Fracture of the Distal Radius
David Ring, MD, Gae Burchill, OT, Donna Ryan Callamaro, OT, Jesse B. Jupiter, MD

Background
Successful treatment of a fracture of the distal radius must respect the soft tissues while restoring anatomic alignment of the bones (Fig. 1–50). The surgeon must choose a treatment method that maintains bony alignment without relying on tight casts or restricting the gliding structures that control the hand. MCP joint motion must remain free. The wrist should not be distracted or placed in a flexed position, because these abnormal positions diminish the mechanical advantage of the extrinsic tendons, increase pressure in the carpal canal, exacerbate carpal ligament injury, and contribute to stiffness. Recognition and prompt treatment of median nerve dysfunction and the avoidance of injury to branches of the radial sensory nerve are also important. Special attention should be given to limiting swelling of the hand. Swelling can contribute to stiffness and even contracture of the intrinsic muscles of the hand. Mobilization and functional use of the hand, wrist, and forearm complete the rehabilitation of the fractured wrist.

The keys to successful treatment of distal radial fractures include restoration of articular congruity, radial length, proper volar inclination, avoidance of stiffness, and early motion of a stable construct.

Clinical Background
Fractures of the distal radius are common in older persons, particularly women, because they have weaker bones and are more susceptible to falls. Older persons are healthier, more active, and more numerous than ever, and treatment decisions cannot be based upon patient age alone, but must consider the possibility of poor bone quality.

Considerable energy is required to fracture the distal radius of a younger adult, and most such fractures occur in motor vehicle accidents, falls from heights, or sports. Displaced fractures in younger adults are more likely to be associated with concomitant carpal fractures and ligament injuries, acute compartment syndrome, and multitrauma.

The distal end of the radius has two important functions: it is both the primary support of the carpus and part of the forearm articulation. When a fracture of the distal radius heals with malalignment, the surface pressures on the articular cartilage may be elevated and uneven, the carpus may become malaligned, the ulna may impact with the carpus, or the distal radioulnar joint (DRUJ) may be incongruent. These conditions can produce pain, loss of motion, and arthrosis.

The alignment of the distal radius is monitored using radiographic measurements to define alignment in three planes. Shortening of the distal radius is measured best as the offset between the ulnar head and the lunate facet of the distal radius on the PA view—the ulnar variance. The alignment of the distal radius in the sagittal plane is evaluated by measuring the inclination of the distal radial articular surface on the PA radiograph—the ulnar inclination. The alignment of the distal radius in the coronal plane is evaluated by measuring the inclination of the distal radial articular surface on the lateral radiograph. Studies of normal volunteers have determined that the articular surface of the distal radius is usually oriented about 11 degrees palmar and 22 degrees ulnar, and has neutral ulnar variance.

Impaction of Distal Radius (Loss of Radial Length)
This involves the loss of radial length or height. Normally, the radial articular surface is level with or within 1 to 2 mm distal (ulnar positive) or proximal (ulnar negative) to the distal ulnar articular surface (Fig. 1–51). Colles fractures tend to lose significant height, which causes loss of congruency with the distal radioulnar joint (DRUJ) and difficulties with wrist rotation.

Dorsal Angulation (Loss of Volar Inclination)
Normally, the distal radius has a volar inclination of 11 degrees on the lateral view (Fig. 1–52). A Colles fracture often reverses that volar inclination. Dorsal inclination of 20 degrees or more significantly affects the congruency of the DRUJ and may cause compensatory changes in the carpal bone alignment.

Dorsal Displacement
Dorsal displacement contributes significantly to the increased instability of the distal fragment by decreasing the contact area between fragments (Fig. 1–53).
Radial Displacement (Lateral Displacement)

Radial displacement occurs when the distal radial fragment displaces away from the ulna (Fig. 1–54).

Loss of Radial Inclination
The radius normally has a radial-to-ulnar inclination of approximately 22 degrees, measured from the tip of the radial styloid to the ulnar corner of the radius and compared with the longitudinal line along the length of the radius (Fig. 1–55). Loss of inclination can cause hand weakness and fatigability following the fracture.
Unrecognized supination of the distal radial fragment also creates fracture instability (Fig. 1–56).

Classification
Successful treatment of fractures of the distal radius requires accurate identification of certain injury characteristics and an understanding of their importance (Table 1–8). Whereas a number of classification systems have been described, most of the important injury elements are captured in the system of Fernandez (Fig. 1–57), which distinguishes bending fractures (type 1), shearing fractures (type 2), compression fractures (type 3), fracture-dislocations (type 4), and high-energy fractures combining multiple types (type 5). Type 1 or bending-type fractures, are extra-articular, metaphyseal fractures. Dorsally displaced fractures are commonly referred to by the eponym Colles fracture. Volarly displaced bending fractures are often called Smith’s fractures. Type 2, or articular shearing fractures, comprise volar and dorsal Barton’s fractures, shearing fracture of the radial styloid (the socalled chauffeur’s fracture), and shearing fractures of the lunate facet. Type 3, or compression fractures, include fractures that split the articular surface of the distal radius. There is a progression of injury with greater injury force—separation of the scaphoid and lunate facets occuring first, with progression to coronal splitting of the lunate or scaphoid facets and then further fragmentation. Type 4, radiocarpal fracture-dislocations, feature dislocation of the radiocarpal joint with small ligamentous avulsion fractures. Type 5 fractures may combine features of all the other types and may also involve forearm compartment syndrome, open wound, or associated injury to the carpus, forearm, or elbow.
Another classification used by orthopaedic surgeons is the universal classification system (Fig. 1–58).

Diagnosis and Treatment
The wrist often appears deformed with the hand dorsally displaced. This is called a “silver fork” deformity because of the semblance to a dinner fork when viewed from the side. The distal ulna also may be prominent. The wrist is swollen and tender, and palpation may elicit crepitus.

Patients with substantially displaced fractures should have rapid closed manipulation under anesthesia to reduce pressure on the soft tissues including nerves and skin and to help define the pattern of injury. Closed manipulation and sugar-tong splints provide definitive treatment in many patients. This is most often accomplished with a so-called hematoma block anesthetic. Five to 10 ml of 1% lidocaine anesthetic without epinephrine is injected into the fracture site. Consideration should be given to injecting the DRUJ and an ulnar styloid fracture in some patients. Injection of the fracture site is easiest from the volar-radial aspect of the wrist in the more common dorsally displaced fractures. Manipulation is performed manually. The use of finger traps is cumbersome, limits the surgeon’s ability to correct all three dimensions of the deformity, and will not help to maintain length in metaphyseal impaction or fragmentation.

Radiographs taken after closed reduction may need to be supplemented by CT scanning to precisely define the pattern of injury. In particular, it can be difficult to tell whether the lunate facet of the distal radial articular surface is split in the coronal plane.

Bending fractures are extra-articular (metaphyseal) fractures. They may displace in either a dorsal or a volar direction. Dorsal displacement—known eponymically as Colles fracture—is much more common. Many dorsally displaced bending fractures can be held reduced in a cast or splint. In older patients, more than 20 degrees of dorsal angulation of the distal radial articular surface on a lateral radiograph taken before manipulative reduction usually indicates substantial fragmentation and impaction of dorsal metaphyseal bone. Many such fractures require operative fixation to maintain reduction. Dorsally displaced fractures are reduced under hematoma block and splinted with either a sugar-tong or a Charnley type of splint. The reduction maneuver consists of traction, flexion, ulnar deviation, and pronation. The wrist should be splinted in an ulnar deviated position, but without wrist flexion. Circumferential casts and tight wraps should not be used (Fig. 1–59). Great care must be taken to ensure that motion of the MCP joints is not restricted.

Options for the treatment of unstable dorsal bending fractures include external fixation that crosses the wrist, so-called nonbridging external fixation that gains hold of the distal fracture fragment and does not cross the wrist, percutaneous Kirschner wire fixation, and internal plate fixation. External fixation that crosses the wrist should be used with great care. The wrist should not be left in a flexed position, and there should be no distraction across the wrist. Usually, this means that Kirschner wires are needed in combination with the external fixator. Plate fixation is usually reserved for fractures with incipient callus formation that are resistant to closed manipulation (this can occur as early as 2 weeks after injury) and fractures with fragmentation of the volar as well as the dorsal metaphysis. All of these methods place the radial sensory nerve at risk. Great care must be taken to protect this nerve and its branches.

Volarly displaced bending fractures (or Smith’s fractures) are subclassified as transverse, oblique, or fragmented. Oblique and fragmented fractures will not be stable in a cast and require operative fixation. Fixation of the distal radius with a plate applied to its volar surface is straightforward and associated with few problems. Therefore, unstable volar bending fractures are best treated with internal plate fixation.

Shearing fractures may involve the volar or dorsal articular margin (so-called Barton’s fractures), the radial styloid, or the lunate facet of the distal radius. These partial articular fractures are inherently unstable. Failure to securely realign the fragment risks subluxation of the carpus. For this reason, shearing fractures are most predictably treated with open reduction and plate and screw fixation.

Many simple compression articular fractures can be treated with closed manipulation, external fixation, and percutaneous Kirschner wire fixation. When the lunate facet is split in the coronal plane, the volar lunate facet fragment is usually unstable and can be held only by a plate or tension band wire applied through a small volar-ulnar incision.

Radiocarpal fracture-dislocations and high-energy fractures require ORIF, in some cases supplemented by external fixation. One must also be extra vigilant regarding the potential for forearm compartment syndrome and acute CTS with these fractures.
For all of these fracture types, the stability of the DRUJ should be evaluated after the distal radius has been fixed. Instability of the distal ulna merits treatment of the ulnar side of the wrist. A large ulnar styloid fracture contains the origin of the triangular fibro-cartilage complex (TFCC), and ORIF of such a fragment will restore stability. Similarly, unstable ulnar head and neck fractures may benefit from internal fixation. If the DRUJ is unstable in the absence of ulnar fracture, the radius should be pinned or casted in midsupination (45 degrees supination) for 4 to 6 weeks to enhance stability of the DRUJ
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Indications for operative treatment of distal radial fractures include an unstable fracture, irreducible fracture, more than 20 degrees of dorsal angulation of the distal fragment, intra-articular displacement or incongruity of 2 mm or more of articular (joint) fragments, and radial (lateral) displacement (Table 1–9).

Rehabilitation after Distal Radial Fractures
The rehabilitation after fracture of the distal radius is nearly uniform among various fracture types, provided that the pattern of injury has been identified and appropriately treated. The stages of rehabilitation can be divided into early, middle, and late.

Conclusions
Rehabilitation after fracture of the distal radius focuses first on preventing a problem with the wrist from creating a problem with the hand; second, on restoring functional mobility quickly; and finally, on optimizing the function of the wrist after injury. Any method of treatment that contributes to excessive swelling or restriction of digit motion or tendon gliding should be abandoned. For instance, if a cast that is molded tightly to maintain fracture reduction increases edema, the surgeon should consider changing to percutaneous pinning and external fixation to avoid a constrictive dressing. Once effective treatment is administered, the rehabilitation program is straightforward.