UP-TO DATE REVIEW AND CASE REPORT

Pyogenic tenosynovitis of the flexor hallucis longus in a healthy11-year-old boy: a case report and review of the literature

Stephane Millerioux • Marie Rousset •

Federico Canavese

Received: 16 November 2012 / Accepted: 28 November 2012

� Springer-Verlag France 2012

Abstract Pyogenic tenosynovitis of the flexor hallucis

longus (FHL) is a rare condition in young healthy patients.

We report the case of a healthy 11-year-old boy who pre-

sented with a history of fever and painful swelling below

the medial malleolus of the left ankle. Imaging and labo-

ratory findings suggested infectious tenosynovitis of the

FHL. Methicillin-sensitive Staphylococcus aureus was

isolated on culture following surgery. Antibiotherapy was

initiated and continued until inflammatory markers

returned to normal. Six months post-surgery, he resumed

sport activities and inflammatory markers remained within

normal limits. We review also the literature and discuss the

clinical characteristics of this condition.

Keywords Pyogenic tenosynovitis � Flexor hallucis

longus � Children � Surgery

Introduction

Inflammation of a tendon sheath can occur in a wide

variety of diseases. Differential diagnosis includes chronic

inflammatory joint disease, connective tissue disorders,

rheumatoid and psoriatic arthritis, and overuse syndrome

and infection [1–11]. Pyogenic tenosynovitis of the flexor

hallucis longus (FHL) at the level of the ankle joint is a

closed space infection involving the flexor tendon sheath.

Diabetes is known to be a risk factor and correlates with

poor prognosis [3, 12, 13]. The condition is rarely seen in

healthy patients, particularly children, and the literature is

very limited. By contrast, tenosynovitis of the FHL related

to mechanical stress is more common, especially in ballet

dancers and in running athletes to a lesser extent [14]. We

report an unusual case of pyogenic tenosynovitis of the

FHL occurring in a healthy 11-year-old boy. To the best of

our knowledge, this is the first report in the English liter-

ature. A review of the literature was performed to support

our conclusions.

Case report

A healthy 11-year-old boy presented to the emergency

department of a regional pediatric hospital following a

history of fever and painful swelling below the medial

malleolus of the left ankle. Pain and joint swelling unre-

lated to specific trauma had appeared 5 days previously.

Fever and pain were unresponsive to paracetamol. He was

36 kg in weight, 1.35 m tall, and with no personal or

family disease history. The patient described ankle pain

associated with joint stiffness, which increased with

walking and was worse in the morning. Other clinical

symptoms included fever between 39� and 40�, headaches,

night sweats, and anorexia.

His clinical examination revealed painful swelling below

the medial malleolus of the left ankle and limited hallux

metatarsophalangeal joint dorsiflexion. The ankle joint was

fully mobile and pain free. Laboratory findings included a

white blood cell count of 5320,000/L, plasma level of

human C reactive protein (CPR) of 40 mg/L, and procalc-

itonin (PCT) of 0.66 ng/ml; hemocultures were negative.

Plain radiographs of the foot and ankle showed no

abnormality (Fig. 1). Ultrasound showed a large fluid

collection on the medial side of the ankle in contact with

S. Millerioux � M. Rousset � F. Canavese (&)

Service de Chirurgie Infantile, Centre Hospitalier

Universitaire Estaing, 1 Place Lucie et Raymond Aubrac,

63003 Clermont Ferrand, France

e-mail: canavese_federico@yahoo.fr

123

Eur J Orthop Surg Traumatol

DOI 10.1007/s00590-012-1147-0

the left posterior tibial tendon (Fig. 2). Doppler examina-

tion revealed a slight hyperemia around the fluid collection

and the surrounding fat tissue had an infiltrated appearance.

Magnetic resonance imaging (MRI) identified a large

hypointense collection of fluid in the tendon sheath of the

left FHL. T2-weighted, short tau inversion recovery

(STIR), and T2 with fat saturation images were suggestive

of tenosynovitis (Fig. 3). The gadolinium-enhanced syno-

vial sheath of the flexor muscle was not significantly

thickened; the ankle joint was normal.

The patient was operated and drainage of the fluid col-

lection was performed through a medial approach. The

collection was abundant and purulent. The collection of

37 mm by 8 mm was limited by the tendon sheath and

extended on either side of the superior extensor retinacu-

lum. Parenteral antibiotics (amoxicillin with clavulanic

acid and gentamicin) were started immediately following

tissue sampling, and swabs were sent for bacteriological

and histological analysis. After thorough lavage of the

wound and a partial tenosynovitis, drains were placed in

contact with the FHL tendon and left in place for 48 h. The

ankle was stabilized in a below-the-knee splint.

Methicillin-sensitive Staphylococcus aureus was iso-

lated on culture. Intravenous antibiotics were continued

until the inflammatory markers had returned to normal. The

patient was then switched to an oral regime of amoxicillin

and clavulanic acid for a duration of 6 weeks. Twelve

months after surgery, the patient had resumed sports

activities and inflammatory markers remained within nor-

mal limits.

Literature review

A search of the Medline database from 1945 to 2012 was

performed to identify papers related to pyogenic tenosyn-

ovitis of the foot. The search strategy is given in Table 1.

As recommended by the Cochrane Handbook of System-

atic reviews [15], a variety of search terms (‘‘tenosynovi-

tis’’, ‘‘children’’, ‘‘foot’’, and ‘‘hallux flexor’’) were used,

including a combination of index and free-text terms.

Fig. 1 Preoperative lateral radiograph of the foot and ankle showing

no abnormality

Fig. 2 Preoperative echography showing a large fluid collection on

the medial side of the ankle in contact with the left posterior tibial

tendon

Fig. 3 Preoperative magnetic resonance imaging of the ankle

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Abstracts were screened and relevant full texts of articles

were retrieved for further review. Reference sections of

papers were also scrutinized to identify additional litera-

ture. All levels of evidence were included. Two hundred

and fifty-four reports concerning children with tenosyno-

vitis were identified. We retrieved 12 case reports for

pyogenic lower limb tenosynovitis in adults and 2 cases

in children [1]. Only one publication reported FHL

tenosynovitis in children [9], but we could not identify any

report on FHL pyogenic tenosynovitis in the pediatric

setting (Table 2).

Discussion

This report presents the first case of pyogenic tenosynovitis

of the FHL occurring in an otherwise healthy child. Most

lower limb cases are stenosing tenosynovitis, chronic

inflammatory joint disease, or a pathology related to

mechanical stress. Patients with tenosynovitis of the FHL

tendon frequently present with overlapping signs and

symptoms of FHL tendinitis, plantar fasciitis, and tarsal

tunnel syndrome. Symptoms associated with FHL pathol-

ogy are collectively known as ‘‘FHL dysfunction’’ and can

manifest themselves anywhere along its length, ranging

from the posterior leg to the plantar foot and the hallux

[16, 17]. Differential diagnosis includes mechanical [3, 4, 11]

or chemical [10] stress, chronic inflammatory joint disease

[3, 9], connective tissue disorders [8], viral infection [1],

and tumor [2, 3, 5–7] (Table 3). In our case, the boy was

athletic, but he had neither a foot wound nor a history of

Table 1 Flow chart of study selection

Keywords Results

Tenosynovitis 3337 publications

Tenosynovitis, children 254 publications

Tenosynovitis, foot, children 22 publications

Tenosynovitis, flexor hallucis 55 publications

Tenosynovitis, flexor hallux 17 publications

Tenosynovitis, children, flexor foot 3 publications

Tenosynovitis, children, flexor hallux 1 publication

Tenosynovitis, foot, children, flexor, pyogenic 0 publication

Tenosynovitis, children, flexor hallux, pyogenic 0 publication

Tenosynovitis, flexor hallux, infectious 0 publication

Tenosynovitis, flexor hallux, children, infectious 0 publication

Table 2 Case reports of adults and children with pyogenic tenosynovitis of the flexor hallucis longus

Authors Number of

cases

Adult (A) or child

(C)

Site of infection Pathogen Medical history

Diwanji SR 1 A Flexor hallucis longus Mycobacteriumtuberculosis

Tuberculosis

Le Meur A 1 A Ankle Capnocytophagacynodegmi

Lee JS 1 A Foot Achlorophyllic algae:Prototheca

Immunocompetent

Ogut T 2 A Achilles tendon Mycobacteriumtuberculosis

Tuberculosis

Jira M 1 A Anterior tibial and common extensor Mycobacteriumtuberculosis

Tuberculosis

Al-Khawari

HA

4 A Foot Diabetes

Memisoglu K 1 A Anterior tibial and extensor hallucis

longus

Mycobacteriumtuberculosis

Tuberculosis

Roca B 1 A Left foot, no precision Mycobacteriumtuberculosis

Tuberculosis

Faraj S 1 A Extensor hallucis longus Neisseria gonorrhoeae

Hooker MS 1 A Tibialis anterior tendon Mycobacteriumtuberculosis

Tuberculosis

Goldberg I 1 A Achilles tendon Mycobacteriumtuberculosis

Tuberculosis

Pimm LH 3 2 A, 1 C Dorsiflexor tendons, tibialis posterior Mycobacteriumtuberculosis

Tuberculosis

Brown JT 1 C Peroneal tendons Neisseria gonorrhoeae

Ogawa S 2 A Foot Mycobacteriumtuberculosis

Tuberculosis

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trauma or infection during the last month. Thus, we are unable

to provide any insight into the presence of hematogenous or

contiguous infection without any predisposing factor.

MRI was valuable in establishing the correct primary

diagnosis in our patient. However, although MRI can

identify and locate fluid collection, it does not provide

information about its specific nature. In the presence of

dense collection, ultrasound can suggest pyogenic collec-

tion, but it does not provide accurate information about the

localization of the collection. In this case, biological find-

ings are questionable. Clinical examination is the key

diagnostic step in the evaluation of the patient.

Pyogenic tenosynovitis has rarely been reported in the

lower extremities. Kayabas et al. [18] reported a case of

ciprofloxacin-induced urticaria and FHL tenosynovitis.

MRI revealed increased synovial fluid surrounding the

tendon of the FHL muscle representing tenosynovitis.

Brown and Miller [19] reported a case of peroneal teno-

synovitis after acute gonococcal infection. Eberle et al. [20]

reported a case of the flexor digitorum accessorius longus

(FDAL) muscle causing tenosynovitis. Given its variability

and mostly asymptomatic presentation, FDAL muscle may

go unnoticed on an MRI scan. Ogut and Ayhan [21] sug-

gested that FDAL muscle can be excised through hindfoot

endoscopy. However, most reported cases of pyogenic

tenosynovitis occurred in adult immunocompromised

patients with predisposing factors, such as the presence of

diabetes mellitus, peripheral vascular disease, or renal

failure [12].

Pyogenic tenosynovitis prognosis is directly related to

early recognition of the disease process, prompt surgical

drainage, and sheath irrigation, combined with an appro-

priate antibiotic regimen.

Pyogenic tenosynovitis should be differentiated from

tenosynovitis secondary to overuse syndrome. It is believed

to represent overuse with attendant tenosynovitis of the

tendon in the fibro-osseous tunnel extending from the ankle

to the midfoot. Pain and joint swelling appear often after

intensive physical activity. Although conservative therapy

benefits most patients, some recalcitrant cases may require

surgical intervention.

Conclusion

This rare case of pyogenic tenosynovitis of the FHL

demonstrates that tenosynovitis is a clinical entity, which

suggests many different causes. The main cause seems to

be mechanical stenosing. However, despite low occurrence

and atypical presentation, the surgeon must keep in mind

the pyogenic form because of its potential complications.

Clinical examination, together with biological and radio-

logical signs, leads to a correct diagnosis. Once diagnosis is

made, surgical treatment is required.

Conflict of interest None.

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Table 3 Differential diagnosis of symptoms associated with a flexor

hallucis longus pathology

Differential

diagnosis

Symptoms

Osteoarthritis Direct tenderness over joint. No tenderness over

tendon

Septic arthritis Open wound, joint functional disability, pain

Fracture Direct tenderness over bone. No tenderness over

tendon

Cellulitis Tenderness, macular erythema, warmth, edema.

Sometimes open wound

Rheumatoid

arthritis

Systemic symptoms, other joint involvement, no

fever, rheumatoid nodules

Gout Swelling, warmth, erythema, tenderness of the

involved joint

Soft tissue

injuries

Hematoma, wound, tenderness

Septic

tendonitis

Tenderness, edema, warmth

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14. Theodore GH, Kolettis GJ, Micheli LJ (1996) Tenosynovitis of

the flexor hallucis longus in a long-distance runner. Med Sci

Sports Exerc 28:277–279

15. http://www.cochrane-handbook.org. Accessed 15 June 2012

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function: an overview. Clin Podiatr Med Surg 19:411–418

17. Oloff LM, Schulhofer SD (1998) Flexor hallucis longus dys-

function. J Foot Ankle Surg 37:101–109

18. Kayabas U, Yetkin F, Firat AK, Ozcan H, Bayindir Y (2008)

Ciprofloxacin-induced urticaria and tenosynovitis: a case report.

Chemotherapy 54:288–290

19. Brown JT, Miller A (1996) Peroneal tenosynovitis following

acute gonococcal infection. Am J Orthop 25:445–447

20. Eberle CF, Moran B, Gleason T (2002) The accessory flexor

digitorum longus as a cause of Flexor Hallucis Syndrome. Foot

Ankle Int 23:51–55

21. Ogut T, Ayhan E (2011) Hindfoot endoscopy for accessory flexor

digitorum longus and flexor hallucis longus tenosynovitis. Foot

Ankle Surg 17:e7–e9

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