Stress fractures are partial or complete fractures of a bone resulting from an inability to withstand stress applied in a repeated manner (Jones, 2006). In the upper extremity, stress fracture of the first rib, the olecranon, and the metacarpal bone have been reported as sports related injury (Jones, 2006). In the present report, we present stress fracture of the carpal scaphoid in an adolescent gymnast who was treated with internal fixation. The patient and his families were informed that data from the case would be submitted for publication and gave their consent.

A case report
An eighteen-year-old man, who is a gymnast ranked at the Japanese National Team level, felt pain over the dorsum of the right wrist when he was doing handstands and pushing-up activities on the floor in the absence of any major traumas or identifiable causes. Wrist pain increased gradually and the patient visited us. Palmar flexion of the wrist was not limited but dorsal flexion was limited to 70 degree because of wrist pain. Tenderness was detected at the anatomical snuff box. On the radiograph at the first visit, a fracture line was not detected and the osteophyte was observed, however, on magnetic resonance imaging (MRI), the low-intensity on the T1-weighted image and the high-intensity on T2-weighted image were detected at the waist of the scaphoid (Figure 1). We suspected stress fracture of the scaphoid and instructed the patient to immobilize the wrist with a wrist brace and to reduce the sports activities using the right hand for two months. However, his wrist pain was not relieved by this conservative treatment and a follow-up radiograph of the wrist clearly revealed a displaced fracture line in contrast with the radiographs from the first visit (Figure 2A). Therefore, we treated the patient surgically.

A 1 cm-skin incision was made over the scaphotrapezoid joint at the volar aspect of the wrist and the distal portion of the scaphoid was exposed. A Kirschner wire (1.0 mm in diameter) at the optimal position of the scaphoid under fluoroscope without using the jig. After removing the Kirschner wire, the drill hole was made in the scaphoid using the track made by the Kirschner. The fracture site was not exposed and a Herbert screw (Zimmer, U.S.A.) was inserted to fix the fracture site of the scaphoid under fluoroscope. After two weeks immobilization with a thumb spica cast, the patient started the range of motion exercise of the wrist and the physical exercise. At postoperative 2 months, fracture line of the scaphoid disappeared suggesting fracture union on the radiogrpahs (Figure 2B) and returned to the original activity level. At postoperative one year, union of scaphoid fracture was confirmed on radiographs (Figure 2C). The patient could perform gymnastics without any complaints at the two year follow-up.

Stress fracture of the carpal scaphoid is very rare disorder and have been only reported in gymnasts and a shot putter (Hanks et al., 1989; Mazione and Pizzutillo, 1981). The upper extremities are used for weight-bearing in gymnastics unlike in other sports and the wrist, during gymnastic activities, is exposed to many different types of stress, including repetitive motion and high impact loading, and axial compression (Webb and Rettig, 2008). Hanks et al. suggested that stress fracture of the scaphoid in nationally ranked gymnasts is caused by repeated dorsiflexion of the wrist such as the mechanism of the scaphoid impaction syndrome (Hanks et al., 1989). A recent biomecahnical study of the wrist demonstrated that loading patterns at the wrist extension position are altered from that at the neutral position and that force transmission in the wrist extension position shifts radially, concentrating at the scaphoid (Majima et al., 2008) . Excessive repetitive compressive loading forces to the scaphoid in the wrist extension position during the gymnastic activities may thus lead to the development of scaphoid stress fracture.

In the present report, the patient felt wrist pain when he was doing handstands and pushing-up activities on the floor without any specific trauma. When the patient initially visited our institution, a fracture line of the scaphoid was not detected on the radiographs but osetophyte at the radial styloid process was observed suggesting repetitive impaction at the radioscaphoid joint. Moreover, MRI demonstrated changes of the intensity of the scaphoid bone suspecting stress fracture. Therefore, we diagnosed the patient with scaphoid stress fracture caused by excessive repetitive loads to the wrist during gymnastic activities.

Stress fractures of the carpal scaphoid in the previous reports have been successfully treated with immobilization (Hanks et al., 1989; Mazione and Pizzutillo, 1981). In contrast, in the present case, we initially instructed the patient to immobilize the wrist with a wrist brace and to reduce sports activities using the right hand for two months, however, his wrist pain was not relieved and the displacement of the fracture site increased. Therefore, we concluded that conservative treatment in the present case might not be impossible and chose surgical treatment.

In the present report, the patient was adolescent and the growth plate of the distal radius was observed. To treat established scaphoid nonunion in skeletally immature patients, several reports recommend surgical treatment with internal fixation and bone grafting, because internal fixation with a screw for the scaphoid does not interfere scaphoid maturation (Mintzer et al., 1995; Toh et al., 2003). Therefore, we treated the adolescent patient surgically with internal fixation using a headless screw through the small skin incision.

Internal fixation of scaphoid fracture through a small incision without open reduction of the fracture site of the scaphoid has been reported (Haddad and Goddard, 1998; McQueen et al., 2008). Recently, several cannulated headless screw systems using a guide wire for scaphoid fixation have been developed and available. Percutaneous scaphoid fixation for acute fractures with a headless screw, which has a cannulated system using a guide wire to ensure a better position, obtained satisfactory results and rapid functional recovery (McQueen et al., 2008). In the present report, we used the conventional Herbert screw to fix the fracture site through a small incision, however, we would like to use the headless screw with a cannulated guide wire system when we have a chance to treat the similar case in future.

The physicians should be aware of the risk of stress fracture of the scaphoid in gymnast. We recommend surgical treatment of internal fixation with a screw through a small incision, which is one of the good options for stress fracture of the scaphoid in order to return to the original sports activity quickly.

• There is a risk of stress fracture of the scaphoid in gymnast.
• Internal fixation with a screw is one of the good options for stress fracture of the scaphoid.