Incidence and diagnosis of ‘the double lesion’ of the triangular fibrocartilage complex

Triangular fibrocartilage complex (TFCC) tears are recognized as major causes of ulnar-sided wrist pain. The concept of TFCC injury was developed in the early 1980s (Palmer and Werner, 1981), and Palmer’s classification has contributed to establishing the treatment of TFCC injury (Palmer, 1989). Various variants of TFCC tears have been found over the past decades. We have sometimes encountered two different tears coexistent in one wrist, i.e. double lesions. The incidence of double lesions seen in our unit and key points relating to their diagnosis are described here. Since 1992, 336 wrists with TFCC injuries have been examined arthroscopically by the first author (YA). The patterns of TFCC injury were categorized according to Abe’s classification (Abe et al., 2012). Double lesions were recognized in 24 of 336 (7.1%) wrists of 24 patients (8 men and 16 women, aged between 15 and 84 years, average 58 years). To ensure inter-observer reliability, the patterns of TFCC tears were diagnosed at the operation by at least two surgeons, including the first author, and reconfirmed by two other hand surgeons, through surgical records and photographs, or video recordings made during surgery. All the surgeons agreed with the diagnosis of the double lesions. There were 11 distal radius fractures, two with distal radioulnar joint (DRUJ) subluxation, and one each of Galeazzi fracture-dislocation and malunion of distal radius fracture. The most common pattern of double lesion was a slit tear on the radial side of the disk along the radial sigmoid notch coexistenting with an ulnar styloid tear: avulsion from the ulnar styloid, was observed in 16 wrists. Other combinations were a dorsal tear with a foveal tear in three wrists, and one each of a slit tear with an ulnocarpal ligament tear, a slit tear with a dorsal tear, a slit tear with a foveal tear, a flap tear with an ulnar styloid tear, and a radial tear with a foveal tear. The combinations were divided into two patterns: a disk tear and a peripheral tear (20); and two peripheral lesions (4). The clinical diagnosis of double lesions is challenging. In our experience, physical examination and magnetic resonance imaging (MRI) provide little information in making a diagnosis of the double lesion; we consider wrist arthroscopy the only method by which we can establish the diagnosis. The slit tear coexistenting with the ulnar styloid tear (Figure 1) was the most common pattern of the double lesion in this study. Therefore, identifying a slit tear does not necessarily imply that other tears do not coexist. If only the slit tear is debrided, while the ulnar styloid tear is left without repair, ulnar-sided wrist pain may persist. Therefore, the surgeon should be circumspect when only one tear is detected. The disk tear is easy to recognize, whereas the peripheral tear is often difficult to diagnose because it is frequently covered with proliferating synovium. Surgeons should be vigilant and not overlook the peripheral tear when detecting a disk tear. It is unclear as to whether the two injuries occur simultaneously or separately. We speculate, however, that when a person falls and twists their wrist, the force of traction can produce an avulsion tear from the ulnar styloid, and torsional force could induce a simultaneous slit tear of the disk. Our analysis of a large number of cases reveals that a small percentage of these cases with arthroscopically validated TFCC injury have two tears in one wrist. Surgeons need to be vigilant when making a diagnosis based on wrist arthroscopy, in order to avoid overlooking concomitant peripheral tears.