New classification of lunate fossa fractures of the distal radius

Abstract

Background: A die-punch fracture is a depression fracture of the lunate fossa of the distal radius. We propose a morphological classification of die-punch fractures that includes five types: center depression fractures, vertical depression fractures, volar depression fractures, dorsal depression fractures, and double die-punch fractures.

Methods: The radiographs of 112 die-punch fractures treated between January 2005 and January 2015 were retrospectively reviewed. The clinical images were examined independently for two rounds by six orthopedists with different clinical experiences: two residents, two attending physicians, and two consultants. A category-specific kappa score and a kappa score for more than two observers were analyzed. We used Cohen's kappa to test intraobserver variation.

Results: The kappa score for interobserver reliability was 0.69 for the first round and 0.70 for the second round. The intraclass correlations were 0.65 and 0.63, respectively. Intraobserver reproducibility using Cohen's kappa test was satisfactory. All of the results indicated a kappa value >0.4, suggesting good agreement within, as well as between, observers.

Conclusions: The outcome was assessed using kappa statistics, which showed good interobserver reliability and intraobserver reproducibility.

Keywords: Classification; Die-punch fracture; Radius.

Fig. 1

Center depression fracture. a The depression fracture occurs in the center of the lunate fossa of the distal radius (left, anterior view; right, lateral view). b, c Computed tomography (CT) (left)

Fig. 2

Vertical depression fracture. a The entire lunate fossa is vertically depressed (left, anterior view; right, lateral view). b, c Anteroposterior and lateral radiographs (right)

Fig. 3

Volar depression fracture. a The volar half of the lunate fossa is depressed (left, anterior view; right, lateral view). b–d CT and three-dimensional CT (left) scans

Fig. 4

Dorsal depression fracture. a The dorsal half of the lunate fossa is depressed (left, anterior view; right, lateral view). b, c CT and three-dimensional CT (left) scans

Fig. 5

Double die-punch fracture. a The lunate fossa is split into two halves, each depressed toward the volar and dorsal directions, respectively (left, anterior view; right, lateral view). b–d Anteroposterior lateral radiograph and CT scans (right)