Distal radius fractures are currently among the most common fractures of the musculoskeletal system. With a population that is living longer, being more active, and the increasing incidence of osteoporosis, these injuries will continue to become increasingly prevalent. When operative fixation is indicated, the volar locking plate has recently become the treatment of choice. However, despite its success, suboptimal position of the volar locking plate can still result in radiographic loss of reduction. The distal dorsal cortical distance is being introduced as an intraoperative radiographic tool to help optimize plate position and minimize late loss of fracture reduction.
Key points
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Surgical treatment of distal radius fractures with volar locked plates can lead to satisfactory outcomes in most patients with the adequacy of the reduction and maintenance of this reduction leading to better outcomes.
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A number of radiographic parameters are used to assess adequate distal radius fracture reduction, including volar tilt, radial height, radial inclination, ulnar variance, and articular congruency. Among these, volar tilt has been shown to be most related to late fracture collapse and subsequent altered wrist kinematics.
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Loss of reduction is not uncommon after volar locked plate fixation of distal radius fractures, and is most closely related to subchondral screw position rather than plate position.
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The distal dorsal cortical distance (DDD), analogous to the “tip-apex” distance in the hip, may serve as a critical measurement that the surgeon can use intraoperatively to guide adequacy of subchondral screw position and fracture stability.
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We recommend a DDD of 6 mm as the maximum distance intraoperatively to avoid late fracture collapse.
Introduction
Fractures of the distal radius are among the most common injuries to the musculoskeletal system and typically result from a fall onto an outstretched arm. The patients affected by this pathology tend to be distributed bimodally with a great variety of fracture patterns and clinical presentations. On one end of the spectrum, are the young high-energy trauma patients, and on the other end are the elderly patients with a low-energy mechanism of injury, typically a fall from standing height. With the prevalence of osteoporosis on the rise, and the aging population living longer and remaining more active, one can expect the incidence of these fractures to rise.
When surgery is indicated to treat distal radius fractures, volar locked plates have recently become the treatment of choice. The literature is replete with studies examining the outcomes of this procedure, first introduced by Orbay and Fernandez in 2002. The purported advantages of volar locked plates include a stable peri-articular reduction affording earlier return to function, decreased need for postoperative immobilization, a consistent surgical approach, and a hardware complication profile relative to late tendon injury that can be minimized with thoughtful screw and plate positioning.
The goals of treatment for distal radius fractures are to achieve and maintain anatomic reduction relative to the radiographic parameters listed in this article. The authors use the following values:
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Volar tilt (11° ± 5°)
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Radial height (14 ± 1 mm)
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Radial inclination (22° ± 3°)
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Ulnar variance (0.7 ± 1.5 mm)
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Articular step-off (≤2 mm) ( Fig. 1 ).
Fig. 1
Method of measuring the radiographic parameters of the distal radius fractures. ( A ) Volar tilt (VT). ( B ) Radial height (RH). ( C ) Radial inclination (RI). ( D ) Ulnar variance (UV).
Introduction
Fractures of the distal radius are among the most common injuries to the musculoskeletal system and typically result from a fall onto an outstretched arm. The patients affected by this pathology tend to be distributed bimodally with a great variety of fracture patterns and clinical presentations. On one end of the spectrum, are the young high-energy trauma patients, and on the other end are the elderly patients with a low-energy mechanism of injury, typically a fall from standing height. With the prevalence of osteoporosis on the rise, and the aging population living longer and remaining more active, one can expect the incidence of these fractures to rise.
When surgery is indicated to treat distal radius fractures, volar locked plates have recently become the treatment of choice. The literature is replete with studies examining the outcomes of this procedure, first introduced by Orbay and Fernandez in 2002. The purported advantages of volar locked plates include a stable peri-articular reduction affording earlier return to function, decreased need for postoperative immobilization, a consistent surgical approach, and a hardware complication profile relative to late tendon injury that can be minimized with thoughtful screw and plate positioning.
The goals of treatment for distal radius fractures are to achieve and maintain anatomic reduction relative to the radiographic parameters listed in this article. The authors use the following values:
- •
Volar tilt (11° ± 5°)
- •
Radial height (14 ± 1 mm)
- •
Radial inclination (22° ± 3°)
- •
Ulnar variance (0.7 ± 1.5 mm)
- •
Articular step-off (≤2 mm) ( Fig. 1 ).
Fig. 1
Method of measuring the radiographic parameters of the distal radius fractures. ( A ) Volar tilt (VT). ( B ) Radial height (RH). ( C ) Radial inclination (RI). ( D ) Ulnar variance (UV).
Indications/contraindications for volar locked plating
The indications and contraindications are listed in Table 1 . However, they are intended to serve as a rough guideline, and may be titrated up or down based on individual patient characteristics, such as age, functional demands, and occupation.
| Indications | Contraindications |
|---|---|
| Dorsal angulation ≥20° | Acceptable radiographic parameters after closed reduction and immobilization |
| Radial inclination ≤20° | Medical comorbidities precluding surgery |
| Ulnar variance ≥5 mm | Soft tissue condition precluding surgical approach |
| Articular step-off ≥2 mm | Dorsal shear fractures |
| Reduction loss on follow-up radiographs | — |
The Concept of the Volar Locked Plate
The impetus for the development of volar locked plates came from the issues seen with previous fixation constructs. Nonlocking volar plates were limited by inadequate bicortical screw stability due to the presence of dorsal comminution. Dorsal plates also suffered from fracture displacement but also soft tissue complications, such as complex regional pain syndrome and extensor tendon irritation or rupture ( Fig. 2 ). The volar locked plate was intended to serve as a fixed-angle buttressing construct for the subchondral surface of the distal radius using a more generous soft tissue envelope provided by the volar side of the distal forearm. The critical nuances of this technique and device are to achieve an appropriate reduction and proper plate placement proximal to the watershed line. As the initial implants were all fixed-angle constructs, the trajectory of the screw or pegs were predicated on a near anatomic reduction ( Fig. 3 ). Initial designs included only 4 screws or pegs in the distal row, which were designed to capture the radial styloid, the central articular surface, and the volar-ulnar corner of the distal radius.
With the advent of variable-angle locking screws, there is potentially more latitude with plate placement and articular fracture fixation ( Fig. 4 ). Hart and colleagues demonstrated that with the standard variable-angle locking plates, there was a 3-mm zone of forgiveness relative to the watershed line provided with these designs without compromising stability. However, the advantages afforded by variable-angle constructs have been called into question in other series.
Achievement and Maintenance of Reduction
One of the principal tenets of fracture surgery is both restoring and maintaining normal anatomy. Surgical techniques and implants have evolved over time to better achieve these goals, and the distal radius is no exception. However, both achieving and subsequently maintaining fracture reduction can be challenging and highly variable, resulting in potentially disparate outcomes.
In a retrospective review of 185 distal radius fractures treated with a single implant performed by Mignemi and colleagues in 2013, the investigators attempted to determine the ability of the volar locked plate to provide durable results with the maintenance of radiographic parameters. In their series, the volar tilt, radial inclination, ulnar variance, radial height, and articular step-off were measured immediately postoperatively and at final follow-up. They found that in most cases, the articular step-off was less than 2 mm at all points in the postoperative course. However, this series demonstrated that there was a change in reduction over time with the volar tilt, radial inclination, and ulnar variance having changed but still within normal parameters in roughly 50% of the cases, but radial height in only 12% of cases. The loss of reduction was correlated to initial fracture severity.
Other studies have shown that radiographic parameters are typically maintained postoperatively. However, on closer examination of the results, there are nuances worth noting. In a review by Stevenson and colleagues from 2009, the investigators conclude that the volar locking plate is a good technique for restoring and maintaining radiographic parameters of these fractures postoperatively. However, volar tilt was restored to an average of 1°, the range of values reported in their series ranged from 7.3° to 3.7° of undercorrection and overcorrection, respectively, yielding an 11° range. In the same series, radial inclination ranged from 10° undercorrected to overcorrection of 8.4°, with a mean of 1.9° of undercorrection. The ulnar variance showed a tighter measurement range with an absolute measurement of −2 mm to +3.5 mm. Figl and colleagues showed similar ranges of measurements in 2 other series. In a series from 2009 examining reduction in distal radius fractures treated with volar locked plates, there was a 22° range for radial inclination, and an 18° range for the volar tilt. In their 2010 study, which focused on fractures in the elderly, there was similarly a 17° and 13° range in measurements for the radial inclination and volar tilt, respectively.
The Importance of Maintaining Reduction
When normal anatomy is not restored, numerous adverse consequences have been noted. In particular, persistent radial shortening and/or distal radioulnar joint (DRUJ) incongruency has been shown to be a troublesome problem. Common sequelae include altered carpal kinematics, Kïenbock disease, scapholunate instability, triangular fibrocartilage complex (TFCC) tears, and ulnar impaction.
In a biomechanical cadaveric study by Nishiwaki and colleagues, the effects of dorsal angulation of the distal radius on the kinematics of the DRUJ with and without an intact TFCC were evaluated. The impact of simulated malunions of 10°, 20°, and 30° of dorsal angulation on ulnar displacement in supination was shown to progressively adversely impact the kinematics of the DRUJ. Significant displacement of the ulna in the volar, ulnar, and distal directions was noted in all simulated malunions, with an increase in the volar translation in specimens with the TFCC sectioned. These changes were noted with as little as 10° loss of volar tilt, which is deemed an acceptable reduction by many investigators. This series has been echoed in other biomechanical studies that show an adverse effect on the DRUJ with dorsally angulated malunions. An additional concern with altered kinematics with distal radius fractures is the high incidence of primary and secondary TFCC tears, which have been reported to be as high as 45% to 57% after a distal radius fracture.
McQueen and Caspers studied the final function of patients with varying anatomic reductions in distal radius fractures. In this series, a reduction in grip strength was noted in many patients. This was attributed to pain as well as the shortening of the radius, which decreases the power and mechanical advantage of the flexor tendons when compared with an uninjured wrist. The investigators go on to propose that increasing dorsal tilt will shift the axis of rotation of the wrist, leading to compromise of the flexion-extension arc of the radiocarpal joint.
Focusing on secondary fracture displacement, when treated nonoperatively, Altissimi and colleagues noted that with increased settling, patients had more functional deficits and were more predisposed to radiocarpal arthrosis. In this study, dorsal tilt of 1° to 15° resulted in 8% of patients having fair to poor results and in patients with 15° or greater, fair to poor outcomes were reported in 50% of patients. Although this is not a typical postoperative finding, there are patients in other series who fall into these ranges with fracture settling and may be experiencing underappreciated functional deficits.
Potential Factors Influencing Reduction Maintenance
Once surgical fracture reduction is achieved, maintaining the reduction with internal fixation presents the next challenge to the surgeon. Previous investigators have studied various parameters to be considered to maximize stable internal fixation with locked volar plates in distal radius fractures. In an osteoporotic biomechanical model, Wall and colleagues studied the effect of screw length on stability in distal radius fracture volar locked plate constructs. Their work showed that a screw length greater than 75% of the bicortical distance provides excellent stability and minimizes the chance for extensor tendon rupture by obviating the need for bicortical drilling and eliminating the possibility of dorsal screw prominence, while still maintaining adequate subchondral screw support. With respect to the use of screws versus pegs for fixation, Weninger and colleagues found that screws proved to be biomechanically superior, particularly when loaded in torsion, then compared with smooth pegs, which demonstrated a 17% reduction in stiffness. Crosby and colleagues, in a biomechanical model using 24 sawbone specimens, sought to determine if the amount of screws in the distal fragment of the fracture had any impact on stability in extra-articular fragments. Their results supported the fact that the number of screws in the distal row did not show a significant influence on the stiffness or stability of the final construct.
The placement and position of the volar locked plate also has been a topic of a number of studies. Some investigators have recommended that the plate be placed as distal as possible without crossing the watershed line to place the screws as close as possible to the subchondral bone. However, this requires diligence to avoid placing the plate too distal and causing plate prominence and potential risk of flexor tendon ruptures. This risk is increased in cases with fractures healing in residual dorsal angulation ( Fig. 5 ).
