Fractures of the Base of the Proximal Phalanx in Children: Remodeling of Malunion in the Radioulnar Plane With a Diaphyseal Axis-Metacarpal Head Angle of 156° to 163°.

BACKGROUND: The diaphyseal axis-metacarpal head angle (DHA) measures the angle between the axis of the proximal phalanx and the center of the metacarpal head. In unfractured fingers, the normal DHA ranges from 177.1° to 180.0°. The angle may be used to quantify the degree of lateral displacement of pediatric fractures of the base of the proximal phalanx. Previous authors have shown that if the postreduction x-rays show an angle greater than 169° remodeling with normalization of the DHA is expected to occur in children. The degree of remodeling of more severe angulations is unknown.

PATIENTS AND METHODS: This is a retrospective study (over the last 5 years) that identified 8 late referrals (4-6 weeks after injury) of inadequately reduced pediatric fractures of the base of the proximal phalanx with a postreduction DHA of 156° to 163°. At the time of presentation to the author, there was lateral deviation of the finger, and the fracture site was not tender, indicating malunion. All patients were offered surgery, but this was refused by the parents. Follow-up appointments to the clinic were made, and the DHAs were serially measured to investigate the degree of remodeling.

RESULTS: Seven patients had normalization of the DHA (ie, an angle >177°) between 9 and 18 months. In the remaining patient, the DHA was 175.7° at 2 years.

CONCLUSIONS: The current study shows adequate remodeling of severe residual angular deformities (DHA of 156°-163°). The clinical implication of this finding is regarding late referrals with no tenderness at the fracture site. In these cases, refracturing usually requires general anesthesia. Our study shows that patients may be given the option of conservative management awaiting remodeling.