First reported case of brachymetatarsia treated with a hexapod external fixator: a case report.

Introduction and importance: Brachymetatarsia is a rare deformity characterized by abnormal shortening of one or more metatarsals due to premature physeal closure. If conservative treatment fails, surgical options such as one-stage lengthening or progressive distraction with an external fixator are the usual alternatives. This report presents the case of a patient with type 1 Rubinstein-Taybi syndrome and first-metatarsal brachymetatarsia, who was treated by progressive distraction with a hexapod external fixator. This is the first such case reported in the literature. Presentation of case: An 11-year-old girl presented with plantar pain and central metatarsal keratosis in the left foot. After 1 year of unsuccessful conservative treatment, progressive distraction with a hexapod external fixator was indicated to achieve multiplanar correction. Distraction began 7 days later at a rate of 1 mm per day. Premature healing required a second osteotomy, while a metatarsophalangeal subluxation was corrected by fixator adjustment. Two superficial infections were resolved with antibiotic therapy. The fixator was removed at 6 months after achieving 40 mm of lengthening and 12 mm of plantar translation, with a homogeneous regenerate. At 24 months, the patient had complete symptom resolution and substantially normalized function. Clinical discussion: Progressive distraction using a hexapod external fixator can serve as an effective alternative in cases requiring extensive lengthening and multiplanar corrections. Conclusion: This is the first documented case in which brachymetatarsia was treated using a hexapod system, achieving a healing index of 45 days per centimeter and a final AOFAS score of 85.