Rationale and Basic Biomechanics

Although the concept of volar plating could be initially attributed to Lanz and Kron³ back in 1976 for plate fixation after osteotomy of malunited distal radius fractures, the volar approach remained restricted to fixation of volar rim fractures in the acute setting only.⁴ Volar plating was first recommended for fixation of both typical and atypical distal radius fractures by Georguoulis and associates in 1992.⁵ This was published in a little-known journal and was not widely accepted for dorsally displaced fractures until the landmark paper by Orbay and Fernandez in 2002.⁶ Volar plating offers many advantages when used in dorsally displaced fractures. The key to its success is to ensure that this was a locking plate, hence creating a fixed-angle device that would maintain the reduction and eliminate screw toggle (Fig. 13-1). Volar plating also provides the opportunity to release the pronator quadratus muscle, which is often trapped in the fracture and can be a cause of pronation contracture. A nonlocking plate when used in buttress mode can resist only moderate axial and bending forces. Thus, a simple nonlocking volar plate used in a dorsally displaced fracture without any bony contact in the opposite cortex is subject to much higher axial and bending loads, leading to failure. Therefore, a stable and strong volar fixation of a dorsally displaced fracture is only possible with a fixed-angle locking plate that can resist such high forces. Fixed-angle implants transfer load stress from the fixed distal fragment to the intact radial shaft, thus enhancing peg/plate/bone construct stability (Fig. 13-2), unlike rigid internal fixation devices that rely mainly on the frictional force between plate and bone to achieve fixation.⁷

FIGURE 13-1 Schematic diagram showing volar fixation maintaining the anatomy of the radius but screw toggle leads to plate motion relative to the shaft, which can lead to late failure.

FIGURE 13-2 Schematic diagram showing fixed-angle implant transferring load stress from the fixed distal fragment to the proximal radial shaft.

The ideal volar implant should have a design compatible with the volar articular surface of the radius and should provide concomitant angular and axial stability while stabilizing the dorsal surface.⁸ The distal volar plate (DVR Hand Innovations, Depuy Orthopedics, Warsaw, Indiana) has two parallel rows, and the orientation planes of their respective pegs specifically match the complex three-dimensional shape of the radial articular surface. The primary row pegs are directed obliquely from proximal to distal to support the dorsal aspect of the articular surface. They are angled accurately to provide support for the radial styloid and the dorsal ulnar fragment. These pegs are most effective in supporting the dorsal aspect of the subchondral plate and hence avoid the re-displacement of the dorsally displaced fractures. Concurrently, their action induces a volar force that tends to displace the fragments in a volar direction, an effect that must be opposed by a properly configured volar buttressing surface. To enhance fracture fixation in cases of severe comminution, volar instability, or osteoporosis, an additional row of pegs originating from a more distal position on the plate and having an opposite inclination to the proximal row was conceived. The distal row is directed in a relatively proximal direction and crosses the proximal row at its midline and is intended to support the more volar and central part of the subchondral bone. It prevents the dorsal rotation of a volar marginal fragment and volar rotation of severely osteoporotic or unstable distal fragments with central articular comminution, thus neutralizing volar displacing forces of the pegs in the proximal row.

Newer generation of volar plates have now introduced the concept of variable-angle locking screws and/or pegs. This provides the distinct advantage of being able to vary the plate placement with the locking screws adjusting to the necessary angle to be placed in the strongest subchondral bone. One of the newest generation plates, APTUS (Medartis, Basel, Switzerland), utilizes a revolutionary multidirectional infinitely variable locking system facilitated by the Trilock concept—a spherical three-point wedge locking mechanism. Other variable locking systems utilize variable hardness of materials whereby the threaded peg literally cuts its own thread. The biomechanical soundness of these newer systems remains to be seen, and clinical studies are forthcoming.

Indications and Contraindications

Volar plating is indicated in nearly all unstable fractures of the distal radius. It is used in young and active patients for optimal reconstruction of the articular surface and restoration of bony anatomy while allowing nearly immediate, but protected, active range of motion. It is also ideally suited for polytraumatized patients facing potential rehabilitation problems or elderly patients who particularly benefit from a quicker recovery. The inherent biomechanical advantages previously mentioned lead us to indicate this approach for virtually all cases.

An unstable distal radius fracture has been defined as a fracture that, after an attempt at closed reduction, demonstrates radiographic evidence of more than 15 degrees of angulation in any plane, articular step-off of more than 2 mm, and/or radial shortening of more than 2 mm.⁶ However, fractures with severe comminution or pronounced initial articular displacement or that are simply osteoporotic are also termed “unstable” despite possible initial good alignment.

Malunions and the rare nonunions after distal radial fractures can also be considered for this procedure with slight modification of technique.

The ideal timing for the surgery is within 1 week of injury, although this implant can be used in a patient even after a malunion of the fracture after other forms of managements. There is no time limit for the procedure as such, and volar plating can be used even after consolidation for correction of the deformities.

The absolute contraindications for volar plating are severely contaminated open injuries and compartment syndrome. The relative contraindication is open distal radial epiphysis in which smooth wires are preferable. The rare distal shear fracture is also poorly suited for volar plate fixation because the fragments may not be substantial enough to permit purchase of the volarly placed pegs. These severe comminuted fractures can be managed with external fixation maintaining relative wrist alignment, arthroscopic reduction, and excision of small osteochondral fragments with subchondral fixation by K-wires supporting the reduction. Age or medical status should not be a contraindication unless the patient absolutely cannot undergo surgery of any type. In these scenarios, one must accept the resultant malunion unless an attempt is made to use simple K-wire fixation utilizing local anesthesia.

Surgical Technique

Unless the patient suffered polytrauma, or is medically unstable, the internal fixation procedure is performed in the outpatient setting. Regional anesthesia, usually a three-nerve block at the elbow level, is performed along with intravenous sedation to control tourniquet discomfort. Axillary regional blocks are more difficult to perform and have occasional complications. Bier blocks can have profound systemic complications and take longer to take effect. This is not as practical in the ambulatory setting of a busy surgery center running two rooms sequentially.

The patient is placed in the supine position with the arm extended on the hand table. A simple fracture less than 7 to 14 days old can be managed through a standard flexor carpi radialis (FCR) approach (distal Henry) (Fig. 13-3). On the other hand, complex intra-articular fractures, nascent malunions, and 2- to 3-week old fractures require a more extensile exposure, facilitated via the extended FCR approach.⁹ This approach allows an intrafocal reduction by using the fracture plane itself to reduce the articular major fragments. The radial shaft (proximal fragment) is rotated into pronation (Fig. 13-4