Palmar Dislocation of the Trapezoid
Authors: Costa Marcella Rodrigues , de Queiroz Tailsom Nunes Chaves , Pereira André Lourenço , Simões Guilherme Ferreira 
Published: September 2016

Objective: The dislocations of carpal bones, including the trapezoid, are uncommon. However, in recent years it has shown increased incidence due to growth in high-energy trauma rates. The trapezoid is the least common carpal bone involved in isolated dislocations owing to its ligamentous stability and its position of relative protection within the carpal geometry. The purpose of this article is to present a case study of trapezoid dislocation in palmar direction, which is an even rarer event for anatomical reasons, and to review the literature and then discuss aspects related to clinical presentation, diagnostic tests, management, and treatment options. Materials and Methods: A case report of a young male patient, victim of automotive vehicle collision, admitted in the urgency care of a referral hospital for trauma is presented. Patient presented left hand and wrist pain, moderate edema, local deformity, crackling and decreased range of motion and functional capacity, and absence of neurological deficits. Trauma series radiographs and left wrist anteroposterior (AP) and lateral radiographic incidences initially demonstrated, respectively, pubic symphysis stable dislocation (type I), dorsal metacarpal dislocation (second and third metacarpal), and palmar trapezoid dislocation. Failed closed reduction was attempted in the emergency room. Computed tomography (CT) was held for better assessment of the damage and possible associated lesions. Patient was submitted to open reduction and internal fixation with Kirschner wires and mini anchors. A literature review of trapezoid dislocation case reports since the first description on 1969 by W. Gay was conducted. Results: The patient was maintained with a splint for 8 weeks after surgery and weekly hospital returns for wound assessment. In the following appointments, patient evolved with stiffness of the wrist, though good aspect of serial radiographs. In our review since the first report in 1969, there were only about 35 cases of trapezoid dislocation described in the literature, and palmar dislocations accounted for less than 10 cases reported. Due to the high energy required to cause the displacement, extensive bone and ligament injury are assumed. For diagnostic imaging, AP and pronated oblique radiographic incidences of the wrist associated with CT appear to be the most appropriate. Treatments available range from closed to open reduction with several options of materials for internal fixation. Complications such as degenerative process or osteonecrosis can be found. Conclusion: The dislocation of the trapezoid is a rare event, and according to previous published reports it happens in most cases to the dorsal region. Knowledge of the injury and the correct imaging evaluation could avoid late diagnosis and allow proper handling and treatment of the patient, which could improve the prognosis. The surgical treatment of trapezoid dislocation is often associated with better results according to literature, with open reduction and internal fixation being the best method, while the excision of the bone appears to be associated with the development of degenerative changes of the carpus. The preservation of the soft tissues may reduce the risk of osteonecrosis.