The Journal of Foot & Ankle Surgery xxx (2015) 1–2

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Case Reports and Series

A Missing Flexor Hallucis Longus Muscle and Tendon in a Young Female Patient: A Case Report of a Rare Anomaly Konstantinos C. Xarchas, MD, PhD 1, Leon Oikonomou, MD 2 1 2

Assistant Professor of Orthopaedics, First Department of Orthopaedics, General Hospital G. Gennimatas, Athens, Greece Resident Orthopaedic Surgeon, First Department of Orthopaedics, General Hospital G. Gennimatas, Athens, Greece

a r t i c l e i n f o

a b s t r a c t

Level of Clinical Evidence: 4

Anatomic variations of the long flexor tendons of the foot are not common. Tendinous bands connecting the flexor hallucis longus and the flexor digitorum longus are well known and have even been classified. Although the congenital absence of the flexor pollicis longus in the hand is well known, we found no reports of the absence of the flexor hallucis longus in the foot. We describe the case of a 32-year-old female who stepped on a crystal ashtray and transected the flexor hallucis tendon arising from the flexor digitorum longus. During surgery, the absence of the proper flexor hallucis longus muscle and tendon became apparent. This anomaly appears to be extremely rare, and its clinical importance is unknown, although our patient reported no functional problems before the accident. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.

Keywords: anatomic variation flexor hallucis longus trauma

Tendon trauma can be challenging to treat, particularly when the margins of the disrupted tendon are fragmented or infected, or when either the proximal or distal portion of the tendon has retracted or displaced along the course of the supporting tendon sheath. Herein we describe the case of an adult female who sustained flexor tendon laceration in her foot. It was not until surgical inspection was undertaken in an attempt to repair the tendon that absence of the normal anatomic tendon and anomalous anatomy was revealed. It had functioned in an apparently normal fashion before the injury. Case Report A 32-year-old female was admitted to the emergency department with complete transection of the flexor hallucis longus tendon in the sole of her right foot from stepping on a broken crystal ash tray approximately 1 hour earlier in the day. She had a more-or-less longitudinal cut over the medial aspect of the plantar surface of her right foot, starting from the base of the first phalanx of her great toe and extending 8 cm proximally. She was unable to flex her great toe, although movement of the lesser toes was normal. The remainder of her medical history and physical examination findings were unremarkable. Her tetanus immunization history was current, and, after Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Konstantinos C. Xarchas, MD, PhD, Assistant Professor of Orthopaedics, First Department of Orthopaedics, General Hospital G. Gennimatas, Athens, Greece. E-mail address: [email protected] (K.C. Xarchas).

initial cleansing of the wound in the emergency department and intravenous administration of cefuroxime (750 mg 3 times daily), amikacin (500 mg twice daily), and metronidazole (500 mg twice daily), preparations were made to surgically inspect and repair her lacerated flexor hallucis longus tendon. Less than 24 hours after presentation to our emergency department, the patient was taken to the operating room. The patient was given general anesthesia, placed prone on the operating table, and a thigh pneumatic tourniquet was placed to aid hemostasis. Next, her right foot plantar wound was surgically explored. The small distal part of the transected tendon was immediately identified, just as were the 2 heads of the flexor hallucis brevis, which were also completely divided close to their insertion. The proximal part of the flexor hallucis longus was then examined through the existing wound; however, we were unable to find it, even when we extended the wound proximally to the level of the navicular bone, until the insertion of the tibialis posterior was identified. A second incision was, therefore, made behind the medial malleolus in an attempt to retrieve the tendon and pull it back in place for repair. The anatomic elements were easily identified, including the tibialis posterior, neurovascular bundle, and flexor digitorum communis; however, the tendon of the flexor hallucis longus, which ought to be the most posterior and running in its own sheath, was absent. Additional exploration was performed proximally to the level of the flexor digitorum longus, but the muscle and tendon of the flexor hallucis longus were not found. Attention was then turned to the foot. Through the existing wound that was laterally retracted, we sought the tendons of the flexor digitorum longus. To our surprise, we finally found the divided flexor tendon of the hallucis close to the flexors of the lesser toes as a fifth band arising from the

1067-2516/$ - see front matter Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2014.12.005

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K.C. Xarchas, L. Oikonomou / The Journal of Foot & Ankle Surgery xxx (2015) 1–2

Fig. 1. The proximal stump of the flexor hallucis tendon arising from the flexor digitorum longus of the right foot of a 32-year-old female. Blood is present in the tendon sheath.

Fig. 2. The repaired flexor hallucis tendon.

flexor digitorum longus (Fig. 1). The tendon was repaired with a modified Kessler and a running suture (Fig. 2). The flexor hallucis brevis was also repaired, the wound was closed, and a plaster of Paris backslab was applied with the foot in equinus. The tendon healed uneventfully with the backslab in place for 6 weeks. Physiotherapy was then started, and the functional outcome at 3 months postoperatively was excellent. At the latest follow-up visit, 6 months after tendon repair, the patient had resumed all her normal activities without restrictions.

knowledge of them has improved (3,4). The flexor hallucis longus itself, other than the tendon unions, has few variations. A doubled flexor hallucis longus has been reported, with both tendons inserting on the terminal phalanx of the great toe (5). In conclusion, the absence of the flexor hallucis longus muscle and tendon, with a fifth band arising from the flexor digitorum longus to the great toe, appears to be extremely rare. Its clinical importance is, therefore, unknown. This anatomic possibility should be known to surgeons treating flexor tendon injuries of the foot to avoid unnecessary dissection of the foot.

Discussion The congenital absence of the flexor pollicis longus in the hand, with or without thumb hypoplasia and thenar atrophy, although rare, has been well documented (1,2). In contrast, we found no report of the absence of the flexor hallucis longus. Anatomic variations of the foot flexors have also been well documented and will usually involve cross-connections between the flexor hallucis longus and the flexor digitorum communis. Such connections between the tendon of the long flexor of the great toe and that of the flexor digitorum longus are constant, but varied. A slip is commonly sent from the flexor hallucis to the flexor digitorum; however, frequently, an additional slip passes, in the reverse direction, from the flexor digitorum to the flexor hallucis. Attempts have been made to classify these interconnections as

References 1. Chaudhary V, Sehgal H, Bano S, Parmar P, Kumar S. Bilateral congenital absence of flexor pollicis longus with thumb hypoplasia and thenar atrophy. Indian J Radiol Imaging 24:268–270, 2014. 2. Demisseren M, Afandiyev K, Durgun M. Congenital absence of flexor pollicis longus tendon without associated anomalies of thumb hypoplasia: a case report and review of the literature. Hand 2:184–187, 2007. 3. LaRue BG, Anctil EP. Distal anatomical relationship of the flexor hallucis longus and flexor digitorum longus tendons. Foot Ankle Int 27:528–532, 2006. 4. Plaass C, Abuharbid G, Waizy H, Ochs M, Stukenborg-Colsman C, Schmiedl A. Anatomical variations of the flexor hallucis longus and flexor digitorum longus in the chiasma plantare. Foot Ankle Int 34:1580–1587, 2013. 5. Bergman R-A, Afifi AK, Miyauchi R. Illustrated Encyclopedia of Human Anatomic Variation: Flexor Hallucis Longus. In: Anatomy Atlases. Available at: http://www. anatomyatlases.org/. Accessed September 2014.

A Missing Flexor Hallucis Longus Muscle and Tendon in a Young Female Patient: A Case Report of a Rare Anomaly.

Anatomic variations of the long flexor tendons of the foot are not common. Tendinous bands connecting the flexor hallucis longus and the flexor digito...
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