Comparison of Tibial Sesamoid Position on Anteroposterior and Axial Radiographs Before and After Triplane Tarsal Metatarsal Joint Arthrodesis

We reviewed the radiographic results of a group of patients who had undergone triplane correctional tarsometatarsal arthrodesis for symptomatic hallux abducto valgus with metatarsus primus abducto valgus. Of the 21 feet included in the present review, 17 (81%) displayed radiographic findings of metatarsal pronation preoperatively based on axial sesamoid views and positive lateral round sign on anteroposterior radiographs. At a mean follow-up period of 5.2 ± 1.6 months, a significant improvement in the tibial sesamoid position (TSP) on both anteroposterior (AP) and axial radiographs was measured. A negative metatarsal round sign, indicating correction of coronal plane metatarsal rotation, was observed in 20 of the 21 feet (95.2%) on AP radiographic evaluation. All 21 patients (100%) had obtained resolution of sesamoid subluxation on the sesamoid axial view at the final follow-up examination. The sesamoid axial position was consistently normal when the round sign was absent, and the TSP was in the normal range of 1 to 3 on the AP radiograph. Sesamoid subluxation from the normal position with the tibial sesamoid on or lateral to the crista was noted in 4 feet (19%) preoperatively and 0 feet postoperatively. This confirmed that lateral round sign of the first metatarsal head and a high TSP noted on the AP radiograph are both related to metatarsal pronation and can be corrected concurrently with coronal plane varus rotation of the first metatarsal as a part of the procedure.