The spontaneous extensor pollicis longus (EPL) tendon rupture is a well-documented complication of non-displaced or minimally displaced distal radius fracture. Authors analyzed the radiographs of patients treated for closed EPL rupture after distal radius fracture.

Twenty-eight patients (21 females, 7 males; average age of 58 years) with tendon transfer for spontaneous rupture of EPL after distal radius fracture were included. Wrist radiographs were taken at the first visit with EPL rupture. On the lateral view, posterior cortical displacement, distance from highest point in Lister's tubercle to fracture line, and height of the Lister's tubercle were measured. The distance from the lunate facet to the fracture line was measured on anteroposterior view. Radiologic change at the time of EPL rupture around the Lister's tubercle was evaluated by comparing it with the contra lateral wrist radiograph. Radial beak fracture pattern was also identified.

The interval between the injury and the spontaneous EPL rupture varied from 2 to 20 weeks, with an average of 6.7 weeks. There were 25 cases of non-displacement, 3 cases of mean 2.0 mm cortical displacement. The average distance from the lunate facet to the fracture line was 9.1 mm (3-12.1 mm), from the highest point in Lister's tubercle to the fracture line was 3.0 mm toward proximal radius (1.7-4.9 mm). The average height of the Lister's tubercle was 3.4 mm in the injured wrist and 3.1 mm in the opposite wrist. Radial beak fracture pattern was shown at 11 cases.

All cases presented no or minimal displaced fracture, and the fracture line was in the vicinity of the Lister's tubercle. Those kinds of fractures can highlight the possibility of spontaneous EPL rupture, depites its rarity.