14 Multiplanar Fixation in Severe Articular Fractures

10.1055/b-0039-169254

14 Multiplanar Fixation in Severe Articular Fractures

Peter C. Rhee, Alexander Y. Shin

Abstract

Severely comminuted distal radius fractures can pose tremendous challenges in restoring articular congruity and achieving anatomic alignment. Successful management of these fractures requires a thorough understanding of the osteoligamentous fracture fragments and the deforming forces that must be mitigated. Although volar locking plates (VLPs) can be used in the management of most distal radius fractures, their use should be limited in complex, multi-fragmentary fractures. In these situations, the surgeon must be facile with various surgical approaches and be ready to provide alternative methods to stabilize unstable fragments.

14.1 Introduction

Volar locking plate (VLP) fixation can be utilized in the surgical management of most distal radius fractures to effectively stabilize sizable fracture fragments. The fixed-angle construct of a VLP provides stable fixation, even in the setting of metadiaphyseal comminution, by transferring forces from the distal fragments to the volar cortex of the intact radial shaft. ¹ ^, ² However, there are limitations to these implants when used in isolation to reconstruct multifragmentary distal radius fractures, especially in the setting of marked articular comminution with small fracture fragments. Successful surgical management of complex distal radius fractures requires versatility in surgical approaches and techniques, in addition to a familiarity with a variety of fixation methods including multiplanar fragment-specific (F-S) fixation. ²

14.1.1 Understanding the Fracture Characteristics

Multifragmentary distal radius fractures result in characteristic fracture fragments. ³ ^, ⁴ ^, ⁵ Melone noted that intra-articular fractures of the distal radius often results in a coronal plane fracture line that separates the dorsal and volar surfaces of the lunate facet. ⁶ Teunis et al reviewed computed tomography (CT) scans of 41 intra-articular distal radius fractures (Association for Osteosynthesis [AO] type C3) and noted that 93% (n = 38) fit the Melone distribution of fracture fragments. ⁴ Rikli and Regazzoni initially described the distal end of the radius as two columns, radial and intermediate, which contain bony and ligamentous structures that provide stability to the radiocarpal and distal radioulnar joints (DRUJs). ² ^, ⁷ Medoff further classified the common fracture fragments that reside within these columns (▶Fig. 14.1). ² ^, ³ The intermediate column is composed of the volar rim, dorsal ulnar corner, dorsal wall, and a free intra-articular fragment, while the radial column consists of the radial styloid fragment alone (▶Fig. 14.2).

**Fig. 14.1** Column model for distal radius fractures. Intermediate (I), radial (R), and ulnar (U) columns.

**Fig. 14.2** Common fracture fragments in comminuted, intraarticular distal radius fractures. An axial computed tomography scan of the articular surface of a multifragmentary distal radius fracture illustrates the volar rim (VR), dorsal ulnar corner (DUC), free intra-articular (FI), dorsal wall (DW), and radial column (RC) fragments.

Articular fractures at the distal radius occur at inherent areas of weakness between sites of ligamentous attachments. ⁴ ^, ⁵ ^, ⁸ ^, ⁹ Mandziak et al reviewed CT scans of 100 intra-articular distal radius fractures to identify common patterns and locations of fracture lines. ⁸ They noted that fractures sites commonly occurred between ligament attachments. Similarly, Bain et al utilized CT scans of 42 intra-articular distal radius fractures and observed cortical breaches in an interligamentous zone in 85% of cases (71 of 84 fracture lines), thus resulting in three characteristic fracture fragments involving the radial styloid and the dorsal or volar articular surfaces of the lunate facet, each with their own subtypes. ⁹ Given the fact that ligamentous origins were relatively preserved despite marked comminution, the authors suggested that the fracture fragments should be conceptualized as osteoligamentous units that should be taken into consideration during reconstruction.

Understanding the fracture fragments and their role in providing stability to the radiocarpal and distal radioulnar joints is paramount to successful reconstruction of complex distal radius fractures. Teunis et al utilized quantitative CT to evaluate the articular surface area of the radial styloid (radial column), volar lunate facet (volar rim), and dorsal lunate facet (dorsal ulnar corner and dorsal wall) fragments in 41 intra-articular distal radius fractures. ⁴ They noted decreasing mean articular surface area from the volar lunate facet (39%) and radial styloid (37%) to the dorsal lunate facet (24%) fragments. The authors concluded that anatomic reconstruction of the radial styloid and volar rim fragments may be the key elements to imparting a stable foundation for the radiocarpal joint. However, the volar rim and dorsal ulnar corner fragments create the sigmoid notch as well as the lunate facet; thus, both fragments are indispensable to providing stability at both the radiocarpal and distal radioulnar joints. ² ^, ³ ^, ⁴ Unfortunately, the volar rim and dorsal ulnar corner fragments can often malrotate and may be irreducible with ligamentotaxis and manipulation alone. ³ ^, ⁴ ^, ⁵

14.1.2 Limitations of Volar Locking Plate Fixation

Although versatile, the VLP may not provide stability to all critical fracture fragments in many multifragmentary distal radius fractures. ¹⁰ ^, ¹¹ ^, ¹² Harness et al initially described the inability of a VLP, appropriately placed proximal to the so-called watershed line at the junction of the pronator fossa and the volar rim of the lunate, to stabilize a small volar rim fragment, thus resulting in loss of fixation and radiocarpal instability in seven patients. ¹² Beck et al further noted that volar shear fractures with separate radial styloid and lunate facet fragments (AO type B3.3) with less than 15 mm of lunate facet volar cortical length available for VLP fixation or greater than 5 mm of initial lunate facet subsidence were at risk for failure with a properly positioned VLP alone. ¹¹ In these instances, additional fixation methods should be implemented in addition to the VLP to stabilize the unstable volar rim fragment or to utilize alternative forms of fixation and techniques such as F-S fixation, external fixation, or distraction bridge plate fixation. ² ^, ¹⁰

14.1.3 Rationale for Fragment-Specific Fixation

Due to the inability of a single implant or technique to reconstruct all unstable distal radius fractures, the concept of F-S fixation was introduced. ¹³ ^, ¹⁴ F-S fixation involves the application of individualized, low-profile implants and the use of corresponding surgical exposures to stabilize all unstable fracture fragments with only a minimal footprint within the fragment itself. ² These implants create a multiplanar, load-sharing construct that anatomically restores the articular surface while providing enough stability to allow immediate motion after surgery. ² ^, ¹³ ^, ¹⁴

Although small and low profile, F-S implants can provide tremendous stability to comminuted distal radius fractures, particularly the dorsal ulnar corner fragment. ¹⁵ ^, ¹⁶ Dodds et al performed a cadaveric biomechanic study comparing the stability of three- and four-part distal radius fractures reconstructed with dedicated F-S implants to external fixation with 0.062-inch Kirschner wires (K-wires) in each fracture fragment. ¹⁵ Although both forms of fixation provided equal stability in a simulated three-part fracture, F-S fixation alone resulted in greater stability in all six axes of motion compared to external fixation with supplemental pin fixation in four-part fractures of the distal radius. Taylor et al compared the stability of a fixed-angle VLP to F-S implants in a cadaveric, biomechanic study with a simulated AO type C2 fracture. ¹⁶ The authors noted that although there were no significant differences in load to failure between groups, the F-S group resulted in significantly stiffer fixation of the dorsal ulnar corner fragment in cyclic-loading compared to the VLP group.

14.2 Indications

The indications for operative management of distal radius fractures include postreduction radial shortening > 3 mm, dorsal tilt > 10°, and intra-articular displacement or step-off > 2 mm. Distal radius reconstruction with F-S fixation is indicated when fracture fragments are too small for screw fixation through a VLP or when the fracture line courses distal to the watershed line. ¹⁰ ^, ¹¹ ^, ¹² In many instances, supplemental F-S fixation can be utilized in addition to a VLP if reduction and stabilization of a free intra-articular fragment is necessary or if the dorsal ulnar corner, dorsal wall, or radial column fragments remain unstable after initial VLP fixation. ²

14.3 Surgical Technique (Authors’ Preferred)

14.3.1 Preoperative Planning

Traction or reduction radiographs (posteroanterior, lateral, and oblique views) are and can be used to visualize the fracture fragments more clearly than the nonreduced injury images. More complex fractures may require CT images with sagittal and coronal reformats to clearly delineate the fracture patterns (▶Fig. 14.3). As one gain more experience in correlating CT findings with radiographic findings, the need for CT diminishes. However, CT scan should be obtained for fractures where the fragments are not clearly identified or is unusual, or if there is concern for concomitant carpal injuries.

**Fig. 14.3** Radiographs and CT scan of a multifragmentary, intra-articular distal radius fracture. Posteroanterior (PA) radiographs upon presentation **(a)**, traction view **(b)**, oblique **(c)**, and lateral **(d)** can identify most fracture fragments. The sagittal reformat of the volar rim fragment **(e)** clearly identifies the small fragment with a very distal fracture line that may not be amenable to standard volar locking plate fixation.

14.3.2 Sequence of Reconstruction

The sequence of reconstruction starts with the volar rim fragment and progresses in a step-wise fashion addressing all of the unstable fracture fragments (▶Fig. 14.4). The volar rim fragment is the cornerstone of the other fragments within the intermediate column. With its attachment to the short radiolunate ligament, it also has the ability to reduce the displaced carpus that often follows the volar rim fragment. The next fragment to address is the dorsal ulnar corner fragment. Note that reduction of the volar rim and dorsal ulnar corner fragments permit restoration of the lunate facet and sigmoid notch articular surfaces. Reduction of any depressed free intra-articular fragments is then performed followed by reduction and fixation of the dorsal wall fragments. At this point, the intermediate column is fully reconstructed and the radial column (styloid) fragment can then be reduced and buttressed to the intermediate column, thus completing the reconstruction of the distal radius. Lastly, fractures and soft tissue injuries involving the distal ulna or the triangular fibrocartilage complex (ulnar column) are addressed if the DRUJ remains unstable. However, this will be further discussed in Chapter 19.

**Fig. 14.4** Sequence of reconstructing the comminuted distal radius fracture. Step-wise reconstruction of the volar rim (VR), dorsal ulnar corner (DUC), free intra-articular (FI), dorsal wall (DW), and radial column (RC) fragments.

Examination of the normal, uninjured wrist is extremely helpful prior to surgery. It will allow for comparison of motion and stability of the DRUJ. When planning for F-S fixation, understanding the angiosomes of the wrist as well as incision placement is essential. ¹⁷ ^, ¹⁸ As multiple incisions may be needed to approach the various fragments, they should be longitudinal while preserving the angiosomes demarcated by the radial and ulnar arteries. Up to four longitudinal incisions can be placed on the wrist without skin necrosis or wound issues in the authors’ experience. These incisions include a volar incision, dorsal midline incision, radial incision, and, when necessary, an ulnar incision (▶Fig. 14.5). The specific approaches will be detailed with each fragment.