Continuing Education Activity

The Achilles tendon ranks as the strongest tendon in the human body connecting the plantaris, gastrocnemius, and soleus to the calcaneus bone. This activity reviews the evaluation and management of achilles tendonitis, and highlights the role of the interprofessional team in caring for patients suffering from achilles tendonitis and related conditions.

Objectives:

• Review the risk factor for developing achilles tendonitis.
• Outline the typical presentation of a patient with achilles tendonitis.
• Review treatment options for patients with achilles tendonitis.
• Review the importance of improving care coordination amongst interprofessional team members to improve outcomes for patients afflicted by achilles tendonitis.

Introduction

The Achilles tendon ranks as the strongest tendon in the human body. This tendon connects the plantaris, gastrocnemius, and soleus to the calcaneus bone. A sheath-like structure comprised of a single layer of cells surrounds the tendon; this is called the paratenon. The paratenon supplies a significant portion of the blood supply to the tendon. Studies have shown an area of hypovascularity 2 to 6 cm proximal to calcaneal insertion; this is a common area of injury. The Achilles tendon allows the calf muscles to act on the heel, which is necessary for walking or running. The tendon has several causes of injury as well as several locations that are the most commonly injured. In this review, we will discuss insertional tendinitis, mid-body Achilles tendonitis, paratenonitis, and tendon rupture. Please refer to the tendinosis chapter for more information regarding the histological differences between tendinitis and tendinosis. 

Etiology

The causes and mechanisms of Achilles tendinopathy (AT) include the following:

• Intrinsic factors: This includes anatomic factors, age, sex, metabolic dysfunction,[1] foot cavity, dysmetria, muscle weakness, imbalance, gastrocnemius dysfunction,[2] anatomical variation of the plantaris muscle,[3] tendon vascularization,[4] torsion of the Achilles tendons,[5] slippage of the fascicle,[6] and lateral instability of the ankle.

• Extrinsic factors: These include mechanical overload, constant effort, inadequate equipment,[7] obesity,[8] medications (corticosteroids, anabolic steroids, fluoroquinolones,)[9][10], improper footwear, insufficient warming or stretching,[11] hard training surfaces, and direct trauma, among others.[12]

Factors related to a high risk of rupture of the Achilles tendon link to advanced age due to a lack of uniformity of the tendons, slippage of the fascicles, and excessive exercise in athletes,[13] Sports minded individuals tend to have an injury at the Achilles tendon insertion site.[14]

Epidemiology

The Achilles tendon has a cumulative lifetime injury incidence of approximately 24% in athletes. Running-related injuries have a prevalence between 11% and 85% or 2.5 to 59 injuries per 1000 hours of running [15]. Results from one study cite the frequency of Achilles tendinopathy to be 1 to 2% in elite adolescent athletes [16]. Another study cited the frequency of injury as 9% in recreational athletes, [17]. The lifetime injury incidence of 2.35 per 1000 is strongly associated with sporting activities.[18][19][20] This incidence increases in older men.[21] The overall incidence rate of Achilles tendinopathy ruptures is 2.1 per 100000 person-years, and most AT ruptures occur in males, with a 3.5 to 1 male to female ratio.[22]

Pathophysiology

The Achilles tendon has two tendinous portions; one proximally and then another merging gradually distally, resulting in a single, homogenous tendon. It comprises three muscular heads; the soleus is monoarticular and the plantaris and gastrocnemius, which are biarticular. There are two sites where the mechanical tension of the tendon occurs, the medial/central portion of the paratenon and the middle part of the tendon which is the most common site of injury.[23]

Histopathology

The Achilles tendon is comprised of type I collagen fibers; these fibers are both very strong and very flexible. The tendon is covered in a thin layer of connective tissue known as paratenon, which is rich in elastin and penetrates into the tendon, keeping the collagen bundles together while allowing movement between them.[24]

The difference between tendinosis and tendinitis is that in the former there are degenerative changes in the tendon's structure and the sheath, making it more vulnerable and prone to breaking. At the cellular level, there is no evidence of an acute or recent inflammatory process. In tendinitis, the opposite happens; there is an acute inflammatory process, resulting from acute trauma, excessive use, or lack of training.[25] Paratenonitis is an inflammation of the outer layers of the tendon and encompasses conditions such as tenosynovitis and tenovaginitis.[26] This pathology generates edema and exudate with inflammatory cells, followed by a fibrinous exudate that causes crepitus and limitation of the tendinous course within the sheath. It can become chronic by developing an immature connective tissue that expands an organized fibrin network known as adhesions.[27]

One study found that the microenvironment of the Achilles tendon in rats induced the stem cells to differentiate into chondrogenic and osteogenic lineages, which predispose to tendon rupture (tendinosis). After this rupture, an inflammatory cascade appears that increases the expression of proinflammatory cytokine mRNA, matrix metalloproteinase-3 (MMP-3), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6) and necrosis factor tumor alpha (TNF-a).[28]

However, the chronic inflammation induces neovascularization that promotes the rupture of the tendon, increasing disability and complexity in management.[29] In a study with rats, researchers observed that denervated tendons express morphological changes such as disorganization of the collagen network, increased production of type III collagen, hypercellularity; disfigured cells, and increased expression of NK-1R, somewhat similar changes to Achilles tendon injury.[30]

History and Physical

The term "Achilles tendinopathy" refers to tendinitis (acute inflammation) and tendinosis (chronic inflammation). It is a condition characterized by pain, inflammation, and stiffness of the Achilles tendon. The inflammation limits lower extremity functionality. Achilles tendinopathy takes a long time to heal; over time there is thickening of the tendon and loss of elasticity. The pain is related to an alteration of the mechanical properties of tension and rigidity of the aponeurosis of the Achilles tendon.[31][32][33]

Evaluation

Physical exploration:  Clinical signs and symptoms of Achilles tendinopathy include localized pain, focal or diffuse sensitivity,  swelling, stiffness/morning pain, perceived rigidity in the Achilles tendon, positive arc sign, Royal London Hospital test, and Thompson test.

Tests used to diagnose Achilles tendinopathy:

• Lateral and axial calcaneus x-rays: May detect calcifications in the proximal extension of the tendon insertion or bony prominences in the upper portion of the calcaneus. Also, x-rays can help exclude pathological bone tumors.[34][35][36]

• Ultrasound: Can help assess injury to the tendon[37]; can be used to predict the risk of tendinopathy and rupture.[38] Ultrasound may reveal increased thickness of the Achilles tendon with hyperemia associated with hypervascularity, a decrease in the gastrocnemius-soleus rotation angle and a decrease in the length of the Kager fat pad. Ultrasound is also useful during interventional treatment.[39]

• Magnetic Resonance Imaging: Provides significant information about the state of joint structures with a study in multiple planes in static and dynamic views.[40][41] One study found that MRI had lower sensitivity than ultrasound in the detection of early changes of enthesopathy.[42]. Another study found an excellent agreement between tendon thickness measurement between magnetic resonance and ultrasound.[43]

• Computed Tomography (CT): The CT scan is useful to rule out trabecular structural alterations of the calcaneus in Achilles pathology of insertion. However, it exposes the patient to radiation.[44][45][46]

• Victoria Institute of Sports Assessment - Achilles (VISA-A) remains the gold standard for assessing pain and function,[47] but it requires additional studies to increase its reliability.[48] Nevertheless, it is an essential tool for patient post-treatment follow-up. 

Treatment / Management

Management of Achilles tendinopathy can divide into conservative and surgical. Additionally, one must consider whether it is an acute or chronic condition. Finally, for those with a full rupture, the treatment is usually surgical.  

1. Conservative therapy:  It is the first line of management and includes the following[49][50][51][52][53][54][55][56][57][58][59][60]:

• Reduction of activity levels
• Administration of non-steroidal anti-inflammatory drugs (NSAIDs)
• Adaptation of footwear, manual therapy directed at local sites may enhance the rehabilitation
• Eccentric stretching exercises should comprise an integral component of physiotherapy and can achieve a 40% reduction in pain; moderate level evidence favors eccentric exercise over concentric exercise for reducing pain
• Tendon loading exercise at short- and long-term follow-up
• If unresponsive to initial management, extracorporeal shock wave therapy reduces pain by 60%, with 80% patient satisfaction, improving functionality and quality of life, with a follow-up at 4 weeks; this might be the first choice because of its safety and effectiveness
• Physiotherapy improves the pain and functionality of the Achilles tendinopathy of the middle portion; however, studies do not show preferences for any particular exercise over another - overall, use of a splint to an eccentric exercise protocol or the use of orthoses to improve pain and function are not a recommendation
• Current evidence shows a lack of efficacy on the use of platelet-rich plasma for Achilles tendinopathy

2. Surgical therapy is optional for 10 to 30% of patients who fail conservative therapy after six months.[61][62] The success rate is higher than 70%, but reports show complication rates of 3 to 40%.[63] The Achilles tendon should undergo reattachment with a tendon rupture of more than 50%.[64]

Differential Diagnosis

Posterior heel and ankle pain is a frequent presentation in primary care, and the risk of developing pain is higher with increasing body mass index and age. Primarily, when patients do not improve despite the management established, further investigations are necessary.[65] The most common musculoskeletal disorders of the soft tissues related to ankle pain are[66][67]:

• Olecranon bursitis
• Plantar fasciitis
• Nerve entrapment or neuroma (pain accompanied by burning, tingling, or numbness)
• Heel pad syndrome  (deep, bruise-like pain in the middle heel)
• Haglund deformity (prominence of the calcaneus that may lead to retrocalcaneal bursa inflammation)
• Sever disease (calcaneal apophysitis common in children and adolescents)

Erdheim-Chester disease (ECD) is a rare histiocytosis of non-Langerhans cells, reported in a 36-year-old male, with bilateral xanthogranulomas of the Achilles tendon. Although rare, ECD should be a consideration in the differential diagnosis of intratendinous masses.[68] As with all clinical presentations, the potential for non-musculoskeletal, more sinister causes of pain and systemic disease deserve scrutiny.[69]

Prognosis

Achilles tendinopathy has a better prognosis with early and adequate initial management. Surgical intervention for Achilles tendinosis of insertion (TAI) is successful in over 80% of cases. Stenson and his colleagues,[70] discovered that as the number of risk factors increased, the possibility of failure in non-operative treatment also increased. With the usage of the visual analog scale, limited range of motion of the ankle, prior injection of corticosteroids, and the presence of enthesophytes of the Achilles tendon, the probability of failure of the conservative treatment was 55%. Therefore, usage of the risk factors mentioned above can help the surgeon in the decision to perform surgery in the appropriate clinical setting. In a retrospective study of Sanalla and colleagues, they found that strengthening of the Achilles tendon with bone-tendon autograft was an effective procedure with a low risk of complications and reliable results.[71]

Complications

In a systematic review, Lohrer and colleagues,[72] concluded that the open and minimally invasive surgical treatment success rates did not differ (83.4%) and that there were no differences in patient satisfaction, but complication rates were lower for the minimally invasive procedures. Baltes and his colleagues classified the complications as follows[73]:

• Major complications: Such as ruptured AT, any reoperation, deep vein thrombosis, reflex dystrophy, persistent neuralgia, deep infections, major wound problems
• Minor complications Such as discomfort. Infections superficial, minor wound problems, scar sensitivity, hypertrophy, mild paraesthesia, prolonged hospitalization.

In another review, the surgical results were excellent or good in 89.6% of the cases and fair or poor in 10.4%. The average complication rate was 18.3%, with 15.7% minor complications and 2.6% major complications for surgical treatment of the Achilles tendinopathy insertion.[74]

Deterrence and Patient Education

Patient education and a more conservative approach can prevent chronic tendinopathy[75][76][77][78]:

• A change to another sport (swimming, weight training, rowing, cycling) allows the tendon to rest
• Eccentric exercise therapy (exercises that cause stretching combined with the contraction of a muscle) decreases pain and prevents chronicity
• Scientific evidence supports many conservative treatments, such as the use of non-steroidal anti-inflammatory drugs (e.g., ibuprofen, naproxen)
• The choice of running shoes that provide enough cushioning for the heel strike
• A warm-up exercise routine, and stretching the calf muscles before playing sports
• Gradually increasing the distance and running speed by only 10% per week, avoid running unhurriedly, running on slopes, and cooling properly after exercise
• Extracorporeal shock wave therapy may help
• Moreover, surgery is usually the last resort if recovery is prolonged

Enhancing Healthcare Team Outcomes

Achilles tendinopathy (AT) is a multi-factorial disease, which causes considerable morbidity by limiting exercise in athletes and non-athletes alike. The evidence recommends conservative or physical therapies as first-line treatment of AT; however, despite an increasing volume of research, there is still a lack of high-quality studies that test its effectiveness.[79][80] [Level I]

• Inspection and clinical examination supplemented by ultrasound and magnetic resonance imaging (MRI) are essential to achieving the correct diagnosis. A high interrelation between hypervascularization and tendinopathy of the Achilles tendon was found using Doppler ultrasound [Level 1], but these outcomes were not reproducible.[65]
• There is evidence to support the use of eccentric exercises by providing short-term benefits over brace for persistent Achilles tendinopathy.[56] [Level I]
• Soft tissue treatment plus eccentric exercise appears to be a beneficial treatment program that clinicians should recommend to patients with insertional AT.[54] [Level II]
• Surgery for insertional Achilles tendinopathy can lead to good functional outcomes and satisfactory return to sports when the tailoring of surgical care matches the degree of tendon involvement.[62][Level IV].
• Evidence for the effectiveness of traditional needle acupuncture may be beneficial for Achilles tendinopathy.[81] [Level I]
• Articles comparing minimally invasive techniques to open procedures reported on an average success rate of 83.6 % and 78.9% respectively (p = 0.987). The complication rate was 5.3 % with minimally invasive techniques and 10.5 % for open procedures.[72][Level II]
• In conclusion, endoscopic and minimally invasive procedures may prove to be the future of surgical treatment of middle Achilles tendinopathy.[73] [Level IV]
• There is no unequivocal evidence to advise any pharmacological treatment (comprising injection of a substance or local application) as the best advisable non-operative option for Achilles tendinopathy as an alternative to the most commonly used eccentric loading rehabilitation program. However, the combination of different medications administered with physical therapy may prove beneficial. There is a need for more long-term investigations.[82][Level I]
• Local infiltrations of autologous plasma,[83] [Level I] and the injection of platelet-rich plasma with eccentric training should be avoided, as there is no association between the therapeutic effects and the duration of symptoms in patients with chronic Achilles tendinopathy.[84][Level I]

Review Questions

• Access free multiple choice questions on this topic.
• Comment on this article.

References

1.

Abate M, Salini V. Mid-portion Achilles tendinopathy in runners with metabolic disorders. Eur J Orthop Surg Traumatol. 2019 Apr;29(3):697-703. [PubMed: 30367279]

2.

Zhao H, Ren Y, Roth EJ, Harvey RL, Zhang LQ. Concurrent deficits of soleus and gastrocnemius muscle fascicles and Achilles tendon post stroke. J Appl Physiol (1985). 2015 Apr 01;118(7):863-71. [PMC free article: PMC4385882] [PubMed: 25663670]

3.

Olewnik Ł, Wysiadecki G, Podgórski M, Polguj M, Topol M. The Plantaris Muscle Tendon and Its Relationship with the Achilles Tendinopathy. Biomed Res Int. 2018;2018:9623579. [PMC free article: PMC6000875] [PubMed: 29955614]

4.

Yang X, Coleman DP, Pugh ND, Nokes LD. The volume of the neovascularity and its clinical implications in achilles tendinopathy. Ultrasound Med Biol. 2012 Nov;38(11):1887-95. [PubMed: 22975033]

5.

Slane LC, Dandois F, Bogaerts S, Vandenneucker H, Scheys L. Non-uniformity in the healthy patellar tendon is greater in males and similar in different age groups. J Biomech. 2018 Oct 26;80:16-22. [PMC free article: PMC6231227] [PubMed: 30224164]

6.

Pękala PA, Henry BM, Ochała A, Kopacz P, Tatoń G, Młyniec A, Walocha JA, Tomaszewski KA. The twisted structure of the Achilles tendon unraveled: A detailed quantitative and qualitative anatomical investigation. Scand J Med Sci Sports. 2017 Dec;27(12):1705-1715. [PubMed: 28139009]

7.

Federer AE, Steele JR, Dekker TJ, Liles JL, Adams SB. Tendonitis and Tendinopathy: What Are They and How Do They Evolve? Foot Ankle Clin. 2017 Dec;22(4):665-676. [PubMed: 29078821]

8.

Moon JL, Moon KM, Carlisle DM. Obesity-Related Foot Pain: Diagnosis and Surgical Planning. Clin Podiatr Med Surg. 2019 Jan;36(1):141-151. [PubMed: 30446041]

9.

Bolon B. Mini-Review: Toxic Tendinopathy. Toxicol Pathol. 2017 Oct;45(7):834-837. [PubMed: 28553748]

10.

Alušík Š, Paluch Z. [Drug induced tendon injury]. Vnitr Lek. 2018 Winter;63(12):967-971. [PubMed: 29334747]

11.

Camargo PR, Alburquerque-Sendín F, Salvini TF. Eccentric training as a new approach for rotator cuff tendinopathy: Review and perspectives. World J Orthop. 2014 Nov 18;5(5):634-44. [PMC free article: PMC4133471] [PubMed: 25405092]

12.

Godoy-Santos AL, Bruschini H, Cury J, Srougi M, de Cesar-Netto C, Fonseca LF, Maffulli N. Fluoroquinolones and the Risk of Achilles Tendon Disorders: Update on a Neglected Complication. Urology. 2018 Mar;113:20-25. [PubMed: 29074337]

13.

Almekinders LC, Engle CR. Common and Uncommon Injuries in Ultra-endurance Sports. Sports Med Arthrosc Rev. 2019 Mar;27(1):25-30. [PubMed: 30601398]

14.

Brund RBK, Rasmussen S, Kersting UG, Arendt-Nielsen L, Palsson TS. Prediction of running-induced Achilles tendinopathy with pain sensitivity - a 1-year prospective study. Scand J Pain. 2019 Jan 28;19(1):139-146. [PubMed: 30407913]

15.

Colbert LH, Hootman JM, Macera CA. Physical activity-related injuries in walkers and runners in the aerobics center longitudinal study. Clin J Sport Med. 2000 Oct;10(4):259-63. [PubMed: 11086751]

16.

Cassel M, Risch L, Intziegianni K, Mueller J, Stoll J, Brecht P, Mayer F. Incidence of Achilles and Patellar Tendinopathy in Adolescent Elite Athletes. Int J Sports Med. 2018 Sep;39(9):726-732. [PubMed: 29940667]

17.

Mulvad B, Nielsen RO, Lind M, Ramskov D. Diagnoses and time to recovery among injured recreational runners in the RUN CLEVER trial. PLoS One. 2018;13(10):e0204742. [PMC free article: PMC6193581] [PubMed: 30312310]

18.

Molyneux P, Carroll M, Stewart S, Brenton-Rule A, Rome K. Ultrasound characteristics of the mid-portion of the Achilles tendon in runners: a systematic review protocol. Syst Rev. 2017 May 30;6(1):108. [PMC free article: PMC5450404] [PubMed: 28558847]

19.

de Jonge S, van den Berg C, de Vos RJ, van der Heide HJ, Weir A, Verhaar JA, Bierma-Zeinstra SM, Tol JL. Incidence of midportion Achilles tendinopathy in the general population. Br J Sports Med. 2011 Oct;45(13):1026-8. [PubMed: 21926076]

20.

Weber J, Buchhorn T. [Midportion Achilles tendinopathy]. Unfallchirurg. 2017 Dec;120(12):1038-1043. [PubMed: 28921035]

21.

Wezenbeek E, De Clercq D, Mahieu N, Willems T, Witvrouw E. Activity-Induced Increase in Achilles Tendon Blood Flow Is Age and Sex Dependent. Am J Sports Med. 2018 Sep;46(11):2678-2686. [PubMed: 30067065]

22.

Lemme NJ, Li NY, DeFroda SF, Kleiner J, Owens BD. Epidemiology of Achilles Tendon Ruptures in the United States: Athletic and Nonathletic Injuries From 2012 to 2016. Orthop J Sports Med. 2018 Nov;6(11):2325967118808238. [PMC free article: PMC6259075] [PubMed: 30505872]

23.

Li HY, Hua YH. Achilles Tendinopathy: Current Concepts about the Basic Science and Clinical Treatments. Biomed Res Int. 2016;2016:6492597. [PMC free article: PMC5112330] [PubMed: 27885357]

24.

Kvist M, Józsa L, Järvinen MJ, Kvist H. Chronic Achilles paratenonitis in athletes: a histological and histochemical study. Pathology. 1987 Jan;19(1):1-11. [PubMed: 3588019]

25.

Klatte-Schulz F, Minkwitz S, Schmock A, Bormann N, Kurtoglu A, Tsitsilonis S, Manegold S, Wildemann B. Different Achilles Tendon Pathologies Show Distinct Histological and Molecular Characteristics. Int J Mol Sci. 2018 Jan 30;19(2) [PMC free article: PMC5855626] [PubMed: 29385715]

26.

Feilmeier M. Noninsertional Achilles Tendinopathy Pathologic Background and Clinical Examination. Clin Podiatr Med Surg. 2017 Apr;34(2):129-136. [PubMed: 28257670]

27.

DeCarbo WT, Bullock MJ. Midsubstance Tendinopathy, Surgical Management. Clin Podiatr Med Surg. 2017 Apr;34(2):175-193. [PubMed: 28257673]

28.

Jeong C, Kim SE, Shim KS, Kim HJ, Song MH, Park K, Song HR. Exploring the In Vivo Anti-Inflammatory Actions of Simvastatin-Loaded Porous Microspheres on Inflamed Tenocytes in a Collagenase-Induced Animal Model of Achilles Tendinitis. Int J Mol Sci. 2018 Mar 12;19(3) [PMC free article: PMC5877681] [PubMed: 29534523]

29.

Dakin SG, Newton J, Martinez FO, Hedley R, Gwilym S, Jones N, Reid HAB, Wood S, Wells G, Appleton L, Wheway K, Watkins B, Carr AJ. Chronic inflammation is a feature of Achilles tendinopathy and rupture. Br J Sports Med. 2018 Mar;52(6):359-367. [PMC free article: PMC5867427] [PubMed: 29118051]

30.

El-Habta R, Chen J, Pingel J, Backman LJ. Tendinosis-like changes in denervated rat Achilles tendon. BMC Musculoskelet Disord. 2018 Nov 30;19(1):426. [PMC free article: PMC6267070] [PubMed: 30497469]

31.

Obst SJ, Heales LJ, Schrader BL, Davis SA, Dodd KA, Holzberger CJ, Beavis LB, Barrett RS. Are the Mechanical or Material Properties of the Achilles and Patellar Tendons Altered in Tendinopathy? A Systematic Review with Meta-analysis. Sports Med. 2018 Sep;48(9):2179-2198. [PubMed: 29961208]

32.

Tu P. Heel Pain: Diagnosis and Management. Am Fam Physician. 2018 Jan 15;97(2):86-93. [PubMed: 29365222]

33.

Martin RL, Chimenti R, Cuddeford T, Houck J, Matheson JW, McDonough CM, Paulseth S, Wukich DK, Carcia CR. Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision 2018. J Orthop Sports Phys Ther. 2018 May;48(5):A1-A38. [PubMed: 29712543]

34.

Bulstra GH, van Rheenen TA, Scholtes VA. Can We Measure the Heel Bump? Radiographic Evaluation of Haglund's Deformity. J Foot Ankle Surg. 2015 May-Jun;54(3):338-40. [PubMed: 25179453]

35.

Gladman DD, Abufayyah M, Salonen D, Thavaneswaran A, Chandran V. Radiological characteristics of the calcaneal spurs in psoriatic arthritis. Clin Exp Rheumatol. 2014 May-Jun;32(3):401-3. [PubMed: 24850064]

36.

Rachel JN, Williams JB, Sawyer JR, Warner WC, Kelly DM. Is radiographic evaluation necessary in children with a clinical diagnosis of calcaneal apophysitis (sever disease)? J Pediatr Orthop. 2011 Jul-Aug;31(5):548-50. [PubMed: 21654464]

37.

Mahoney JM. Imaging Techniques and Indications. Clin Podiatr Med Surg. 2017 Apr;34(2):115-128. [PubMed: 28257669]

38.

Matthews W, Ellis R, Furness J, Hing W. Classification of Tendon Matrix Change Using Ultrasound Imaging: A Systematic Review and Meta-analysis. Ultrasound Med Biol. 2018 Oct;44(10):2059-2080. [PubMed: 30007477]

39.

Romero-Morales C, Martín-Llantino PJ, Calvo-Lobo C, Palomo-López P, López-López D, Pareja-Galeano H, Rodríguez-Sanz D. Comparison of the sonographic features of the Achilles Tendon complex in patients with and without achilles tendinopathy: A case-control study. Phys Ther Sport. 2019 Jan;35:122-126. [PubMed: 30543997]

40.

Bullock MJ, Mourelatos J, Mar A. Achilles Impingement Tendinopathy on Magnetic Resonance Imaging. J Foot Ankle Surg. 2017 May-Jun;56(3):555-563. [PubMed: 28258946]

41.

Tuite MJ. MR imaging of the tendons of the foot and ankle. Semin Musculoskelet Radiol. 2002 Jun;6(2):119-31. [PubMed: 12077701]

42.

Kamel M, Eid H, Mansour R. Ultrasound detection of heel enthesitis: a comparison with magnetic resonance imaging. J Rheumatol. 2003 Apr;30(4):774-8. [PubMed: 12672198]

43.

Albano D, Messina C, Usuelli FG, De Girolamo L, Grassi M, Maccario C, Bignotti B, Tagliafico A, Sconfienza LM. Magnetic resonance and ultrasound in achilles tendinopathy: Predictive role and response assessment to platelet-rich plasma and adipose-derived stromal vascular fraction injection. Eur J Radiol. 2017 Oct;95:130-135. [PubMed: 28987658]

44.

Ficek K, Filipek J, Ficek J, Muzalewska M, Humpa F. Calcaneal CT is a useful tool for identifying Achilles tendon disorders: a pilot study. J Orthop Surg Res. 2017 Sep 25;12(1):139. [PMC free article: PMC5613452] [PubMed: 28946912]

45.

Huang YB, Zhao YX, Xiao JJ, Li MW, Zhang R, Li SL. [Comparative analysis of the ankle joints in juvenile male soccer players with imaging]. Zhonghua Yi Xue Za Zhi. 2016 Jul 05;96(25):1971-5. [PubMed: 27470952]

46.

Lang TR, Cook J, Rio E, Gaida JE. What tendon pathology is seen on imaging in people who have taken fluoroquinolones? A systematic review. Fundam Clin Pharmacol. 2017 Feb;31(1):4-16. [PubMed: 27477928]

47.

Murphy M, Rio E, Debenham J, Docking S, Travers M, Gibson W. EVALUATING THE PROGRESS OF MID-PORTION ACHILLES TENDINOPATHY DURING REHABILITATION: A REVIEW OF OUTCOME MEASURES FOR SELF- REPORTED PAIN AND FUNCTION. Int J Sports Phys Ther. 2018 Apr;13(2):283-292. [PMC free article: PMC6063067] [PubMed: 30090686]

48.

Palazón-Bru A, Tomás-Rodríguez MI, Mares-García E, Gil-Guillén VF. A Reliability Generalization Meta-Analysis of the Victorian Institute of Sport Assessment Scale for Achilles Tendinopathy (VISA-A). Foot Ankle Int. 2019 Apr;40(4):430-438. [PubMed: 30569746]

49.

McClinton S, Luedke L, Clewley D. Nonsurgical Management of Midsubstance Achilles Tendinopathy. Clin Podiatr Med Surg. 2017 Apr;34(2):137-160. [PubMed: 28257671]

50.

Bussin ER, Cairns B, Bovard J, Scott A. Randomised controlled trial evaluating the short-term analgesic effect of topical diclofenac on chronic Achilles tendon pain: a pilot study. BMJ Open. 2017 May 04;7(4):e015126. [PMC free article: PMC5566615] [PubMed: 28473518]

51.

Heinemeier KM, Øhlenschlæger TF, Mikkelsen UR, Sønder F, Schjerling P, Svensson RB, Kjaer M. Effects of anti-inflammatory (NSAID) treatment on human tendinopathic tissue. J Appl Physiol (1985). 2017 Nov 01;123(5):1397-1405. [PubMed: 28860166]

52.

Jayaseelan DJ, Kecman M, Alcorn D, Sault JD. Manual therapy and eccentric exercise in the management of Achilles tendinopathy. J Man Manip Ther. 2017 May;25(2):106-114. [PMC free article: PMC5430449] [PubMed: 28559670]

53.

Verrall GM, Dolman BK, Best TM. Applying physical science principles to mid-substance Achilles tendinopathy and the relationship to eccentric lengthening exercises. Scand J Med Sci Sports. 2018 Mar;28(3):1159-1165. [PubMed: 28948634]

54.

McCormack JR, Underwood FB, Slaven EJ, Cappaert TA. Eccentric Exercise Versus Eccentric Exercise and Soft Tissue Treatment (Astym) in the Management of Insertional Achilles Tendinopathy. Sports Health. 2016 May/Jun;8(3):230-237. [PMC free article: PMC4981065] [PubMed: 26893309]

55.

Wilson F, Walshe M, O'Dwyer T, Bennett K, Mockler D, Bleakley C. Exercise, orthoses and splinting for treating Achilles tendinopathy: a systematic review with meta-analysis. Br J Sports Med. 2018 Dec;52(24):1564-1574. [PubMed: 30170996]

56.

Woitzik E, Jacobs C, Wong JJ, Côté P, Shearer HM, Randhawa K, Sutton D, Southerst D, Varatharajan S, Brison RJ, Yu H, van der Velde G, Stern PJ, Taylor-Vaisey A, Stupar M, Mior S, Carroll LJ. The effectiveness of exercise on recovery and clinical outcomes of soft tissue injuries of the leg, ankle, and foot: A systematic review by the Ontario Protocol for Traffic Injury Management (OPTIMa) Collaboration. Man Ther. 2015 Oct;20(5):633-45. [PubMed: 25892707]

57.

Rabello LM, van den Akker-Scheek I, Brink MS, Maas M, Diercks RL, Zwerver J. Association Between Clinical and Imaging Outcomes After Therapeutic Loading Exercise in Patients Diagnosed With Achilles or Patellar Tendinopathy at Short- and Long-Term Follow-up: A Systematic Review. Clin J Sport Med. 2020 Jul;30(4):390-403. [PubMed: 29952842]

58.

Murphy M, Travers M, Gibson W, Chivers P, Debenham J, Docking S, Rio E. Rate of Improvement of Pain and Function in Mid-Portion Achilles Tendinopathy with Loading Protocols: A Systematic Review and Longitudinal Meta-Analysis. Sports Med. 2018 Aug;48(8):1875-1891. [PubMed: 29766442]

59.

Dedes V, Stergioulas A, Kipreos G, Dede AM, Mitseas A, Panoutsopoulos GI. Effectiveness and Safety of Shockwave Therapy in Tendinopathies. Mater Sociomed. 2018 Jun;30(2):131-146. [PMC free article: PMC6029898] [PubMed: 30061805]

60.

Le ADK, Enweze L, DeBaun MR, Dragoo JL. Current Clinical Recommendations for Use of Platelet-Rich Plasma. Curr Rev Musculoskelet Med. 2018 Dec;11(4):624-634. [PMC free article: PMC6220007] [PubMed: 30353479]

61.

Alfredson H, Masci L, Spang C. Surgical plantaris tendon removal for patients with plantaris tendon-related pain only and a normal Achilles tendon: a case series. BMJ Open Sport Exerc Med. 2018;4(1):e000462. [PMC free article: PMC6280899] [PubMed: 30588327]

62.

Hardy A, Rousseau R, Issa SP, Gerometta A, Pascal-Moussellard H, Granger B, Khiami F. Functional outcomes and return to sports after surgical treatment of insertional Achilles tendinopathy: Surgical approach tailored to the degree of tendon involvement. Orthop Traumatol Surg Res. 2018 Sep;104(5):719-723. [PubMed: 29852319]

63.

Aicale R, Tarantino D, Maffulli N. Surgery in Tendinopathies. Sports Med Arthrosc Rev. 2018 Dec;26(4):200-202. [PubMed: 30395068]

64.

Baumbach SF, Braunstein M, Mack MG, Maßen F, Böcker W, Polzer S, Polzer H. [Insertional Achilles tendinopathy : Differentiated diagnostics and therapy]. Unfallchirurg. 2017 Dec;120(12):1044-1053. [PubMed: 28980027]

65.

Gaulke R, Krettek C. [Tendinopathies of the foot and ankle : Evidence for the origin, diagnostics and therapy]. Unfallchirurg. 2017 Mar;120(3):205-213. [PubMed: 28120032]

66.

Hubbard MJ, Hildebrand BA, Battafarano MM, Battafarano DF. Common Soft Tissue Musculoskeletal Pain Disorders. Prim Care. 2018 Jun;45(2):289-303. [PubMed: 29759125]

67.

Weigelt L, Wirth SH. [Not Available]. Praxis (Bern 1994). 2017;106(5):265-268. [PubMed: 28253811]

68.

Nadjiri J, Woertler K, Specht K, Harrasser N, Toepfer A. Erdheim-Chester disease with bilateral Achilles tendon involvement. Skeletal Radiol. 2016 Oct;45(10):1437-42. [PubMed: 27506209]

69.

Rio E, Mayes S, Cook J. Heel pain: a practical approach. Aust Fam Physician. 2015 Mar;44(3):96-101. [PubMed: 25770572]

70.

Stenson JF, Reb CW, Daniel JN, Saini SS, Albana MF. Predicting Failure of Nonoperative Treatment for Insertional Achilles Tendinosis. Foot Ankle Spec. 2018 Jun;11(3):252-255. [PubMed: 28884594]

71.

Sanalla H, Hart R, Komzák M, Paša L. [Surgical Treatment of the Achilles Insertional Tendinopathy Using the Augmentation with the BT Graft from M. Quadriceps Femoris]. Acta Chir Orthop Traumatol Cech. 2018;85(4):266-270. [PubMed: 30257757]

72.

Lohrer H, David S, Nauck T. Surgical treatment for achilles tendinopathy - a systematic review. BMC Musculoskelet Disord. 2016 May 10;17:207. [PMC free article: PMC4862213] [PubMed: 27165287]

73.

Baltes TPA, Zwiers R, Wiegerinck JI, van Dijk CN. Surgical treatment for midportion Achilles tendinopathy: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2017 Jun;25(6):1817-1838. [PMC free article: PMC5487601] [PubMed: 26971111]

74.

Traina F, Perna F, Ruffilli A, Mazzotti A, Meliconi R, Berti L, Faldini C. Surgical treatment of insertional Achilles tendinopathy: a systematic review. J Biol Regul Homeost Agents. 2016 Oct-Dec;30(4 Suppl 1):131-138. [PubMed: 28002910]

75.

Barry ME. Patient-education guide. Heel pain. Nursing. 2004 Feb;34(2):43. [PubMed: 14758327]

76.

Chang HJ, Burke AE, Glass RM. JAMA patient page. Achilles tendinopathy. JAMA. 2010 Jan 13;303(2):188. [PubMed: 20068216]

77.

Chinn L, Hertel J. Rehabilitation of ankle and foot injuries in athletes. Clin Sports Med. 2010 Jan;29(1):157-67, table of contents. [PMC free article: PMC2786815] [PubMed: 19945591]

78.

Sartorio F, Zanetta A, Ferriero G, Bravini E, Vercelli S. The EdUReP approach plus manual therapy for the management of insertional Achilles tendinopathy. J Sports Med Phys Fitness. 2018 May;58(5):664-668. [PubMed: 28222571]

79.

Sussmilch-Leitch SP, Collins NJ, Bialocerkowski AE, Warden SJ, Crossley KM. Physical therapies for Achilles tendinopathy: systematic review and meta-analysis. J Foot Ankle Res. 2012 Jul 02;5(1):15. [PMC free article: PMC3537637] [PubMed: 22747701]

80.

Yu H, Randhawa K, Côté P, Optima Collaboration The Effectiveness of Physical Agents for Lower-Limb Soft Tissue Injuries: A Systematic Review. J Orthop Sports Phys Ther. 2016 Jul;46(7):523-54. [PubMed: 27266884]

81.

Cox J, Varatharajan S, Côté P, Optima Collaboration Effectiveness of Acupuncture Therapies to Manage Musculoskeletal Disorders of the Extremities: A Systematic Review. J Orthop Sports Phys Ther. 2016 Jun;46(6):409-29. [PubMed: 27117725]

82.

Maffulli N, Papalia R, D'Adamio S, Diaz Balzani L, Denaro V. Pharmacological interventions for the treatment of Achilles tendinopathy: a systematic review of randomized controlled trials. Br Med Bull. 2015 Mar;113(1):101-15. [PubMed: 25583629]

83.

Lin MT, Chiang CF, Wu CH, Hsu HH, Tu YK. Meta-analysis Comparing Autologous Blood-Derived Products (Including Platelet-Rich Plasma) Injection Versus Placebo in Patients With Achilles Tendinopathy. Arthroscopy. 2018 Jun;34(6):1966-1975.e5. [PubMed: 29685839]

84.

Zhang YJ, Xu SZ, Gu PC, Du JY, Cai YZ, Zhang C, Lin XJ. Is Platelet-rich Plasma Injection Effective for Chronic Achilles Tendinopathy? A Meta-analysis. Clin Orthop Relat Res. 2018 Aug;476(8):1633-1641. [PMC free article: PMC6259774] [PubMed: 29601383]