Simultaneous Fractures of the Scaphoid and Distal Radius

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CHAPTER 21 Simultaneous Fractures of the Scaphoid and Distal Radius

Greg A. Merrell, MD, Joseph F. Slade, III, MD

Although uncommon, simultaneous fractures of the distal radius and scaphoid can be challenging to treat. Once the decision has been made to surgically treat these injuries, the question arises on the order of treatment of these combined fractures. The goal of surgical treatment is rigid fixation. Once fixation is achieved in one fracture, the treatment of the second fracture risks disruption of fixation of the first fracture. If the scaphoid is fixed first, there is potential for screw pullout or loosening during the substantial forces applied during reduction of the distal radius. If the first fracture treated is the radius, reduction of the second fracture, that of the scaphoid, may result in a loss of reduction and a malunion in the radius. The purpose of this chapter is to present a tactical approach to the surgical treatment of these combined fractures, which results in rigid fixation of both fractures using arthroscopic and percutaneous techniques.

The incidence of combined injuries varies from 0.7% to 6.5% of all distal radius fractures.1–4 The mechanism is a high-energy injury with rapid forced loading of an outstretched radial-deviated dorsiflexed wrist.1,3,5,6 These injuries are often associated with a displaced and angulated scaphoid fracture.

The rare isolated stable nondisplaced scaphoid fracture and distal radius fracture might be safely managed with plaster immobilization for periods of 3 to 4 months. Unfortunately, this period of immobilization for the treatment of distal radius fractures, at best, results in delay in recovery of hand and wrist function and, at worst, permanent stiffness.6,7

A review of the relatively few published reports on combined scaphoid and distal radius fractures demonstrates that treatments have evolved over the past decade. Historical references site the primacy of addressing the distal radius fracture, but this predated the operative treatment of acute scaphoid fractures.5,8,9 We now understand that both fractures must be adequately reduced and treated. The arthroscopic care of both distal radius and scaphoid fractures and the use of percutaneous techniques have permitted the rigid fixation of these fractures while preserving uninjured tissues.10–13 This has allowed for the early recovery of hand function with minimal complications.

The techniques presented in this chapter will describe in a step-by-step manner the evaluation and fixation of a specific case to help provide clarity. This injury occurred in a 22-year-old right-handed skateboarder who had a fracture through an old scaphoid nonunion and a distal radius fracture (Figs. 21-1 and 21-2).

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FIGURE 21-1 Anteroposterior radiograph demonstrating distal radius fracture and a combined scaphoid nonunion with a new fracture at the distal edge of the nonunion site. Sequential images of the technique for fixation of this injury form the basis for discussion of this chapter. The patient is a 19-year-old skateboarder.

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FIGURE 21-2 Lateral radiograph demonstrating dorsal comminution of the distal radius fracture and a flexion deformity of the scaphoid.

Indications

The typical patient who presents with these injuries is male in his 20s or 30s after a fall, motor vehicle accident, or sports injury. Any patient with combined fractures with displacement of either the scaphoid or distal radius greater than 1 mm would be an operative candidate. If the patient is going to benefit from operative intervention of one fracture and the other is nondisplaced, then stable fixation of the other fracture while in the operating room probably makes sense to allow for the earliest possible mobilization of the extremity. If both fractures are nondisplaced and the scaphoid fracture is mid to distal, one could make a case for either operative or nonoperative intervention depending on the specific circumstances of the patient (e.g., age, comorbidities, tolerance of a cast). Typically, these are treated within 2 weeks, although treatment after that date is not necessarily contraindicated.

Contraindications

Treatment of pediatric patients with nondisplaced fractures is relatively contraindicated because in these patients the scaphoid fracture will usually heal in a reasonable amount of time and there are not as many problems with joint stiffness. A common problem today with the treatment protocol of children is that many caregivers neglect to utilize a cast or limit casting in children, resulting in nonunions. It should be understood that adolescents have similar healing potential as adults and should be provided the same treatment as adults.

Overview of Surgical Technique

The treatment of combined fractures of the scaphoid and distal radius includes the arthroscopic-assisted/percutaneous reduction of both fractures and their rigid fixation. The key to success is a three-step process:

1. The percutaneous/arthroscopic reduction of the scaphoid fracture and provisional stabilization with a guidewire placed along its central axis
2. The reduction and rigid fixation of the distal radius fracture to permit early motion
3. The fixation of the scaphoid fracture by the percutaneous implantation of a cannulated headless compression screw along the central scaphoid axis

This surgical staging permits reduction of both fractures without compromising the final rigid fixation of either fracture. Arthroscopy is used to confirm fracture reduction and identify occult injuries.

Setup

Equipment includes a headless cannulated compression screw for scaphoid fixation to permit percutaneous fixation and some type of distal radius fixation system that can provide rigid fixation with the least complications. We prefer screws of standard size for scaphoid fractures of the middle third, because the larger core shaft increases the ability to resist lateral displacement forces.14 Mini-fluoroscopy permits real-time imaging during surgery. Although standard fluoroscopy units can be used, they are cumbersome and emit a significant amount of radiation. Additional equipment includes 0.045-inch and 0.062-inch double-cut Kirschner wires (K-wires), a wire driver, and a small joint arthroscopy setup, including a traction system.

Surgical Technique

Imaging

The patient is placed supine, with the upper extremity extended on a hand table in a neutral position with a roll under the ulnar side of the wrist. A fluoroscopic survey of the wrist and carpus is performed to evaluate the personality of the fractures, including the direction of displacement, the presence and degree of comminution, and associated ligamentous injuries. Radiographic views of the distal radius, to account for the palmar tilt and ulnar inclination, are useful in evaluating fracture displacement of the articular surface. Longitudinal traction is then applied to the wrist, and a second fluoroscopic survey is conducted through a 90-degree arc. This helps determine the reduction achieved by ligamentotaxis and whether there is any remaining displacement.

Scaphoid Fracture Reduction and Dorsal Guidewire Placement along the Scaphoid Central Axis

The wrist is in an ulnarly deviated position extended on the arm table with a mini-fluoroscopy unit placed horizontal on the arm table and perpendicular to the wrist. The starting position for the guidewire is the proximal scaphoid pole at the 3-4 arthroscopic portal (Fig. 21-3). This dorsal approach permits easy access to the central scaphoid axis because the base of the scaphoid is covered only by soft tissue. The distal scaphoid is covered by the trapezium and obstructs direct line of sight, making central axis wire placement difficult. With the wrist supported by a roll and mini-fluoroscopy perpendicular to the wrist, a guidewire is placed at the proximal scaphoid pole and driven dorsally along the central axis of the scaphoid passing through the trapezium. The wrist is maintained in a flexed position to avoid bending the guidewire. As the wire is advanced, its position in two planes is confirmed using fluoroscopy (Fig. 21-4). The wire is advanced from a dorsal to volar position until the dorsal trailing end of the wire clears the radiocarpal joint, permitting full extension of the wrist. The volar end of the wire exits from the radial base of the thumb, which is a safe zone devoid of tendons and neurovascular structures. Once the dorsal trailing end of the guidewire has been buried into the proximal scaphoid pole, the wrist can be extended for imaging to confirm scaphoid fracture alignment and correct positioning of the guidewire.

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FIGURE 21-3 Driving the central axis wire.

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FIGURE 21-4 Central axis wire in correct position on the anteroposterior view.

If the scaphoid is displaced, the proximal pole is ignored and the guidewire is placed through the distal scaphoid fragment along its central axis and withdrawn volarly beyond the fracture site (Fig. 21-5). A second antirotation wire is usually added, particularly in less stable displaced fractures (Fig. 21-6).

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FIGURE 21-5 Central axis wire is withdrawn volarly all the way to the fracture site to allow reduction of the fracture. Wire placement in a displaced fracture is crucial in the distal fragment but initially less important in the proximal fragment until reduction is performed.

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FIGURE 21-6 A second antirotation wire is placed.

Often the lunate sits in a dorsiflexed intercalated segment instability (DISI) position. This is corrected by hyperflexing the wrist and driving a 0.062-inch wire from the distal radius into the lunate to capture the lunate in a corrected position (Fig. 21-7). This also helps stabilize the proximal pole of the scaphoid, assisting with the reduction. The scaphoid fracture is reduced percutaneously using dorsally placed 0.062-inch K-wires as joysticks in each fracture fragment. When the dorsal joysticks are brought together, the flexion deformity of the scaphoid is corrected. This is best confirmed on lateral fluoroscopy (Fig. 21-8). The previously placed distal wires are driven retrograde to capture the reduction.

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FIGURE 21-7 The wrist is hyperflexed to correct the lunate DISI position, and a 0.062-inch wire is driven from radius to lunate to hold this position. A joystick is also placed in the distal scaphoid.

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FIGURE 21-8 The joystick is used to extend the distal pole of the scaphoid while the two axis wires are driven retrograde to capture the reduction.

With acute fractures, there is usually no loss of volar cortex because the volar scaphoid fails in tension in a hyperextension injury. Older or impacted displaced fractures may require the direct introduction of a small hemostat at the fracture site to achieve reduction. The hemostat is introduced through a midcarpal or an accessory portal. Once reduction is achieved, the previously placed wire in the distal fragment is driven from its volar position into the proximal fragment to capture and secure reduction.

Distal Radius Fracture Reduction

Once the scaphoid fracture is reduced and provisionally stabilized, attention is turned to the distal radius fracture. Again, like the scaphoid, the distal radius is percutaneously reduced using mini-fluoroscopy, 19-gauge needles to locate the fracture site, a small curved hemostat placed percutaneously to achieve reduction, and K-wires to provide provisional fixation (Fig. 21-9

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