Once in a while, you come across something in your practice you’ve not encountered before and this month I’ve had a few of these which I will be writing about in the future. For this month's blog however, I thought I would cover an unusual case of a foreign body in the foot.
Case Report
A 68-year-old man presented in the clinic in December 2023 complaining of forefoot pain affecting his left foot. Apart from hypertension he was in good health with normal circulation and no neurological deficit evident in his feet.
According to the patient, the ball of his foot had been sore for some time. He could not recall any specific incident or injury. On examination there was a small area of callus around the fourth met area which was painful upon palpation. Upon debridement, there was a small sinus evident (Figure 1). The wound was probed and explored but nothing was evident. No discharge could be expressed and there was no sign of infection. The area was redressed, and it healed uneventfully.
A foreign body emerges
Six months later in June 2024, the patient returned to the clinic again with a “painful foot”. However, this time, a raised nodule was present on the dorsum of the left with a localised cellulitis. It was tender to palpation and the area was cleaned and dressed. He was issued with a week's worth of flucloxacillin and rebooked for a review a week later.
Upon his return, removal of the dressing revealed a small ulcer with a foreign body (FB) evident in the centre. It was easily removed and was identified as an 10mm metal fragment, probably part of a broken pin or needle (Figure 2). The area was redressed and healed uneventfully. An X-ray was ordered to check for any underlying bone infection or residual foreign body, but nothing was found.
Discussion
Foreign bodies are a common risk to the foot, particularly in the summer months when open footwear is worn more frequently. They can be retained in the foot for months or even years undetected [1]. The published literature covers many cases affecting the foot along with the difficulties in diagnosis and treatment. In one review of FB affecting the whole body, the feet were by far the most affected area of the body (54% of all cases) with metal, wood, glass and plastic being the most common materials. Needles were the most prevalent object retrieved from the foot in this review (73%) [2].
The introduction a foreign body made of organic materials such as splinters of wood which can potentially lead to localised infection or even abscess formation. Where FB end up in close proximity to bone it may cause irritancy and inflammation causing osteolytic and osteoblastic changes evident on imaging sometimes with chronic osteomyelitis [3].
Identification of potential FB can be challenging. Plain radiographs can often show fragments of radio-opaque materials such as ceramic and metal, occasionally large glass shards but may miss splinters and organic materials [4]. Ultrasonography has been shown to be a more useful imaging modality for wood and plastic FB and a cheaper alternative to Magnetic Resonance Imaging (MRI) [1]. MRI provides detailed images and can show the sinus tracts, soft tissue oedema and sometimes even the radiolucent foreign body itself.
Migration of a FB is an issue documented in the literature, with long, thin and smooth materials more likely to migrate within tissues with reports of FB moving along tendon sheaths, however this is more frequent in the upper limb but very uncommon in the foot [5]. In this case, the patient presented with an unusual migration, the metal needle travelling from the plantar surface to the dorsum of the foot in a period of around six months. Once removed there were no further issues and imaging of the foot showed no bony involvement.
References
1. Hiremath, R., et al., Soft Tissue Foreign Body: Utility of High Resolution Ultrasonography. J Clin Diagn Res, 2017. 11(7): p. Tc14-tc16.
2. Kurtulmuş, T., et al., Tips and tricks in the diagnostic workup and the removal of foreign bodies in extremities. Acta Orthop Traumatol Turc, 2013. 47(6): p. 387-92.
3. Huang, Y.M., et al., Residual foreign body in the foot causing chronic osteomyelitis mimicking a pseudotumor: A case report. J Int Med Res, 2020. 48(6): p. 300060520925379.
4. Flom, L.L. and G.L. Ellis, Radiologic evaluation of foreign bodies. Emerg Med Clin North Am, 1992. 10(1): p. 163-77.
5. Albay, C., O. Adanır, S. Çağlar, and O. Beytemür, Migration of a toothpick along the flexor tendon sheath in a lower extremity. Acta Orthop Traumatol Turc, 2016. 50(2): p. 245-7.
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