Extra-Articular Distal Radius Fractures With Metaphyseal Comminution

Key Points

The mainstay treatment for displaced extra-articular distal radius fractures with limited metaphyseal comminution is closed reduction and plaster immobilization. However, not all patients benefit.
Carpal alignment and coronal plane translation are less familiar parameters to surgeons but important reduction criteria for these extra-articular distal radius fractures.
Patients aged 18–75 years benefit from early open reduction and volar plate fixation, notably in more comminuted fractures.
Optimal plate and screw positioning will decrease likelihood of tendinitis or tendon rupture.
In case of more extensive metaphyseal comminution, (longer) volar plates, various methods of external fixation and intramedullary nailing result in comparable good outcomes.

Panel 1: Case Scenarios

A 55-year-old, right-handed female interior decorator visits the emergency department with a swollen and deformed right wrist after a fall from a horse on the outstretched hand. Radiographs show an extra-articular distal radius fracture with 20 degrees of dorsal angulation and dorsal metaphyseal comminution ( Fig. 1 ). After closed reduction 15 degrees dorsal angulation persists ( Fig. 2 ).

$Fig. 1, Radiographs show an extra-articular distal radius fracture with 30 degrees of dorsal angulation and dorsal metaphyseal comminution.$

Fig. 2, After closed reduction 15 degrees dorsal angulation persists.

At the same time a 97-year-old lady comes in with a comminuted metaphyseal DRF as part of a distal forearm fracture and associated 2 cm-wound on the volar ulnar side ( Fig. 3 ).

$Fig. 3, Comminuted metaphyseal DRF as part of a distal forearm fracture and associated 2 cm-wound on the volar ulnar side.$

Which treatment is most effective for these comminuted extra-articular distal radius fractures?

Importance of the Problem

One in six fractures are distal radius fractures (DRFs). Moreover, in the United States 600,000 DRFs are diagnosed every year causing 480 million USD of direct cost of care. As the population continues to age, the burden of distal radius fractures and the direct and indirect healthcare costs are expected to increase.

Overall incidence for DRFs in adults is 20 per 10,000 person-years. Extra-articular fractures are most common with an estimated incidence of 50%. However, these figures are based on conventional radiographs. When using CT scans, the true incidence of AO type A fractures may be lower.

For displaced extra-articular distal radius fractures with limited comminution closed reduction and plaster immobilization is recommended as the treatment of choice. However, secondary dislocation is common and may result in poor patient-rated outcomes if left untreated. Therefore, the question remains what the most effective therapeutic approach for comminuted extra-articular DRFs is?

Accurate assessment of standard radiographs is essential for appropriate treatment of extra-articular DRFs ( Box 1 , Fig. 4 ). Fracture anatomy and the degree of displacement may guide treatment.

Box 1

Radiographic Parameters

Posterior Anterior View

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Radial inclination: Measures from the tip of radial styloid process (PSR) to the center point of the ulnar side of the distal radius. This center point (CRP) is located between the volar and dorsal rim which can easily be identified on the PA radiograph. Radial inclination is normally 20–25 degrees.
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Ulnar Variance: The distance between the CRP and distal articular surface of the ulna. Normally + 0.9 mm (range − 4.2 to 2.3 mm).
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Radial length: is defined by the length measured between the tip of the radial styloid and the distal articular surface of the ulna. Normally 10–13 mm.
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Coronal plane translation : is used to describe radial displacement of the distal fragment. Radial translation of the distal fragment might be associated with DRUJ instability due to lack of tension on the distal oblique bundle (the most distal part of the distal interosseous membrane) and the pronator quadratus. Coronal plane translation can be measured by drawing a line on the ulnar side of the radius which intersects the lunate. The point of intersection within the lunate is evaluated by drawing a second line along the transverse width of the lunate parallel with the distal joint. In a normal situation the lines should bisect at 50%.
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In a congruent DRUJ the ulnar side of the distal radius and radial side of the ulna should converge in the form of a Gothic arc. This arc should not be interrupted.

Lateral View

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On a pure lateral radiograph, the pisiform projects over the distal pole of the scaphoid, between the distal pole of the scaphoid and the capitate. Only then, can the surgeon assess volar or dorsal dislocation of the ulna.
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Volar tilt: Angle between a line drawn through the center of the radial shaft and a line drawn through the apices of the palmar and dorsal rims of the radius. The normal volar tilt is between 5 and 11 degrees
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Carpal alignment: It is measured by drawing a line along the inner rim of the volar cortex of the radius (marginal line of Lewis) and determining the center of the capitate. (The center of the capitate is at the center of a circle drawn around the base of the capitate.) The carpus is aligned when the line along the inner rim transects the center of the capitate. By measuring the perpendicular distance to the center of the capitate, the degree of carpal malalignment can be quantified. Carpal malalignment is correlated with poor functional outcome. Based on the study of Selles et al., a margin of 0.5 cm of dorsal and 0.5 cm of volar displacement would be within the range of normal alignment ( Fig. 5 ).

Fig. 4, Accurate assessment of standard radiographs is essential for appropriate treatment of extra-articular DRFs.

Fig. 5, A margin of 0.5 cm of dorsal and 0.5 cm of volar displacement would be within the range of normal alignment.

The definition of a dislocated extra-articular fracture is when extra-articular radiologic parameters are not within the normal ranges as described in Box 1 . In most situations, a closed reduction will be performed followed by a radiograph. However, what radiographic anatomy can we accept to continue nonoperative treatment? Historically, Lafontaine's criteria were used as the main guideline (See Chapter 9 ). Currently, the AAOS guidelines advise nonoperative treatment for fractures with post reduction radial shortening < 3 mm and dorsal tilt of < 10 degrees. On the contrary, the Dutch guidelines are more liberal: less than 10 degrees tilt in any direction and less than 5 mm radial shortening. If all of these are applicable, conservative treatment is advised.

In 2015, a systematic review was performed by Walenkamp et al. to identify predictors of secondary displacement in DRFs. Female gender, age over 60 and dorsal comminution were significant predictors for secondary displacement. Associated ulnar styloid fractures, initial dorsal angulation > 20 degrees or articular involvement were found to be nonsignificant.

Main Question

What is the most effective therapeutic approach for comminuted extra-articular displaced DRFs?

Current Opinion

The mainstay treatment of displaced extra-articular DRFs with limited comminution in adults is closed reduction and immobilization in a cast. However, even in case of adequate reduction, secondary dislocation of the fracture occurs in up to 60% of cases. In recent years operative treatment of extra-articular DRFs with open reduction and fixation with a volar locking plate has become increasing popular. Open reduction and volar plate fixation allows for early mobilization and therefore may lead to improved functional outcome. In case of more extensive metaphyseal comminution, longer volar plates with optional bone grafting ( Fig. 6 ) or alternative solid constructs such as bridging spanning plates, or external fixation are recommended.

$Fig. 6, Example of distal radius and ulna fractures with extensive metaphyseal comminution and intraarticular extension of the radius requiring long plating to achieve adequate stability. © Dr. Buijze 2020.$

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