Flexor tenotomy for mallet toe with penetration of the middle phalanx head by dual-component intramedullary implant following proximal interphalangeal arthrodesis

Introduction: There is a risk of mallet toe following proximal interphalangeal (PIP) joint fusion for hammertoe. Here we describe a rare case of penetration of the dorsal aspect of the middle phalanx head by the distal portion of a dual-component intramedullary implant during progression of mallet toe that was treated with flexor tenotomy.
Presentation of case: A 59-year-old man underwent uneventful arthrodesis of the third PIP using a dual-component intramedullary implant and presented 6 months later with progressive mallet toe and swelling, pain, and ulceration over the distal interphalangeal joint of the third toe. Imaging showed that the distal portion of the implant had penetrated the dorsal aspect of the middle phalanx head. A longitudinal incision was made over the dorsum of the middle and proximal phalanges of the third toe and the implant was removed. A plantar incision was made at the metatarsophalangeal joint and the flexor tendon was cut to correct the mallet toe deformity. One year later, correction was satisfactory with an acceptable functional outcome and good pain relief.
Discussion: We successfully treated a man with penetration of the dorsal border of the middle phalanx head in the third toe by the distal portion of a dual-component intramedullary implant as a result of mallet toe that developed following PIP arthrodesis, by removing the implant and performing flexor tenotomy.
Conclusion: Addition of flexor tenotomy should be considered when performing PIP arthrodesis in a patient with risk factors for severe mallet toe.

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