Technique Spotlight: Fragment Specific Options for Distal Radius Fractures

Introduction

The last two decades have seen the introduction of new implants and techniques revolutionize the capacity to successfully stabilize displaced and unstable distal radius fractures. The advent and sweeping adoption of volar locked plating in the new millennium quickly broadened indications for surgery. ^, The demonstrated success and versatility of volar locked plating have led to its adoption as the most common method of fixation of distal radius fractures. However, while volar locking plates (VLPs) are a crucial tool in a surgeon’s armamentarium, they are not the panacea for all distal radius fractures. A subset of fracture patterns will benefit from alternative approaches and implant selection. Fragment-specific fixation utilizes multiple implants, through one or more incisions, each designed to secure an individual fracture fragment. In comminuted intra-articular distal radius fractures, the epiphysis commonly separates into five characteristic fragments with fault lines at the intervals between radiocarpal ligament attachments. The most common fragments include the radial column, dorsal ulnar corner, dorsal wall, volar rim or volar ulnar corner (VUC), and free intra-articular fragments ( Fig. 63.1 ).

Advantages of Fragment-Specific Fixation

Increased articular cavity depth or intra-articular step-off ≥3 mm has been shown to increase radiocarpal contact stress. The goals of fragment-specific techniques are to achieve direct open visualization, manipulation, and buttress-style fixation of each fragment to facilitate anatomic reduction and create a load-sharing construct. Buttress-style fixation with low-profile implants eliminates dependency on screw thread purchase of the dorsal ulnar corner, dorsal wall, and radial styloid fracture fragments, as is necessary when relying on isolated fixation with a volar plate. Often these fragments are small, secondary to a shear or avulsion mechanism, and pose a challenge in capturing from the volar side while minimizing dorsal prominence of the screws. ^, Distal fractures of the volar surface are also difficult to stabilize with a standard VLP without risking flexor tendon injury. Low-profile fragment-specific implants minimize tendon irritation on the dorsal surface or when volar fixation is required distal to the watershed line, as is often the case with the critical VUC fragment. Fragment-specific implants can be utilized in isolation, in combination, or as adjunctive fixation ^, to other fixation methods to stabilize very distal or highly comminuted distal radius fractures.

Radiographic Considerations

Careful analysis of injury radiographs is crucial when considering or planning fragment-specific fixation techniques. Measurements of radial height, radial inclination, ulnar variance, volar tilt, and articular step-off provide insight into the global displacement of a distal radius fracture; well-described thresholds for each value identify unacceptable deformity and inform indications for operative treatment. Abnormalities in these radiographic parameters act synergistically and should be considered in the context of the total deformity, rather than in isolation ( Fig. 63.2 ).

A systematic and reproducible method for identifying the character and degree of displacement of each fracture fragment is critical for treatment planning. The central reference point (CRP) is an important landmark to identify on the posteroanterior (PA) radiograph ( Fig. 63.3 ). The CRP is the point halfway between the dorsal and volar corners of the sigmoid notch. This point should be used as the more proximal reference point when measuring radial inclination, ulnar variance, and radial height because it remains consistent despite excess dorsal or volar angulation.

On both the PA and lateral radiographs, radiodense lines below the subchondral radius may represent a rotated dorsal wall fragment ( Fig. 63.4 ) or a free intra-articular fragment that has rotated into the metaphyseal cavity. On the lateral radiograph, it is important to identify incongruency of the joint interval, widening of the anteroposterior (AP) distance, depression of the teardrop angle, and carpal malalignment. In the absence of radiocarpal ligament injury or articular step-off, a contiguous and smooth radiocarpal articulation should be noted, from the dorsal to volar margin. Similarly, the arc of curvature of the articular surface of the distal radius should be congruent to the proximal pole of the lunate; incongruency can occur when volar or dorsal ulnar corner fragments separate or rotate in the sagittal plane ( Fig. 63.5 ). A 10-degree lateral view provides a clearer view of the articular surface by positioning the X-ray beam parallel to the radial inclination of the joint.

In extra-articular fractures, a depression of the teardrop angle implies increased dorsal angulation of the epiphyseal fragment. However, in an intra-articular fracture, a depressed teardrop angle of <45 degrees often corresponds to dorsal angulation of the volar portion of the lunate facet, as is seen in a standard Colles’ fracture ( Fig. 63.6 ).

Alternatively, a volar shear injury may cause proximal displacement of the VUC and subsequent volar translation of the carpus. In some fractures, a small avulsion fracture of the attachment of the volar carpal ligaments may escape distally with corresponding volar subluxation of the carpus, particularly in the setting of an impacted volar lunate facet. Recognition of this carpal malalignment on injury radiographs is critical to inform surgical planning; distal radius fractures with carpal malalignment are usually treated operatively. To better evaluate these fractures, computed tomography (CT) scans are often employed. While not critical for every pattern, CT scans can help with preoperative planning for complex intra-articular fractures, particularly if the surgeon has less experience with highly comminuted fractures.

General Principles for Fragment-Specific Fixation

In this section, we will present our preferred techniques and sequence to address each fracture fragment that may be present. The ultimate goals are to achieve articular congruency, restore length, and ensure stability of the radiocarpal and distal radioulnar joints (DRUJ). When planning to utilize a fragment-specific technique, our preferred sequence to address each fracture fragment is as follows: (1) reduction of intra-articular fragments, (2) bone grafting of the metaphyseal void, (3) reduction and provisional stabilization of the radial column, (4) fixation of the volar lunate facet, (5) fixation of the dorsal ulnar corner, (6) additional fixation of the radial column as needed, and (7) fixation of the dorsal wall.