Miyamura Satoshi, Shigi Atsuo, Kraisarin Jirachart, Omokawa Shohei, Murase Tsuyoshi, Yoshikawa Hideki, Moritomo Hisao
Department of Orthopaedic Surgery, Osaka University, Graduate School of Medicine, Osaka, Japan.
Department of Orthopedics, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
J Hand Surg Am. 2017 Mar;42(3):e185-e191. doi: 10.1016/j.jhsa.2017.01.008.
Certain distal ulna fractures may contribute to distal radioulnar joint (DRUJ) instability. We hypothesized that residual distal ulna translation could affect DRUJ stability by slackening the distal interosseous membrane (DIOM). We aimed to test this hypothesis in a cadaver model.
We created an ulnar translated distal ulna fracture model in 6 cadavers. Dorsal and palmar displacements of the ulna relative to the radius were measured and DRUJ instability was staged under the following conditions: (1) 0-, 2-, and 4-mm ulnar translation of the distal ulna with an intact triangular fibrocartilage complex (TFCC) and DIOM; (2) 0-, 2-, and 4-mm translations with TFCC divided and an intact DIOM; and (3) a 0-mm translation with TFCC and DIOM divided.
With an intact TFCC, dorsal and palmar displacements were not increased with any amount of distal ulna translation. After TFCC division with 0-mm translation, dorsal displacement increased significantly with DRUJ dislocation, whereas palmar displacement increased to a lesser extent with DRUJ subluxation. Palmar displacement gradually increased as the translation increased, and with 4-mm translation the ulnar head displaced to a perched position off the sigmoid notch. With TFCC and DIOM division, displacements increased markedly with DRUJ dislocation both dorsally and palmarly.
Dorsal dislocation occurred when the TFCC was divided regardless of the amount of distal ulna translation. Palmar subluxation occurred when the TFCC alone was divided. Palmar displacement to a perched position occurred because of slackening of the DIOM as a result of translation of the distal ulna. Bidirectional DRUJ instability with dorsal dislocation and palmar displacement to a perched position occurred when the TFCC was divided and the distal ulna was ulnarly translated.
Bidirectional DRUJ instability might occur when distal ulna translation deformity is associated with TFCC injury because the DIOM loses its function as a secondary stabilizer.
某些尺骨远端骨折可能导致下尺桡关节（DRUJ）不稳定。我们推测尺骨远端残余移位可能通过松弛远侧骨间膜（DIOM）影响DRUJ稳定性。我们旨在在尸体模型中验证这一假设。
我们在6具尸体上创建了尺骨移位的尺骨远端骨折模型。测量尺骨相对于桡骨的背侧和掌侧移位，并在以下条件下对DRUJ不稳定进行分期：（1）尺骨远端分别进行0、2和4mm的尺侧移位，三角纤维软骨复合体（TFCC）和DIOM完整；（2）TFCC切断且DIOM完整的情况下分别进行0、2和4mm的移位；（3）TFCC和DIOM均切断且移位为0mm。
TFCC完整时，任何程度的尺骨远端移位均未增加背侧和掌侧移位。TFCC切断且移位为0mm后，随着DRUJ脱位背侧移位显著增加，而随着DRUJ半脱位掌侧移位增加程度较小。掌侧移位随移位增加而逐渐增加，在4mm移位时尺骨头移位至位于乙状切迹外的高位。TFCC和DIOM均切断时，随着DRUJ脱位背侧和掌侧移位均显著增加。
无论尺骨远端移位程度如何，TFCC切断时均发生背侧脱位。仅TFCC切断时发生掌侧半脱位。由于尺骨远端移位导致DIOM松弛，从而发生掌侧移位至高位。TFCC切断且尺骨远端向尺侧移位时发生伴有背侧脱位和掌侧移位至高位的双向DRUJ不稳定。
当尺骨远端移位畸形与TFCC损伤相关时，可能发生双向DRUJ不稳定，因为DIOM失去了作为二级稳定器的功能。
