Achilles tendon rupture

INTRODUCTION — 

The Achilles is the largest tendon in the body and endures large loads during running, jumping, and sudden acceleration or deceleration. Thus, the tendon is at risk of acute injury, particularly during competitive and recreational athletics.

The mechanism, diagnosis, and management of Achilles tendon rupture are reviewed here. Achilles tendinopathy and other injuries and conditions affecting the ankle and heel region are discussed separately. (See "Achilles tendinopathy" and "Calf injuries not involving the Achilles tendon" and "Ankle sprain in adults: Evaluation and diagnosis" and "Ankle fractures in adults".)

EPIDEMIOLOGY AND RISK FACTORS — 

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 [1-4]. 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 [5].

Tendon rupture occurs in 8.3 percent of competitive athletes. Competitive athletes with a high lifetime incidence of tendon rupture include sprinters (18 percent), decathletes (17 percent), football (soccer) players (17 percent), track and field jumpers (12 percent), basketball players (12 percent), and ice hockey players (9 percent) [6].

Increased age, male sex, and obesity are risk factors for Achilles tendon problems (table 1) [7-9]. 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 [1]. As participation in recreational sports has increased over the past 50 years, so has the rate of tendon rupture [10]. Achilles tendon rupture is rare among children and more likely to be sustained through direct, often penetrating, trauma [11]. Childhood injuries involving the Achilles tendon and other structures around the heel are discussed separately. (See "Heel pain in the active child or skeletally immature adolescent: Overview of causes".)

Fluoroquinolone antibiotics are rarely associated with Achilles tendinopathy or tendon rupture [12,13]. A study of 46,776 patients treated with fluoroquinolones found 3.2 cases of tendon problems for every 1000 years of exposure [14]. 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) [15]. The risk of suffering an Achilles tendon rupture is increased threefold during the first 90 days among patients taking fluoroquinolone for the first time [16]. The mechanism remains unknown. Age older than 60 years and concurrent use of systemic glucocorticoids appear to compound the risk [14,17-19]. Past fluoroquinolone use does not appear to confer future risk. (See "Fluoroquinolones", section on 'Tendinopathy'.)

Other potential risk factors with less support in the medical literature include glucocorticoid or oral bisphosphonate medication and chronic medical conditions such as diabetes, impaired kidney function, and hyperparathyroidism [8]. Findings from a case-control study with 182 Achilles tendon ruptures suggest that smoking and high concentrations of total cholesterol or uric acid elevate risk [9].

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 (figure 4) cushion the insertion area anteriorly and posteriorly. Tendon rupture typically occurs where the blood supply to the Achilles tendon and gastrocnemius-soleus muscle complex is poorest, 2 to 6 cm above the insertion point [20]. A peritendinous sheath of connective tissue allows the tendon to slide relative to surrounding tissue.

MECHANISM OF INJURY AND PATHOPHYSIOLOGY — 

Recurrent microtrauma causes degeneration of the Achilles tendon [10,21]. The relative hypovascularity of the tendon 2 to 6 cm from its insertion point may prevent adequate healing [20]. 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 gradually 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.

CLINICAL PRESENTATION — 

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 football [soccer]; running up a flight of stairs). In contrast with ankle sprains, where injury occurs with landing, symptom onset with tendon rupture generally occurs as the patient is pushing off with their foot. 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 [22].

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. (See "Lower extremity peripheral artery disease: Clinical features and diagnosis".)

Palpate the entire length of the Achilles tendon for tenderness, thickening, or a defect, recognizing that edema or a hematoma may mask such a defect. 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. A deficit from a tendon tear (or localized tenderness from tendinopathy) is typically present about two to six centimeters proximal to the insertion of the tendon (picture 1), a region of hypovascularity. Palpation has a sensitivity of approximately 73 percent and a specificity of 89 percent in detecting a partial tendon tear [23]. Comparison with the unaffected side is often helpful. (See 'Clinical anatomy' above.)

Special tests — The calf squeeze (or Thompson) test and the Matles test are useful maneuvers for detecting a ruptured Achilles tendon.

●Calf squeeze test – To perform the calf squeeze 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 (picture 2 and movie 1). The absence of plantarflexion when squeezing the gastrocnemius muscle marks a positive test, indicative of rupture.

●Matles test – To perform the Matles test, the patient lies prone with knees flexed to 90 degrees (picture 3). Observe whether the affected foot is dorsiflexed or neutral (both are abnormal) compared with the uninjured side, where the foot should appear plantarflexed.

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 to 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 [23]. 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 sensitivity and specificity of the Matles test were 88 percent and 85 percent, respectively, in the study described above [23].

DIAGNOSTIC IMAGING — 

Achilles tendon rupture may be diagnosed solely by clinical examination, but ultrasound enables rapid bedside confirmation of the diagnosis [23-26]. 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 (movie 2) [25,26]. In a meta-analysis of 15 studies involving 808 patients, ultrasound was reported to have 94.8 percent sensitivity (95% CI 91.3-97.2) and 98.7 percent specificity (95% CI 97-99.6) when assessing Achilles tendon tears, using surgical findings as the gold standard in many cases [26].

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, typically sagittal and transverse views. Visualized lack of continuity of tendon fibers is an indication for surgical repair. Performance of the ultrasound examination is discussed in detail separately. (See "Musculoskeletal ultrasound of the ankle and hindfoot".)

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 [27].

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 (table 3). Injuries and conditions more likely to be mistaken for Achilles tendon tear are discussed below. (See "Hindfoot pain in adults: Evaluation and diagnosis of common causes".)

●Ankle sprain – Ankle sprain is the most common misdiagnosis when Achilles tendon rupture is the actual cause of pain [22]. Differentiating the two can be difficult. In contrast with ankle sprains, where injury occurs with landing, symptom onset with tendon rupture generally occurs as the patient is pushing off (plantar-flexing) forcefully with their foot. Do not assume rupture is absent because the patient can ambulate or plantarflex their ankle. The tibialis posterior and peroneus longus provide significant strength in plantarflexion and compensate partially for a ruptured Achilles tendon. Imaging, including ultrasound, is effective for identifying injured tendons and ligaments in the ankle region. (See "Ankle sprain in adults: Evaluation and diagnosis".)

●Achilles tendinopathy – Achilles tendon rupture occurs acutely with sudden onset of pain and disability. In contrast, tendinopathy develops gradually over weeks to months. Palpation of the tendon at rest and while the patient dorsiflexes and plantarflexes the foot, often reveals a gap when rupture has occurred. The absence of a gap and the presence of crepitus with motion suggest tendinopathy. The Thompson squeeze and Matles tests are negative with tendinopathy. Ultrasound reveals the presence of a significant tendon tear and can reveal findings consistent with tendinopathy. (See "Achilles tendinopathy".)

●Gastrocnemius muscle tear – Gastrocnemius muscle tear, partial or complete, occurs from a sudden overstretch of the muscle, such as during rapid pivoting maneuvers, jumping, or sudden deceleration during sport. Most often, tears occur in the medial gastrocnemius near the distal musculotendinous junction and cause sudden pain. Tenderness localized to the medial distal calf, bruising, and swelling are present, while ankle dorsiflexion exacerbates pain. Sometimes a palpable defect is present in the medial belly of the gastrocnemius just above the musculotendinous junction. With isolated gastrocnemius tears, no gap is palpable and no tenderness is present in the Achilles tendon. Ultrasound can help to identify gastrocnemius injury. MRI can provide a definitive diagnosis but is usually not necessary. (See "Calf injuries not involving the Achilles tendon".)

●Posterior tibialis tear – Although not common, tear or complete rupture of the posterior tibialis tendon can cause posterior ankle swelling that may be mistaken for Achilles tendon injury. In a series of 17 patients with posterior tibial tendon rupture, an average of 43 months passed before the diagnosis was established [28]. Typically, the mechanism involves forced ankle eversion (rather than forceful ankle plantar flexion). Younger patients, usually athletes, tend to sustain a traumatic avulsion at the insertion on the navicular; middle-aged or older adults often sustain a mid-substance, degenerative tear [29]. Examination may reveal tenderness along the course of the posterior tibialis tendon, a palpable defect in the tendon, and loss of the medial longitudinal arch if the tendon is completely ruptured, creating the appearance of a flat foot, and a positive "too many toes" sign (figure 5) [30]. With isolated posterior tibialis tears, no gap is palpable and no tenderness is present in the Achilles tendon.

●Peroneal tendon dislocation or tear – Acute trauma to the lateral ankle may cause dislocation or a tear of the peroneal tendon. These peroneal tendon injuries are associated with pain and swelling at the posterolateral leg, generally along the course of the tendons as they travel around the lateral malleolus, a location distinct from the Achilles tendon. Dislocation results from an incompetent or torn superior peroneal retinaculum. (See "Non-Achilles ankle tendinopathy", section on 'Differential diagnosis of lateral ankle tendinopathy'.)

●Soleus muscle tear – Full or partial tear of the soleus muscle is uncommon but usually occurs during forceful eccentric contraction of the calf muscles (ie, muscles elongating during contraction). Partial tears occur more often than complete ruptures, which usually occur at the site where the soleus muscle attaches to the Achilles tendon. Pain increases with contraction of the posterior calf muscles (ankle plantar-flexors). With isolated Soleus muscle tear, no gap can be palpated in the Achilles tendon and the Thompson squeeze and Matles tests are negative.

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 being managed conservatively that fail to improve with three to six months of treatment may benefit from consultation with a specialized runners' clinic, sports medicine or physical medicine and rehabilitation specialist, physical therapist, or orthopedic surgeon [31]. (See 'Treatment' below.)

TREATMENT

Initial care — Initial management of Achilles tendon rupture consists of ice applied to the area, analgesics (acetaminophen and/or nonsteroidal antiinflammatory drugs [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, and re-rupture continues to be significantly less common following surgical repair [32,33]. 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) [34]. Management should involve shared decision-making around patients' comorbidities, goals, and preferences [35].

●Heavy laborers and athletes – Patients who wish to return to heavy labor or a demanding sport involving sprinting and jumping often opt for surgical repair, as these activities place greater stress on the tendon and increase the risk of re-rupture.

●Patients seeking to avoid surgery or unable to perform functional rehabilitation – Nonathletes, older adults, and other patients who wish to avoid surgery or are not able to participate in early mobilization or accelerated functional rehabilitation may 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 basic rehabilitation program for patients who choose to be treated with functional rehabilitation is provided (table 4).

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 3/4 inch (2 cm) thick, and removing one wedge every one to two weeks until the ankle returns to neutral position [36]. An optimal protocol for progressively decreasing heel elevation has not been determined. Ideally, casting or bracing is implemented within 48 hours of injury.

●Patient with chronic rupture – 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.

Approaches such as minimally invasive surgery merit strong consideration based on a systematic review and meta-analyses that showed equivalent functional outcomes and re-rupture rates and a number of advantages [37].

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 basic rehabilitation program for patients who choose to be treated with functional rehabilitation is provided (table 4). For older adult patients (over 70 years) and others likely to be at lower risk of tendon re-rupture or who wish to avoid surgery, conservative care offers a reasonable treatment option [38].

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 [39]. Rates of return to play do not differ significantly between those treated surgically and nonoperatively [40].

Early mobility following surgical repair appears to be beneficial. According to a systematic review of 14 studies involving 1007 patients, the combination of early ankle mobility exercises and early weight-bearing was associated with better functional outcomes without differences in major complications compared with conventional approaches to postoperative immobilization, although differences did not reach statistical significance [41].

Re-rupture rates are consistently lower with surgical repair. 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 nonsurgery group (risk ratio [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 nonsurgery group [32]. 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 [42], but this has not been borne out in subsequent trials [32,33].

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 [43]. The results of this trial were largely consistent with the meta-analysis: While no significant difference was found in functional outcomes overall (as determined by the Achilles Tendon Total Rupture Score and rigorous, blinded physical testing), 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. Comparing open to minimally invasive surgery, the risk of skin infection is slightly higher with open repair and the risk of transient sural nerve injury is higher with minimally invasive surgery [37].

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 young (eg, adolescent), active athletes 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.

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 [44,45]. 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 with patients managed with casting [44,46].

Partial tendon tear — The clinical diagnosis of partial Achilles tendon tear or rupture is imperfect, and studies to determine optimal management are lacking. Examination findings and maneuvers such as the calf squeeze test are accurate but not infallible and a complete tendon rupture may be mistaken for a partial tear. The increasing use of ultrasound and MRI may improve this situation. If a clinician has any doubt about the extent of injury, they should assume a complete tear is present and manage appropriately, including obtaining diagnostic imaging and timely surgical referral.

It remains unclear whether surgery or nonoperative management leads to better outcomes [47,48]. We treat most cases of partial Achilles tear nonsurgically, as we would chronic tendinopathy. (See "Achilles tendinopathy", section on 'Chronic tendinopathy'.)

Partial tears can be painful. To reduce discomfort, initial management may include immobilization in a controlled ankle motion (CAM) boot (picture 6), possibly including a heel lift that places the ankle in some plantar flexion, thereby reducing stress on the Achilles. 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 [49]. 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 below.

COMPLICATIONS — 

Major complications associated with Achilles tendon tear include reinjury and thromboembolism [50,51]. Complications associated with surgical management are discussed 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 [52]. 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 tendinopathy and other injuries of the lower extremities. Such interventions are discussed in detail separately. Interventions and studies of special relevance to preventing Achilles tendon rupture are described below. (See "Running injuries of the lower extremities in adults: Risk factors and prevention", section on 'Training suggestions to reduce injury risk'.)

●Gradual, dynamic warm-up before rigorous exercise – 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 [53].

●Structural support – Evidence demonstrating that wraps or braces reduce the risk of Achilles injury is lacking. However, additional support, such as a neoprene sleeve (picture 7) or taping (picture 8), may be helpful for some patients as they resume activity after recovering from such an injury.

●Mobility and strength exercises – Clinical studies evaluating the impact of stretching specifically upon Achilles tendon injury are lacking. Nevertheless, many clinicians believe imbalances in muscle strength or flexibility or both predispose some athletes to injury.

We believe it is reasonable to include stretching after exercise or a dynamic warm-up as part of an Achilles injury prevention regimen. Typical techniques include stretching the gastrocnemius (picture 9) and soleus muscles while bracing one's hands against a wall. Stretches are performed both with the knee bent and straight. The stretch can also 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.

Heavy load exercises of the type used in the treatment of Achilles tendinopathy improve the strength, mobility, and tissue quality of the lower leg (picture 10). While there is little evidence about their role in prevention, we believe that incorporating such exercises into the patient's exercise program is a sensible intervention. (See "Achilles tendinopathy", section on 'Rehabilitation using resistance exercise'.)

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.

●Weight loss – Although high body mass index (BMI) is associated with tendon problems, no studies demonstrate that weight loss prevents such problems. Nevertheless, common sense suggests that obese patients should try to lose weight to reduce strain on the lower extremity, among many other health benefits. Appropriate programming should include a dynamic warm-up, gradual increases in intensity and duration, and exercises to improve Achilles tendon flexibility and strength, as above. (See "Obesity in adults: Overview of management" and "Overweight and obesity in adults: Health consequences".)

Injury risks associated with fluoroquinolones — The risk of fluoroquinolone-associated tendon problems is low. However, in general, we prefer to avoid treatment with 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. These measures are described separately. (See "Achilles tendinopathy", section on 'Measures for patients on fluoroquinolones'.)

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 5^th to 6^th 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 10^th to 12^th 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: How to use crutches (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Epidemiology and mechanism of injury – Achilles tendon rupture occurs when a sudden shear stress is applied to an already weakened or degenerative tendon. (See 'Epidemiology and risk factors' above.)

●Differential diagnosis – 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 (table 2). (See 'Differential diagnosis' above.)

●Clinical presentation – Achilles 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. (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 'Special tests' above.)

●Diagnostic imaging – Achilles tendon rupture is often diagnosed clinically. Plain radiographs are generally unhelpful. Musculoskeletal ultrasound and MRI are accurate tests that can be used to diagnose 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 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 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:

•Heavy laborers, athletes, other highly active adults – For active patients who place a high value on regaining preinjury levels of activity with a lower risk of re-rupture, 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 is a reasonable alternative. (See 'Complete tendon rupture' above.)

•Patients who are inactive, seeking to avoid surgery, or unable to perform functional rehabilitation – 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 weight-bearing, with functional outcomes the same as surgical repair. However, re-rupture rates are higher.

•Functional rehabilitation – For patients with a complete Achilles tendon rupture who are able to participate in a rigorous physical therapy program (table 4), we suggest that treatment include early mobilization and accelerated functional rehabilitation, rather than a longer period of rest followed by traditional rehabilitation (Grade 2C). We prefer this approach regardless of whether patients undergo surgery or nonsurgical management.

●Prevention – Several interventions may reduce the risk of developing lower extremity injuries, including Achilles tendinopathy. (See "Running injuries of the lower extremities in adults: Risk factors and prevention", section on 'Training suggestions to reduce injury risk' and "Achilles tendinopathy", section on 'Prevention'.)

ACKNOWLEDGMENT — 

The editorial staff at UpToDate acknowledge Peter Ham, MD, who contributed to an earlier version of this topic review.