Galeazzi Fracture-Dislocations

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CHAPTER 22 Galeazzi Fracture-Dislocations

David E. Ruchelsman, MD, Keith B. Raskin, MD, Michael E. Rettig, MD

Galeazzi fracture-dislocations are defined by fracture of the middle to distal third of the radial diaphysis with simultaneous traumatic disruption of the distal radioulnar joint (DRUJ), resulting in either dorsal or ulnar subluxation/dislocation of the ulnar head from within the sigmoid notch. Although first described by Cooper in 1882,^1,² this complex forearm fracture-dislocation has been credited to Galeazzi,³ who in 1934 reported a series of 18 patients with this injury pattern. Mikic¹ proposed that both-bone forearm fractures with concomitant DRUJ dislocation be considered within the spectrum of the classic Galeazzi fracture-dislocation because similar principles of management are applied.

Several early series demonstrated uniformly poor results with nonoperative management, and, as a result, the Galeazzi fracture-dislocation has been referred to as a “fracture of necessity.” Hughston ⁴ reported that nonoperative treatment of the classic Galeazzi lesion resulted in unsatisfactory results in 92% (35 of 38) of patients. Mikic¹ reported an 80% failure rate with conservative management in 86 adults with Galeazzi fracture-dislocations due to both inability to control progressive displacement of the radius fracture as well as recurrent subluxation or dislocation of the DRUJ despite cast immobilization. Mikic postulated that rupture of the triangular fibrocartilage complex (TFCC) was the primary cause of redislocations and the poor results observed. Other early series reported similar disappointing results with closed reduction and immobilization.^2,⁵

With advances in surgical techniques to achieve osteosynthesis and soft tissue reconstruction, open reduction and internal fixation (ORIF) has become the standard of care to optimize outcomes after forearm fractures associated with DRUJ disruption. Operative management has yielded satisfactory results in more than 80% of adult patients with these injuries.⁶^–⁹

Regional Anatomy and Biomechanics

Stability of the forearm, and specifically the DRUJ, is dependent on the presence of dynamic (musculotendinous) and passive (ligamentous) soft tissue stabilizers and, to a lesser extent, osseous anatomy. Bony congruity between the ulnar head and sigmoid notch of the radius contributes only approximately 20% of total DRUJ stability. In the transverse plane, the sigmoid notch is shallow relative to the ulna seat and the radii of their articular seats are disparate; thus, appositional contact is small.^10,¹¹ As a result, motion at the DRUJ is predominantly translational—a combination of sliding and rotation. However, its axis of motion remains adjacent to the center of the ulnar head.

Tolat and associates ¹¹ analyzed the osseous characteristics of the sigmoid notch and ulnar head in 50 cadaveric specimens in the coronal and transverse planes with multiple articular surface-based measurements. Three midcoronal DRUJ articular types (types I to III) were confirmed: type I DRUJ (55%)—apposing joint surfaces are parallel to the long axis of the radius and ulna; type II DRUJ (33%)—oblique apposing surfaces at the sigmoid and ulnar articular seats; and type III DRUJ (12%)—“reverse oblique” joint orientation with the DRUJ angular apex formed proximal to the DRUJ. In addition, four axial plane anatomical variants of the sigmoid notch were also noted and included flat face (42%), ski slope (14%), C-type (30%), and S-type (14%) notches. Furthermore, an extra-articular palmar osteocartilaginous lip was found in 80% of specimens and was found to serve as a consistent point of attachment for the volar radioulnar ligament and volar DRUJ capsule. When the TFCC is sectioned in the laboratory or incompetent in the clinical setting, this palmar lip serves as a buttress to palmar dislocation of the ulnar head and, thus, acts as a supplemental stabilizer to the interosseous membrane (IOM). This buttress effect is lost when there is a longitudinal tear in the interosseous membrane or fracture of the palmar rim (i.e., sigmoid notch fracture).

The soft tissue anatomy about the DRUJ is well defined,¹² and its stabilizers include the pronator quadratus, ulnocarpal ligaments, extensor carpi ulnaris subsheath, dorsal and volar radioulnar ligaments, IOM, and DRUJ capsule. The TFCC is considered the primary stabilizer of the DRUJ, and the IOM is a secondary restraint. The ulnar styloid projects 2 to 6 mm and is the site of attachment for the superficial (distal) limbs of the radioulnar ligaments and the extensor carpi ulnaris subsheath. The deep (proximal) fibers of the distal radioulnar ligaments and the ulnocapitate ligament insert into the fovea at the styloid base. Gofton and colleagues¹³ found that the radioulnar ligaments and the triangular fibrocartilage maintain DRUJ kinematics with simulated active forearm motion when more proximal soft tissue stabilizers (i.e., pronator quadratus, IOM, extensor carpi ulnaris subsheath, ulnar collateral ligament) are sacrificed. Furthermore, the radioulnar ligaments may play a greater stabilizing role in DRUJ stability in patients with flat sigmoid notches.¹¹

The IOM has multiple biomechanical functions: it helps to transmit force from the radius to the ulna, acts to prevent excessive supination, serves as an aponeurosis for insertions of the deep flexors and extensors, and resists radius and ulna diastasis. The complexity of the IOM structure has been studied by several groups.¹⁴^–¹⁶ In a cadaveric study, Hotchkiss and associates¹⁴ defined a central band of ligamentous tissue that contributed 71% of the longitudinal stiffness of the IOM after radial head excision. Injury to this region may represent the pathoanatomy responsible for proximal migration of the radius after radial head excision. Skahen and coworkers¹⁶ found that the IOM was consistently organized into a central band, one to five accessory bands, a dorsal proximal interosseous band, and membranous portions. Fibers from the central band originate from the radius and run in a distal-ulnar direction at a 20-degree angle to the long axis of the ulna. Peak strain occurs in the central band during pronation, the assumed position of the forearm when a Galeazzi fracture-dislocation is sustained. Other authors ^17,¹⁸ have demonstrated that the IOM also serves as a coronal (transverse) and sagittal (dorsal-volar) plane stabilizer of the DRUJ, in addition to its described role as a longitudinal restraint. Analyses by Watanabe and colleagues¹⁸ suggest that it is a specific injury to the distal portion of the IOM (distal to the central band) that confers increased dorsal-volar instability at the DRUJ throughout a range of forearm rotation when the TFCC and distal radioulnar ligaments are incompetent; when the midportion of the IOM (including the central band) is sectioned together with the distal IOM, the DRUJ becomes unconstrained. Similarly, in a cadaveric biomechanical model, Gofton and coworkers¹³ demonstrated that the IOM was essential in the maintenance of DRUJ kinematics when distal soft tissue stabilizers are sacrificed (i.e., radioulnar ligaments and triangular fibrocartilage).

True Galeazzi fracture-dislocations have not been reproduced in an ex vivo biomechanical model.¹⁹^–²¹ As a result, although these injuries are assumed to occur in definable stages, the failure sequence of the regional soft tissue restraints after fracture of the radius has not been elucidated. However, the contributions of the TFCC and IOM to the biomechanics of the Galeazzi fracture-dislocation have been studied. Moore and associates,²⁰ in a cadaveric model, produced artificial Galeazzi fractures composed of transverse, uncomminuted radial metadiaphyseal fractures created with a Gigli saw at the distal insertion of the pronator teres followed by sequential sectioning of the TFCC and IOM. Moore and associates²⁰ and Schneiderman and coworkers¹⁵ independently demonstrated that radial shortening greater than 10 mm required complete disruption of both the TFCC as well as the IOM. Intermediate shortening occurred with isolated sectioning of the TFCC or IOM, respectively. The dorsal carpal retinaculum and ulnar collateral ligaments of the wrist were not found to be significant soft tissue constraints.

Classification

Galeazzi fracture-dislocations are relatively rare injuries, constituting 3% to 7%²² of all forearm fractures. In a retrospective review, Ring and colleagues²³ reported that the incidence of isolated radial diaphyseal fractures without DRUJ involvement is greater than that of the true Galeazzi fracture-dislocations. Of the 36 radial shaft fractures, only 9 (25%) occurred in conjunction with DRUJ disruption, whereas 27 (75%) radial diaphyseal fractures occurred in isolation and had no evidence of DRUJ dysfunction at latest follow-up. If both-bone forearm fractures with DRUJ dislocation are included, the incidence is higher. In Mikic’s series of 125 patients with Galeazzi fracture-dislocations,¹ 20% of cases included fractures of both the radius and ulna.

Dameron ²⁴ originally subdivided Galeazzi fracture-dislocations into the ulna-volar type (ulna volar to the radiocarpal complex) and the ulna-dorsal type (ulna dorsal to the radiocarpal complex). In a retrospective review of 40 operatively treated Galeazzi fracture-dislocations, Rettig and Raskin⁸ introduced a classification scheme for these injuries with prognostic value with regard to the probability of intraoperative DRUJ instability after ORIF of the radial shaft fracture. Two patterns of fracture-dislocation were identified based on the distance of the radial shaft fracture from the midarticular surface of the distal radius. In 12 of 22 (55%) type I fractures, occurring within the distal third of the radial shaft and within 7.5 cm of the midarticular surface (Fig. 22-1), operative stabilization of the DRUJ was required with percutaneous Kirschner wire (K-wire) fixation secondary to persistent DRUJ instability after ORIF of the radial shaft fracture. Three of these 12 patients underwent concomitant open repair of the TFCC because the DRUJ was found to be irreducible. In contrast, only 1 of 18 (6%) patients with a type II injury, within the middle third of the radial shaft and more than 7.5 cm from the midarticular surface of the distal radius (Fig. 22-2), required percutaneous fixation of an unstable DRUJ (P < .001).

FIGURE 22-1 Preoperative posteroanterior (A) and lateral (B) radiographs reveal a fracture of the radial shaft within 7.5 cm of the midarticular surface of the distal radius—type I injury. DRUJ disruption as well as ulnar styloid fracture is appreciated.

FIGURE 22-2 Preoperative posteroanterior (A) and lateral (B) radiographs demonstrating a short oblique fracture of the radial shaft more than 7.5 cm from the midarticular surface of the distal radius—type II injury.

The mechanism of injury includes a high-velocity direct impact with axial loading of an outstretched arm. Axial loading of the forearm combined with hyperpronation of the forearm is the most common mechanism and causes dorsal dislocation of the DRUJ ¹; conversely, hypersupination leads to volar dislocation of the ulnar head from the sigmoid notch. We have postulated that for distal radial shaft fractures (type I injuries) within 7.5 cm of the midarticular surface, a high-impact hyperextension mechanism results in a direct continuum of complete injuries through the TFCC and IOM, which predisposes the DRUJ to residual instability and dorsal subluxation despite anatomical radial shaft fracture fixation⁸ (Fig. 22-3A). With fractures through the middle third of the radial shaft (type II injuries) an indirect pronation force is incurred with incomplete disruption to the regional stabilizing soft tissue structures (see Fig. 22-3B). This may account for the high likelihood of DRUJ and ulnar head stability within the sigmoid notch after fixation of more proximally located radial shaft fractures. However, a significant relationship between the magnitude of initial radial shortening and DRUJ stability was not identified. In a retrospective review of 36 patients with radial shaft fractures treated with plate and screw fixation, Ring and coworkers²³ observed a similar trend toward DRUJ stability with proximal and middle third fractures in accord with our findings. In this series, 5 of 8 distal third fractures were associated with DRUJ instability, whereas only 4 of 28 proximal/middle third radius fractures had DRUJ involvement.