Lower extremity musculoskeletal conditions, such as ankle sprains,¹ Achilles tendinopathy,^2,3 and plantar fasciitis,³ are commonly diagnosed by primary care physicians, whereas other tendon injuries involving the medial (i.e., posterior tibial), lateral (i.e., peroneal), and anterior (i.e., tibialis anterior) ankle can be missed. The biomechanics of the foot and ankle are intricate. They are responsible for energy absorption and transfer during propulsion, stability during stance, and proprioception. Abnormal mechanics can result in connective tissue changes and alterations in muscle function. Tendinopathy refers to tendon degeneration without substantial inflammation and a generally chronic presentation. The cause of tendinopathy is often multifactorial, involving intrinsic and extrinsic risk factors (Table 1).^4–7 The anatomy (Figure 1⁸) and pathophysiology of ankle tendinopathy have been described in detail.² This article reviews the diagnosis and treatment of posterior tibial, peroneal, and tibialis anterior tendinopathies (Table 2).

Diagnosis and Treatment: General Considerations

HISTORY AND PHYSICAL EXAMINATION

Components of the history for foot and ankle tendinopathies include asking about previous or new activity level, location of pain, timing of pain in relation to activity or rest, swelling, and aggravating and relieving factors. Commonly, patients report starting a new physical activity or increasing the intensity of an existing activity, leading to overuse injuries. Patients may experience pain over the involved tendon with activity, which can progress to pain at rest. Physical examination should be bilateral noting any asymmetry. Possible findings include the presence of swelling and tenderness over the involved tendon and pain with tendon activation. Passive range of motion and strength deficits should be assessed. During weight-bearing, the arch type and overall foot and ankle alignment can be noted. A video of a complete foot and ankle examination is available at https://www.youtube.com/watch?v=LIB6czBMHgE.

IMAGING

Imaging is generally not necessary unless trauma is suspected. For chronic tendinopathy (i.e., more than six weeks' duration), radiography should be considered as the initial imaging study.⁹ It can identify bony abnormalities that may be contributing to the patient's symptoms. Further imaging with ultrasonography or magnetic resonance imaging can be performed if the diagnosis is unclear or nonoperative treatment is ineffective. Ultrasonography has become more readily available and is a less expensive alternative to magnetic resonance imaging. An added benefit of ultrasonography is its dynamic nature, enabling evaluation of abnormal motion or subluxation.¹⁰ If ultrasonography is unavailable, magnetic resonance imaging can be obtained if surgery is being considered.

TREATMENT

Although chronic tendinopathies are not inflammatory processes,² short-term use of acetaminophen and nonsteroidal anti-inflammatory drugs can help provide pain relief. However, they can alter tendon and skeletal muscle extracellular matrix remodeling, which may interfere with recovery.¹¹ It is necessary to address footwear, including high heels or worn-out athletic shoes, and over-the-counter orthotics that can help correct arch deficits. Pain with ambulation can be treated with short-term immobilization.¹² Rehabilitation should focus on eccentric exercises¹³ and foot intrinsic muscles.¹² Topical low-dose nitroglycerin patches, studied in the setting of Achilles, rotator cuff, and patellar tendinopathies, produced improvements in pain, strength, and patient satisfaction for up to six months in the treatment of those tendinopathies,¹⁴ but headaches are a common adverse effect that may limit their use.¹⁵ If pain and function do not improve after eight to 12 weeks of treatment, minimally invasive procedures can be used.

Corticosteroid injections have shown effectiveness in the short-term, but there is concern that they can weaken the tendon structure and increase the likelihood of rupture, especially if the corticosteroid is injected into the tendon.¹⁶ It is prudent to limit corticosteroid treatment to a single injection. A six-year retrospective review of 109 corticosteroid injections in 96 patients reported only one tendon rupture in patients who received corticosteroid injections into the peroneus tendon sheath,¹⁷ and a systematic review of randomized controlled trials with more than 2,600 participants resulted in one tendon rupture.¹⁶