By Howard Kashefsky, DPM
Achilles tendinopathy is a common lower extremity injury in athletes as well as nonathletes. The Achilles tendon is often a site of injury in runners and is the second-most common running-related musculoskeletal injury, after medial tibial stress syndrome, with an incidence of 9.1% to 10.9%.1 The lifetime risk in former elite male distance runners is a whopping 52%.2
Factors that may contribute to Achilles tendinopathy include overuse, systemic disease, older age, sex, body composition, and biomechanics.3 Elevated biomechanical load has been shown to cause both microscopic and macroscopic failures.4-6
The Achilles tendon is the strongest and largest tendon in the body.7 This tendon connects the gastrocnemius and soleus muscles to the posterior aspect of the calcaneus. The group of muscles is collectively called the triceps surae, which serves as the primary plantar flexor of the foot and ankle, but also flexes the knee. Insertional fibers of the Achilles tendon are in continuity with the plantar aponeurosis. The Achilles tendon does not have a true synovial sheath, but rather a single layer of paratenon. The paratenon is responsible for a significant portion of the blood supply to the Achilles tendon, most of which enters anteriorly; studies have identified a hypovascular area of the Achilles tendon 2 cm to 6 cm proximal to its insertion on the calcaneus, which appears to be an area at risk for complete rupture.8,9
Achilles tendinopathy can be progressive and can be characterized using terminology that reflects the condition’s stage. In the acute phase, Achilles tendinitis refers to inflammatory changes at the tendon level, which may include the paratenon that surrounds the tendon.1 Achilles tendinosis depicts a more chronic and degenerative process. Achilles tendinopathy is our preferred term for Achilles tendon pain.
The two most common sites of injury in runners include midportion Achilles tendinopathy (2 cm to 6 cm proximal to the calcaneal insertion) and insertional Achilles tendinopathy (injury localized to the insertion of the Achilles tendon at the calcaneus).10 Less commonly, injuries may occur at the myotendinous junction.
Differential diagnoses that should be considered in cases of suspected Achilles tendinopathy include posterior ankle impingement; retrocalcaneal bursitis; symptomatic Haglund deformity; bone stress injury (BSI) of the distal tibia, fibula, or calcaneus; peroneal tendinopathy; and hindfoot arthrosis.11
In my opinion, one cannot overstate the importance of a good physical exam. In cases of Achilles tendinopathy, the exam includes finding the exact location of the pain and rating its severity using a scoring system with which the patient’s progress can be tracked. It is helpful to compare limbs and look for a relative temperature increase, thickening, or overlying erythema in the painful limb. The posterior calcaneus should be evaluated for a prominence of the posterior aspect that may suggest the presence of Haglund deformity or a large posterior spur.
Testing of muscle strength and ankle range of motion (ROM) are also helpful. Dorsiflexion ROM assessment should be done with the knee in full extension and in 90° of flexion to determine differences in ROM (the Silfverskiold test); less ROM in full knee extension suggests gastrocnemius tightness or contracture that may increase tension on the Achilles tendon.12 Evaluation of strength should include a series of single-leg calf raises and evaluating for pain, between-limb differences in heel height, and fatigue during this maneuver.11
If a patient’s history or the presence of a palpable gap in the tendon raises concern for an Achilles tendon rupture, Thompson’s test should be performed.13 The patient lies prone and the examiner squeezes the triceps surae distal to the knee in both limbs. Passive foot plantar flexion in both limbs suggests the painful Achilles tendon is contiguous with the calcaneus and unlikely to have a full-thickness tear. If there is no foot plantar flexion with calf squeeze on the affected side, there should be concern for Achilles rupture. Extensor lag and a palpable gap are also signs of rupture.
The calcaneal squeeze test is helpful to exclude a calcaneal BSI. The clinician presses both medially and laterally on the calcaneus and evaluates for pain localized to the calcaneus.11 Weightbearing radiographs (lateral and axial views of the heel) may be helpful to evaluate for Haglund deformity, calcific tendinopathy, or if the diagnosis is unclear. Magnetic resonance imaging (MRI) is appropriate if there is concern for a significant rupture of the Achilles tendon or to evaluate for a BSI.11 Ultrasonography is a useful modality that can help verify Achilles tendon injury.14
I also cannot understate the importance of a thorough history in the athletic patient. Thoughtful questions regarding training patterns may uncover the cause of the injury and assist in managing recovery and prevention of recurrence.
In the acute phase, initial management includes rest, activity modification, a trial of heel lifts, and stretching the triceps surae. If the patient has significant weightbearing pain, a brief period of immobilization in a boot can help to alleviate this, but lengthy periods of immobilization should be avoided due to the risk of muscle atrophy and deep vein thrombosis. Local modalities—including ice, massage, and ultrasound—may reduce pain.15-17 Iontophoresis may also be considered to reduce inflammation associated with acute presentations.18 A short course of nonsteroidal anti-inflammatory drugs (NSAIDs) is commonly prescribed, though the degree of true inflammation is questionable in more chronic conditions. Topical nitroglycerin does not have clear evidence to support its use.19
After achieving pain control, treatment should focus on strengthening the Achilles tendon and triceps surae. Alfredson and colleagues demonstrated the efficacy of an eccentric loading protocol for addressing pain and strength in patients with Achilles tendinopathy.20 In this landmark study, 15 recreational athletes with unilateral midportion Achilles tendinopathy completed a 12-week session of a single-leg eccentric heel-drop program with progressive weight loading.
Individuals who completed this protocol (three sets of 15 repetitions, with both knees bent and straight, twice per day) had normalization of strength and reduction of pain, and all returned to running during the 12 weeks. A larger study using Alfredson’s protocol in athletes with a five-year follow-up reported that most individuals experienced gains in function, though nearly half pursued other therapies, and most reported mild pain.21 A modified version of Alfredson’s protocol with eccentric-load calf raises that do not include a heel drop has been proposed for insertional Achilles tendinopathy.11,22
Additionally, rehabilitation exercises that address the full kinetic chain are important, given the evidence suggesting that biomechanical factors—including reduced activity of the tibialis anterior, rectus femoris, gluteus medius, and gluteus maximus muscles—may contribute to Achilles tendinopathy.23,24 Foot intrinsic strengthening and restoring proprioception is important for this condition, as with any foot and ankle disorder.
Treatment for chronic refractory Achilles tendinopathy may include injection of platelet-rich plasma (PRP) at the affected site. In published case series, PRP injection has been associated with symptom improvement in patients with noninsertional Achilles tendinopathy.25,26 However, in a randomized controlled trial, PRP was no more effective than saline for supplementing the effects of eccentric exercise in patients with chronic midportion Achilles tendinopathy.27,28
There is evidence that orthotic intervention may reduce Achilles tendon load in healthy runners29 as well as symptoms in runners with Achilles tendinopathy.30-32 Mayer et al documented significant reductions in pain symptoms in runners with Achilles tendinopathy following an intervention with semirigid orthoses.31 Donoghue et al evaluated the effectiveness of custom foot orthoses in runners with chronic Achilles tendon pathology.32 An improvement of 92% was noted in pain symptoms with the use of the orthoses.
A more recent study33 found that custom orthoses were no more effective than sham orthoses for people with midportion Achilles tendinopathy. However, the study participants were not athletes, and the orthoses were customized based on foot posture index alone, which could have affected the findings.
I have utilized foot orthoses clinically in runners with Achilles tendinopathy, in combination with other conservative therapies, and have consistently seen improvement. But more research is clearly needed to determine the mechanism of action, which will more accurately guide orthotic treatment.
Traditionally, the mechanism by which foot orthoses were believed to alleviate Achilles tendon pain involved reducing rearfoot eversion and vertically aligning the calcaneus, thereby reducing the shear stress experienced by the Achilles tendon.34 However, there is also evidence to suggest the mechanism of action may be multifactorial.35,36
A deep heel cup with extrinsic varus or valgus posting will control any subtalar eversion or inversion while ambulating.37 The full-contact orthosis shell is important for full functionality of the rearfoot posting and controlling midtarsal joint articulation. Proper casting is also critical. When suspension casting with plaster or a similar material, one must load the midtarsal joints to a pronated position while keeping the subtalar joint neutral.38,39
The effect of running shoe design on Achilles loading has been controversial. As often is the case, conflicting information has been published. In a study of 12 male runners, Sinclair et al found that Achilles tendon forces during running were higher for minimalist footwear than conventional or maximalist footwear, and suggested that running in minimalist shoes may increase the risk of Achilles injury.40 Conversely, Wearing reported that, in 12 recreationally active men, peak acoustic velocity (a measure of tensile load) during walking was higher when participants wore running shoes with a 10-mm offset than when they were barefoot.41 Although walking and running are different activities, one would expect the loading patterns to be similar. However, in this study the techniques used to measure load varied between conditions, and the study sample was small. More research needs to be done.
If conservative care fails, one may consider surgery. Operative management of this condition may include debridement of degenerative areas of the tendon and repair of remaining healthy tendon. In cases of recalcitrant insertional Achilles tendinopathy, removal of an associated Haglund deformity and retrocalcaneal bursectomy can be beneficial. In individuals aged 50 years and older or with severe tendon degeneration, augmenting the repair with ipsilateral flexor hallucis longus transfer may provide additional benefit.42,43
Howard Kashefsky, DPM, is the director of podiatry services at UNC Healthcare at the University of North Carolina at Chapel Hill.
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- Chen TM, Rozen WM, Pan WR, et al. The arterial anatomy of the Achilles tendon: Anatomical study and clinical implications. Clin Anat 2009;22(3):377-385.
- Stein V, Laprell H, Tinnemeyer S, Petersen W. Quantitative assessment of intravascular volume of the human Achilles tendon. Acta Orthop Scand 2000;71(1):60-63.
- Zantop T, Tillmann B, Petersen W. Quantitative assessment of blood vessels of the human Achilles tendon: An immunohistochemical cadaver study. Arch Orthop Trauma Surg 2003;123(9):501-504.
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- Tenforde AS, Yin A, Hunt KJ. Foot and ankle injuries in runners. Phys Med Rehabil Clin N Am 2016;27(1):121-137.
- Silfverskiold N. Reduction of the uncrossed two-joint muscles of the leg to one-joint muscles in spastic conditions. Acta Chir Scand 1924;56:315-330.
- Thompson TC. A test for rupture of the tendo achillis. Acta Orthop Scand 1962;32:461-465.
- Paavola M, Paakkala T, Kannus P, Jarvinen M. Ultrasonography in the differential diagnosis of Achilles tendon injuries and related disorders. A comparison between pre-operative ultrasonography and surgical findings. Acta Radiol 1998;39(6):612-619.
- Speed C. Current treatment paradigms in the management of soft tissue disorders. Curr Med Res Opin 2013;29(suppl 2):7-9.
- Hsu AR, Holmes GB. Preliminary treatment of Achilles tendinopathy using low-intensity pulsed ultrasound. Foot Ankle Spec 2016;9(1):52-57.
- Chang YP, Chiang H, Shih KS, et al. Effects of therapeutic physical agents on Achilles tendon microcirculation. J Orthop Sports Phys Ther 2015;45(7):563-569.
- Neeter C, Thomee R, Silbernagel KG, et al. Iontophoresis with or without dexamethazone in the treatment of acute Achilles tendon pain. Scand J Med Sci Sports 2003;13(6):376-382.
- Kane TP, Ismail M, Calder JD. Topical glyceryl trinitrate and noninsertional Achilles tendinopathy: a clinical and cellular investigation. Am J Sports Med 2008;36(6):1160-1163.
- Alfredson H, Pietila T, Jonsson P, et al. Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. Am J Sports Med 1998;26(3):360-366.
- van der Plas A, de Jonge S, de Vos RJ, et al. A 5-year follow-up study of Alfredson’s heel-drop exercise programme in chronic midportion Achilles tendinopathy. Br J Sports Med 2012;46(3):214-218.
- Jonsson P, Alfredson H, Sunding K, et al: New regimen for eccentric calf-muscle training in patients with chronic insertional Achilles tendinopathy: results of a pilot study. Br J Sports Med 2008;42(9):746-749.
- Azevedo LB, Lambert MI, Vaughan CL, et al. Biomechanical variables associated with Achilles tendinopathy in runners. Br J Sports Med 2009;43(4):288-292.
- Franettovich Smith MM, Honeywill C, Wyndow N, et al. Neuromotor control of gluteal muscles in runners with Achilles tendinopathy. Med Sci Sports Exerc 2014;46(3):594-599.
- Gaweda K, Tarczynska M, Krzyzanowski W. Treatment of Achilles tendinopathy with platelet-rich plasma. Int J Sports Med 2010;31(8):577-583.
- Owens RF Jr, Ginnetti J, Conti SF, et al. Clinical and magnetic resonance imaging outcomes following platelet rich plasma injection for chronic midsubstance Achilles tendinopathy. Foot Ankle Int 2011;32(11):1032-1039.
- de Vos RJ, Weir A, van Schie HT, et al. Platelet-rich plasma injection for chronic Achilles tendinopathy: a randomized controlled trial. JAMA 2010;303(2):144-149.
- de Jonge S, de Vos RJ, Weir A, et al. One-year follow-up of platelet-rich plasma treatment in chronic Achilles tendinopathy: a double-blind randomized placebo-controlled trial. Am J Sports Med 2011;39(8):1623-1629.
- Sinclair J, Isherwood J, Taylor PJ. Effects of foot orthoses on Achilles tendon load in recreational runners. Clin Biomech 2014;29(8):956-958.
- Gross ML, Davlin LB, Evanski PM. Effectiveness of orthotic shoe inserts in the long-distance runner. Am J Sports Med 1991;19(4):409-412.
- Mayer F, Hirschmuller A, Muller S, et al. Effects of short‐term treatment strategies over 4 weeks in Achilles tendinopathy. Br J Sports Med 2007;41(7):e6.
- Donoghue OA, Harrison AJ, Laxton P, et al. Orthotic control of rear foot and lower limb motion during running in participants with chronic Achilles tendon injury. Sports Biomech 2008;7(2):194-205.
- Munteanu SE, Scott LA, Bonanno DR, et al. Effectiveness of customised foot orthoses for Achilles tendinopathy: a randomised controlled trial. Br J Sports Med 2015;49(15):989-994.
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- Sinclair J, Richards J, Shore H. Effects of minimalist and maximalist footwear on Achilles tendon load in recreational runners. Comp Exerc Physiol 2015;11(4):239-244.
- Wearing SC, Reed L, Hooper SL, et al. Running shoes increase Achilles tendon load in walking: an acoustic propagation study. Med Sci Sports Exerc 2014;46(8):1604-1609.
- Schon LC, Shores JL, Faro FD, et al. Flexor hallucis longus tendon transfer in treatment of Achilles tendinosis. J Bone Joint Surg Am 2013;95(1):54-60.
- Hunt KJ, Cohen BE, Davis WH, et al. Surgical treatment of insertional Achilles tendinopathy with or without flexor hallucis longus tendon transfer: a prospective, randomized study. Foot Ankle Int 2015;36(9):998-1005.