A delayed diagnosis of Achilles tendonitis can lead to recalcitrant cases of posterior heel and leg pain. With this in mind, this author discusses common etiologies of this condition and reviews the evidence on a range of conservative therapies.
The Achilles tendon is the largest tendon in the body and is one of the strongest tendons in the body. During the gait cycle, the Achilles tendon can receive a load stress that is 3.9 times body weight during walking and 7.7 times body weight when running.1 The Achilles tendon arises from the aponeuroses of the gastrocnemius muscle and the soleus muscle as their slips course distally along the posterior aspect of the leg. Approximately 15 cm in length, the Achilles tendon forms by bundles of collagen fibers that rotate anterior to medial to posterior to lateral as the tendon courses proximally to its insertion along the posterior and inferior aspect of the calcaneus.2,3
Although the Achilles tendon can withstand great stresses from physical activities such as from running and jumping, it is also prone to injury, particularly in the context of biomechanical abnormalities within the gait cycle that further promote the development of Achilles tendon injuries.4,5
Delays in diagnosis and treatment can often lead to the development of recalcitrant cases of posterior heel and leg pain. These delays can make the conservative management of these injuries a challenge for clinicians. Despite these challenges, there are a variety of current and emerging conservative care modalities available in the clinical armamentarium for the management of this challenging clinical presentation.
Tendonitis Versus Tendinosis
When discussing Achilles tendinopathy, it is important to establish a consistent nomenclature to adequately describe these complex injury presentations. Tendon injuries can be largely grouped into several broad categories: traumatic rupture, tendonitis and tendinosis (which can ultimately lead to atraumatic rupture).6,7
Simply defined, tendonitis is inflammation of a tendon secondary to an acute injury.8,9 Inflammation is the body’s natural response to injury or disease, and this inflammation often causes swelling, pain or irritation. Achilles tendonitis can be further subdivided into various types based upon the anatomic locations involved. The two most commonly described presentations of Achilles tendonitis are insertional and non-insertional tendonitis.7
Insertional Achilles tendonitis involves inflammation at the broad insertion of the Achilles tendon along the posterior aspect of the calcaneus. This type of Achilles tendonitis can occur even with minimal levels of physical activity. Non-insertional Achilles tendonitis commonly presents with inflammation of the Achilles tendon fibers along the more central portions of the Achilles tendon. These types of injuries are common in younger, more active patients. Often, clinicians will find these injuries in the “watershed region,” an area of relative avascularity along the distal course of the Achilles tendon, approximately 2 to 6 cm from its insertion along the posterior aspect of the calcaneus.10,11
Both insertional and non-insertional Achilles tendinopathy can, if left untreated, lead to tendon degeneration and scar tissue formation. In some instances, these areas of degeneration can ossify, creating retrocalcaneal osteophytes (in the context of insertional Achilles tendonitis) and intra-substance tendon calcifications in those patients suffering from non-insertional Achilles tendonitis.7,12,13
In contrast to Achilles tendonitis, Achilles tendinosis is a chronic degenerative process that occurs when acute inflammation about the tendon is allowed to progress unchecked.14,15 Achilles tendinosis is commonly associated with long-term repetitive actions such as running, heavy lifting and excessive training. These injuries are chronic in nature and are commonly recalcitrant to many of the more conservative treatment modalities.16
Reviewing The Possible Etiologies For Achilles Tendonitis
As I noted previously, the Achilles tendon forms from the distal slips of aponeurosis from two muscles, the gastrocnemius and the soleus. These muscles play an important role in both the swing and stance phase of the gait cycle.4,5,17 Virtually all cases of Achilles tendon injury appear to result from anatomic, structural or dynamic disturbances in normal lower leg mechanics, and require active treatment regimens that attempt to establish normal function to prevent recurrence of injury.
Microtrauma produced by the eccentric loading of fatigued muscle and vascular blanching of the Achilles tendon produced by conflicting internal and external rotatory forces impart to the tibia by simultaneous pronation and by knee extension with running.18 This pronation can exacerbate a preexisting anatomic or structural equinus deformity, creating increased tension along the triceps surae complex. Sports that require jumping — like basketball — can further increase the level of tension along the Achilles tendon and these activities are commonly associated with the development of Achilles tendonitis. However, even patients who are participating in lower impact activities such as walking develop inflammation, particularly in the context of biomechanical instability.19
In addition to the underlying biomechanical etiology, Achilles tendonitis can occur as a consequence of an overuse injury, particularly in younger patient populations. Tendinopathy is likely to develop in those patients who have sudden increases in the amount or intensity of activity. For example, tendinopathy may occur when one increases a distance run every day by a few miles without allowing the body a chance to adjust to the new distance. Additionally, patients who demonstrate posterior soft tissue equinus are prone to develop Achilles tendonitis due to the chronic tightness in the triceps surae during the gait cycle, leading to increased stress forces being transmitted throughout the Achilles tendon and the subsequent development of inflammation.20,21
Apart from biomechanical and activity-related causes of Achilles tendinopathy, several studies have also demonstrated the development of Achilles inflammation associated with arthritis and infection.22-25 Tendonitis associated with concomitant arthritic conditions is more common in middle-aged and elderly patients, and is often associated with the development of enthesopathy.26
Key Symptoms And Characteristics Of Achilles Tendonitis
Patients suffering from Achilles tendonitis commonly complain of pain and stiffness along the posterior aspect of the ankle and along the heel in the area of the Achilles insertion. This pain can be worse in the morning and following activity. As this disease process progresses, one may observe fusiform thickening along the Achilles tendon and often this area is focally tender to palpation.27
During the physical exam, there is commonly pain with resisted plantarflexion, particularly in the later stages of Achilles tendonitis. Swelling can be present and authors have noted that it often increases throughout the day with activity.28 Occasionally, one may note palpable enthesopathy with the presence of Haglund’s deformities and retrocalcaneal spur formation.26,29
Treating Achilles Tendon Pathology: What The Research Reveals
The successful management of Achilles tendon pathology is a challenge to the foot and ankle surgeon. The initial approach to care should be largely conservative in nature. Patients rarely require initial surgical intervention for the management of these conditions. Regardless, Achilles tendinopathy often requires two to three months of conservative care to fully heal and allow a full return to pain-free function.
During that time, clinicians should encourage patients to engage in RICE (rest, ice, compression, elevation) therapy while modifying activities to reduce the forces along the Achilles tendon. Encourage patients to decrease or stop the activities that cause pain, and transition over to low-impact activities, such as cycling and swimming, to further reduce the stress along the Achilles tendon. Functional rehabilitative exercises geared toward eccentric (lengthening) exercises and training — that can train muscle groups and increase strength and resiliency with low-energy exercise — lead to faster muscle and tendon repair. Studies demonstrate that eccentric exercises often provide excellent results in the management of Achilles tendonitis to the point where many authors recommend utilizing this modality as a first-line treatment for Achilles tendinopathy.30,31
The use of orthotic control devices is of particular value in those patients who demonstrate biomechanical instability as an underlying cause of Achilles tendonitis.32 Additionally, shoe gear modification, with the addition of heel lifts and varus or valgus wedges, can be beneficial in the management of these conditions in patients who demonstrate underlying biomechanical etiology. Functional bracing can be appropriate in cases of significant tendinopathy in which protective immobilization is indicated. This is of particular value in those patients who present with chronic Achilles tendinosis and there is a concern for potential pathologic Achilles tendon rupture.
Clinicians may also use nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen to address pain and swelling. However, one must exercise caution with these medications in patients with cardiovascular disease, hypertension and gastroesophageal reflux disease (GERD) as these medications can exacerbate symptoms in those patients who suffer from these concomitant disease processes.33
In many cases of long-standing Achilles tendinopathy, patient symptoms are commonly recalcitrant to simple RICE therapy. Despite these challenges, however, surgery is often unnecessary. As I previously noted, functional rehabilitation and physical therapy can often be beneficial in the management of this patient population with goals of reducing pain and swelling while improving mobility and strength.
However, in some cases, exercise and stretching paradigms alone are inadequate to address the symptomatology of chronic Achilles tendinopathy. In these cases, rehabilitative physical therapy activities in conjunction with anti-inflammatory modalities, such as therapeutic ultrasound, electrical stimulation and low-level laser light therapy, can often break the pain-inflammation cycle and allow for appropriate healing in the Achilles tendon.34-37
Emerging Conservative Therapies
In addition to more traditional modalities in the management of chronic Achilles tendinopathy, including eccentric (lengthening) exercises, functional orthoses and immobilizing splints, a review of the current literature demonstrates an increasing number of conservative therapeutic modalities that one can utilize in the management of recalcitrant cases.
Extracorporeal shockwave therapy (ESWT) has demonstrated promise in the conservative management of insertional Achilles tendonitis.34,38,39 The SWAAT study demonstrated improvement in both the anke-hindfoot score as well as in objective function following the administration of ESWT in conjunction with the use of dietary supplementation with arginine, ViNitrox (Nexira), collagen, methyl-sulfonyl-methane, vitamin C and bromelain.38 The theory is that ESWT creates a positive, inflammatory effect while also improving blood flow within the tendon to allow for tissue healing. Despite these apparent successes, further study is necessary.
There has been much recent discussion in the literature regarding the efficacy of autologous platelet-rich plasma (PRP) injections in the management of chronic insertional and mid-substance Achilles tendinopathy. Some studies have shown little positive effect in the improvement of Achilles tendon symptoms but others have found greater success.40,41 In 2011, Owens and colleagues demonstrated an improvement of functional outcomes in patients suffering from Achilles tendinopathy following intratendinous injection of PRP.42 However, MRI evaluation of the same patient cohort demonstrated little to no change in the substance of the diseased Achilles tendons.
There is growing interest in the working mechanisms of autologous growth factors and how clinicians can apply them to the management of chronic tendinopathy. In 2011, a prospective, double-blind, randomized trial of patients suffering from chronic elbow tendinopathy demonstrated that growth factor-based therapies provide additional benefit beyond physical therapy in recalcitrant cases of tendinopathy.43 Several studies have demonstrated efficacy in the management of Achilles tendinopathy with intra-tendon application of recombinant human platelet-derived growth factor-BB (rhPDGF-BB).44,45 The rhPDGF-BB treatment resulted in a dose-dependent, transient increase in cell proliferation and sustained improvement in biomechanical properties. However, the exact amount and mixture of growth factors necessary to facilitate a positive response is unknown, and further study is required.46
The Achilles tendon is the strongest tendon in the body and it functions with every step people take. Achilles tendinopathy is a common lower extremity complaint that can prove challenging due to anatomical, biomechanical and activity-related considerations. While a prolonged recovery process is common for this pathology, clinicians can successfully manage many patients with conservative care modalities.
The literature demonstrates that appropriate early intervention is associated with improved outcomes as well as an earlier return to function. If left untreated or under-treated, Achilles tendonitis can progress toward degenerative tendinosis if clinicians do not adequately address the underlying etiology.
There are a variety of conservative modalities available to the foot and ankle clinician involved in the management of Achilles tendinopathy. A review of the current literature demonstrates a variety of emerging techniques and modalities — from both a conservative and surgical aspect — that show promise in the management of acute and chronic Achilles tendonitis and subsequent tendinosis. While further research is necessary, there is strong evidence to suggest that these technologies will provide numerous treatment options in the future.
Dr. Fitzgerald is a Fellow of the American College of Foot and Ankle Surgeons. He is board-certified in foot surgery and reconstructive foot and ankle surgery by the American Board of Podiatric Surgery. Dr. Fitzgerald is in private practice at Hess Orthopaedics and Sports Medicine in Harrisonburg, Va.
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