Imaging in the Assessment and Management
of Achilles Tendinopathy and Paratendinitis
Nevin T. Wijesekera, B.Sc., M.B.B.S., M.R.C.P., F.R.C.R.,1
James D. Calder, M.D., F.R.C.S., F.F.S.E.M.,2
and Justin C. Lee, B.Sc., M.B.B.S., M.R.C.S., F.R.C.R.1
ABSTRACT
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Achilles tendinopathy is a common overuse injury in patients engaged in athletic
activities. Tendon degeneration is often accompanied by paratendinitis. Radiologists are
frequently asked to use imaging techniques to evaluate patients with problems at or around
the Achilles tendon. The main imaging modalities used in the assessment of Achilles
tendon disorders are plain radiography, ultrasound, and magnetic resonance imaging. In
recent years, ultrasound has also been used to guide minimally invasive local treatments for
Achilles tendinopathy, which may prevent the need for surgery if conservative treatments
have failed. In this article, we review the imaging features of Achilles tendinopathy and
consider the relative strengths and weaknesses of the various imaging techniques. The role
of imaging in directing patient management is also discussed, with particular focus on
ultrasound-guided treatments.
KEYWORDS: Achilles, tendinopathy, paratendinitis, ultrasound, MRI, treatment
A
chilles tendon problems are a frequent cause of
foot and ankle pain. The incidence of Achilles tendinopathy is highest in athletes, but it is also common
among so-called weekend warriors in the general population. Injuries of the Achilles tendon are classified by
anatomical location, occurring at either the main body of
the tendon or the osseotendinous junction (Table 1). Of
the Achilles overuse injuries, noninsertional Achilles
tendon pathology (tendinopathy and paratendinitis) are
the most common clinical diagnoses (50 to 75%), followed by insertional disorders (insertional tendinosis and
retrocalcaneal bursitis) (20 to 25%).1,2 A third area
involves injuries to the myotendinous junction, although
these are far less frequent.
The terminology used to describe Achilles tendon
disorders has been confusing and often does not reflect the
underlying pathology, with terms such as tendonitis,
tendinosis, tendinopathy, and partial tear used for apparently similar conditions.3 In recent years, efforts to clarify
the nomenclature has led to the term tendinopathy being
recommended to refer to the clinical syndrome of activityrelated pain, swelling, and impaired performance.4 This
clinical diagnosis includes the histological diagnoses tendinosis and paratendinitis. The term tendinosis is considered appropriate because it recognizes the degenerative
changes present within the tendon substance, but the term
tendonitis has fallen out of favor because there is no
inflammatory response in a chronic tendinopathy.
1
nosis and Management; Guest Editors, Jeremiah C. Healy, F.R.C.P.,
F.R.C.R., F.F.S.E.M. and Justin C. Lee, M.R.C.S., F.R.C.R.
Semin Musculoskelet Radiol 2011;15:89–100. Copyright # 2011
Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY
10001, USA. Tel: + 1(212) 584-4662.
DOI: http://dx.doi.org/10.1055/s-0031-1271961.
ISSN 1089-7860.
Department of Radiology, Chelsea and Westminster Hospital, London, United Kingdom; 2Department of Orthopaedic Surgery, Basingstoke and North Hampshire Hospital, Basingstoke, United Kingdom.
Address for correspondence and reprint requests: Justin C. Lee,
M.R.C.S., F.R.C.R., Department of Radiology, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
(e-mail: Justin.Lee@chelwest.nhs.uk).
Sports Injury of the Lower Extremity: Role of Imaging in Diag-
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Table 1 Classification of Achilles Tendon Injuries by
Anatomical Area
NONINSERTIONAL AREA
Noninsertional Achilles tendinosis
Achilles paratendinitis
Adhesive tendinopathy
Achilles tendon rupture
INSERTIONAL AREA
Insertional Achilles tendinosis
Retrocalcaneal bursitis
Retro-Achilles bursitis
Distal Achilles tendo-fasciitis
Avulsion fracture of the calcaneus
No specific temporal criteria define tendon overuse injuries as acute or chronic. El Hawary et al suggested that the Achilles tendon disorder should be
classified as ‘‘acute’’ if symptoms are present for < 2
weeks, ‘‘subacute’’ is present for 2 to 6 weeks, and
‘‘chronic’’ if present for > 6 weeks.5 These arbitrary
distinctions are not based on clinical criteria or histopathological findings but provide a useful framework for
the condition.
Clinical differentiation between the many causes
of achillodynia can be difficult, and lesions may coexist.
However, it is important for clinicians to distinguish
between the various types of Achilles tendon disorders
because this will affect treatment and rehabilitation. The
goal of management is to return patients to their desired
level of activity without significant residual pain. Achieving an accurate diagnosis requires a detailed injury
history, a comprehensive knowledge of local anatomy,
and, often, diagnostic imaging techniques.6 This article
reviews the imaging features of Achilles tendinopathy
and outlines the potential uses and limitations of various
imaging modalities in the noninvasive evaluation of the
tendon and the role of imaging in guiding treatment.
ANATOMY
The Achilles tendon is the conjoint aponeurosis of the
gastrocnemius-soleus musculotendinous unit (Fig. 1).
The medial and lateral heads of the gastrocnemius
muscle originate from the posterior surface of the femoral condyles. The soleus originates from the posterior
surfaces of the tibia, fibula, and interosseous membrane.
The muscles that form the Achilles tendon act mainly to
plantarflex the ankle, and the gastrocnemius muscle also
flexes the knee joint. Together with the plantaris tendon
and the retrocalcaneal (Kager’s) fat pad, the Achilles
tendon fills the distal part of the posterior compartment
of the calf.
The Achilles tendon inserts on the posterior
surface of the calcaneus distal to the posterior-superior
calcaneal tuberosity. Approximately 12 to 15 cm prox-
Figure 1 Sagittal T2-weighted magnetic resonance image
showing normal Achilles tendon (arrows).
imal to its insertion, the fibers of the conjoint tendon
begin to spiral through 90 degrees, such that the
medial fibers proximally become the most posterior
fibers distally at the insertion. This rotation produces
stress within the tendon, shown to be greatest 2 to
6 cm above the calcaneal insertion, which is a common
site for tendinopathy. The plantaris tendon runs along
the medial aspect of the Achilles tendon (Fig. 2). It
may become confluent with the Achilles tendon or
Figure 2 Axial T2-weighted MR image demonstrating
plantaris tendon (curved arrow) on the medial aspect of the
Achilles tendon (straight arrow).
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Figure 3 Extended field-of-view sonogram of the posterior
calf. Note the anatomical variant of an accessory (Acc) soleus
muscle running alongside the flexor hallucis longus muscle
(FHL).
have an independent insertion on the calcaneus.
Although often thought of as a vestigial structure—
the plantaris is absent in 7 to 20% of limbs—pathology
of the plantaris tendon is an important differential
diagnosis for pain arising from the proximal posterior
aspect of the leg.7,8 An accessory soleus muscle is a rare
anatomical variant that may insert directly onto the
anterior margin of the Achilles tendon or via a separate
tendon on the calcaneus, anteromedial to the Achilles
tendon (Fig. 3). When an accessory soleus muscle is
present, it may manifest as a soft tissue mass bulging
medially between the distal tibia and the Achilles
tendon.9
Two important bursal sacs are associated with the
Achilles tendon insertion: a retrocalcaneal bursa between
the insertion of the tendon and the calcaneus, and a
subcutaneous bursa between the distal tendon and the
skin.10 Pathology in the Achilles tendon can cause these
bursae to become inflamed. The retrocalcaneal bursa
may be seen in normality, although a bursa > 1 mm
anteroposteriorly, 11 mm transversely, or 7 mm craniocaudally is abnormal.11 The subcutaneous bursa is acquired, and its presence usually indicates local trauma or
inflammation.
The Achilles tendon is covered along its entire
length by a thin paratenon sheath. The paratenon is
composed of both visceral and parietal layers, rather than
a true synovial sheath, and facilitates gliding movement
of the tendon within the surrounding tissues. The paratenon forms a thin space between the tendon and the
crural fascia. Under the paratenon lies the epitenon,
which is a loose connective tissue layer surrounding the
Achilles tendon. The inner surface of the epitenon is
continuous with the endotenon, which binds the muscle
fibers together and also provides the neurovascular
supply to the tendon.
The Achilles tendon receives its blood supply
from three sources: the osseous insertion, the musculotendinous junction, and via the paratenon.12 Nerve fibers
follow the vascular channels, forming a rich plexus in the
paratenon before penetrating the epitenon and terminating as nerve endings on the tendon surface. Studies
ETIOLOGY AND PATHOPHYSIOLOGY
Achilles tendinopathy is seen in both athletic and nonathletic individuals and, although its cause remains
unclear, it is strongly associated with overuse and repetitive tendon loading. Pathogenesis is considered to be
multifactorial, with mechanical, vascular, neural, and
‘‘failure of healing’’ models having been proposed. Training errors are implicated in up to 70% of running
injuries.15 These include running too long a distance,
running at too great an intensity, or performing too
much uphill or downhill training.
In acute Achilles tendinopathy, an inflammatory
cellular reaction occurs, with circulatory impairment and
edema formation. If this acute condition is untreated or
inadequately treated, the inflammatory exudate may
organize and form peritendinous adhesions.16 Tendon
degeneration (tendinosis) may be found in conjunction
with peritendinous adhesions, although a causal link has
not been established.
The chronic phase of Achilles tendinopathy is
characterized by a ‘‘disordered’’ healing response, with
collagen degeneration, increase in ground substance, and
neovascularity. Although acute inflammatory tendonitis
was once thought to precede tendinosis, inflammatory
cell infiltration has not been shown in biopsy specimens
of chronically painful tendons.17
The origin of pain in chronic Achilles tendinopathy is still unclear. Given the paucity of evidence
supporting an inflammatory basis, alternative theories
for the cause of pain have been proposed. These include
increased levels of nociceptive neurotransmitters (e.g.,
glutamate and substance P) and peritendinous vasculoneural ingrowth.18,19
DIAGNOSIS
Achilles tendinopathy is clinically manifest by pain,
swelling, and impaired performance. A correct diagnosis
can often be established by clinical examination alone.
However, differentiating between Achilles tendon disorders can be difficult, and Achilles tendon ruptures are
reportedly missed by up to 20% of primary care physicians.20 If a diagnosis is not clear, imaging may be useful
to identify pathology within and around the Achilles
tendon. The imaging modalities most commonly used in
the evaluation of the Achilles tendon are conventional
radiography, ultrasonography, and magnetic resonance
imaging (MRI).
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have demonstrated a ‘‘watershed area’’ of relative hypovascularity 2 to 6 cm proximal to the tendon insertion,
corresponding with the site of pathology in noninsertional tendinopathy.13,14 The poor blood supply to this
region is implicated in the pathophysiology of tendinopathy and tendon tears.
SEMINARS IN MUSCULOSKELETAL RADIOLOGY/VOLUME 15, NUMBER 1
Plain Radiography
Plain radiographs provide limited information on soft
tissues structures due to lack of soft tissue contrast and
therefore not recommended routinely for all patients
with suspected Achilles tendinopathy. However, conventional radiography is easily accessible and inexpensive, and it may provide useful information in some
patients with posterior heel pain. Plain radiographs
should include a lateral weightbearing view of the foot
and ankle and an axial view of the heel. On conventional
radiography, the Achilles tendon has well-defined margins, particularly anteriorly, due to the interface between
the anterior surface of the tendon and the pre-Achilles
(Kager’s) fat pad. This sharp interface may be obscured
in patients with Achilles tendinopathy.6 Plain radiography can also demonstrate calcification or ossification
within the Achilles tendon, which can be a feature of
chronic tendinosis or previous tendon rupture.
In patients with insertional tendinopathy, there is
often a posterosuperior exostosis arising from the lateral
side of the calcaneal tuberosity, known as Haglund’s
deformity. Also known as a ‘‘pump bump’’ due to the
association with certain shoes, Haglund’s deformity is
seen in up to 60% of patients with insertional Achilles
tendinopathy, although not all patients with pump
bumps have insertional tendinopathy.21 In 1982, Pavlov
and colleagues defined the radiological criteria of a
Haglund’s deformity by the use of parallel pitch lines
on a lateral radiograph of the heel (Fig. 4).22
Figure 4 Lateral radiograph of the ankle demonstrating the
parallel pitch line method for diagnosing Haglund’s deformity.
Line A is drawn from the anterior tubercle to the medial
tubercle. Line B parallels line A and starts at the highest point
of the posterior facet of the subtalar joint surface. The tip of
the posterior superior tubercle of the calcaneum (arrow) lies
above line B, diagnostic of a Haglund’s deformity.
2011
Ultrasound
Ultrasound examination plays an important role in the
evaluation of musculoskeletal disorders owing to its low
cost, relative availability, noninvasiveness, and dynamic
character. The technique also allows easy contralateral
comparison.6 Furthermore, ultrasound is increasingly
being used to direct therapeutic interventions for
Achilles tendinopathy refractory to conservative treatment regimes, thus offering an alternative to surgical
management. Ultrasonography carries a high positive
predictive value for Achilles tendinopathy, although a
negative examination can occur in patients with clinically
proven tendinopathy.23
The Achilles tendon is ideally examined with the
patient lying prone with the foot hanging freely. A linear
or small footprint high frequency (7 to 12 MHz) ultrasound probe should be used. Ultrasonographic evaluation of the tendon is ideally performed in both transverse
and longitudinal planes. The ultrasound probe should be
aligned perpendicular to the tendon fibers to avoid
artifacts from acoustic anisotropy, which can simulate
the appearance of tendinopathy. Simultaneous use of
color or power Doppler ultrasound can add information
about blood flow. Extended-field-of-view scanning enables panoramic imaging of the Achilles tendon from its
origin to the calcaneus.24
The healthy Achilles tendon exhibits an echogenic pattern of parallel fibrillar lines in the longitudinal
plane and an echogenic round-to-ovoid shape in the
transverse plane. Normal tendon thickness ranges between 4 mm and 7 mm.25 The retrocalcaneal and
subcutaneous bursae, if present, are usually well defined
by ultrasonography.
Figure 5 A 57-year-old woman long-distance runner with
chronic noninsertional Achilles tendinopathy. Transverse
sonogram with color Doppler (color not shown) demonstrating
neovascularity (arrow) in the tendon. Note also the reduced
echogenicity in the superficial tendon (arrowhead), consistent
with tendinopathy.
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Figure 6 A 31-year-old male professional soccer player
with chronic noninsertional Achilles tendinopathy. Extended
field-of-view sonogram displaying the entire length of the
Achilles tendon from the myotendinous junction to the
calcaneal insertion. Note the fusiform thickening in the midportion of the tendon, characteristic of tendinopathy.
Typical ultrasonographic findings in patients with
Achilles tendinopathy include spindle shape/fusiform
thickening of the tendon and ill-defined hypoechoic
areas within the tendon, which may or may not have
associated areas of increased vascularity on color Doppler
(Figs. 5 and 6). Blood flow is not detected in the normal
Achilles tendon, but color Doppler often reveals blood
flow in tendinopathic tendons. This neovascularization
has been linked to greater pain, poorer function, and
longer symptoms in Achilles tendinopathy.26
In acute Achilles paratendinopathy, ultrasound
can reveal fluid around the tendon. Peritendinous adhesions, seen as thickening of the hypoechoic paratenon,
may be apparent in the chronic form of the disorder and
can be defined with dynamic sonographic examination
(Fig. 7).27
Sonoelastography is a new ultrasound-based technique that is able to evaluate tissue elasticity. Real-time
sonoelastography has been shown to perform well compared with conventional ultrasound findings in depicting
the Achilles tendons of healthy volunteers.28 Painful
thickened Achilles tendons show increased stiffness on
Figure 7 A 35-year-old male rugby union player with
Achilles paratendinitis. Transverse sonogram showing thickening of the hypoechoic paratenon (between arrowheads).
Magnetic Resonance Imaging
Owing to its multiplanar imaging capabilities and excellent soft tissue contrast characteristics, MRI is a useful
modality for imaging the Achilles tendon. However,
MRI is expensive and may not be widely available in
some countries, and scanning can be time consuming. As
with ultrasound, MRI has a high sensitivity and specificity for detection of abnormalities in cases of achillodynia, but MRI has a greater correlation with 12-month
clinical outcome.30
Several MRI scanners and pulse sequences are now
available. The choice of sequences varies between institutions, but conventional imaging of the Achilles tendon
should include a combination of T1-weighted (T1W) and
fluid-sensitive sequences in the axial and sagittal planes.31
Our routine ankle MRI protocol includes fat-saturated
T1W sequences in both planes, axial fat-saturated protondensity, and sagittal short tau inversion recovery (STIR)
imaging. Some authors favor fat-suppressed T2-weighted
(T2W) fast spin-echo sequences. In addition, we also
advocate the routine use of intravenous gadolinium enhanced fat-saturated T1W imaging. Contrast enhancement within the tendon suggests neovascularity, whereas
Figure 8 A 54-year-old male cricketer with chronic Achilles
tendinopathy. Sagittal short tau inversion recovery magnetic
resonance image showing fusiform swelling within the
midportion of the Achilles tendon (arrows) and focal areas
of intratendinous high signal.
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sonoelastography compared with normal tendons.29
However, further studies are required to define the role
of real-time sonoelastography in the routine assessment
of Achilles tendinopathy.
SEMINARS IN MUSCULOSKELETAL RADIOLOGY/VOLUME 15, NUMBER 1
Figure 9 A 34-year-old male long-distance runner with
posterior heel pain. Sagittal short tau inversion recovery
magnetic resonance image demonstrating insertional
Achilles tendinopathy (arrow) in association with the Haglund’s deformity (H).
paratendinous enhancement is indicative of paratendinitis. Importantly, contrast-enhanced MRI sequences can
aid differentiation of paratendinitis from effusion of
bursitis, which directs management decisions. MRI of
the Achilles tendon using ultrashort TE pulse sequences
has recently been promoted because it has been shown to
provide anatomical detail not apparent with conventional
sequences and increased conspicuity of contrast enhancement in tendinopathy.32
The normal Achilles tendon is of low signal on
conventional MRI pulse sequences, reflecting the compact ultrastructural arrangement and low intrinsic water
content. The MRI findings in Achilles tendinopathy
include anteroposterior tendon thickening, fusiform tendon shape, and areas of high signal within the tendon on
T1W, T2W, and STIR sequences (Figs. 8 and 9).33
Areas of intratendinous increased signal are thought to
represent areas of collagen disruption and partial tearing.
It should be noted that intratendinous high signal can
also be found in asymptomatic individuals that may
reflect subclinical tendinopathy or mucoid degeneration.
Artifact related to the magic angle phenomenon can also
cause areas of increased signal within normal tendons,
particularly on T1W sequences that have a low TE. This
effect is observed when the orientation of tendon fibers
relative to the static magnetic field approaches 55 degrees,
which can occur as the Achilles tendon fibers spiral
internally. The magic angle phenomenon can be deliberately exploited when imaging the Achilles tendon. By
imaging the Achilles tendon at the magic angle (the long
2011
Figure 10 A 44-year-old male runner with Achilles paratendinitis. Axial T2-weighted magnetic resonance image
showing a rim of paratendinous fluid (between arrowheads)
around the anterior and lateral aspects of the Achilles tendon.
axis of the tendon at 55 degrees to the main magnetic
field, rather than the normal 0 degrees8), pathological
intratendinous signal change on STIR and contrastenhanced sequences becomes more apparent.34,35
Achilles paratendinopathy may be seen on T2W
or STIR sequences as linear or reticular high signal areas
alongside the deep surface of the tendon, representing
areas of edema or increased vascularity (Fig. 10).27
Figure 11 A 35-year-old elite triple jumper with a long
history of posterior calf pain. Sagittal short tau inversion
recovery magnetic resonance image demonstrating chronic
plantaris tendon rupture. There is marked inflammation
(arrowheads) around the retracted end of the ruptured
tendon (arrow).
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MRI is also useful to differentiate Achilles tendinopathy from other causes of calf pain. Plantaris
tendon strains or rupture, for example, are commonly
misdiagnosed as injury to the Achilles tendon. Plantaris
strain may be seen on MRI as abnormally high signal
intensity both within and adjacent to the fibers of the
plantaris muscle on T2W or STIR sequences. Rupture
of the plantaris most often occurs at the myotendinous
junction, resulting in proximal retraction of the muscle
(Fig. 11). Complete plantaris rupture may appear as a
high signal intensity mass located between the soleus
muscle and the medial head of the gastrocnemius on
T2W and fat-suppressed images.
TREATMENT
The traditional approach to managing chronic Achilles
tendinopathy is aimed at symptom control, with therapeutic options falling into either conservative or operative groups.14,36 Conservative measures are usually
attempted in combination for between 3 to 6 months
but may be unsuccessful in up to 25% of patients. Most
authors report up to 85% success rates from open
surgery; however this may be lower in nonspecialized
clinical practices.37 Therefore, it is usual to exhaust all
nonoperative measures before considering surgery. Recently, several minimally invasive treatments have been
used with the aim of promoting healing. Imaging is
useful to guide these interventions, ensuring that treatment is delivered to the exact site of pathology (Fig. 12).
Conservative Treatments
Many conservative treatments are available to patients
with painful Achilles tendons, but the evidential basis for
most of these therapies remains sparse. Strategies such as
rest (complete or modified activity), orthotic treatments,
pharmacological agents, and various physical therapy
modalities (heat, ultrasound, and electrical stimulation),
are used in combination with the aim of correcting
possible etiological factors and controlling symptoms.
Treatments that have been investigated with randomized controlled trials include eccentric musculoskeletal
training, topical glyceryl trinitrate (GTN), nonsteroidal
anti-inflammatory drugs, and extracorporeal shock wave
therapy.14,38
A regimen of intensive heavy-load eccentric
muscle training has been shown to be superior to concentric training for the treatment of chronic Achilles
tendinopathy. Alfredson and colleagues38 developed a
model of eccentric training in which the load is increased
until the patient experiences pain. This 12-week program is successful in 90% of patient with midportion
Achilles tendon pain, but only 30% of those with
insertional pain.39,40
Topical GTN, a prodrug of nitric oxide, is thought
to induce tendon healing by stimulating collagen synthesis in fibroblasts. A double-blind randomized study
involving 65 patients with chronic Achilles tendinopathy
compared the continuous application of a GTN patch to
the tendon with a placebo patch. At 6 months, activity
pain in the treatment group was significantly reduced
compared with the placebo group.41
Nonsteroidal anti-inflammatory drugs (NSAIDs)
are often used in the management of acute athletic
injuries for analgesic purposes. However, there is evidence that NSAIDs have little or no effect on the clinical
outcome of chronic Achilles tendinopathy and may even
impair tendon healing by inhibiting tendon cell migration and proliferation.42,43
Extracorporeal shock wave therapy (ESWT) is a
treatment in which acoustic shock waves are directed
through the skin to the affected area. Ultrasound guidance can be used to optimally position the device. The
mechanism of action is unknown, but it is speculated
that the energy delivered may promote diffusion of
cytokines across vessel walls, resulting in the stimulation
of a healing cascade. A randomized controlled trial of 75
patients compared ESWT, eccentric loading, and a waitand-see policy for the treatment of chronic midportion
Achilles tendinopathy. At 4-month follow-up, there was
no difference in clinical outcome between those treated
by EWST and those treated by eccentric loading. However, both of these therapies were significantly better
than the wait-and-see policy.44
Minimally Invasive Treatments
Figure 12 Transverse sonogram showing a needle (arrows) within the Achilles tendon (AT) during a dry needling
procedure.
LOCAL ANTI-INFLAMMATORY INJECTIONS
Local corticosteroid injections are commonly used in
the treatment of tendinopathies. However, the role of
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SEMINARS IN MUSCULOSKELETAL RADIOLOGY/VOLUME 15, NUMBER 1
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Figure 13 Longitudinal sonograms with color Doppler (color not shown) of a tendinopathic Achilles tendon (AT) (A) before
and (B) immediately after injection of hyperosmolar dextrose solution into the neovessels. Note the absence of color flow within
the tendon following injection of the sclerosant.
inflammation in chronic tendinopathy is unclear, and
the rationale for the use of anti-inflammatory injections
in Achilles tendinopathy is controversial. Furthermore,
many clinicians advise against injection of corticosteroid in or around the Achilles tendon due to the
potential risk of tendon rupture, although this has not
been substantiated in large studies.45 Other risks, including fat atrophy and skin discoloration, are also well
recognized.
Fredberg et al46 performed a double-blind placebo-controlled study of peritendinous triamcinolone
injections in 24 athletes with chronic Achilles tendonitis,
in which sonography was used to diagnosis and direct
placement of the injections. After 6 months, the steroid
injections had a significant effect in reducing pain and
thickening of tendons, compared with no change in the
placebo-treated group. However, when combined with
aggressive rehabilitation, many patients suffered a relapse of symptoms within 6 months.
Ultrasound-guided peritendinous injections of
two new anti-inflammatory drugs, adalimumab (a tumor
necrosis factor a blocker) and anakinra (an interleukin-1
receptor antagonist), have also been evaluated in a small
study including patients with chronic Achilles tendinopathy. Both drugs improved pain sensation at rest,
although neither had a significant beneficial effect on
tendon thickness.47
Achilles tendinopathy, randomized to treatment with
either polidocanol (5 mg/dL) or lidocaine (5 mg/mL)
plus adrenaline (5 mg/mL).48 Both polidocanol and the
combination of lidocaine plus adrenaline have immediate local anesthetic and vasoconstrictive effects, but
polidocanol also has a sclerosing effect. After a maximum of two injections, the short-term results (mean
follow-up: 3 months) showed significantly reduced tendon pain following treatment with polidocanol but not
with the nonsclerosing combination. In a pilot study, the
same investigators reported good results in 8 of 11
patients with insertional tendinopathy, where neovascularization was demonstrated with Doppler ultrasound.47
Based on the same rationale as sclerotherapy, electrocoagulation has also been used to eliminate neovessels
but is potentially more destructive.52
Chan et al53 hypothesized that high-volume ultrasound-guided injection of normal saline around the
Achilles tendon would produce local mechanical effects
causing neovessels to rupture or occlude. A local anesthetic and steroid combination was injected between the
anterior aspect of Achilles tendon and Kager’s fat pad,
followed by 40 mL of injectable saline (Fig. 14). They
OBLITERATION OF NEOVESSELS
Tendon neovascularization is a common feature on color
Doppler ultrasound of painful Achilles tendons but not
in those that are pain free. This observation led to the
hypothesis that obliterating the new vessels may reduce
refractory Achilles tendon pain (Fig. 13). Alfredson and
Öhberg performed a series of studies using polidocanol
as a sclerosing agent in the treatment of chronic tendinopathies.48–51 Using ultrasound and color Doppler
guidance, the injections targeted areas of neovascularization just outside the ventral part of the tendon. One
study involved 20 patients with chronic midportion
Figure 14 Extended field-of-view sonogram following
injection of 50 mL of normal saline into Kager’s fat pad for
treatment of Achilles tendinopathy (AT). Note how the fluid
tracks up to the musculotendinous junction (arrow).
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STIMULATION OF HEALING RESPONSE
The pathophysiological basis of Achilles tendinopathy
may be explained as a disordered wound-healing response. This model is supported by histological features
of haphazard healing.54 Therapies that directly target the
abnormal areas of tendon aim to interrupt the degenerative cycle by initiating a wound-healing cascade. It is
hypothesized that the inflammatory response induces the
formation of granulation tissue, ultimately leading to
improved tendon strength and clinical outcomes.
The technique known as prolotherapy, whereby
small volumes of an irritant solution are injected around
a painful tendon or ligament, has long been in use. The
injected solution is thought to initiate a local inflammatory response, causing fibroblast proliferation and subsequent collagen production, resulting in increased
tendon strength. In patients with chronic Achilles
pain, Maxwell et al55 modified this technique by injecting hyperosmolar dextrose directly into areas of tendinopathy under ultrasound guidance. The study showed
that in the 33 treated tendons there was a significant
reduction in pain at rest and during tendon-loading
activities.
Dry needling is the repeated lancing of an abnormal area of tendon to incite internal hemorrhage. The
consequent inflammatory response may lead to formation
of granulation tissue that strengthens the tendon. The
technique may be combined with intratendinous injection of autologous whole blood or autologous plateletrich plasma. These injectates are thought to provide
cellular and humoral mediators to promote healing in
areas of degeneration. Ultrasound-guided dry needling
followed by autologous blood injections has been shown
in patients with refractory epicondylitis and patellar
tendinosis, but no studies of this technique have been
published in patients with Achilles tendinopathy.56,57
tendon to break up adhesions. Volume adhesiotomy
may be performed using ultrasound guidance to better
direct the injection into the paratenon/tendon interspace. Peritendinous injection of low molecular weight
heparin has also been used with the aim of limiting the
formation of adhesions. However, some evidence indicates there is no beneficial effect, and it has been
suggested that heparin, in itself, causes a degenerative
tendinopathy.59
Other injectates such as aprotinin (a protease
inhibitor) have been used in the management of Achilles
tendinopathy. Brown et al60 performed a double-blind
placebo-controlled trial in patients with Achilles tendinopathy, comparing aprotinin injections with saline injections (0.9%) as part of a rehabilitation program.
Thirty-three affected tendons were treated with three
peritendinous injections, each a week apart. In this
study, aprotinin was not shown to offer any statistically
significant benefit over placebo.
Surgery
Open procedures include paratenon stripping and debridement of tendinopathic lesions. In patients with no
evidence of true tendinosis on imaging, adhesiolysis may
be considered whereby adhesions between the tendon
and the paratenon are divided.61,62 In patients with frank
paratendinitis, the paratenon may also be excised. Success rates of 86 to 96% have been described for such
treatment of isolated paratendinitis.61,63
If there are discrete tendinopathic lesions on
imaging, these can be identified at surgery as macroscopically dull and yellowed areas that may contain
crystalline deposits compared with the glistening white
appearance of normal tendon. This abnormal tissue can
be excised and the tendon repaired with resorbable
sutures (Figs. 15 and 16).
In those patients where there is no discrete area of
abnormality but a more generalized tendinopathy is
present, multiple longitudinal incisions may be made in
the tendon because this has been shown to initiate
PERCUTANEOUS TENOTOMY
Open longitudinal tenotomy is an established surgical
treatment for chronic Achilles tendinopathy if conservative measures fail. The operation aims to promote wound
repair by modulation of the tendon cell-matrix environment. Testa et al58 evaluated ultrasound-guided percutaneous longitudinal tenotomy in 75 athletes with
chronic achillodynia and found that their results were
comparable to those reported after more extensive open
surgical procedures.
OTHER TREATMENTS
Volume adhesiotomy, also known as brisement, is the
injection under pressure of dilute local anesthetic or
saline solution between the paratenon and Achilles
Figure 15 Photograph of swollen Achilles tendon at open
surgery.
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found that high-volume injections significantly reduced
pain and improved function in 30 patients with chronic
Achilles tendinopathy.
97
SEMINARS IN MUSCULOSKELETAL RADIOLOGY/VOLUME 15, NUMBER 1
2011
problems. Steenstra et al reported on 16 patients
undergoing this technique with a 2.7-mm arthroscope
following a minimum period of 6 months of conservative management.73 At a follow-up of 2 to 7 years,
all patients had improvement in their symptoms.
Several other authors have reported similarly promising results in a small series of patients, and all report
few complications.74–76
Figure 16 Photograph taken during open debridement
procedure with excision of macroscopically abnormal tissue.
vascular ingrowth and a healing response.62,64 Neovascularization and accompanying sensory nerves from the
ventral paratendinous tissue have also been implicated
in the development of pain transmission in Achilles
tendinopathy.65,66 Therefore, in all surgical interventions,
the anterior attached fat pad with ‘‘neovessels and/or
nerves’’ should be dissected and released from the
Achilles tendon.
Even after extensive debridement, there is usually enough tendon to achieve side-to-side closure of
the tenotomy. However, if > 50% of the Achilles
tendon has been excised, it is often necessary to
augment the repair using a turn-down flap of more
proximal tendon or perform a tendon transfer using
flexor digitorum longus, flexor hallucis longus, or even
peroneal tendons.67–69
The results of surgery following the debridement
of intratendinous lesions are not as good as those for
paratendinitis. Nelen reported a success rate of 73% for
patients undergoing open surgical debridement of tendinopathic lesions.61 Paavola demonstrated a significant
difference in outcome between patients with a focal
intratendinous lesion and those without in terms of
success (54% and 88%, respectively).70 Maffulli et al
also noted that those patients with chronic tendinopathy
had a worse outcome: In 14 patients undergoing surgery
with an average duration of symptoms of 87 months,
only 5 had good or excellent outcomes, and 6 required
further surgery.71
The complications of open procedures are well
documented. In a series of 432 consecutive patients,
Paavola et al presented a complication rate of 11% and
a reoperation rate of 3%.72 The complications included
wound edge necrosis (3%), superficial infection (2.5%)
and sural nerve irritation (1%). Other complications
included seroma, hematoma and fibrotic reactions, and
one thrombosis.
The advancement in endoscopic techniques and
arthroscopic shavers has enabled the development of
minimally invasive procedures to improve recovery
time and reduce the incidence of wound-healing
CONCLUSION
Achilles tendinopathy is a common overuse injury in
patients engaged in athletic activities. The imaging
modalities most often used in the diagnostic assessment
of the Achilles tendon include plain radiography, ultrasound, and MRI. Conservative strategies remain the
mainstay of treatment. Although surgery is occasionally
required, ultrasound may be used to guide local therapeutic interventions. Therefore, the radiologist plays an
increasingly important role in the diagnosis and treatment of Achilles tendinopathy.
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