Os intermetatarseum presenting as splay foot; Case report and literature review

Introduction and importance: This report described the management of a lady with a rare finding of a large size of Os intermetatarseum in a bizarre location. This unique condition resulted in a splay foot which was rarely discussed in the literature. Case presentation: A lady in her early fifth decade has complained of foot swelling and difficulty wearing shoes for the last two years. Her main concern was the worry of a malignant condition. Clinical discussion: She had an unusually huge articulated lump in the third web space. Also, it showed a central foot splay. A full battery of radiological investigation gave a narrow list of possible differential diagnoses. The final diagnosis showed that it was Os intermetatarseum. Surgical treatment involved enucleating the mass and correcting foot splay using a mini-tight rope (R). The histopathology report confirmed the diagnosis of Os intermetatarseum. The central forefoot splay was treated by a known surgical tool differently. Post-operatively she was put on physical therapy. Five years follow-up showed improved foot anatomy and functional outcomes with no recurrence. Conclusion: Awareness of this rare condition as a differential diagnosis. Complete excisional biopsy of the lump will be a valid option for this condition, as well as using a mini-tight rope (R) in dealing with central foot splay.