![]() 25.1c).įractures Close to the Base of Metacarpal Iįractures of the base of the metacarpal I are of special interest since the trapeziometacarpal joint of the thumb is extremely mobile because of the shape of the joint surfaces and tension exerted by the attached muscles. Three-Dimensional surface images are useful for planning surgery for complex fractures of the metacarpal head, espe especially when they depict the fracture area after electronic exarticulation of the less-affected joint partner ( Fig. If necessary, axial MPR images can also be computed. Coronal multiplanar reconstruction (MPR) images are computed from sagittal source images. The slice thickness should be between 0.5 and 1.0mm, with overlapping increment. To avoid streaky artifacts on the forearm (off-center artifacts), the metacarpals II and III are scanned in ulnar inclination of the wrist and the metacarpals IV and V in radial inclination. If the patient tolerates the positioning, sagittal CT slices are useful. Computed tomography is also generally indicated in comminuted fractures of the metacarpal heads, whose extent and displacement often can be identified only in 2D and 3D image reconstructions ( Fig. 1 Classification of metacarpal fracturesįracture near the base of the metacarpal Iįracture near the base of the metacarpals II–VĪs explained in Chapter 24, fractures of the metacarpal bases often require CT imaging to provide clarity when radiographic findings are uncertain and to determine the pattern of injury ( Figs. Malrotation cannot be diagnosed on radiographs, but with clinical examination, and usually indicates surgical treatment. To check for malrotation after a fracture, it must be clinically assured that, when all finger joints are flexed, the pulps of the individual fingers converge in the direction of the scaphoid tubercle and do not cross. Clinically, remaining fragment dislocations on the ulnar side of the metacarpals are tolerated better than those on the radial side. Normally the line connects the metacarpals III–V, whereas the metacarpal II is considerably below these straight lines.Ī strictly lateral view of the metacarpus is required to assess a palmar tilt in the axis of the peripheral metacarpal fragment. The shortening of a metacarpal is assessed according to the connecting line along the heads of metacarpals III–V (so-called “metacarpal sign”). The following rules apply for assessment of the extent of dislocation: Fractures of metacarpal shaft and neck can be readily identified identified in survey views, but not fractures of the metacarpal bases and heads. There are special views for visualizing the trapeziometacarpal joint of the thumb (Kapandji’s special trapezium view) (Chapter 1). ![]() After a recent injury, the dorsopalmar view of the thumb often cannot be taken in hyperpronation. If fracture of the metacarpals is suspected, radiographs of the metacarpus in dorsopalmar and oblique planes that include the carpometacarpal (CMC) and metacarpophalangeal joints should be taken.
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