- Relevant Anatomy of Distal Radius
- Biomechanics of Wrist
- Presentation Fractures of Distal Radius
- Classification of Distal Radius Fractures
- Treatment of Distal Radius Fracture
- Other Injuries of Distal Radius
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Distal radius fracture refers to can be either extra-articular or intraarticular fractures of distal end of the radius.
The treatment of these fractures varies with the type of fracture, the age of the patient, associated soft tissue injury and demand of the patients. While fractures in younger patients demand an aggressive approach, older patients with lesser demand have a high acceptability of conservative treatment.
Distal radius fractures have peaks of occurrence in children ages 5 to 14 years and adults >50 years.
In elderly patients, it is an insufficiency fracture while in younger males it is a traumatic injury.
Distal radius fracture is the most common osteoporotic fractures.
Relevant Anatomy of Distal Radius
[read more about anatomy of radius bone]
Distally, the radial shaft expands to form a rectangular end. The lateral side projects distally as the styloid process. In the medial surface, there is a concavity, called the ulnar notch, which articulates with the head of the ulna, forming the distal radioulnar joint.
The distal surface of the radius has two facets, for articulation with the scaphoid and lunate carpal bones. This makes up the wrist joint.
The distal radius is made up of the metaphysis and three articular surfaces
- Laterally the scaphoid facet
- Medially, the lunate facet
- Sigmoid notch for distal radioulnar joint
The ulna plays an important part in the ligamentous integrity of the distal radio-ulnar joint and triangular fibrocartilage. The metaphysis is flared distally in both the AP and the lateral planes. There is a thin cortical bone on dorsal and radial aspect making the fractures typically collapse dorsoradially. The bone with the greatest trabecular density lies in the palmar ulnar cortex.
Distally, the radius has a somewhat trapezoidal shape. The radial styloid rotates palmarly 15 degrees off the axis of the radius.
The palmar ulnar part is often referred to as the keystone of the radius. It serves as the attachment for the palmar distal radioulnar ligaments and also the stout radiolunate ligament. Displacement of this fragment is associated with palmar displacement of the carpus and also with the loss of forearm rotation.
Attachments to distal radius are
- The brachioradialis inserts on the lowest part of the lateral surface just above the styloid process.
- The pronator quadratus is inserted into the lower part of the anterior surface and into the triangular area on the medial side of the lower end.
- The articular capsule of the wrist joint is attached to the anterior and posterior margins of the inferior articular surface.
- The extensor retinaculum is attached to the lower part of the anterior border.
- The interosseous membrane is attached to the lower three-fourths of the interosseous border.
- The articular disc of the inferior radioulnar joint is attached to the lower border of the ulnar notch
Biomechanics of Wrist
The palmar extrinsic ligaments are relied on to reduce the components of a fracture using closed methods.
The palmar ligaments are stronger than the thinner dorsal ligaments and more vertically oriented than dorsal ligaments. Any force applied would make palmar ligaments taut before the dorsal ligaments bringing the palmar cortex to length before the dorsal cortex.
Columns of Wrist
The wrist is said to consist of three distinct columns, each of which is subjected to different forces and must be addressed as discrete elements.
- Columns of Wrist
The radial column consists of the scaphoid fossa and the radial styloid. It is best stabilized by buttressing the lateral cortex.
The intermediate column consists of the lunate fossa and the sigmoid notch of the radius. It is critical for both articular congruity and distal radioulnar function.
The ulnar column consists of the ulna styloid with TFCC and the ulnocarpal ligaments.
Radial inclination is also termed as radial angle.
This measurement is taken in the posteroanterior radiograph of the wrist.
Radial inclination represents the angle between one line connecting the radial styloid tip and the ulnar aspect of the distal radius and a second line perpendicular to the longitudinal axis of the radius.
- Radial Inclination
The radial inclination ranges between 21° and 25°. Radial inclination value would change in fractures of the articular surface.
Loss of radial inclination will increase the load across the lunate. It is also called radial height.
Radial length is measured on the posteroanterior radiograph. It is measured as the distance between the following two lines.
The first line is drawn a perpendicular to the long axis of the radius passing through the distal tip of the radial styloid.
The second line is along the articular surface of the radius. The average value of this measurement averages 10-13 mm.
Presentation Fractures of Distal Radius
There is often a history of fall on the hand of the involved side. The patient presents with a wrist deformity and swelling of the wrist.
This accounts for radial deviation and dorsal angulation found in a number of cases [An example of typical Colle’s fracture].
Because of dorsal angulation, the palmar portion [on the side of the palm] of the fragment becomes prominent, it might result in the displacement of median nerve palmarward.
This displacement of the nerve and the associated hematoma in the carpal tunnel may result in symptoms of an acute carpal tunnel syndrome.
The acute shortening of the radius relative to the ulna may also cause ulna to cause a wound on the palmar side.
Other parts of the limb that required to be seen in the examination are ipsilateral shoulder and elbow.
Often the fracture may be associated with fractures of either the radial head or supracondylar humerus of the same limb. When associated with these fractures, it indicates a high energy trauma and may pose rehabilitation challenges
Ipsilateral radial head and distal radial fractures may indicate that sufficient energy has been imparted to result in an Essex-Lopresti lesion.
A thorough evaluation of the extrinsic flexor and extensors is done, particularly extensor pollicis longus, which may be injured acutely at Lister’s tubercle or may present with a late spontaneous rupture.
Median nerve injury is a common cause of functional impairment and chronic pain. An abnormal sensory examination may occur due to direct contusion, mechanical deformation of the nerve and abnormal pressure within the carpal tunnel.
Classification of Distal Radius Fractures
Several distal radius fracture classification systems have been proposed for fractures of the distal radius. Here are the major ones used widely
Gartland and Werle
A distal radius fracture classification system that assessed the three basic components of these injuries
- Metaphyseal comminution
- Intra-articular extension
- Displacement of the fragments.
Fractures are classified into four groups
Simple Colles’ fracture with no involvement of the radial articular surfaces
Comminuted Colles’ fractures with the intraarticular extension without displacement
Comminuted Colles’ fractures with intra-articular extension with displacement
It included individual involvement of the radiocarpal and radioulnar joints-
- Type I: Extra-articular fracture
- Type II: Extra-articular fracture with the ulnar styloid fracture
- Type III: Radiocarpal articular involvement
- Type IV: Radiocarpal involvement with ulnar styloid fracture
- Type V: Radioulnar involvement
- Type VI: Radioulnar involvement with ulnar styloid fracture
- Type VII: Radioulnar and radiocarpal involvement
- Type VIII: Radioulnar and radiocarpal involvement with ulnar styloid fracture
AO Distal Radius Fracture Classification
Fractures are classified with the increasing severity of the bony injury:
- Type A: Extra-articular fracture. Subgroups are based upon angulation and comminution
- Type B: Partial articular fracture. Subgroups are based upon lateral (radial styloid) palmar or dorsal fragments
- Type C: Complete articular. Subgroups are based on the articular surface’s degree of comminution and the metaphysis
Fernandez proposed a mechanism-based classification system. It also addressed the potential for ligamentous injury
Metaphyseal bending fractures with the of loss of palmar tilt and radial shortening relative to the ulna, (distal radioulnar joint injuries).
Shearing fractures requiring reduction and often buttressing of the articular segment.
Compression of the articular surface without the characteristic fragmentation; also includes the potential for significant interosseous ligament injury.
Avulsion fractures or radiocarpal fracture dislocations.
Combined injuries with significant soft tissue involvement due to the high-energy nature of these fractures.
There is also a separate grouping of the possible associated distal radioulnar joint lesions.
The initial investigation is an x-ray of the wrist. The views include anteroposterior, lateral and pronator oblique views.
If a fracture is extra-articular [ Does not involve the joint] radial shortening and comminution are noted. In addition, if present, the location of fracture of ulnar styloid is noted (tip/waist/base).
In case of intra-articular fractures any impacted fragment including depression of the lunate facet is noted [articular surface of distal end radius for lunate bone] is looked for. Interruption of the proximal carpal row, if any would be visible on this view.
Palmar tilt, the extent of metaphyseal comminution, displacement of the volar cortex, the scapholunate angle, and position of the distal radioulnar Joint is to be noted in extra-articular fractures.
Palmar Tilt represents the angle between a line joining the dorsal and volar margins of the articular surface and the long axis of the radius on a lateral xray.
- Palmar Tilt of Distal Radius, Image Credit : http://www.radiologyassistant.nl/en/476a23436683b
It is also called Volar Angle or Radial Tilt.
The normal palmar tilt averages 11° and has a range of 2°-20°.
It is an important parameter in treatment of distal radius fractures.
For intra-articular fractures depression of the palmar lunate facet and/or depression of the central fragment, and the gap between palmar and dorsal fragments is noted.
Oblique views are done for better assessment of radial comminution in extraarticular fractures or to look for radial styloid split/depression and depression of the dorsal lunate facet.
Tilted Lateral View
Lateral view is taken with a pad under the hand to incline the radius 22% toward the beam. It eliminates the shadow of the radial styloid and provides a clear tangential view of the lunate facet.
It is useful to assess any residual depression of the palmar lunate facet. It is also done in suspected possible hardware penetration into the articular surface.
Traction is applied on the fingers either manually or with finger traps and anteroposterior and lateral views are taken. These x-rays are taken to assess the effectiveness of reduction and external fixation. If not effective then direct reduction and internal fixation would be required.
Proximal row congruity can be judged. If it is not congruent, it indicates interosseous ligament injury.
Ap and lateral views of opposite To assess the patient’s normal ulnar variance and scapholunate angle [formed by the intersection of longitudinal axes of scaphoid & lunate].
CT is a better investigation to look for intra-articular extension and is more accurate. CT is also superior in defining steps and gaps if any.
MRI is useful in the assessment of soft tissue injuries particularly intercarpal ligament injury or triangular fibrocartilage complex tears are well visualized with the use of a fine wrist coil.
Treatment of Distal Radius Fracture
Approach to Treatment Formulation
The ultimate treatment goal in fractures of the distal radius is a wrist that has sufficient pain-free motion and stability to permit vocational and avocational activities without the propensity for future degenerative changes.
There are certain radiological parameters that would help to achieve these goals-
- Intra-articular Incongruity
- Step-off should not be more than 2mm.
- Palmar Tilt
- Acceptable limit is up to neutralization of the tilt.
- Radial Length
- Acceptable radial length is within 2 to 3 mm of the contralateral wrist.
- Radial Inclination
- Less than 5 degrees of loss is acceptable.
- Carpal Malalignment
- Indicates ligamentous injuries.
- Lateral scapholunate angle widening 25 degrees correlated with a worse outcome
- Dorsiflexed lunate is associated with a worse outcome.
Now the treatment with closed reduction and cast immobilization is indicated in stable fractures in which the goals of treatment can be expected to be achieved and patients with low functional demands.
A fracture is likely to be unstable if there is concomitant ligamentous injury, greater initial displacement, metaphyseal comminution and displacement after closed treatment
Nonoperative treatment consists of closed reduction and cast application.
Closed Reduction Technique
Closed reduction and cast immobilization is an important method of treatment of distal radius fracture.
Any successful reduction would require pain relief to overcome muscle spasm.
Most of the reductions in distal radius can be done in Hematoma Block supplemented with sedation or Bier block provides adequate anesthesia in most settings. Few patients may need general anesthesia.
Longitudinal traction is applied to the affected limb while assistant provides countertraction. After that direct pressure is applied to the displaced radial metaphyseal fragment for reduction.
Whenever possible, reduction and cast application should be done under C-arm image intensifier control so that reduction can be confirmed. Otherwise, the reduction should be confirmed using plain x-rays after the maneuver.
The cast provides a dorsal buttress to prevent collapse. Excessive palmar flexion of the radius should be avoided to avoid the risk of acute carpal tunnel syndrome. Some authors have suggested placing the radioulnar joint in supination but there is no consensus yet.
Postreduction x-rays are obtained at 7, 14, and 21 days. The postreduction x-rays must be compared with the initial postreduction x-rays to accurately determine displacement.
Following are the indications for surgical treatment of distal radius fractures.
- Comminuted displaced intra-articular fracture
- Open fractures
- Associated carpal fractures
- Associated neurovascular injury or tendon injury
- Failed conservative treatment
- Bilateral fractures
- Impaired opposite limb
When a patient of distal radius fracture is a candidate for operative treatment, there are many surgical options to consider depending on injury and patient characteristics.
The optimal timing of the surgical intervention depends on the associated soft tissue factors and the type of surgical procedure
When a fracture is acute, the fracture should be reduced by closed reduction and the surgery should be carried when the swelling is sufficiently reduced. In the case of minimal swelling, the surgery can be done immediately.
For arthroscopically assisted reduction and stabilization, the operative treatment is delayed for at least 3 to 5 days.
Following surgical options can be considered in the surgical treatment of distal radius fracture
Percutaneous pinning and plaster immobilization are unable to neutralize the axial forces. External fixation allows distraction across the radiocarpal joint and directly neutralizes axial load.
External fixation alone may not be sufficiently rigid to prevent some degree of collapse and a loss of palmar tilt as good as an internal fixation. But they provide good results with adjunctive fixation like supplemental bone grafts or K-wire fixation.
Combined External Internal Fixation
This involves inserting pins into the distal metaphyseal fragment and attaching them directly to the external fixator resulting in improved mechanical stability and control over palmar tilt.
Arthroscopically Assisted Reduction and External Fixation of Intra-Articular Fractures
Role of arthroscopy and its superiority over the conventional techniques has not been established yet and the indications of the type of fractures best suited for arthroscopically assisted reduction and external fixation are also controversial.
Fractures that may benefit most from adjunctive arthroscopy are
- Complex articular fractures without metaphyseal comminution
- Fractures with evidence of substantial interosseous ligament or triangular fibrocartilage injury but without a large ulnar styloid fragment
The procedure is usually performed between 3 and 15 days postinjury to allow healing of rents in the capsule to avoid extravasation of irrigation fluid.
Open Reduction and Internal Fixation
Early range of motion of the joint, and avoidance of constrictive dressings or casts are major advantages of the internal fixation but the technique is considered difficult and a number of soft tissue complications have been noted with the use of plate fixation.
The plate can be either applied on a dorsal or palmar aspect of the radius.
When applied on dorsal aspect, the fixation provides a buttress against collapse and has the advantages of avoiding neurovascular injury [NV bundle is on palmar side].
However, extensor tendon ruptures due to prominent hardware and palmar displacement of the distal fragment has been noted.
With palmar plating, the advantage of direct buttressing as in dorsal side is lost, but can be managed by the screw position in the distal fragment to buttresses collapse.
Other injuries around the wrist injuries with a fracture of the distal radius are
- Radial styloid fractures
- Isolated volar lip fractures
- Isolated volar lip fractures
- Ulnar styloid fractures
Each of this injury indicates a high energy injury to the wrist.
Other Injuries of Distal Radius
Radial Styloid Fractures
These fractures are associated with scapholunate ligament injuries. Treatment should include stabilization of the radial styloid with a cannulated screw or K-wires may be used to stabilize the fracture.
Volar Lip Injuries
The management of volar lip injuries to the radius is dependent on fragment size. If a fragment is small, it indicates a distal radioulnar joint injury and stabilization of distal radioulnar joint shoud be carried out.
Larger fragments indicate true palmar radiocarpal instability. These fragments represent the insertions of the volar extrinsic ligaments and recent studies have better results with repair than excision.
Dorsal Lip Injuries
This indicates intercarpal ligament injuries most common being avulsion of the dorsal radiolunotriquetral ligament.
External fixation and percutaneous k-wires may be used for the treatment.
Combined injuries are high energy injuries with extensive comminution or/and significant soft tissue injuries.
Simple articular fractures with diaphyseal extension are best managed with a palmar plate.
With distal comminution, hybrid fixation and grafting may be necessary.