Achilles tendinopathy (AT) is an umbrella term used to describe a spectrum of tendon disorders including tendinosis and paratendinopathy, which all present with similar clinical symptoms of pain, swelling and impaired Achilles tendon function. Tendinopathy can be acute or chronic (lasting longer than 12 weeks). The two anatomical classifications include insertional (at the calcaneus-achilles tendon junction) and non-insertional (2 – 6 cm proximal to the insertion of the achilles tendon onto the calcaneus).4,5
AT is frequently associated with an overuse injury despite being able to bear loads in excess of 3500N.3 In addition to sporting activities, there are other intrinsic and extrinsic factors contributing to development of this condition. Intrinsic factors include increasing age, gender, systemic diseases (diabetes, rheumatologic conditions, and metabolic disorders), biomechanical abnormalities (foot pronation, leg length discrepancy, pes cavus, and/or varus foot deformity) and obesity. Extrinsic factors include drugs (fluoroquinolones), excessive mechanical overload, and training errors such as excessive hill training and poor shock absorption.4,5
Epidemiology including risk factors and primary prevention
Achilles tendon pathology is associated with 50% of all sports related injuries. 75% of Achilles tendon ruptures occur in middle aged men participating in sports.3 AT may affect 9% of recreational runners and cause 5% of professional athletes to end their careers.5 Up to 4% of active adults may have asymptomatic degeneration, but it is frequently linked with jumping and running activities. Other causes of AT include fluoroquinolone use (0.2-2.0%) and systemic diseases (2.0 %) such as ankylosing spondylitis, psoriatic and rheumatoid arthritis. One study described the prevalence of non-insertional AT as 2.01 per 1000 patients.3
The Achilles tendon originates from the gastrocsoleus complex and inserts onto the calcaneus distally. Histologically, it is composed of tenoblasts and tenocytes (90-95%), chondrocytes (5-10%) and some synovial cells. The extracellular matrix is made up of glycosaminoglycans, proteoglycans, and glycoproteins. Collagen accounts for 70-80% of the dry weight of the tendon and is composed primarily of type I (95%), type III, V, and XII. Elastin accounts for 2% of the dry weight; however, the tendon can undergo 200% strain before failing. Collagen forms fibrils, fibers, fascicles which come together to form bundles surrounded by an endotenon which carries the blood supply, nerves and lymphatics.3
Biomechanical intrinsic factors which contribute to AT include hyperpronation of the foot, along with ankle equinus (frequently caused by pes planus). Ankle equinus is defined by ankle dorsiflexion limited to 10-20°. This causes increased foot pronation in order to gain the added benefit of increased dorsiflexion in order to maintain proper gait mechanics. This excessive hyperpronation at the subtalar joint causes the gastrocnemius-soleus complex and tibiialis posterior to eccentrically contract with greater force. This compensation occurs to decelerate the rotation of the lower extremity and pronation of the foot. The frequent forceful contraction contributes to the development of AT.14
In AT, the tendon becomes thickened, brown and uneven. At the cellular level, there is an increase in the number of tenocytes, concentration of glycosaminoglycans, disorganization of the collagen fibers and neovascularization. In chronic AT, there is an increased concentration of type III collagen, fibronectin, tenascin C, aggrecan, and biglycan.4
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
The majority of patients with AT recover fully and are able to return to sports participation. Grading is based on the severity of symptoms.
Grade 1: Morning discomfort in tendon, which resolves shortly after waking.
Grade 2: Pain during athletic activities that does not interfere with performance.
Grade 3: Pain that interferes with performance.
Grade 4: Pain that precludes sports participation.
In AT, tendon injury/repair occurs in three stages:4
Stage 1: Inflammatory – Lasts a few days with release of vasoactive and chemotactic factors
Stage 2: Proliferative – Lasts a few weeks and type III collagen levels peak
Stage 3: Modeling – Decreased collagen production and fibrous consolidation process beginning after 6 weeks.
Specific secondary or associated conditions and complications
Achilles tendon rupture is the most feared complication of AT. It may happen acutely or as an extension of a pre-existing partial tear of the tendon’s dorsal surface. Fluoroquinolone use has been linked to an increased risk of rupture, particularly in older populations taking concomitant oral steroids.4,6 Histologic examination confirms the presence of degenerative changes in > 75% of cases.1
Inflammation of the subcutaneous or retrocalcaneal bursae may mimic insertional AT. Extrinsic factors, such as high-heel or tight-fitting shoes with hard heel counters have been implicated in the development of calcaneal bursitis. In a small percentage of patients, the etiology may be infectious or reactive. In skeletally immature athletes, calcaneal apophysitis (Sever’s disease) is the most common cause of Achilles-related pain. Symptoms of Sever’s disease respond well to activity modification.
2. ESSENTIALS OF ASSESSMENT
Patients with AT generally complain of a dull, burning pain along the tendon itself. The triad of pain, swelling and functional impairment are indicative of AT. It is important to evaluate for the intrinsic and extrinsic risk factors as outlined above.
A sudden “popping” sensation followed by pain and swelling during sudden pivoting movements or rapid acceleration should be suspicious for a tendon rupture.
Examination of the Achilles tendon begins with inspection of the tendon for any bruising or swelling. The tendon should be palpated along its length to assess for tenderness, thickness or any palpable gaps along the tendon. The ankle should be ranged in dorsiflexion and plantarflexion, which may reveal some crepitus. It is important to remember that an Achilles tendon rupture may be missed on exam due to inability to palpate a defect in the tendon, patient’s inability to walk and plantarflex the tendon, or a painless tendon rupture.
The sensitivity of palpation to detect a tendon abnormality is about 0.73. Other tests that can be used to assess tendon pathology include Matles test, O’brien’s test, Copeland test and the Thompson test. The Thompson and Matles tests have the highest sensitivities close to 0.9.7
As part of a thorough patient evaluation, it is important to assess for any gait and biomechanical abnormalities, which may be present such as leg length discrepancy, pes planus, or varus deformity of the foot.
If a systemic inflammatory process is suspected, a laboratory work-up may include complete blood count with differential, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor and anti-DNA antibody levels.
Plain radiography has a low yield in detecting soft tissue pathology; however it can be helpful for detecting bony pathology. Both ultrasound (US) and magnetic resonance imaging (MRI) provide the necessary anatomical detail for detecting AT pathology. Typical findings include a thickened paratenon, heterogeneity of tendon structure and increased vascularity of the ventral aspect of the tendon on Doppler-augmented US and contrast-enhanced MRI. Early AT may present with increased fluid surrounding the tendon. Increased vascularity of the tendon’s dorsal side may indicate a partial tear, which may progress, unless managed appropriately.3
Hartgerink et al performed a study of 26 Achilles tendon tears using ultrasound and compared this to surgical findings. They found a sensitivity of 100%, specificity of 83% and positive predictive value of 83% in detecting partial from full thickness tears using ultrasound15. This and other studies show that US is helpful in detecting AT, however MRI is necessary to establish a definitive diagnosis.16
New advances are being made in the field of sheer wave ultrasound elastography to assess tendons. Ultrasound elastography uses mechanical impulses to produce sheer waves in the tissues of interest to measure tissue displacement and other characteristics. This technique may complement B-mode ultrasonography in the future.13
Supplemental assessment tools
Visual analog pain scale (VAS) and Victorian Institute of Sports Assessment – Achilles (VISA-A), an 8-question survey, have been validated for use in the AT population17
Training in inclement weather, excessive uphill or downhill running and physical deconditioning is associated with an increased risk of AT. Those at greater risk for Achilles tendon rupture tend to be older and less physically conditioned
Social role and social support system
Since rehabilitation of AT may require significant changes to training/competition regimen, assistance of a sports psychologist may be necessary.
Each clinician should address any risk factors for rupture of the Achilles if the older patient returns to “weekend athletics” or if the high level athlete returns to the court or field. Treatment may vary for patients depending on their previous level of activity. For example a high level athlete or individuals with physically demanding jobs will require more aggressive management. A full recovery is important to maintain their previous of function. It is important for the clinician to determine the patients personal and professional needs in order to create a personalized treatment regimen. Physicians should also make patients aware that their rehabilitation management to full recovery may take time and weigh patient’s personal desire to return to usual activity. As a general principle, their overall rehabilitation management should be closely monitored. Rehabilitation Management and Treatments
3. REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
Current published guidelines do not exist. Treatment starts with pain/inflammation control, and then progresses to rehabilitation. Occasionally immobilization in a walking boot is needed and in recalcitrant cases, surgery may be considered.
At different disease stages
- Avoid aggravating factors with relative rest. Braces and immobilization with a cast or pneumatic boot. Heel lifts or taping can off-load and support the tendon. Prolonged immobilization should be avoided.5,6
- Cryotherapy to control pain and edema.
- Non-steroidal anti-inflammatory drugs (NSAIDs) reduce pain and inflammation and facilitate physical therapy. Studies between oral NSAIDs and placebo show no overwhelming evidence of quicker return to activity, but they are reasonable medications for pain relief.
- Intratendinous steroid injections are not recommended due to reported increased risk of Achilles tendon rupture although no randomized study has shown that to be true. However, adverse events have been reported in 82% of corticosteroid trials while only providing short term pain improvement.4,5
- Once healing has begun patients can begin a rehabilitation program. Many systematic reviews show benefit of eccentric strength training (EST) in non-insertional AT.4
- Includes secondary prevention and disease management strategies
- Gastrocnemius/soleus stretching and EST are important in maintaining mobility and decreasing muscle tension.
- If malalignment exists orthotics may be helpful but braces and splints show no long-term benefit.
- Ultrasound decreases pain and swelling in the acute inflammatory phase of tendon injuries, but there is lack of evidence to support its use in AT.4,5
- Includes secondary prevention and disease management strategies and rehabilitation strategies that intend to optimize function.
- Studies have shown eccentric strengthening can produce normalization of tendon tissue for Achilles tendinopathy2,20-22
- In respect to injections, ultrasound guided paratenon injection using high volumes of local anesthetic, saline, with or without corticosteroid is an option and has a role for chronic cases of non-insertional AT. Current studies have shown that the procedure is safe and there are benefits in improving pain and function (yet short term), but more study is needed.18-20
- As stated in above section, intratendinous corticosteroid injections are not recommended because of the high risk of adverse events including Achilles tendon rupture.5,8,20
- For recalcitrant pain not improved with lifestyle modification, medications, and physical therapy, surgical management of recalcitrant pain can be considered. Repair of an elongated or a partially torn tendon should be considered for patients with high functional demands. Physiatrist’s role should be to help establish the necessity of surgery in certain clinical scenarios.
- Surgical management of recalcitrant pain can be considered. The incidence of postsurgical complications 11%.4,5
In chronic cases, a multidisciplinary team is helpful to optimize patient outcomes. Ideally, the physiatrist would lead a clinical team of physical therapists, orthotists, surgical consultants, nutritionist, and sports psychologist.
Patient & family education
Patients should be educated regarding activity progression and Achilles tendon rupture prevention. Performance of eccentric exercises after a symptom free period, as well as warm ups before exercise initiation to prevent tendon injury should be stressed.
Given the current emphasis on healthcare metrics, both VAS and VISA-A can be used to monitor patients’ progress in a clinical setting.
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
Patient education should focus on preventive strategies, and validated outcomes measures (VAS/VISA-A) should be employed to document treatment progress. Training and exercise modification is very important. Analysis of gait and incorporation of strengthening other muscles besides the ankle/foot complex, such as the core and hip would be ideal in decreasing the risk for further injury.
4. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
Cutting edge concepts and practice
Extracorporeal shock wave therapy (ESWT) is believed to stimulate angiogenesis and inhibit pain receptors. Studies reveal conflicting results, but recent research in randomized, placebo controlled studies showed high efficacy in chronic AT (both insertional and midsubstance forms).5,18-22 The most effective dose and duration remains unknown.4,5
Topical glyceryl trinitrate theoretically increases nitric oxide concentrations leading to improved fibroblast function and wound healing. One randomized, double blind, placebo controlled study showed improvement in symptoms, while others found no difference.4,6
In respect to dietary supplements, mucopolysaccharides may complement physical therapy in decreasing pain.2
A number of different injectable therapies are available, but high quality research comparing the effectiveness of these interventions is lacking. In 2015, Lynen et al compared three once weekly ESWT and two once weekly ultrasound guided hyaluronic acid paratendinous injections for AT. Statistically significant improvements in pain were reported with the hyaluronic acid injection group at one, three, and sixmonths.8 Platelet-rich plasma (PRP) injections appear to show promise in recalcitrant mid-portion AT.9,10 PRP is believed to facilitate healing due to its high concentration of growth factors which may promote tendon remodeling, especially when combined with percutaneous needle tenotomy. Krogh et al, in a recent randomized placebo controlled blinded study of 24 patients compared one single ultrasound guided PRP injection versus a saline injection over a 3 month period found no statistically significant improvement in VISA-A score.11 Limitations of this study included a poor follow up rate, questionable needle tenotomy technique, and an unstructured post-procedure rehabilitation protocol. Based on the available research, PRP therapy may be reserved for those patients who fail to improve with anti-inflammatories, activity modification, bracing, and physical therapy.10,11 Due to conflicting literature, a greater call for larger studies (and in comparison to surgical techniques) is required for further clarification.5,9,18-21
Prolotherapy, an intratendinous sclerosing injection therapy, is thought to produce a local inflammatory response, thereby reducing pain, stiffness, size of intratendinous tears, and neovascularization.4,6 Other sclerosing agents, including polidocanol, which promotes vessel thrombosis, may result in decreased tissue inflammation and neovascularity in patients with chronic AT.4,6
Percutaneous needle tenotomy of the tendon is a promising, effective minimally invasive option for patients not alleviated with standard conservative treatment, based on existing literature for treatment for other tendons such as lateral epicondylosis.25,26 Devices such as the Tenex Health TX system, which takes advantage of this technique, seem to show that it is a safe procedure, which can result in very good outcomes for up to over a year (based on a retrospective study of 26 patients by Ellis et al., 88.5% reported pain relief up to the 18 month follow up period).21,22,27
Another percutaneous technique that has been studied is radiofrequency microtenotomy and coblation of the affected tendon. Here, a radiofrequency probe generating at a low temperature (40-70 degrees Celsius) is activated for 0.5 seconds while light axial pressure is applied to puncture the tendon perpendicularly over a number of areas.21,22 Approximately 20 points over the tendon are mapped prior to the procedure. 21 Based on a 2012 review of 47 patients by Shibuya et al., their study reported that 14.7% of patients had to be re-operated on due to ineffective results, with 6.4% of patients having AT rupture (associated with higher BMI).22,23 Other smaller studies have reported more successful results (“90-95 % success rate”) lasting at least 6 months to 3 years.24 Due to the lack of level 1 studies with other studies using concurrent potentially confounding surgical techniques (e.g. arthroscopy, adhesiolysis) and variable results, this treatment option should not recommended.
5. GAPS IN THE EVIDENCE-BASED KNOWLEDGE
Gaps in the evidence-based knowledge
No objective test exists to monitor the progression of AT or predict the risk of tendon rupture. Future double-blinded randomized controlled studies are needed to clarify the best option among the novel therapies and procedures available (ie, PRP, prolotherapy, ESWT) for pain reduction and functional improvement in non-surgical candidates.4,5,6,18-20,22
- Alfredson H, Masci L, Ohberg L. Partial mid-portion Achilles tendon ruptures: new sonographic findings helpful for diagnosis. Br J Sports Med. 2011;45:429-32.
- Balius R, Alvarez G. A 3-Arm randomized trial for Achilles tendinopathy: eccentric training, eccentric training plus a dietary supplement containing mucopolysaccharides, or passive stretching plus a dietary supplement containing mucopolysaccharides. Current Therapeutic Research. 2016; 78: 1-7.
- Freedman B, Gordon J. The Achilles tendon: fundamental properties and mechanisms governing healing. Muscles, Ligaments, and Tendons Journal. 2014; 4(2): 245-255.
- Li HY, Hua YH. Achilles tendinopathy: current concepts about the basic sciences and clinical treatments. BioMed Research International. 2016; 2016: 1-9.
- Zwiers R, Wiegerinck JI, van Dijk N. Treatment of midportion Achilles tendinopathy: an evidence-based overview. Knee Surgery, Sports Traumatology, Arthroscopy. July 2016; 24(7):2103–2111.
- Maffulli N, Papalia R. Pharmacological interventions for the treatment of Achilles tendinopathy: a systematic review of randomized controlled trials. British Medical Bulletin. 2015; 113; 101-115.
- Maffulli N. The clinical diagnosis of subcutaneous tear of the Achilles tendon. The American Journal of Sports Medicine. 1998; 26(2): 266-270.
- Lynen N, De Vroey T, Spiegel I. Comparison of peritendinous hyaluronan injections versus extracorporeal shock wave therapy in the treatment of painful achilles’ tendinopathy: a randomized clinical efficacy and safety study. Archives of Physical Medicine and Rehabilitation. 2017; 98: 64-71.
- Di Matteo B, Filardo G, Kon E, Marcacci M. Platelet-rich plasma: evidence for the treatment of patellar and Achilles tendinopathy–a systematic review. Musculoskelet Surg. 2015;Apr 99(1):1-9.
- Guelfi M, et al. Long-term beneficial effects of platelet-rich plasma for non-insertional Achilles tendinopathy. Foot and Ankle Surgery. 2015;Sep 21(3):178-81.
- Krogh T, Ellingson T. Ultrasound-guided injection therapy of Achilles tendinopathy with platelet-rich plasma or saline. The American Journal of Sports Medicine. 2016; 44(8): 190-197.
- Calder J, Stephen J, Dijk N. Plantaris Excision Reduces Pin in Midportion Achilles Tendinopathy Even in the Absence of Plantaris Tendon. The Orthopaedic Journal of Sports Medicine. 2016; 4(12): 1-9
- Petrescu P, Izvernariu D. Evaluation of the normal and pathological Achilles tendon by real-time shear wave elastography. Rom J Morphol Embryol. 2016; 57(2): 785-790.
- Brukner P, Khan K. Clinical Sports Medicine 3rd Edition. Australia; McGraw-Hill Book Company; 2010: 40-54.
- Hartgerink P, Fessell DP. Full- versus partial-thickness Achilles tendon tears: sonographic accuracy and characterization in 26 cases with surgical correlation.Radiology. 2001; 220(2): 406-412.
- Kayser R, Mahlfeld K. Partial rupture of the proximal Achilles tendon: a differential diagnostic problem in ultrasound imaging. Br J Sports Med. 2005;39(11):838.
- McCormack J, Underwood F. The minimum clinically importance difference VISA-A and LEFS for patients with insertional achilles tendinopathy. International Journal of Sports Physical Therapy. 2015 10(5): 639-644.
- Caudell GM. Insertional Achilles Tendinopathy. Clin Podiatr Med Surg.2017;34:195–205,
- Wiegerinck JI, et al. Treatment for insertional Achilles tendinopathy: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2013;21:1345–1355.
- Roche AJ. Calder JDF. Achilles Tendinopathy: A Current Review of the Current Concepts of Treatment. Bone Joint J. 2013;95-B:1299–1307.
- Smith WB, Melton W, Davies J. Midsubstance Tendinopathy, Percutaneous Techniques (Platelet-Rich Plasma, Extracorporeal Shock Wave Therapy, Prolotherapy, Radiofrequency Ablation). Clin Podiatr Med Surg. 2017;34:161–174.
- Roche C. A review of the current concepts of treatment: Achilles tendinopathy. Bone Joint J 2013;95-B(10):1299–307.
- Shibuya N, Thorus J, Humphers J, et al. Is percutaneous radiofrequency coblation for treatment of Achilles tendinosis safe and effective? J Foot Ankle Surg. 2012;51:767–71.
- Tasto JP. The use of bipolar radiofrequency microtenotomy in the treatment of chronic tendinosis of the foot and ankle. Tech Foot Ankle Surg. 2006;5(2):110–6.
- Finnoff JT, Fowler SP, Lai JK, et al. Treatment of chronic tendinopathy with ultrasound-guided needle tenotomy and platelet-rich plasma injection. PMR. 2011 Oct;3(10):900-11.
- Barnes D, Beckley J, Smith J. Percutaneous ultrasonic tenotomy for chronic elbow tendinosis: a prospective study. J Shoulder Elbow Surg. 2015;24(1):67–73.
- Ellis M, Johnson K, Freed L, et al. Fasciotomy and surgical tenotomy for chronic Achilles insertional tendinopathy: a retrospective study using ultrasound-guided percutaneous tenotomy approach. J Am Podiatr Med Assoc, in press.
Original Version of the Topic
Clark C. Smith, MD and Grigory Syrkin, MD. Achilles tendinopathy. 07/20/2012.
Richard G. Chang, MD, MPH
2016 Foundation for PM&R Richard S. Materson ERF New Investigator Grant, Research Grant; paid to institution, Principal Investigator
Brian Pekkerman, DO
Nothing to Disclose
Puneet Ralhan, DO
Nothing to Disclose