There are numerous eponyms for fractures of the distal radius and ulna (see Chapter 2). Currently, these terms are less frequently used for describing fractures. It is more important to describe the relationships, degree and direction of displacement, and degree of comminution of the injury. Suspected soft tissue injuries should also be noted.

There have been numerous classification systems developed for the distal radius and ulna including the Mayo, Melone, Frykman, and AO (Arbeitsgemeinshaft fur Osteosynthesefragen) classifications. Classification systems should suggest treatment approaches, indicate prognosis, and demonstrate intra- and interobserver reliability. The Frykman classification is based on the extent of articular involvement and presence


or absence of an ulnar styloid fracture (see Fig. 13-2). This classification system does not address the direction and extent of displacement. The Mayo, Melone, and Association for Study of Internal Fixation (ASIF) systems consider the degree of comminution, degree of displacement, articular involvement, and mechanism of injury. The AO system considers extra-articular fractures. Type I, simple or partial articular type II, and complex or comminuted fractures are considered complete articular or type III. There are numerous subcategories for each type. The Mayo system is based on the degree of displacement and reducibility. For example, extra-articular fractures are subdivided into undisplaced (type I) and displaced (type II). Type III fractures are intra-articular and undisplaced and type IV are displaced articular fractures. Type IV is further subdivided based on being stable and reducible (type IVA), reducible and unstable (type IVB), and irreducible (type IVC). Studies using any of the above-mentioned systems fail to demonstrate highly reproducible inter- and intraobserver agreement for any of the classification methods discussed earlier. A more practical approach is to consider three major categories (see Fig. 13-3). These include extra-articular (Fig. 13-3A), simple articular (Fig. 3-13B and D), and complete articular (see Figs. 13-3C and 13-4).

Undisplaced extra-articular or simple articular fractures can be managed with closed reduction and cast immobilization. Circular or bivalved casts (see Chapter 2) may lead to compartment syndrome. Therefore, padded splints with the wrist in slight palmar flexion and neutral rotation are most often used. Displaced extra-articular or simple articular fractures can also be managed with closed reduction, but require fracture manipulation to achieve anatomic reduction. This may require finger traction before application of sugar-tong splints. Surgical intervention is indicated if reduction cannot be maintained as demonstrated on follow-up radiographs. In this setting, percutaneous pinning with K-wires or plate and screw fixation may be required.

External fixation is useful for unstable distal radial fractures and provides a less invasive option to internal fixation. Static and dynamic devices along with radiolucent external fixators are available (see Figs. 13-6 and 13-7). Selection of the external fixation device is based on the perceived difficulty in maintaining radial length and alignment as well as surgical preference.

Initial fracture reduction can be accomplished with finger traction using 10 to 15 lb of weight. External fixation is then applied using four to five pins. Dynamic devices allow wrist motion, which should be started when tolerated to reduce stiffness and adhesive capsulitis following treatment.

Internal fixation with open reduction is indicated for unstable fractures (does not adequately reduce with closed methods or reduction cannot be maintained). As noted earlier, percutaneous pins can be used for extra-articular fractures with dorsal or volar displacement and simple articular fractures (see Fig. 13-8). Volar plate and screw fixation is used when there is comminution of the metaphysis or there are multiple articular fragments (see Fig. 13-9).

Depressed central fragments in the lunate or scaphoid fossa should be evaluated with CT and repositioned using bone graft to reestablish the articular surface. Stabilization can be established with percutaneous pins or volar plate and screws.

Scaphoid fractures are the most common carpal fracture accounting for 70% of carpal fractures and more than half of carpal injuries. Associated osseous and soft tissue injuries are not uncommon. Associated fractures occur in 5% to 12% of patients involving the radial styloid, triquetrum, capitate, and trans-scaphoid perilunate dislocations. Associated fractures of the radial head have been reported in 6% of patients. The mechanism of injury is a fall on the outstretched hand. Most injuries are sports related or occur with motor vehicle accidents. Patients present with pain and swelling. There is tenderness over the snuff box on the radial side of the wrist. Fractures can occur at any age, but males aged 20 to 30 years are affected most commonly.

Scaphoid fractures may involve the proximal, mid or distal scaphoid, or the tubercle (see Fig. 13-25). Most fractures (70%) involve the waist, 10% to 20% the distal pole, 5% to 10% the proximal pole, and 5% involve the tuberosity. Two classification systems are used for scaphoid fractures. The Russe classification is based on the orientation of the fracture line (see Fig. 13-26). The vertical oblique fracture is most susceptible to shearing forces, but accounts for only 5% of scaphoid fractures. Horizontal oblique fractures are subjected to compressive forces across the fracture site and transverse fractures have combined shearing and compressive forces.

The Herbert classification is based on stability and prognosis for delayed or nonunion. Fractures of the tubercle (type A1—Fig. 13-25, number 1) and incomplete fractures of the waist (type A2) are stable injuries. Type B includes acute unstable fractures. Type B1 is a distal oblique fracture, type B2 a fracture through the waist (Fig. 13-25, number 4), type B3 is a proximal pole fracture (Fig. 13-25, number 5), and type B4 injuries are trans-scaphoid perilunate fracture dislocations.

Detection of scaphoid fractures may be accomplished with routine radiographs of the wrist. A special scaphoid view is typically added to the standard PA, lateral, and oblique images described in the prior section. The soft tissues and fat planes should be carefully evaluated along with the features described earlier. Specifically, the navicular fat stripe is a useful tool



for detection of subtle scaphoid fractures. This fat plane lies between the radial collateral ligament and the tendon sheaths of the abductor pollicis longus and extensor pollicis brevis. Although the fat stripe is not consistently seen on radiographs in children, it is evident in 96% of adults. The fat plane is displaced or obliterated in 88% of radial-sided wrist fractures and 87% of scaphoid fractures (see Fig. 13-27).

Subtle fractures may go undetected. When radiographs are negative or the fat stripe is not clearly seen and when there is clinical suspicion for fracture, MRI can be obtained. CT is also more sensitive and specific compared to radiographs for detection of carpal fractures. In addition, CT is often performed to permit more accurate treatment planning (see Fig. 13-28).

Fracture management depends on patient factors and comorbidities, the type of fracture, and associated injuries. Fractures
of the distal pole or tuberosity (Fig. 13-25, number 1) generally heal well, are likely related to vascularity, and can be managed with closed reduction and cast immobilization (long-arm or short-thumb spica) for 4 to 6 weeks.

Fractures of the waist may be managed with closed reduction and cast immobilization or internal fixation. CT (Fig. 13-28) is useful to evaluate displacement. Reformated coronal and sagittal images are obtained along the axis of the scaphoid. The fracture is displaced or unstable if there is >1 mm of cortical step off, angulation, or associated ligament injury. When the scapholunate angle exceeds 60 degrees and the radiolunate angle exceeds 15 degrees the fracture is considered displaced. The interscaphoid angle should not exceed 35 degrees (Fig. 13-28). Internal fixation using a Herbert screw or fully threaded Acutrak screw is used in this setting (see Fig. 13-29). Internal fixation provides the additional advantage in that the patient can begin motion earlier and the fracture is rigidly fixed so that loss of alignment is unlikely.

Fractures of the proximal pole should be treated with internal fixation. The approach and fixation used varies with the size of the proximal fragment. In recent years, percutaneous pinning over a guidewire placed down the axis of the scaphoid has become more popular. When combined with arthroscopy, the fracture site can be directly visualized during the procedure.

Scaphoid fractures present significant problems in management. Following diagnosis, imaging is important to assure that position is maintained and healing occurs. Delayed union and nonunion are common. Delayed union (failure to heal in 4 months) is even more common than nonunion and is evident in up to 30% of waist and proximal pole fractures. The incidence of nonunion is reported to range from 5% to 25%. Undisplaced fractures treated with cast immobilization heal in 90% of cases. The incidence of nonunion is higher with displaced fractures. Imaging is most easily accomplished with serial radiographs (see Fig. 13-30). However, CT is often required regardless of the treatment approach to evaluate position and healing more effectively (Fig. 13-29). MRI demonstrates low-intensity fracture margins with fluid signal intensity between the fragments when fractures are ununited (see Fig. 13-31). MRI is



optimal for evaluation in patients treated with closed reduction. In the presence of nonunion, internal repair with bone grafting may be required.

Avascular necrosis is reported to occur in 15% to 30% of scaphoid fractures, occurring most commonly with proximal pole fractures. Radiographs may demonstrate sclerosis and fragmentation of the proximal fragment (see Fig. 13-32). Both CT and MRI are more sensitive and can make the diagnosis earlier. However, over time it has become evident that neither modality is perfect. Signs suggesting avascular necrosis vary with the time between the injury and imaging. Abnormal signal intensity on MRI (see Fig. 13-33) and increased attenuation on CT images (see Fig. 13-34) may be reversible and do not always indicate impending osteonecrosis. Dynamic contrast-enhanced MR images with fat-suppressed T1-weighted sequences provide more effective evaluation of flow. This enhances the sensitivity and specificity for blood flow to the scaphoid and areas of necrosis.

Post-traumatic arthropathy is not uncommon, especially with nonunion or scaphoid fractures with associated osseous or soft tissue injury. Over time, carpal instability may also occur. In

patients with nonunion, this is termed scaphoid nonunion advanced collapse (SNAC). Serial radiographs are adequate for evaluation of joint and osseous changes. If fusion or surgical intervention may be indicated, MRI or CT are useful for more complete evaluation of cartilage and soft tissues. MR arthrography is optimal for evaluation of associated ligament and triangular fibrocartilage complex (TFCC) injuries.