Introduction
Distal radius fractures are common and comprise 15% of extremity fractures. The injuries occur when the wrist is subject to non-physiologic loads, such as falling on an outstretched hand.
Anatomy
Bony
The bony anatomy involves the distal radius, distal ulna and carpal bones. The distal radius is made up of three articular surfaces, beginning laterally with the scaphoid facet and progressing medially to the lunate facet and lastly the sigmoid notch. The ulna articulates with the distal radius at the sigmoid notch. The ulna plays an important part of the ligamentous integrity of the DRUJ and TFCC.
Ligamentous
The wrist joint contains a complex system of ligaments that provide stability without sacrificing significant motion. The distal radioulnar joint (DRUJ) is the distal articulation between the radius and ulna. The joint extends from the lunate facet and sigmoid notch of the radius and attaches to the ulnar head and styloid. The DRUJ can be disrupted with any medial column fracture (discussed later). The triangular fibrocartilage complex (TFCC) is part of the DRUJ. The TFCC is often thought of as the meniscus of the wrist and provides a "trampoline" like articulation on the ulnar aspect of the wrist. The TFCC extends from the sigmoid notch to the ulnar styloid and is often disrupted with displaced ulnar styloid fractures. Furthermore, there are multiple radiocarpal and ulnocarpal ligaments which play a significant role in wrist stability and fracture patterns via ligomentotaxis.
Classification
Distal radius and ulna fractures can be classified with the columnar classification system. The columnar classification divides the distal radius and ulna into three columns: 1) lateral distal radius (radial styloid, scaphoid facet), 2) medial distal radius (lunate facet), and 3) the ulnar column (TFCC, ulnar styloid). The medial column of the distal radius is the attachment point of strong volar and dorsal ligaments that often displace separately and therefore the medial column is further subdivided into the dorsal and volar medial column. Fractures between each column correlate with classical descriptions of distal radius fractures. Extra-articular fractures with displacement of the lateral and medial column as a unit correlates with the classic Colles fracture (dorsal displacement) or Smith's fracture (volar displacement). Similarly, an intra-articular fracture of the lateral radial column represents a chauffeur's fracture. A classic Barton's fracture is equivalent to volar medial column displacement and a reverse Barton's represents dorsal medial column displacement.
Presentation/Physical Exam
The typical presentation is a swollen and deformed distal forearm with localized tenderness. Thorough inspection should be performed to rule-out open fracture. A detailed neurovascular exam is imperative. A traction median nerve palsy is possible with displaced fractures as it may compromise the carpal tunnel. Also, examination of the elbow should be performed to rule-out any associated injury.
Radiology
Imaging studies should include a posteroanterior (PA) and lateral view. Traction and post-reduction views are often helpful in assessing comminution and whether a fracture is intra or extra-articular. CT scans are rarely needed but can provide better visualization of comminuted fractures. Radiographs should be evaluated for intra verses extra-articular extension, articular step-off, radial inclination, radial shortening, sagittal tilt, articular incongruity of the DRUJ, ulnar variance, and ulnar styloid fracture displacement. These parameters should be compared to the contralateral wrist.
Associated Injuries
Associated soft tissue injuries are common and have been described in up to 68% of distal radius fractures. These include partial or complete tears of the scapholunate (SL) ligament, lunotriquetral (LT) ligament, and the TFCC. Close attention should be paid to scapholunate and lunotriquetral diastasis on the PA radiograph for this may indicate a grossly unstable wrist. Clinical and radiographic evaluation of the DRUJ and TFCC should also be performed. Significant displacement of the ulnar styloid (>2mm) is a sign of DRUJ instability.
Treatment
Closed Reduction
More and more distal radius fractures are being treated with ORIF, however, closed reduction and sugar tong splint immobilization is the first line of treatment and should be attempted.
Acceptable reduction guidelines include:
- Radial Inclination of greater than 15 degrees
- Radial Shortening of less than 5 mm compared to contralateral side
- Sagital Tilt between 15 degrees dorsal and 20 degrees volar tilt
- Intra-articulat step-off of less than 2 mm
- Articular incongruity of DRUJ less than 2 mm
Surgical Fixation
Surgical fixation should be considered in patients with open injuries, multiple trauma, and unstable fractures. Unstable fractures are distinguished by the inability to maintain an adequate reduction. There are multiple surgical option including closed reduction and percutaneous pinning, open reduction and pinning, and open reduction and internal fixation (ORIF). ORIF can be performed using conventional plates or locking plates via either a volar or dorsal approach. Injury pattern and surgeon preference are the determining factors.
Complications
Complication after surgical fixation include: tendon injuries (most common), median nerve dysfunction, reflex sympathetic dystrophy, painful hardware, loss of reduction, non-union and mal-union.
