INTRODUCTION — Pain of the Achilles tendon commonly affects both competitive and recreational athletes as well as the sedentary patient. The largest tendon in the body, the Achilles tendon, endures strain and risks rupture from running, jumping, and sudden acceleration or deceleration. Overuse, vascular diseases, neuropathy, and rheumatologic diseases may cause tendon degeneration. The hallmarks of Achilles tendon problems seem to be damaged, weak, and inelastic tissue.
This topic review will discuss the mechanism, diagnosis, and management of Achilles tendinopathy and tendon rupture. A general discussion of treatments for tendinopathy is provided separately. (See "Overview of the management of overuse (persistent) tendinopathy".)
TERMINOLOGY — "Tendonitis," "tendinosis," "tendinopathy," "paratendinitis," "enthesopathy," and "insertional tendonitis" are among the terms used to characterize acute or chronic tendon pain. The common term "tendonitis" is confusing because inflammation is often not seen on histopathology. Throughout this review, we will use the term "tendinopathy" to refer to acute and chronic pain associated with an Achilles tendon injury other than tendon tear or rupture. (See "Overview of overuse (persistent) tendinopathy", section on 'Pathology and terminology'.)
EPIDEMIOLOGY AND RISK FACTORS — Achilles tendinopathy affects competitive and recreational athletes as well as people who are not active [1]. The incidence of Achilles tendon rupture in the general population is approximately 5 to 10 per 100,000, but may be higher in some regions and populations, and is increasing overall [2-5]. Over 80 percent of ruptures occur during recreational sports. Approximately 10 percent of patients who sustain an Achilles tendon rupture had preexisting Achilles tendon problems [6].
Observational data suggest that competitive athletes have a lifetime incidence of Achilles tendinopathy of 24 percent, with 18 percent sustained by athletes younger than 45 years [7]. Tendon rupture occurs in 8.3 percent of competitive athletes. Among competitive runners, the lifetime incidence of Achilles tendinopathy may be as high as 40 to 50 percent.
Competitive athletes with a high lifetime incidence of tendon rupture include sprinters (18 percent), decathletes (17 percent), soccer players (17 percent), track and field jumpers (12 percent), basketball players (12 percent), and ice hockey players (9 percent) [7]. Achilles tendinopathy in recreational runners, although less likely to involve rupture, accounts for 6 to 17 percent of all running injuries [8]. Military recruits develop tendinopathy at a rate of 6.8 percent [9].
Although evidence is limited, a number of conditions may be associated with an increased risk of Achilles tendinopathy [10]. Cold-weather training is associated with higher rates of tendon pain generally and Achilles tendinopathy specifically [9,10]. A prior history of tendinopathy, foot misalignment, poor running mechanics (eg, excessive supination, inadequate dorsiflexion), inappropriate footwear, weakness in plantarflexion, and leg-length discrepancy are associated with Achilles tendinopathy [10-12].
Age, male sex, and obesity are risk factors for Achilles tendon problems (table 1) [13]. The peak age for rupture is 30 to 40 years for both men and women; this may be when degenerative changes and occasional high stress from sports coincide. Rupture is four to five times more common in men than women [2]. As participation in recreational sports has increased over the past 50 years, so has the rate of tendon rupture [14].
Fluoroquinolone antibiotics are rarely associated with Achilles tendinopathy or tendon rupture [10,15]. A study of 46,776 patients treated with fluoroquinolones found 3.2 cases of tendon problems for every 1000 years of exposure [16]. According to a large case-control study, the incidence of tendon rupture associated with fluoroquinolone therapy is estimated at 12 per 100,000 treatment episodes (odds ratio [OR] 1.3; 95% CI 1.0-1.8) [17]. The risk of suffering an Achilles tendon rupture is increased threefold during the first 90 days among patients taking a fluoroquinolone for the first time [18]. The mechanism remains unknown. According to a questionnaire study of 42 patients, symptoms typically develop within one week of initiating treatment (median 6 days; range 1 to 510 days), while the majority (85 to 93 percent) of patients report symptoms within one month [19]. Among symptomatic patients without tendon rupture, most reported recovery within two months of discontinuing the fluoroquinolone, but in approximately one quarter pain and disability persisted. Age older than 60 years and concurrent use of systemic glucocorticoids appear to compound the risk [16,20-22]. Past fluoroquinolone use does not appear to confer future risk. (See "Fluoroquinolones", section on 'Tendinopathy'.)
Oral glucocorticoids alone increase the risk of tendinopathy, although studies estimating the precise risk in primary care populations are lacking. Local glucocorticoid injection causes tendon damage in animal models, and there are case reports in humans of tendon rupture following glucocorticoid injection [23].
In women, hypertension is associated with Achilles tendinopathy [13]. Other diseases associated with tendinopathy include psoriasis and ankylosing spondylosis [24]. Heel pain is rarely the presenting symptom in patients with these systemic diseases [25].
CLINICAL ANATOMY — The soleus and gastrocnemius muscles converge to form the Achilles tendon, which inserts posteriorly on the calcaneus (figure 1 and figure 2 and figure 3). Contraction of these muscles, along with the actions of the tibialis posterior and peroneus longus and brevis, causes the foot to plantarflex. The subcutaneous and subtendinous (or retrocalcaneal) calcaneal bursae cushion the insertion area anteriorly and posteriorly. Most pain and tendon ruptures occur where the blood supply of the gastrocnemius-soleus muscle complex is poorest, 2 to 6 cm above the insertion point. A peritendinous sheath of connective tissue allows the tendon to slide relative to surrounding tissue.
MECHANISM OF INJURY AND PATHOPHYSIOLOGY — Acute Achilles tendon pain generally develops when athletes abruptly increase their activity (eg, runners who start training for a marathon). Chronic tendon pain (>3 months) may result from sustained stress, poor running mechanics (eg, supination, heel misalignment), or improper footwear [14,26]. Some experts claim a role for excessive pronation in Achilles tendinopathy among runners, but others dispute this.
Recurrent microtrauma causes degeneration of the Achilles tendon [14,27]. The relative hypovascularity of the tendon 2 to 6 cm from its insertion point may prevent adequate healing. Although inflammation is often not seen on histopathology, clinical signs similar to those seen with inflammation (such as swelling, warmth, and pain) may occur. Damaged tendons become calcified, thickened, inelastic, and fibrotic. Abnormal neovascularization of tissue may be seen on ultrasound. Aging and vascular disease decrease collagen density, break collagen cross-links, and reduce the elasticity of the tendon sheath and tendon itself. Rupture occurs when a sudden shear stress (eg, cutting during a basketball game) is applied to an already weakened or degenerative tendon. The pathophysiology of overuse (chronic) tendinopathy is discussed in greater detail separately. (See "Overview of overuse (persistent) tendinopathy".)
CLINICAL PRESENTATION
Tendinopathy — Patients with Achilles tendinopathy typically complain of pain or stiffness 2 to 6 cm above the posterior calcaneus. They are likely to be casual or competitive athletes who have increased their training regimen beyond their tendon's ability to heal the microtrauma from repetitive stress, or who have been training rigorously for a long time. A history of excessive supination, increased speed work or hill training, or improper or worn out footwear may be found.
The pain is usually described as burning. The pain is worse with activity and may be relieved after a period of rest.
Tendon rupture — Tendon rupture occurs when sudden forces are exerted upon the Achilles tendon during strenuous physical activities that involve sudden pivoting on a foot or rapid acceleration (eg, stop-and-go sports such as tennis, basketball, or softball). Many patients feel as if they were struck violently in the back of the ankle. Some hear a "pop" and experience severe, acute pain, although the absence of pain does not rule out rupture. As an example, a small case series found that one-third of patients with tendon rupture did not report pain [28]. In contrast to ankle sprains, where injury occurs with landing, symptom onset with tendon rupture generally occurs as the patient is pushing off with their foot.
PHYSICAL EXAMINATION
General evaluation — Examination of the Achilles tendon is usually straightforward because the tendon is easily identified and palpated. However, potential pitfalls exist (table 2). Of note, a sizable minority of patients with complete tendon rupture are able to ambulate.
Patients should be examined lying prone with their feet hanging off the end of the examination table. Inspect the region of the Achilles tendon for bruising (blood tracking beneath the malleolus suggests fracture, sprain, or tendon rupture), swelling, and foot misalignment. Assess patients for signs of peripheral artery disease, such as decreased pulsations, decreased capillary refill in the heel or toes, loss of hair, increased skin pigmentation, or edema.
Palpate the Achilles tendon for tenderness, thickening, or a defect, recognizing that edema or a hematoma may mask such a defect. Palpation has a sensitivity of approximately 73 percent and a specificity of 89 percent in detecting a partial tendon tear [29]. Comparison to the unaffected side is useful.
Patients with tendinopathy typically have localized tenderness 2 to 6 cm proximal to the insertion of the tendon (picture 1). By comparison, tenderness around the insertion point near the heel suggests either subcutaneous calcaneal bursitis or enthesopathy (pathology of tendon at its insertion) [30]. Warmth and tenderness localized to the soft tissue anterior to the area where the Achilles inserts suggests subcutaneous bursitis, although this condition is uncommon. Focal tenderness of the tendon itself in the area where it inserts suggests enthesopathy.
The tendon should be palpated as the patient dorsiflexes and plantarflexes the foot, as well as when the ankle is stationary in a neutral position. The presence of crepitus with motion suggests tendinopathy.
Isolating the subtendinous bursa (ie, retrocalcaneal bursa) and palpating it for tenderness may identify bursitis. We perform this examination as follows: Grasp the Achilles tendon with the fingers of one hand and move the tendon side to side. Bursitis should not cause pain when only the tendon is palpated. Next, with the index finger on the opposite hand, apply gentle pressure deep to the tendon. Continue to grasp the tendon with the other hand to be certain you are palpating the bursa and not the tendon. Local warmth and tenderness deep to the tendon with light pressure suggests that the subtendinous (or retrocalcaneal) bursa is inflamed.
Examine the patient's footwear, looking for signs of excessive breakdown (eg, disproportionate wear on the inner or outer edge) or other evidence of poor running mechanics. Examine the architecture of the patient's foot. The presence of flat feet (pes planus), heel malalignment, high arches (pes cavus), or leg-length discrepancy can contribute to poor running mechanics [31]. If possible, assess the patient's gait or running stride, looking for abnormalities or asymmetry.
Special tests — The calf squeeze or Thompson test provides an accurate means for detecting complete Achilles tendon rupture (picture 2 and movie 1). To perform the test, the patient either lies prone, with their feet hanging off the end of the examination table, or kneels on a chair. The clinician squeezes the gastrocnemius muscle belly while watching for plantarflexion. The absence of plantarflexion when squeezing the gastrocnemius muscle marks a positive test, indicative of rupture.
The calf squeeze test is a more reliable indication of tendon rupture than the inability to plantarflex, since patients may be able to plantarflex the foot using accessory muscles (eg, tibialis posterior, peroneals). Achilles tendon ruptures can be missed at the initial visit because the clinician was falsely reassured by the patient's ability to plantarflex or walk.
In a series of 174 patients with a clinical diagnosis of unilateral complete Achilles tendon tear and 28 patients with unilateral suspected (but no actual) Achilles tendon tear, the Thompson test had a sensitivity of 96 percent and a specificity of 93 percent, using magnetic resonance imaging (MRI) or ultrasound as a gold standard [29]. A negative test can miss up to 10 percent of ruptures (assuming a 75 percent pretest probability of rupture). Thus, confirmatory testing such as diagnostic ultrasound or MRI is useful when the Thompson test is negative but clinical suspicion remains high.
The Matles test is another means of assessing Achilles tendon rupture. To perform the test, the patient lies prone with knees flexed to 90 degrees. Observe whether the affected foot is dorsiflexed or neutral (both are abnormal) compared with the uninjured side, where the foot should appear plantarflexed. The sensitivity and specificity of the Matles test was 88 percent and 85 percent, respectively, in the above study [29].
DIAGNOSTIC IMAGING — Achilles tendinopathy (without rupture) is a clinical diagnosis. Imaging is generally not necessary except to rule out other conditions, such as a stress fracture or tendon rupture.
Plain radiographs are generally unhelpful in the assessment of Achilles tendon pathology but may reveal a heel spur or bony bump (called a Haglund's deformity or "pump bump") consistent with both tendinopathy and calcaneal bursitis.
Ultrasound imaging is increasingly used to assess tendon appearance and function [32]. Ultrasound may reveal normal tendon, tendon thickening (image 1), or signs of more significant tendon pathology, such as neovessels, hypoechogenicity, disordered fibers, tissue gaps, and fluid (image 2 and movie 2) [32,33]. In addition to midportion Achilles tendinopathy, ultrasound can reveal enthesopathy or avulsion injuries at the distal portion of the tendon (image 3). Ultrasound can also help to distinguish between Achilles tendon injury and other pathology (image 4).
Achilles tendon rupture may be diagnosed solely by clinical examination, but ultrasound enables rapid bedside confirmation of the diagnosis [29,32]. Although published data are limited, in experienced hands, ultrasound appears to be an accurate tool for diagnosing Achilles tendon tear and distinguishing between partial and complete tears. As an example, ultrasound was reported to have 100 percent sensitivity, 83 percent specificity, and 92 percent accuracy for distinguishing between partial and full thickness Achilles tendon tears, using surgical findings as the gold standard [34]. In addition, dynamic ultrasound can demonstrate whether tendon fragments come into contact during active plantarflexion or separate further during passive dorsiflexion. It is important to perform the ultrasound evaluation in two planes, atypically involving sagittal and transverse views. Visualized lack of continuity of tendon fibers is an indication for surgical repair.
Magnetic resonance imaging (MRI) is often used to assess musculoskeletal complaints and is the study of choice when tendon rupture is suspected and high-quality diagnostic ultrasound is unavailable. MRI provides greater anatomic detail and greater accuracy in detecting partial Achilles tendon tears [35]. With tendinopathy, MRI may demonstrate an increased T2-weighted signal in the tendon or an increased tendon diameter [36]. In addition, MRI may reveal alternative explanations for patient symptoms, such as enlarged calcaneal bursae [32].
Neither ultrasound nor MRI findings appear to correlate closely with clinically significant chronic Achilles tendinopathy. In one small prospective study, ultrasound detected abnormal morphology in 37 of 57 symptomatic Achilles tendons, while MRI detected abnormalities in 19 of 34 (MRI was performed in a subset of 25 consecutive patients) [37]. Better baseline MRI appearance was associated with a successful return to sport and symptomatic benefit after 12 months, but baseline ultrasound findings were not. Further study of these diagnostic tests is needed to determine their appropriate role in the management of Achilles tendinopathy.
ADDITIONAL ULTRASOUND RESOURCES — Instructional videos demonstrating proper performance of the ultrasound examination of the ankle, including the Achilles tendon, and related pathology can be found at the website of the American Medical Society for Sports Medicine: sports US ankle-foot pathology. Registration must be completed to access these videos, but no fee is required.
DIFFERENTIAL DIAGNOSIS — The differential diagnosis of heel and hindfoot pain is extensive and is discussed in detail separately. (See "Evaluation and diagnosis of common causes of hindfoot pain in adults".) Below, diagnoses commonly confused with Achilles tendon injury are reviewed briefly.
Overview — Apart from Achilles tendinopathy, pain arising from the region between the posterior calcaneus and the gastrocnemius-soleus muscle complex may be caused by several other conditions (table 3). Ankle sprain is the most common misdiagnosis when tendon rupture is the actual cause of pain [28]. Differentiating the two can be difficult. In contrast to ankle sprains, where injury occurs with landing, symptom onset with tendon rupture generally occurs as the patient is pushing off with their foot. Do not assume rupture is absent because the patient can plantarflex their ankle or walk. The tibialis posterior and peroneus longus provide significant strength in plantarflexion and compensate partially for a ruptured Achilles tendon. (See 'Physical examination' above and "Ankle sprain in adults: Evaluation and diagnosis".)
Calcaneal bursitis — Calcaneal bursitis (subcutaneous or subtendinous) typically occurs in middle-aged or older adult patients. Patients may complain of pain where the back of a hard shoe, heel cup, or strap rubs against the heel at the Achilles tendon insertion point. Sports in which athletes wear hard-backed footwear or repeatedly strike their heels against walls (eg, indoor soccer, hockey) may cause bursitis. Bursitis generally resolves with basic measures: heel lifts or posterior padding, avoiding bothersome footwear, rest, ice, and nonsteroidal antiinflammatory drugs (NSAIDs). Heel pain may also stem from an injury or strain at the Achilles tendon insertion (ie, enthesopathy). (See "Bursitis: An overview of clinical manifestations, diagnosis, and management".)
Calcaneal apophysitis — Calcaneal apophysitis (ie, Sever disease) is an overuse injury in young athletes aged 8 to 15 years. Patients with calcaneal apophysitis have activity-related pain in the posterior aspect of the heel, which may be unilateral or bilateral. Tenderness is localized to the calcaneal apophysis, usually 1 to 2 cm distal to the Achilles tendon insertion. Symptoms generally resolve within three to six weeks with conservative treatment. (See "Heel pain in the active child or skeletally immature adolescent: Overview of causes", section on 'Calcaneal apophysitis (Sever disease)'.)
INDICATIONS FOR REFERRAL — All complete tendon ruptures merit referral for orthopedic consultation. The patient should be evaluated by the surgeon within approximately a day or two of the injury. It is best to discuss the case with the consulting orthopedist as soon as the injury is diagnosed.
Partial tendon tears and chronic tendinopathy that fail to improve with three to six months of conservative treatment may benefit from consultation with a specialized runners' clinic, physical medicine and rehabilitation specialist, physical therapist, or orthopedic surgeon [38]. (See 'Tendon rupture' below.)
TREATMENT
Acute tendinopathy — Treatment of acute Achilles tendinopathy generally consists of the following:
●Avoid aggravating activities
●Apply ice when symptomatic
●Take a short course (7 to 10 days) of nonsteroidal antiinflammatory drugs (NSAIDs)
●Support the Achilles with a heel lift (approximately 12-mm rise) and with elastic bandage or taping (picture 3) as needed
The goal of therapy is to relieve symptoms and enable a return to activity. Although the approach described here appears reasonable, there is little high-quality evidence to support it.
A systematic review of treatments for "Achilles tendinitis" published in 2001 identified three small controlled trials comparing oral NSAIDs to placebo [39]. Although there is no compelling evidence that NSAIDs enable patients to return to full activity sooner [40], these drugs are a reasonable choice for short-term pain relief in patients with acute Achilles tendinopathy. The role of oral and topical NSAIDs in the treatment of tendinopathy is reviewed separately. (See "Overview of the management of overuse (persistent) tendinopathy", section on 'Antiinflammatory medications'.)
A subsequent systematic review of studies looking at the effect of various injections, including glucocorticoids, for the treatment of Achilles tendinopathy found that the studies were of low quality overall, but the results suggest little (if any) benefit from such therapy [41]. This conclusion is consistent with studies of glucocorticoid injection for other tendinopathies. In addition, there are case reports of Achilles tendon rupture after glucocorticoid injection in patients with chronic tendinopathy [23]. (See "Overview of the management of overuse (persistent) tendinopathy", section on 'Glucocorticoids'.)
Once acute healing has begun, most patients begin some form of rehabilitation. Basic therapy regimens, including such interventions as physical therapy, deep-friction tissue release, and ultrasound, may reduce symptoms over several weeks [42]. Patients should perform an adequate warm-up before and stretch following inciting activities, once these are resumed. Rehabilitation for chronic Achilles tendinopathy and prevention strategies is discussed below. (See 'Chronic tendinopathy' below and 'Prevention' below.)
Small randomized trials have found no benefit from low-dose heparin injections or heel pads, but such pads may reduce pain from calcaneal bursitis [39]. Heel lifts are thought to reduce the load placed on the tendon and are commonly used as an adjunct therapy. (See 'Other interventions' below.)
Chronic tendinopathy — Chronic Achilles tendinopathy exists when pain persists beyond three months. In addition to the basic interventions for acute exacerbations described above, the treatment of chronic midportion Achilles tendon pain should include a rehabilitation program that emphasizes resistance exercises using heavy loads. While methodologic limitations are common in studies of Achilles tendinopathy treatment, rehabilitation using resistance exercises is the best supported approach [43]. A general discussion of treatments for tendinopathy is provided separately. (See "Overview of the management of overuse (persistent) tendinopathy".)
Rehabilitation using resistance exercise — We suggest that patients with chronic midportion Achilles tendinopathy be treated with a rehabilitation program that emphasizes resistance exercises using heavy loads, such as weighted heel raises. Programs that emphasize the eccentric portion of exercise movements or both the eccentric and concentric movements may be used. Tables describing a heavy slow resistance rehabilitation program (emphasizes both concentric and eccentric movement) (table 4) and an eccentric exercise rehabilitation program (table 5) are provided [8,44].
Concentric exercise involves a muscle shortening while working against a load; eccentric exercise involves a muscle lengthening while working against a load. As an example, when a person raises their body to the bar during a pull-up the biceps muscles are working concentrically, and when the person lowers their body to the ground the biceps muscles are working eccentrically.
Studies of rehabilitation programs for chronic midportion Achilles tendinopathy that emphasize the eccentric portions of resistance exercise using heavy loads have found this approach to be an effective nonsurgical treatment [45]. Other research suggests that programs using heavy resistance exercise emphasizing both the concentric and eccentric movements produce comparable outcomes [44,45]. Ultrasound and magnetic resonance imaging (MRI) studies performed during the long-term follow-up of patients who participated in rehabilitation programs involving heavy resistance training of either type (eccentric or combined concentric/eccentric loading) show normalization of tendon tissue [46].
Patients may perform other regular exercise while participating in either type of rehabilitation program, provided that the activities do not exacerbate symptoms. Mild discomfort is permissible.
Eccentric exercise training — Small controlled trials and uncontrolled studies have found that eccentric exercise using heavy loads and involving the gastrocnemius and soleus muscles reduces pain at 12 weeks and long-term follow-up (two to five years) and shortens the time needed to return to sports [8,47-50]. A systematic review found there was higher-quality evidence supporting the use of eccentric exercise than alternative treatments for midportion (ie, not insertional) Achilles tendinopathy [43,51]. It is not known whether eccentric exercise prevents tendon injury or chronic tendinopathy in runners or other athletes. A table describing the most rigorously studied eccentric training rehabilitation protocol is provided (table 5) [8]. (See 'Prevention' below.)
Heavy slow resistance training — According to the results of a well-performed, single-blinded randomized trial involving 58 patients with chronic Achilles tendinopathy, heavy slow resistance training emphasizing both the concentric and eccentric portions of the exercises selected produced the same improvements in symptoms, function, and tissue appearance on ultrasound achieved by patients following a training program that emphasized only the eccentric portion of exercises [44]. The improvements were sustained at one-year follow-up. Of note, patient compliance was significantly better among patients performing the heavy slow resistance rehabilitation (92 versus 78 percent in the eccentric training group). This improved compliance may have been related to the time required, which was 107 minutes per week for the heavy slow resistance training and 308 minutes per week for the eccentric training. The training program used in the study is summarized in the attached table (table 4).
Other interventions — Various treatments have been prescribed for chronic Achilles pain. According to a systematic review, high-quality evidence supporting these interventions is limited [43,51]. Some are suggested as adjuncts to eccentric exercise. Such treatments include the following:
●Heel lifts – In a randomized trial of 100 patients with mid-portion Achilles tendinopathy confirmed by ultrasound, use of a heel lift led to clinically significant reductions in pain and improvements in function at 12 weeks [52].
●Heel brace – In a small randomized trial sponsored by the manufacturer of the AirHeel brace, use of the brace improved symptoms and function in patients with chronic Achilles tendinopathy [53]. The results did not differ between patients managed with the AirHeel brace or eccentric rehabilitation.
●Shoe ware – Arch supports, orthotics, and running shoes that are stable and prevent over-supination are commonly prescribed, but studies supporting these interventions are limited, and no benefit has been demonstrated [54,55]. Night splinting is not beneficial [56].
●Low-level laser therapy – This may be a useful adjunct to eccentric exercise, reducing pain during activity according to small randomized trials [57].
●Dry needling – Dry needling is used by some clinicians to treat Achilles tendinopathy. This involves repeated puncture of the tendon at the site of pain using a small needle with the intent of stimulating an inflammatory response, formulation of granulation tissue, ultimately causing tendon healing. (See "Overview of the management of overuse (persistent) tendinopathy".)
●Kinesiotape – Elastic therapeutic skin tape has been used to treat Achilles tendinopathy, but evidence about its effectiveness is limited [58].
●Extracorporeal shockwave therapy – Extracorporeal shockwave therapy (ESWT) uses pressurized air or electromagnetic pulses to deliver shockwaves and is used as an adjunct treatment for a variety of chronic disorders. A systematic review of the effectiveness of ESWT for common lower-limb conditions found only low-level evidence supporting the use of ESWT for Achilles tendinopathy [59]. The evidence suggests that ESWT may be comparable with eccentric training but superior to watchful waiting at four months in the treatment of midportion Achilles tendinopathy and superior to eccentric training at four months but less effective than glucocorticoid injection in the short term for the treatment of insertional Achilles tendinopathy.
●Topical nitroglycerin (glyceryl trinitrate) – Nitroglycerin patches are placed directly over affected tendons to deliver nitric oxide, a potent signaling molecule that stimulates collagen synthesis in tendon cells. This treatment for tendinopathy is discussed in greater detail separately. (See "Overview of the management of overuse (persistent) tendinopathy".)
Controlled studies of topical nitroglycerin (TNG) in the treatment of Achilles tendinopathy report mixed results. A trial of 65 patients randomly assigned to treatment with physical therapy and TNG or physical therapy alone reported significant reductions in pain with activity and at night at 12 weeks and improvements in overall function [60]. At six months, 28 of 36 tendons (78 percent) in the TNG group were asymptomatic versus 20 of 41 tendons (49 percent) in the control group. Another trial involving placebo controls reported that patients treated with TNG experienced significantly less pain with activity and at night at 12- and 24-week follow-up and a larger percentage of asymptomatic tendons at six months [61].
Conversely, a trial involving 40 patients reported no significant improvement in outcomes among patients treated with TNG and physical therapy compared with controls treated with physical therapy alone [62]. At six months, no significant difference was found in scores for pain and disability, and histologic examination revealed no differences in neovascularization, collagen synthesis, or stimulated fibroblasts.
Local injection therapies — While a number of injection therapies are used to treat Achilles tendinopathy, evidence is limited, and the most effective of these potential interventions remains unknown. The use of injected biologic therapies such as platelet-rich plasma (PRP) for the treatment of muscle and tendon disorders is discussed in detail separately. (See "Biologic therapies for tendon and muscle injury".)
A systematic review of 13 randomized trials (involving a total of 528 patients) investigating the efficacy and safety of local treatments for Achilles tendinopathy concluded that there is no clear evidence to recommend any particular local treatment over an eccentric load rehabilitation program for the nonoperative management of Achilles tendinopathy [63]. However, the authors identified several treatments that may be useful adjuncts to physical therapy. All trials included in the review reported clinically important functional outcomes. Assessment of methodologic quality was performed using the Coleman Methodology Score (CMS), a validated and reliable instrument, and was found to be good overall.
The following interventions have been used to treat chronic midportion Achilles tendinopathy and were among the treatments studied in the systematic review:
●Glucocorticoid injection – Glucocorticoid injection may provide short-term symptom relief in some patients with Achilles tendinopathy, thereby enabling more active participation in exercise therapy, but evidence is mixed and there are case reports of Achilles tendon rupture after glucocorticoid injection. Glucocorticoid therapy for tendinopathy and the risks associated with such treatment are discussed in greater detail separately. (See "Overview of the management of overuse (persistent) tendinopathy", section on 'Glucocorticoids' and 'Epidemiology and risk factors' above.)
In a well-blinded, randomized trial of 100 patients with Achilles tendinopathy causing symptoms for a minimum of three months, those treated with glucocorticoid injection in addition to exercise therapy experienced greater functional and symptomatic improvement at 3 and 6 months than patients given placebo injections in addition to exercise therapy [64]. However, no significant difference in functional outcomes or tendon thickness was noted at 12 or 24 months. No severe adverse events occurred in either group.
●Platelet-rich plasma injection – PRP is a concentrate containing platelet concentrations greater than that found in whole blood and is thought to contain growth factors that stimulate tissue repair. It is manufactured using centrifugation of the patient's blood. Percutaneous injection of PRP is used by some clinicians to treat tendinopathy. The use of PRP and other biologic therapies in the treatment of tendinopathy is discussed in detail separately. (See "Biologic therapies for tendon and muscle injury".)
Several randomized trials comparing PRP injection with placebo injection and to rehabilitation with eccentric load exercise for the treatment of Achilles tendinopathy have found no significant differences between groups in symptoms or function [65-68].
●Autologous blood injection – Autologous blood is another proposed biologic therapy used by some clinicians to treat tendinopathy. It involves injecting a sample of the patient's blood under ultrasound guidance into the tendon. (See "Biologic therapies for tendon and muscle injury".)
Studies of autologous blood injection for the treatment of Achilles tendinopathy are limited. A randomized trial of 33 patients comparing standard eccentric load rehabilitation with the same rehabilitation program plus a single injection of autologous blood reported slight symptomatic improvement among patients who received the injection, but the follow-up period was only three months [69]. Another randomized trial comparing peritendinous injection of autologous blood with dry needling reported no significant differences in symptoms or function after six months [70]. Both groups were also treated with eccentric load rehabilitation.
●Polidocanol injection – Polidocanol is an example of a sclerosing agent used to treat tendinopathy by reducing neovascularity. A preliminary trial involving 20 patients with Achilles tendinopathy reported benefit [71]. Additional high-quality trials are needed to determine the effectiveness of this intervention.
●Aprotinin injection – Aprotinin is a broad-spectrum protease and matrix metalloproteinase (MMP) inhibitor. In a small randomized trial, patients with Achilles tendinopathy treated with eccentric exercise and aprotinin injection experienced no statistically significant benefit compared with those treated with eccentric exercise and injection with a local anesthetic [72].
●Fibroblast injection – This treatment involves injecting laboratory-expanded, skin-derived fibroblasts suspended in autologous plasma into the injured portion of the Achilles tendon under ultrasound guidance. Evidence is limited, but the results of a small randomized trial suggest that the treatment may be beneficial [73]. Further study is needed.
●Prolotherapy – Prolotherapy involves injecting a natural irritant into injured soft tissue. High-quality studies of prolotherapy for the treatment of Achilles tendinopathy are scant. In a randomized trial, 43 patients with midportion Achilles tendinopathy were assigned to one of three groups: eccentric-load exercise, prolotherapy injection (20% glucose, 0.1% lignocaine, 0.1% ropivacaine), or combined treatment [74]. While the patients treated with prolotherapy experienced a more rapid reduction in symptoms early on, there was no significant difference in symptoms among groups over time.
●Percutaneous ultrasonic tenotomy – This procedure involves inserting a needle-like probe into a damaged tendon. The probe tip oscillates, producing ultrasonic energy that breaks down damaged tissue directly ahead of it. Although this procedure is commonly performed in clinics and outpatient surgical centers to treat a range of chronic tendinopathies, it has only been evaluated in small observational studies. As an example, a retrospective chart review of 34 patients with insertional Achilles tendinopathy treated with percutaneous ultrasonic tenotomy reported reductions in the rate of moderate to severe pain from 68 percent at baseline to 15 percent at long-term follow-up and a satisfaction rate of 70 percent [75].
●High-volume injection – This intervention (sometimes referred to as the Brisement procedure) involves injecting a high volume of fluid (typically consisting of isotonic saline, glucocorticoid, and local anesthetic), under ultrasound guidance, into the paratenon with the intent of reducing pain by disrupting abnormal blood vessels and peripheral nerves. Preliminary studies suggest possible benefit in patients with Achilles tendinopathy, including earlier return to sport, but further study is needed [76-78].
Tendon rupture
Initial care — Initial management of Achilles tendon rupture consists of ice applied to the area, analgesics (acetaminophen and/or NSAIDs are generally sufficient), rest (ie, non-weightbearing with crutches), immobilization with the ankle in some plantarflexion (generally a short-leg splint is used (picture 4)), and referral to an orthopedic surgeon.
Complete tendon rupture
Management options — Surgical consultation should be obtained for all complete Achilles tendon ruptures. The optimal management of Achilles tendon rupture is controversial. Traditionally, surgical treatment was favored due to the low rates of re-rupture. However, a growing body of evidence suggests that surgery does not lead to better long-term functional outcomes than nonoperative management and is associated with higher rates of some short-term complications (eg, infection), although re-rupture rates are lower [79,80]. Management should involve shared decision-making around patients' comorbidities, goals, and preferences.
●Patients who wish to return to heavy labor or a demanding sport involving sprinting and jumping might opt for surgical repair, as these activities increase the risk of re-rupture.
●Non-athletes, older adults, and other patients who are not able to participate in early mobilization or accelerated functional rehabilitation may forego surgery and elect to be treated with immobilization. This is done for six to eight weeks using either a short-leg cast starting with the ankle in plantarflexion or a functional brace with a heel lift (picture 5). Patients managed without surgery should be informed of the greater risk of tendon re-rupture.
A short-leg cast is replaced every one to two weeks, gradually reducing the degree of plantarflexion with each cast, until the ankle is back to neutral position.
Many nonoperative protocols involving a functional brace use three or four heel wedges, each about ¾ inch (2 cm) thick, and removing one wedge every one to two weeks until the ankle is back to neutral position [81]. An optimal protocol for progressively decreasing heel elevation has not been determined. Ideally, casting or bracing is implemented within 48 hours of injury.
●For patients who are found to have ruptured their Achilles tendon many weeks or months prior to diagnosis, immobilization with a brace followed by physical therapy is a reasonable management approach.
Additional high-quality trials comparing treatment approaches for acute Achilles tendon rupture are needed. These trials should include assessments of long-term functional status, including the ability to resume pre-injury work and sports activities, complication rates, and patient satisfaction using validated instruments. Approaches such as minimally invasive surgery and accelerated functional rehabilitation are under study. Pending the completion of such trials, we believe that a personalized approach incorporating fully informed shared decision-making remains essential for the management of acute Achilles tendon ruptures [82].
Surgery versus nonoperative treatment — The efficacy and safety of surgery compared with nonsurgical management for Achilles tendon rupture is a subject of ongoing debate and research. A growing body of evidence supports a nonoperative approach for appropriately selected patients.
A 2021 systematic review and meta-analysis of 12 randomized trials (949 Achilles tendons) of good overall quality, with most performing follow-up at 12 months, reported a re-rupture rate of 3.5 percent (n = 17) in the surgery group and 12.1 percent (n = 57) in the non-surgery group (RR 0.30; 95% CI 0.18-0.50), with complication rates (excluding re-ruptures) of 18.5 percent (n = 37) in the surgery group and 7.1 percent (n = 4) in the non-surgery group [83]. Episodes of deep vein thrombosis or pulmonary embolism were uncommon in both groups, but infections occurred significantly more often in surgical patients (5.6 percent of cases). Some early studies suggested that there was an increased risk of sural nerve injury with minimally invasive surgery [84], but this has not been borne out in subsequent trials [83].
In a well-conducted multicenter trial performed after the meta-analysis, 526 patients with acute Achilles tendon rupture were randomly assigned to nonoperative management, minimally invasive surgical repair, or open surgical repair [80]. The results of this trial were largely consistent with the meta-analysis: While no significant difference was found in functional outcomes overall (determined primarily with the Achilles Tendon Total Rupture Score), patients managed nonoperatively did have a higher re-rupture rate (6.2 percent [11 re-ruptures] versus 0.6 percent [1 re-rupture] for each surgical treatment) at 12-month follow-up. The higher re-rupture rate occurred despite following a well-designed, dynamic physical therapy program.
For patients treated with surgery, two to three months off from work that requires ambulation is generally required. Athletes typically return to sport by three to six months, once they have regained adequate strength and mobility. However, additional time is often required to achieve full function [85]. According to a systematic review of 10 studies involving 570 patients, the combination of early ankle mobility exercises and early weightbearing was associated with better functional outcomes without differences in major complications compared with the conventional approach to postoperative immobilization [86].
Nonoperative treatment: casting versus bracing — Standard nonoperative management of a complete Achilles tendon rupture has involved immobilization in a cast for several weeks. While a well-made cast provides excellent protection and immobilization for healing, it may increase the risk for muscle atrophy, loss of ankle mobility, deep vein thrombosis, and chronic disability. Immobilization in a removable, functional brace is a viable alternative that allows for early use of mobility and strength exercises, as appropriate.
When the clinician and patient opt for nonoperative management of an Achilles tendon rupture, we believe functional bracing is a good treatment approach for highly compliant patients. We hesitate to use a functional brace in a young, active athlete or anyone else likely to stress the tendon before it has healed sufficiently. We generally prefer surgery for such patients. Of note, for functional bracing to work effectively, the elevation of the heel must be systematically lowered about every two weeks. This prevents the tendon from shortening excessively during healing. (See 'Management options' above.)
In a multicenter randomized trial of 540 patients (the large majority middle aged and healthy) with acute Achilles tendon rupture, there were no statistically or clinically significant differences in the Achilles Tendon Rupture Score, a well-validated outcome score, or tendon re-rupture at nine months [87,88]. Studies of functional bracing are limited in number, so precise comparisons cannot be made, but the overall tendon re-rupture rate in patients managed with bracing appears higher than that of patients treated surgically and comparable to patients managed with casting [87,89].
Partial tendon rupture — The clinical diagnosis of partial Achilles tendon tear or rupture is imperfect, and studies to determine optimal management are lacking. The increasing use of ultrasound and MRI may improve this situation. It remains unclear whether surgery or nonoperative management leads to better outcomes [90,91]. We treat most cases of partial Achilles tear nonsurgically, as we would chronic tendinopathy. (See 'Chronic tendinopathy' above.)
Partial tears can be painful. To reduce discomfort, initial management may include immobilization in a controlled ankle motion (CAM) boot (picture 6). Physical therapy or home exercises are needed to prevent the loss of motion and strength that can result from immobilization.
FOLLOW-UP CARE — Approximately 80 percent of athletes return to play following rupture of their Achilles tendon [92]. Prevention of reinjury is central to follow-up care. Ten percent of Achilles tendon ruptures occur in previously injured tendons. Prevention of Achilles tendon injury is discussed immediately below.
Although no studies demonstrate the benefit of eccentric exercise in the prevention of acute Achilles tendon injury, we suggest that patients continue to perform these exercises once rehabilitation has been completed and symptoms have resolved. We believe this may be of particular benefit to athletes embarking upon a more intense training regimen. (See 'Chronic tendinopathy' above.)
Some patients treated for chronic Achilles tendinopathy have persistent symptoms, but it is unclear whether this is true of patients who complete a properly designed rehabilitation program emphasizing heavy resistance exercise. Patients who do not fully recover may experience reinjury [93].
COMPLICATIONS — Major complications associated with Achilles tendon tear include reinjury and thromboembolism [94,95]. Complications associated with surgical management are discussed above. (See 'Complete tendon rupture' above.)
Complication rates vary according to a number of factors, including the severity of injury, patient age and comorbidities, and treatment. According to a review of a Danish national registry, of the 28,546 patients who sustained an Achilles tendon rupture between 1997 and 2015, 389 (1.36 percent) were hospitalized for thromboembolic complications following treatment [96]. The risk for such complications was highest among those with a history of previous venous thromboembolism, men over 50 years treated nonoperatively, and women younger than 50 years taking hormonal contraceptives. Prophylaxis against thromboembolic complications following orthopedic injury is discussed separately. (See "Prevention of venous thromboembolism in adults undergoing hip fracture repair or hip or knee replacement".)
PREVENTION
General measures — Several interventions may reduce the risk of developing new or recurrent Achilles tendinopathy and other injuries of the lower extremity. Such interventions are discussed in detail separately. Interventions and studies of special relevance to preventing tendinopathy and tendon rupture of the Achilles are described below. (See "Overview of running injuries of the lower extremity", section on 'Training suggestions to reduce injury risk'.)
Before engaging in any vigorous exercise, it is important to perform an appropriate dynamic warm-up. Although few studies have assessed the Achilles tendon specifically in this regard, the findings of a prospective, observational study of infantry recruits suggest that performing such a warm-up and avoiding cold-weather training reduces the risk of Achilles tendinopathy [9]. Additional support may be helpful for some patients as they resume activity (picture 3).
Clinical studies evaluating the impact of stretching specifically upon Achilles tendinopathy are lacking. Nevertheless, many clinicians believe imbalances in muscle strength or flexibility predispose some athletes to injury. We believe it is reasonable to include stretching following exercise or a warm-up as part of an Achilles injury prevention regimen. Typical techniques include stretching the gastrocnemius and soleus muscles while bracing one's hands against a wall. Stretches are performed both with the knee bent and straight. The stretch can be performed by standing on the edge of a step and letting the heel descend gradually, or by dorsiflexing the foot using a stretch band. It may be helpful for patients to undergo assessment by an athletic trainer, physical therapist, or sports medicine specialist to identify imbalances in flexibility or strength and to receive instruction in appropriate training techniques.
Although high body mass index (BMI) is associated with tendon problems, no studies clearly show that weight loss prevents such problems. Nevertheless, common sense suggests that obese patients should try to lose weight in order to reduce strain on the lower extremity, among many other health benefits. (See "Obesity in adults: Overview of management" and "Overweight and obesity in adults: Health consequences".)
Measures for patients on fluoroquinolones — The risk of fluoroquinolone-associated tendon problems is low. However, in general, we prefer to avoid treatment with a fluoroquinolone in a patient with known tendinopathy or tendon injury if an equally effective alternative treatment with a better safety profile is available. (See "Fluoroquinolones", section on 'Tendinopathy'.)
For athletes or highly active patients who require fluoroquinolone treatment, it is reasonable to take precautions to reduce the risk of Achilles tendinopathy or tendon rupture. High-quality evidence to determine what measures are most effective is lacking, but the following steps are reasonable [97]:
●Beginning with the first fluoroquinolone dose, athletes should reduce their training volume and intensity and maintain these reductions throughout the course of antibiotics. No high-intensity training or ballistic activities (eg, sprinting, jumping, full-speed scrimmages or competition) are permitted until two to four weeks after the completion of fluoroquinolone therapy.
●Runners should decrease total mileage to 60 percent of normal training volume for the first seven days of therapy, and hill and speed interval training should be avoided. Runners who remain free of symptoms two weeks after the completion of therapy may increase mileage by 10 percent per week but should not implement speed or hill training for two additional weeks. If they choose to race during this time, they should be informed of the relatively higher risk of Achilles rupture.
●Athletes who participate in field sports (eg, soccer, football) or other multidirectional activities (eg, tennis) that increase the risk of Achilles injury may choose to resume normal activity and competition two to four weeks after the completion of fluoroquinolone therapy. However, it is best to increase activity gradually, and athletes who resume full activity sooner than four weeks should be informed of the higher relative risk of Achilles rupture.
●Athletes who have no symptoms during therapy and complete the full course of the antibiotic can begin a graduated return to full activity as described above but should monitor themselves closely for any musculoskeletal symptoms at or around the Achilles tendon. They should cease all athletic activity should symptoms develop during this period and be assessed by a knowledgeable clinician. Assuming there is no injury, they may resume a graduated return to full activity once symptoms resolve.
●Athletes who develop symptoms or tenderness around the Achilles tendon while taking a fluoroquinolone antibiotic or in the first three to six months after beginning this treatment merit objective evaluation, preferably with musculoskeletal ultrasound, to assess for findings of tendinopathy or other injury. Individuals with findings suggesting tendinopathy typically require an eccentric exercise rehabilitation program and possibly adjunctive therapy. Their return to play depends upon clinical response and averages 6 to 12 weeks. (See 'Diagnostic imaging' above and 'Rehabilitation using resistance exercise' above.)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General issues in muscle and tendon injury diagnosis and management" and "Society guideline links: Achilles tendon injury".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Achilles tendon injury (The Basics)" and "Patient education: Using crutches (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Epidemiology and mechanism of injury – Acute Achilles tendon pain generally develops when athletes abruptly increase their training intensity. Chronic tendon pain (>3 months) may result from sustained stress, poor running mechanics, or improper footwear. Rupture occurs when a sudden shear stress is applied to an already weakened or degenerative tendon. (See 'Epidemiology and risk factors' above and 'Mechanism of injury and pathophysiology' above.)
●Differential diagnosis – Pain arising from the region between the posterior calcaneus and the gastrocnemius-soleus muscle complex may be caused by a number of conditions (table 3). Ankle sprain is the most common misdiagnosis when tendon rupture is the actual cause of pain. Do not assume rupture is absent because the patient can plantarflex or walk. (See 'Differential diagnosis' above.)
●Clinical presentation – Patients with Achilles tendinopathy typically experience pain or stiffness 2 to 6 cm above the posterior calcaneus. They are likely to be casual or competitive athletes who have recently increased their training intensity. Pain increases with activity and diminishes with a period of rest.
Tendon rupture occurs when sudden forces are exerted upon the Achilles during strenuous activities that involve sudden pivoting on a foot or rapid acceleration. Patients may hear a "pop" and experience severe, acute pain, although the absence of pain does not rule out rupture. (See 'Clinical presentation' above.)
●Physical examination – Examination should include palpation of the tendon for tenderness, thickening, or a defect. Note that edema or a hematoma may mask a defect. Patients with tendinopathy typically have localized tenderness 2 to 6 cm above the tendon insertion. Pain at the insertion point suggests calcaneal bursitis or possibly enthesopathy. (See 'Physical examination' above.)
The calf squeeze (ie, Thompson compression) test provides an accurate means of detecting complete Achilles tendon rupture (picture 2). A sizable minority of patients with complete tendon rupture are able to ambulate. (See 'Physical examination' above.)
●Diagnostic imaging – Achilles tendinopathy (without rupture) is a clinical diagnosis. Imaging is often unnecessary. Plain radiographs are generally unhelpful. Musculoskeletal ultrasound and magnetic resonance imaging (MRI) are accurate tests that can be used to aid in the diagnosis of Achilles tendon rupture, particularly if examination findings are unclear but clinical suspicion remains high. (See 'Diagnostic imaging' above.)
●Indications for surgical referral – All complete tendon ruptures merit surgical consultation. Partial tendon tears and chronic tendinopathy that fail to improve with three to six months of conservative treatment may benefit from consultation with a specialized runners' clinic, sports medicine specialist, physical therapist, or orthopedic surgeon. (See 'Indications for referral' above.)
●Management of tendinopathy – Acute Achilles tendinopathy is treated in standard fashion with rest, ice, and tendon support (eg, heel lift). For chronic midportion tendinopathy (>3 months symptoms), we suggest using a rehabilitation program that emphasizes resistance exercise using heavy loads (table 5). Rehabilitation protocols that emphasize concentric and eccentric movements or only eccentric movements are both reasonable approaches. Exercise programs and other possible interventions for chronic Achilles tendinopathy are discussed in the text. (See 'Acute tendinopathy' above and 'Chronic tendinopathy' above.)
●Management of tendon tear – Surgical consultation should be obtained for all patients with a complete Achilles tendon rupture. The management approach selected will vary based on the patient’s comorbidities, goals, and preferences:
•For active patients who place a high value on regaining preinjury levels of activity quickly and are willing to accept a higher rate of treatment complications (primarily infection), we suggest that Achilles tendon rupture be treated with surgical repair (Grade 2B). Minimally invasive surgical repair may reduce postoperative complications (eg, infection) without increasing the risk of re-rupture compared with open repair. For some active patients, nonoperative management with accelerated functional rehabilitation may be a reasonable alternative. (See 'Complete tendon rupture' above.)
•Inactive patients and those unwilling to accept the higher complication rates of surgery may opt for nonoperative management with either casting or a brace. For highly compliant patients, treatment with a removable, functional brace allows for earlier performance of progressive mobility and strength exercises, and ultimately earlier weightbearing, without increasing the risk of re-rupture.
•For patients with a complete Achilles tendon rupture and who are able to participate in a rigorous physical therapy program, we suggest that treatment include early mobilization and accelerated functional rehabilitation, regardless of whether they undergo surgery or opt for nonsurgical management (Grade 2B).
●Prevention – Several interventions may reduce the risk of developing lower extremity injuries, including Achilles tendinopathy. (See "Overview of running injuries of the lower extremity", section on 'Training suggestions to reduce injury risk' and 'Prevention' above.)
ACKNOWLEDGMENT — The editorial staff at UpToDate acknowledge Peter Ham, MD, now deceased, who contributed to an earlier version of this topic review.
