Common Types of Distal Radius Fractures
In regards to distal radius fractures, it is important to be familiar with the anatomy around the distal radius and there are several places that must be observed on an x-ray when diagnosing a distal radius fracture. Anatomy associated with distal radius fractures is the: radioulnar joint, the sigmoid notch, lunate fossa, the scaphoid fossa, and the ridge between the two fossa. It is also important to view the carpal bones, especially the lunate and the scaphoid. The triangular fibrocartilage must also be considered, as well as the deforming forces of the brachioradialis.
The most common type of distal radius fracture is the Colles Fracture. This fracture occurs at the distal radius, and the wrist has a characteristic backwards displacement of the hand. The Colles fractures is a low energy, extra-articular fracture with a dorsal displacement of the fractured fragment. This injury typically occurs in patients more than 50 years old from attempting to break a fall with an outstretched hand.
The fracture is sometimes referred to as a “dinner fork” deformity, due to the shape of the fractured forearm. Triangular fibrocartilage complex (TFCC) tears occur in 50% of extra articular distal radius fractures, versus 1/3 of intra-articular fractures. The dorsal comminution is significant and important. Dorsal comminutions are frequent and if comminution is up to 50% of the dorsal cortex, then treatment with a cast will not work. The more dorsal flexion, then the more comminution and more chance of fracture failure when using a cast. A Colles fracture that extends to the Distal Radial Ulnar Joint (DRUJ) has the worst prognosis.
A Smith Fracture is an extra-articular transverse fracture that is palmarly displaced and can be thought of as a reverse Colles fracture. This fracture occurs at the distal radius with a forward displacement of the distal fragment and typically occurs due to a fall onto a flexed wrist. There are multiple types of Smith Fractures. Type I fractures are an extra-articular transverse fracture through the distal radius (most common). Type II fractures crosses into the dorsal articular surface. Type II Smith Fractures enter the radiocarpal joint (Volar Barton Fracture = Smith Type III fracture). Both Volar Barton and Smith fractures involve the intra-articular distal radius and include possible dissociation of the carpal bones. A volar approach and plating is typically used in the treatment of this fracture.
The Die-Punch fracture is a depressed fracture of the lunate fossa that results from axial loading forces on the distal radius that is transmitted through the lunate bone. These fractures are intra-articular fractures of the lunate fossa of the distal radius. It is necessary to check to see if there is any carpal bone dissociation.
Barton fractures are an intra-articular fracture of the distal radius with a dislocation of the radiocarpal joint. These fractures can be either dorsal or volar. It is important to check for any carpal bone disruption or dissociation. Barton fractures are caused by a fall on an extended and pronated wrist with the volar type being the most common type. The fracture fragment is usually smaller with the dorsal Barton fracture. A volar Barton’s fracture is a fracture of the volar margin of the distal radius, which is associated with subluxation of the radiocarpal joint.
The most striking finding, is subluxation or dislocation of the wrist. The strong volar radiocarpal ligament avulses the volar lip of the radius. This fracture can be similar to a Smith Type III fracture. Treatment of a volar Barton fracture is usually surgery with a volar approach and volar plate. A dorsal fracture occurs by a dorsal shearing force. It is a distal radius fracture with a dislocation of the radiocarpal joint. This fracture is intra-articular and involves the dorsal lip. Dislocation is the most striking x-ray finding in dorsal Barton fractures. The avulsed fragment is usually small. Treatment typically consists of an open reduction and internal fixation through a dorsal approach.
The final fracture type is a Chauffer’s fracture, which is a fracture of the radial styloid process in association with scapholunate dissociation.
These fractures are caused by compression of the scaphoid bone of the hand against the styloid process of the distal radius. With Chauffer’s fractures, an evaluation of the radial styloid fracture should always include a supinated view x-ray so that the scapholunate dissociation can be ruled out. Observe for any major swelling of the wrist or a DISI deformity on lateral x-rays with a widening gap between the lunate and scaphoid bones on an AP view.
The scapholunate angle is usually about 47–60°. Any angle that is considered greater than 60° is considered to be abnormal. This is usually seen with a dorsal intercalated segment instability deformity due to the palmar flexion of the scaphoid. This means that there is a scapholunate dissociation. The scaphoid and lunate bones turn in opposite directions. Chauffeur’s fractures are usually treated with compression screw fixation at the radial styloid process. The physician will need to assess the scapholunate joint for possible stabilization.
In summary, there are several different kinds of distal radius fractures. During assessment of the x-rays, the physician will need to see if there is any involvement of the dorsal or volar rim of the radius. Check for involvement of the DRUJ and look for die-punch lesions. Check for dislocation of the wrist and the direction of the displacement. Check the carpal disruption to see if there is any dissociation between the carpal bones.
