospective review of 331 patients with Achilles tendon rupture found that 83% of injuries were sustained by men with an average age of 46.4 years. The same study noted that 68% of the sustained injuries were due to sports-related activities. 1 Most Achilles tendon ruptures occur 2 to 6 cm from the insertion of the tendon, with proximal ruptures account ing for only 10% to 15% of all Achilles tendon ruptures. 2 Ruptures at the insertion are rare and are associated with factors such as a Haglund deformity, a history of insertional Achilles tendinosis, or prior steroid therapy in the area. The common mechanism of rupture is a forced eccentric loading of the plantarflexed foot. The exact cause of Achilles tendon rupture remains unclear, but it

ABSTRACT The Achilles tendon is the strongest tendon in the body and plays a significant functional role. Anatomic characteristics of the Achilles tendon contribute to the development of varied pathol ogy, including rupture and tendinopathy. The treatment of acute Achilles tendon ruptures remains controversial. It is important to review surgical and nonsurgical options for both Achilles tendon rupture and Achilles tendinopathy, along with rehabilitation protocols. Chronic Achilles tendon ruptures represent a challenging clinical entity, with most of the literature focused on var ied surgical approaches.

Section 7: Tendon Disorders and Sports-Related Foot and Ankle Injuries

Keywords: Achilles tendinopathy; Achilles tendon; Achilles tendon rupture

INTRODUCTION The functional importance of the Achilles tendon is sug gested by its status as the strongest and thickest tendon in the body. The Achilles tendon is formed by the two heads of the gastrocnemius and the soleus and inserts into the posterior aspect of the calcaneus. The slightly

Neither Dr. Gurbani nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter. This chapter is adapted from Padanilam TG: Disorders of the anterior tibial, peroneal, and Achilles tendons, in Chou LB, ed: Orthopaedic Knowledge Update ® : Foot and Ankle 6 . American Academy of Orthopaedic Surgeons, 2020, pp 377-391. Copyright © Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. 2023

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Orthopaedic Knowledge Update ® : Foot and Ankle 7