Hidden hazards: Retained shoe sole material after nail penetration injuries of the foot—A case series

Introduction: Nail penetration injuries to the foot are a common occupational hazard, particularly among industrial and field workers. However, its incidence has also increased in the common population in the past few years. A unique but often overlooked complication occurs when the nail penetrates the sole of the shoe and is subsequently withdrawn, leaving behind a fragment of the footwear—typically rubber or similar material—embedded in the foot. Due to its radiological properties, this retained foreign body is difficult to detect with conventional imaging and poses diagnostic as well as surgical challenges. Materials and Methods: We present a case series of 12 patients treated between 2018 and 2023 where retained footwear sole fragments were surgically removed following nail penetration injuries. Results: Twelve patients (8 males, 4 females; age range = 16–66 years) with nail puncture injuries through rubber-soled footwear were included in the study. Most injuries occurred at construction or industrial sites, with delayed presentations ranging from 1 to 6 months. Common symptoms were pain and swelling. The midfoot was the most frequently affected site. Imaging modalities such as ultrasound, magnetic resonance imaging, and computed tomography provided indirect signs, but plain radiographs were non-diagnostic. All patients underwent surgical removal of retained rubber fragments. Complete recovery was achieved in all cases. Conclusion: Rubber sole fragments retained in the foot post-puncture injury are radiolucent, diagnostically elusive and require removal for resolution. Clinicians must maintain vigilance and proceed to surgical exploration when suspicion persists despite negative imaging.