20 Arthroscopic Repair of Combined Scaphoid and Distal Radius Fractures

10.1055/b-0034-80585

20 Arthroscopic Repair of Combined Scaphoid and Distal Radius Fractures

Slade III, Joseph F., Merrell, Greg

The incidence of combined injuries involving the distal radius varies from 0.7% to 6.5%.1 ^– 4 The mechanism is a high-energy injury with rapid forced loading of an outstretched radial deviated dorsiflexed wrist.1 ^, 4 ^, 5 These injuries are often associated with a displaced and angulated scaphoid fracture. Although uncommon, simultaneous fractures of the distal radius and scaphoid can be challenging to treat.

Minimally invasive surgical techniques with an organized plan for reduction and fixations of all injuries result in early restoration of hand function. We proposed a three-step plan of scaphoid reduction, distal radius reduction and fixation, and rigid fixation of scaphoid fracture as a reliable technique for treatment of these combined injuries with minimal complication and early recovery of hand function.6 This chapter describes this technique in a step by step manner. Pearls and pitfalls are presented along with an illustrative case ( Fig. 20.1A,B ).

▪ Rationale for Surgical Technique

Combined fractures require the simultaneous repair of all injuries. Immobilization of a distal radius fracture until a scaphoid fracture has healed results in wrist arthrofibrosis and prolonged rehabilitation.7 Once the decision has been made to surgically treat these injuries, the question arises as to the order of treatment of these combined fractures. The goal of surgical treatment is rigid fixation and early motion to restore hand function. 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 a potential for screw pull-out or loosening as a result of the substantial forces applied during distal radius reduction. If the first fracture treated is the radius, reduction of the second fracture, the scaphoid, may result in a loss of reduction and a malunion in the radius. This chapter presents a tactical approach to the surgical treatment of these combined fractures using arthroscopic and percutaneous techniques, which prevents loss of rigid fixation of one or both fractures.

**Fig. 20.1** Combined fractures of the distal radius and scaphoid present a challenging treatment dilemma. The goal of treatment is an early recovery of hand function to prevent prolonged immobilization of these fractures resulting in a stiff arthrofibrotic hand. The challenge to these high-energy injuries is obtaining rigid fixation of both fractures to permit early rehabilitation. This can be accomplished with **(A)** a distal radius intramedullary rod or **(B)** a volar locking plate and a headless compression scaphoid screw

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.8

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; however, this predated operative treatment of acute scaphoid fractures.5 ^, 9 ^, 10 We now understand both fractures must be adequately reduced and treated. The arthroscopic care of both distal radius and scaphoid fractures and the use of percutaneous techniques has permitted the rigid fixation of these fractures while preserving uninjured tissues.11 ^– 14 This has allowed for the early recovery of hand function with minimal complications.

▪ Indications and Contraindications

The typical patient is male in his twenties or thirties after a fall, motor vehicle accident, or sports injury. Any combined complete fractures of either the scaphoid or distal radius would be an operative candidate. If the patient presents with one stable and one unstable fracture then both are treated with operative intervention so recovery of hand function can be started immediately. If both fractures are nondisplaced and the scaphoid fracture is 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, etc.). Typically, these are treated within 2 weeks, although treatment after that date is not necessarily contraindicated. Pediatric patients with nondisplaced fractures would be a relative contraindication because these patients will usually heal their scaphoid fracture in a reasonable amount of time and do not face as many issues with joint stiffness. A common problem today with the treatment protocol of children is that many caregivers neglect or limit casting of children, resulting in nonunions. It should be understood that adolescents have similar healing potential as adults and are treated as adults.

▪ Overview of Surgical Technique

The treatment of combined fractures of the scaphoid and distal radius includes the arthroscopically assisted/percutaneous reduction of both fractures and their rigid fixation.6 ^, 14 The key to success is a three-step process ( Fig. 20.2 ):

**Fig. 20.2** Treatment of combined fractures of the scaphoid and radius is a three-step process. The first step is the percutaneous reduction of the scaphoid fracture and provisional stabilization with a guide wire placed along its central axis. The scaphoid is not rigidly fixed now because reduction of the radius fracture may require significant bending forces to obtain reduction and fixation of the radius. These forces may be unintentionally applied to the scaphoid, and if the scaphoid is fixated may now result in loosening. This leads to a loosening in compression at the fracture site and will eventually result in scaphoid nonunion. This is a particular concern with early motion. This is why we advocate reduction of the scaphoid only for our first step. The second step consists of the percutaneous/arthroscopically assisted reduction and rigid fixation of the distal radius fracture to permit early motion. The third step is the fixation of the scaphoid fracture. This is accomplished by the dorsal percutaneous implantation of a cannulated headless compression screw along the central scaphoid axis. This is accomplished with minimal stress on the radius fixation.

First, the percutaneous/arthroscopic reduction of the scaphoid fracture and provisional stabilization with a guide wire placed along its central axis

Second, the reduction and rigid fixation of the distal radius fracture to permit early motion

Third, the fixation of the scaphoid fracture. This final step is accomplished 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.

▪ Surgical Technique in Detail

Step One: Imaging

The patient is 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.

Step Two: Scaphoid Fracture Reduction and Dorsal Guide Wire Placement along the Scaphoid Central Axis

The wrist is positioned with the arm extended on the arm table in a neutral position with a minifluoroscopy unit placed horizontal on the arm table and perpendicular to the wrist ( Fig. 20.3 ). The starting position for the guide wire is the proximal scaphoid pole at the 3,4 arthroscopic portal ( Fig. 20.3 ). 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 the direct line-of-sight, making central axis wire placement difficult. With the wrist supported by a roll and minifluoroscopy perpendicular to the wrist, a guide wire 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 guide wire. As the wire is advanced, its position in two planes is confirmed using fluoroscopy ( Fig. 20.4 ). 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, a safe zone devoid of tendons and neurovascular structures. Once the dorsal trailing end of the guide wire 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 guide wire.

**Fig. 20.3** The wrist is extended on the arm table with a minifluoroscopy unit placed perpendicular to the wrist. The starting position for the guide wire is the proximal scaphoid pole. The guide wire is driven dorsal to volar along the central axis of scaphoid passing through the trapezium and exiting at the thumb base. The wrist is maintained in a flexed position to avoid bending the guide wire. As the wire is advanced, its position is confirmed using fluoroscopy.

If the scaphoid is displaced, the proximal pole is ignored and the guide wire is placed through the distal scaphoid fragment along its central axis and withdrawn volarly beyond the fracture site. A second antirotation wire is usually added, particularly in less stable displaced fractures ( Fig. 20.5 ).

**Fig. 20.4** The wire is advanced from a dorsal to a volar position until the dorsal trailing end of the wire clears the radiocarpal joint, permitting full extension of the wrist. The wire exits at the thumb base. Fluoroscopic imaging is now used to confirm fracture reduction and wire position along the central axis.

Often the lunate sits in a dorsal intercalated segmental instability (DISI) position. This is corrected by hyperflexing the wrist and driving a 0.062-in. wire from the distal radius into the lunate to capture the lunate in a corrected position ( Fig. 20.5 ). This also helps stabilize the proximal pole of the scaphoid, assisting with the reduction. The caphoid fracture is reduced percutaneously using dorsally laced 0.062-in. 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. The previously placed distal wires are driven retrograde to capture the reduction.

**Figure 20.5** If the scaphoid is displaced and flexed, the lunate may be in the dorsal intercalated segmental instability position. The fracture must be reduced. This is accomplished by hyperflexing the wrist until the lunate is in a neutral position and then driving a 0.062-in. wire from the distal radius into the lunate to capture the lunate in a corrected neutral position. Next, the proximal scaphoid fracture is ignored and a guide wire is placed dorsally through the distal scaphoid fragment along its central axis and withdrawn volarly beyond the fracture site. A second antirotation wire is usually added, particularly in less stable displaced fractures. The scaphoid fracture is reduced percutaneously using dorsally placed 0.062-in. K-wires as joysticks in the distal scaphoid fracture fragment. After extension and reduction of the scaphoid, the volar distal scaphoid K-wires are driven dorsally, capturing the scaphoid 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.

Step Three: 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 minifluoroscopy, 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. 20.6 ). Depending on the fracture type and stability, the patient’s needs and desires, and finally the surgeon’s skill and experience, an appropriate wrist fracture system is selected. As a rule, the simplest system that achieves rigid fixation permits early recovery of hand function with the least complication and is the best. Our goals should be restoration of a congruent joint surface and restoration of the native metaphyseal cortical architecture. It has been the senior author’s (JFS) experience that every patient sustains two injuries. The first is the patient’s misfortune and the second is our treatment. If we can limit the second injury by limiting any additional injury to the uninjured structures, the patient often has less complication and has a quicker recovery of hand function. The use of fluoroscopy and arthroscopy permits the use of percutaneous techniques, which limits these secondary injuries but still facilitates our ultimate goals of fracture reduction and rigid fixation.

The wrist is placed in a neutral position perpendicular to a minifluoroscopy unit with the ulna supported by a towel roll. Imaging locates the fractures, and 19 gauge needles are placed dorsally identifying the fracture site. Limited stab incisions are made and a small curved hemostat is introduced into the fracture site. The distal fracture fragment is leveraged into a reduced position, and a percutaneous 0.062-in. K-wire is placed to provide provisional fixation. Both the radial height and the dorsal tilt should be restored. If an intraarticular fracture is detected on imaging, then this fracture is reduced and secured first using the previously described techniques.

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