Definition

Achilles tendinopathy exists along a spectrum of peritendinitis to tendinosis or tendinopathy. The pathologic process involves a painful, swollen, and tender area of the Achilles tendon and peritenon. Athletes with particularly tight heel cords are predisposed to this injury. This condition commonly affects middle-aged men who play tennis, basketball, or other quick start-and-stop sports. Achilles tendon rupture carries a 200-fold risk of sustaining a contralateral rupture of the Achilles tendon [1], but atraumatic disease associations, such as periarticular manifestation of poststreptococcal reactive arthritis [2], should remain in the atraumatic differential. Collagen vascular disease, inflammatory disease, and diabetes may also be risk factors. The relative avascularity of the region 5 to 7 cm proximal to the calcaneus insertion has long been considered a pathoanatomic structural risk factor, as is the thinning and twisting of the tendon at this midsection [3]. However, morphologic and biochemical differences present within the tendon during Achilles tendinopathy provide a modern addendum to this dogma. Upregulation of collagen 1 and collagen 3 together with mRNA of fibronectin, tenascin C, and fibromodulin as well as degradation factors matrix metalloproteinases 2 and 9 and tissue inhibitor of matrix metalloproteinase 2 in Achilles tendinopathy [4] seem to add to the growing understanding of the cellular and molecular basis of the clinical presentation. The histopathologic feature is angiofibroblastic hyperplasia (tendinosis) of the body of the tendon (a degenerative process) with a concomitant and potentially secondary inflammatory response in the peritenon [5,6]. The maladies often occur simultaneously but may occur individually. An association with chronic quinolone exposure is well documented [7–9] and is worse in patients concomitantly taking prednisone long term.

Symptoms

Pain and tenderness in the Achilles tendon are predominant symptoms, usually in association with running, sports with quick “cutting,” and other fitness activities [10]. Activities with rapid starting and stopping or rapid eccentric contraction, such as classical ballet [11], increase the symptoms and risk of complete tear. In some patients, the pain actually improves with lower extremity exercise. Typically, the pain occurs with a change in activity or training schedule. The most common location for tendinosis symptoms is at the apex of the Achilles tendon curvature. Different activities can lead to pathologic change in other regions of the tendon, namely, at the calcaneal insertion with or without a Haglund deformity or at the myotendinous junction. A history of an acute traumatic event in which the patient reports a “pop” should suggest an Achilles tendon tear, although a similar pop can occur with tear or rupture of the plantaris, peroneus, or posterior tibial tendon. History of quinolone exposure, diabetes, collagen vascular disease, anabolic steroid use, or smoking should be noted.

Physical Examination

The essential element in the physical examination is localization of swelling and tenderness in the critical zone of the Achilles tendon at the apex of the Achilles curve approximately 2 ^1⁄2 inches proximal to the os calcis insertion. Exquisite tenderness to palpation is a classic examination finding. The degree of ankle plantar force generated has been shown to have a strong negative relationship with pain, and a standardized strength testing system has been suggested and shown to be reliable on a small sample of patients [12]. Palpable heat is usually not evident unless peritendinitis is a major component. The Achilles tendon is usually tight, with ankle dorsiflexion rarely extending beyond 90 degrees. Associated findings may include abnormal foot posture (pes planus or cavus), tight hamstrings, and muscle weakness of the entire hip and leg. Heels may not move into a normal varus position in standing on toes. Neurologic evaluation findings, including strength, sensation, and deep tendon reflexes, are normal.

The examination should also include observation for a palpable defect and the Thompson test (squeezing the calf, which should result in plantar flexion in an attached tendon) to rule out rupture of the Achilles tendon (Fig. 81.1).

Functional Limitations

Impact weight-bearing activities, such as jogging and running, are usually limited. Dance or cutting “moves” typical of field sports are virtually impossible. Nonimpact fitness activities, such as cycling and using an elliptical trainer, may also result in symptoms. Patients may complain of pain with daily ambulatory activities, such as walking at work or climbing stairs. Whereas individual differences exist, early recovery of plantar flexion may be seen with little functional change, usually because of flexor hallucis longus compensation [13].

Diagnostic Studies

Unless a special form of calcified Achilles tendinosis occurs at the os calcis insertion, regular radiographs are usually normal. Diagnostic ultrasonography or magnetic resonance imaging is capable of defining the extent of both tendinosis and peritendinitis, but serial magnetic resonance examinations, especially postoperatively, are not indicated and do not correlate with functional outcome [14]. Partial rupture is a diagnostic dilemma for diagnostic ultrasonography [15