Download Accesorry Muscles Around The Ankle

Accesorry Muscles Around The Ankle
Poster No.:
C-0986
Congress:
ECR 2016
Type:
Educational Exhibit
Authors:
M. OYNAK, U. Kesimal, M. A. Oztek, C. Cevikol; Antalya/TR
Keywords:
Congenital, Normal variants, MR, Musculoskeletal system,
Musculoskeletal soft tissue, Anatomy
DOI:
10.1594/ecr2016/C-0986
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Learning objectives
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•
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Describe the anatomic features of accessory muscles of the ankle
Identify MRI findings of accessory muscles of the ankle
Discuss the clinical importance of accessory muscles of the ankle
Background
Accessory muscles around the ankle are not uncommon and can be seen in routine
MRI's. The prevelance is ranging from 1% to 26% [1,2]. They can be asymptomatic or
can cause pain or present as a palpable mass. Noninvasive and accurate diagnosis is
possible with MRI. However, knowledge of the anatomy of these muscles is essential for
precise diagnosis and distinguishing from other entities such as soft tissue neoplasms
in patients with a palpable mass or tendon tears in patients presenting with pain.
The purpose of this exhibit is to review the accessory muscles around the ankle and
demonstrate some examples of accesory muscles in the ankle.
Findings and procedure details
There are many accessory peroneal muscles reported, such as peroneus quartus,
peroneus accessories, peroneocalcaneus externum, peroneus digiti minimi and
peroneus tertius [1,2,3]. However, the name peroneus quartus is sometimes used to
refer to any one of these muscles, therefore reported prevalence of these variations vary
widely.
Peroneus quartus muscles ( Fig. 1 on page 4 ) are more common in males and are
frequently bilateral [1,4]. The most common origin is from peroneus brevis, with posterior
surface of fibula and peroneus longus being other possibilities. It courses inferiorly medial
and posterior to other peroneal tendons. It may insert into different points, according
to which different types of the muscle are classified. The most common insertion point
is the calcaneus (in which case it is called peroneocalcaneus externum), with peroneal
tubercle, the retrocochlear eminence, cuboid bone, base of fifth metatarsal and tendons
of peroneus longus or brevis being other possible insertion points [1,4]. Peroneus quartus
is commonly asymptomatic; however, it causing lateral ankle pain, ankle instability, and,
in case of hypertrophy of its attachments, peroneal tenosynovitis have been reported.
It can also cause crowding in the retromalleolar groove, predisposing to peroneus
brevis tendon dislocation and tear [5]. The muscle can potentially be identified with
ultrasonography [6], however, MRI remains the best imaging modality, where it can
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be seen medial to peroneus brevis, separated from it by a fat plane [1,2). The most
important differential diagnosis is a longitudinal split tear of the peroneal tendons, from
which the muscle can be differentiated by examining the more proximal images where
an anomalous muscle belly will be seen [1,2].
Flexor digitorum accessories longus (FDAL, Fig. 2 on page 6 ) is the second
most common variant in the ankle, seen in 6-8% of people, and is more common in
males [7]. It can originate from either the medial margin of tibia and the fascia of deep
posterior compartment or from the lateral margin of fibula. Its tendon descends posterior
and superficial to the tibial nerve, passes through the tarsal tunnel and inserts into
the quadratus plantae or flexor digitorum longus tendon. It is closely related to the
posterior tibial artery and nerve, therefore its presence can be associated with tarsal
tunnel syndrome [1,2]. It can also be a possible culprit in flexor halluces longus (FHL)
tenosynovitis, causing repeated friction of the FHL in the tarsal tunnel [7]. It can be imaged
on MRI where the muscle is seen in the tarsal tunnel, superficial to the nerve and vessels.
It can contain fleshy fibers in the tarsal tunnel, and this may be helpful for identification.
Peroneocalcaneus internus ( Fig. 3 on page 6, Fig. 4 on page 7 ) originates at the
medial aspect of lower fibula, inferior to the origin of FHL; descends posterior and lateral
to it, passes through the tarsal tunnel and inserts onto the medial aspect of calcaneus
inferior to the sustentaculum. It is frequently bilateral. It is usually asymptomatic; however,
it displaces FHL anteriorly and laterally which may potentially cause compression of the
neurovascular bundle in the tarsal tunnel. It can cause tenosynovitis of FHL and a case
associated with posterior impingement has been reported [8]. It can also be associated
with neurovascular injury in endoscopic surgery, where it can be mistaken for FHL [8].
Once again, MRI is the imaging modality of choice. It can be difficult to differentiate from
FDAL, in which case insertion into calcaneus and the presence of a fat plane between
the muscle and quadratus plantae can be helpful for diagnosis. Another important point
to consider is that sometimes FHL can have two tendinous slips, which may be mistaken
for PCI.
Accessory soleus ( Fig. 5 on page 9 , Fig. 6 on page 9 ) is seen in 0.7-5.5% of
people, is more common in males and usually unilateral [1]. It originates from the anterior
surface of soleus or from the fibula and soleal line of tibia; descends anterior to the
Achilles tendon and then inserts onto the upper surface or the medial aspect of calcaneus
with a muscular or tendinous insertion or onto the Achilles tendon. It can present as a
soft tissue mass in the posterolateral ankle and this appearance can further be mistaken
as a mass in x-rays where an increased soft tissue density obliterates the Kager fat pad
anterior to the Achilles tendon. It can also cause swelling and pain, more common in
athletes and exertional in nature [1,9]. Although its course does not involve the tarsal
tunnel, association with tarsal tunnel syndrome in cases of medial calcaneal insertion
has been reported [2]. Again, MRI is the imaging modality of choice, where the muscle
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is anterior to Achilles tendon and superficial to the flexor retinaculum. Abnormal signal
intensity can be seen on MRI related to trauma, ischemia or atrophy.
Tibiocalcaneus internus is a rare accessory muscle. It originates from medial crest of tibia,
courses inferiorly deep to flexor retinaculum and posterior to the neurovascular bundle;
and inserts onto the medial aspect of calcaneus anterior to the insertion of the Achilles
tendon [1]. A case has been reported where it caused tarsal tunnel syndrome [10].
Images for this section:
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Fig. 1: Peroneus quartus muscle.
© - Antalya/TR
Fig. 2: Axial T1 weighted image shows flexor digitorum accessories longus (red arrow).
TP; tibialis posterior, FDL; flexor digitorum longus.
© - Antalya/TR
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Fig. 3: Sagittal T1 weighted images of peroneocalcaneus internus muscle.
© - Antalya/TR
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Fig. 4: Axial T1 weighted image of peroneocalcaneus internus muscle.
© - Antalya/TR
Fig. 5: Sagittal T1 weighted images of the right ankle shows accessory soleus.
© - Antalya/TR
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Fig. 6: Axial T1 weighted MR image of the ankle with accessory soleus.
© - Antalya/TR
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Conclusion
In some cases accessory muscles may present in routine MRI images and a radiologist
should be familiar with the appearances of the accessory muscles. While the majority
of the muscles are asymptomatic, in some cases they can cause symptoms like pain or
palpable mass. In such situations, it is important to diagnose the cause of the pain or
exclude a neoplasm. MRI is the imaging of choice.
Personal information
References
1- Sookur PA, Naraghi AM, Bleakney RR, Jalan R, Chan O, White LM. Accessory
muscles: anatomy, symptoms, and radiologic evaluation. Radiographics. 2008 MarApr;28(2):481-99.
2- Salvardor Errasti A, Arnaiz J, Piedra Velasco T, Jimenez C, Garcia-Bolado A, Crespo
del Pozo J. MRI atlas of accesory muscles in the lower limb. European Congress of
Radiology 2010, ECR 2010, 4-8 March 2010, Vienna, AUSTRIA.
3- Witvrouw E, Borre KV, Willems TM, Huysmans J, Broos E, De Clercq D. The signifi
cance of peroneus tertius muscle in ankle injuries: a prospective study. Am J Sports Med
2006;34:1159-1163.
4- Cheung YY, Rosenberg ZS, Ramsinghani R, Beltran J, Jahss MH. Peroneus quartus
muscle: MR Imaging features. Radiology 1997;202:745-750.
5- Wang XT, Rosenberg ZS, Mechlin MB, Schweitzer ME. Normal variants and diseases
of the peroneal tendons and superior peroneal retinaculum: MR imaging features.
Radiographics. 2005 May-Jun;25(3):587-602.
6- Precerutti M, Bonardi M, Ferrozzi G, Draghi F. Sonographic anatomy of the ankle.
Journal of Ultrasound. 2014;17(2):79-87. doi:10.1007/s40477-013-0025-x.
7- Batista JP, del Vecchio JJ, Golanó P, Vega J. Flexor Digitorum Accessorius
Longus: Importance of Posterior Ankle Endoscopy. Case Reports in Orthopedics. 2015;
2015:823107.
8- Bennett DL, El-Khoury GY. Case 67: Peroneocalcaneus internus muscle:false flexor
halluces longus (FHL). In: Bennett DL, El-Khoury GY, eds, Pearls and Pitfalls in
Page 11 of 12
Musculoskeletal Imaging Variants and Other Difficult Diagnoses. 1st ed. Cambridge
University Press; 2013.
9- Rossi R, Bonasia DE, Tron A, Ferro A, Castoldi F. Accessory soleus in the athletes:
literature review and case report of a massive muscle in a soccer player. Knee Surg
Sports Traumatol Arthrosc. 2009 Aug;17(8):990-5.
10- Sammarco GJ, Conti SF. Tarsal tunnel syndrome caused by an anomalous muscle.
J Bone Joint Surg Am. 1994 Sep;76(9):1308-14.
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