Orthopedic Teaching Cases 2023, Jan, 20 | 12:00 am

CASE Distal Radius Fractures 20

A 42-year-old, right-hand-dominant police officer sustains an injury to his right wrist in a motor vehicle collision. On examining him in the emergency department he has no open wounds but has obvious deformity and moderate swelling. He also complains of dysesthesias over his volar thumb, index, and long fingers. Sensory examination finds that his two-point discrimination is intact to 5 mm throughout all digits of the right hand. His radiographs are shown in Figure 6–26A and B.

 

 

 

Figure 6–26 A–B

 

After hanging traction in finger traps he regains nearly all of his radial height on AP fluoroscopic imaging but remains slightly dorsally tilted on a lateral view.

Why is longitudinal traction unlikely to restore the native 12-degree volar tilt in this displaced distal radius fracture?

  1. The presence of dorsal comminution

  2. Insufficient muscle relaxation

  3. Differences in strength and orientation between the volar and dorsal extrinsic ligaments

  4. Interposed flexor pollicis longus impeding anatomic reduction of the volar cortex

Discussion

The correct answer is (C). The volar extrinsic ligaments about the radiocarpal joint are shorter and thicker when compared to the dorsal extrinsic ligaments. They are also oriented more vertically than are the dorsal ligaments, which have a relative “z” orientation. The orientation of the dorsal ligaments allows for more lengthening than is allowed by the volar ligaments. This results in earlier tensioning of the short, straight, and strong volar ligaments with the application of longitudinal traction with relative laxity in the dorsal ligaments, preventing the restoration of volar tilt at the distal radius articular surface.

Following reduction and application of a plaster splint, the patient is sent to radiology for postreduction radiographs. Upon his return to the emergency department he complains that his pain is increasing in the wrist and hand. Two-point discrimination now is worsened to 9 mm in the thumb, index, and long fingers.

What is the most appropriate treatment at this stage?

  1. Urgent carpal tunnel release

  2. Elevation above the level of the heart and application of an ice pack

  3. Administration of oral corticosteroids and re-evaluation in 4 to 6 hours

  4. Serial measurement of the pressure within the carpal tunnel with a Stryker needle

Discussion

The correct answer is (A). The development of progressive median nerve dysfunction in the setting of a distal radius fracture is a form of acute carpal tunnel syndrome. This has been a recognized complication of distal radius fractures for many years, and the treatment is surgical release of the carpal tunnel. While acute carpal tunnel syndrome is known to occur more frequently with high-energy distal radius fractures than low-energy fractures, Dyer et al. showed that the amount of translation of the fracture was the most significant radiographic parameter in predicting acute carpal tunnel syndrome in the setting of distal radius fractures.

He is taken to the operating room urgently where a carpal tunnel release is performed. He also undergoes ORIF of the distal radius using a volar plate. Postoperative radiographs are shown in Figure 6–27A and B.

 

 

Figure 6–27 A–B

Which of the following is true regarding differences in volar and dorsal plating for distal radius fractures?

  1. Radiocarpal articular exposure is improved with the volar approach compared to dorsal.

  2. Extensor tendon irritation and rupture is seen in dorsal plating but not in volar plating.

  3. The dorsal aspect of the distal radius provides a more congruent surface than the volar surface for situating a plate for ORIF.

  4. The volar fixed angle plates allow for improved fixation of osteopenic bone or those fractures with metaphyseal defects.

Discussion

The correct answer is (D). While classically the distal radius was approached and plated dorsally, there has been a transition in the recent past to performing a large number of distal radius fracture ORIF procedures through a volar approach. Choice A is incorrect because the radiocarpal joint is visualized more easily from the dorsal approach due to the presence of the volar wrist ligaments. Extensor tendon, as well as flexor tendon, irritation and rupture is seen with both dorsal and volar plating. Lister’s tubercle can be deceiving on the lateral view when performing volar plating, and exposed screw tips dorsally is a risk for tendon irritation. Placing the volar plate too distal on the radius, past the “watershed line,” increases the risk of plate contact with the flexor tendons and subsequent development of irritation and potentially rupture. In addition to the benefit of being able to provide stable fixation to osteopenic bone and fractures with metaphyseal defects, Ruch and Papadonikolakis recently found volar locked plating to have less frequent volar collapse and fewer complications when compared with dorsal plating.

 

Objectives: Did you learn...?

 

Treatment of acute carpal tunnel syndrome in the setting of a distal radius fracture?

 

Volar versus dorsal plating considerations?