Barton Fracture

Etiology

The most common mechanisms of injury vary depending on the patient population. In the pediatric and young adult population, most Barton fractures result from sporting activities and motor vehicle accidents. The most common reason for it to happen is a direct, traumatic wrist injury. Young male workers or motorcycle riders account for 70% of Barton's fracture cases. However, in the elderly, particularly women, decreased bone density from osteoporosis means that less force is needed to cause this injury. [5] Therefore, the majority of these fractures are a result of a fall while standing. 

Epidemiology

The recent increase in distal radius fractures in patients of all ages is attributed to a variety of factors. Fractures in pediatric patients are most common around the time of puberty, with boys tending to suffer the injury more often than girls. The young adult population (ages 19 to 49) is the least affected by Barton fractures, with a greater predilection for males than females. In the elderly, women are more likely to be diagnosed with a Barton fracture than their male counterparts due to higher rates of osteoporosis. Volar Barton fractures make about 1.3 percent of distal radius fractures.[6]

Pathophysiology

A Barton fracture is a compression injury with a marginal shearing fracture of the distal radius. The most common cause of this injury is a fall on an outstretched, pronated wrist. The compressive force travels from the hand and wrist through the articular surface of the radius, resulting in a triangular portion of the distal radius being displaced dorsally along with the carpus.[7] Multiple stabilizing structures help to maintain the relationship between the radius and the carpal bones, including the extrinsic radiocarpal ligaments, the joint capsule, and the scaphoid and lunate fossa of the radius. The associated injuries are distal radioulnar joint disruption, Triangular Fibrocartilage Complex (TFCC) tear, scapholunate ligament injury, and volar intercalated segment instability.[8][9] 

History and Physical

Patients with Barton fractures will typically present to the urgent care or emergency department with acute wrist pain, swelling, and deformity following a recent trauma. The examination may reveal ecchymosis, tenderness, and swollen wrist joint. The range of motion of the wrist joint will be limited due to pain. To rule out associated injuries and complications, the distal neurovascular status must be assessed. A younger patient commonly will describe a sporting injury or motor vehicle accident, while older patients may report a lower energy trauma such as a fall from standing. The patient typically describes a history of fall on an outstretched hand. The type of fracture depends upon the position of the wrist joint during impact e.g. volar shear fractures occur when the wrist is in palmar flexion, while dorsiflexion leads to dorsal shear fractures.

Evaluation

Initial evaluation of the Barton fracture begins with radiographs of the wrist, consisting of at least frontal and lateral views. Oblique views of the wrist often are obtained and may assist in the diagnosis. The radial height inclination, ulnar variance, and articular step are measured on an anteroposterior radiograph. Volar tilt, coronal split, and comminution are visible on lateral radiographs. The radius is 23 degrees inclined in the coronal plane and has an 11 degrees tilt in the sagittal plane. The radius height is approximately 11 mm and ulnar variance ranges from -2mm to +2mm. A radiograph of the unaffected side can be used as a benchmark to see how well all values have returned to normal ranges. An important prognostic factor for wrist arthritis and pain-free range of motion is articular congruity of the distal radius.[10] CT can be used to better evaluate anatomic detail or if radiographs are unclear. It provides information regarding the level of comminution, occult fractures, and the assessment of fracture union. MRI is not the first modality of investigation for acute settings, however, it may be utilized to evaluate for associated ligamentous or soft tissue injuries.[11]

Treatment / Management

The overall goal in the evaluation and treatment of these patients presenting with Barton fractures is to obtain sufficient pain-free motion which will allow the patient to return to their usual activities while at the same time minimizing their risk for developing early-onset osteoarthritis that will lead to disability. Traditionally, the treatment of distal radius fractures is by closed reduction and immobilization in a splint or cast, this has been and remains the treatment of choice in nondisplaced and stable distal radial fractures. [12] Due to the nature of Barton fractures and the implied dorsal displacement of the fracture, many fractures will fail conservative management; therefore, surgical treatment is the preferred option.[13][14] (B2)

The following key radiographic signs should alert the surgeon that the fracture is unstable and indicate closed reduction will be insufficient:

1. Dorsal comminution greater than 50% of the lateral width of the distal radius,
2. Palmar metaphyseal comminution,
3. Initial dorsal tilt greater than 20 degrees, initial fragment displacement greater than 1 cm,
4. Radial shortening of more than 5 mm,
5. Intra-articular disruption or Barton's fracture
6. An associated ulna fracture, and
7. Severe osteoporosis. 

Most Barton fractures are unstable and operative fixation is required. The undisplaced fractures can be managed with immobilization in a cast. While applying the cast, the wrist is slightly volar flexed in volar barton fracture and dorsiflexed in dorsal barton fracture.[15] The exceedingly fragile nature of this injury predisposes to displacement in a cast, therefore even undisplaced fractures need to be constantly monitored radiographically until union. Those who elect to forgo surgery are treated with reduction and immobilization for at least six weeks. [16]When electing to treat these patients with either operative or nonoperative therapy, it is essential to include the patient in the management decision, clearly allowing them to establish and understand the pre-management expectations. Open reduction and internal fixation are recommended for Barton's fracture due to the unstable fracture pattern and the strong pull of flexor tendons.

Volar Approach for Volar Barton's Fracture 

A Volar T-buttress plate is used for the fixation of volar rim fracture. In contrast to the principle of fixation, the plate is applied on the volar surface rather than the tensile/dorsal surface due to less soft tissue irritation.[15] Henry's approach or trans-FCR approach is used to approach volar barton fracture. Henry's approach includes the interval between the flexor carpi radialis tendon and the radial artery, while the fracture is approached through the tendon sheath of the flexor carpi radialis tendon in the trans-FCR approach. The dissection is done radial to flexor carpi radialis to prevent injury to the palmar cutaneous branch of the median nerve. Flexor carpi radialis, the flexor digitorum superficialis, and profundus tendons are retracted towards the ulnar side. in order to prevent the possible denervation of the muscle, avoid radial retraction of the flexor pollicis longus. The volar radiocarpal ligaments that stabilize the wrist are preserved as the pronator quadratus is lifted off from the radial side.[17] Every effort should be made to stabilize the volar lunate facet fragment to prevent carpal subluxation and instability. This may require an extension of the volar incision that incorporates a carpal tunnel release or a separate ulnar incision is made to stabilize the lunate facet fragment.[18] A volar barton's fracture with dorsal rim fracture of the distal radius requires a well-contoured volar plate to prevent dorsal angulation of distal radius articular surface and poor wrist functional outcome.[8] Following surgery, the wrist is immobilized in a splint for five to ten days and then active wrist mobility is started.(B3)

Dorsal Approach for Dorsal Barton's Fracture

A preoperative CT scan is required for the evaluation of fracture patterns and the level of comminution. The dorsal approach is used for dorsal barton and fragment-specific fixation of distal radius fracture through the 3rd dorsal compartment. A 5-6 cm longitudinal incision is made along the lister tubercle. The extensor pollicis longus tendon is retracted radially after incising the roof of the 3rd dorsal compartment. Subperiosteal dissection is done in the 2nd and 4th dorsal compartments to expose the distal radius. [19] To prevent postoperative wrist pain, the posterior interosseous nerve is sacrificed proximally or preserved by dissecting it in a subperiosteal fashion in the 4th compartment.[20] In order to prevent radiocarpal instability, the scapholunate ligament is preserved while performing a dorsal wrist capsulotomy. The dorsal capsule is incised vertically along the skin incision. The dorsal barton fracture is reduced with traction and dorsiflexion maneuver. The dorsal buttress plate or locking plate is used to stabilize the fracture and maintain articular congruity.

K-wires have been used along with a spanning external fixator for barton fracture with a success rate of 80-90%.[21] The disadvantages of K-wire fixation are mal-reduction, tendon penetration of wires, and pin site infection. The overall success rate with the plating system is 90-95% however it is associated with wound-related complications. The long-term outcome depends upon the level of fracture comminution, joint arthrosis, and range of motion wrist exercises postoperatively.[3] If volar Barton fractures do not include carpal subluxation, closed reduction with the cast is advised. However, a 2mm articular step warrants operative fixation.[16](A1)

Differential Diagnosis

Various distal radius fractures can have similar clinical presentations and may appear radiographically similar to the Barton fracture. 

• The reverse Barton fracture is an articular fracture of the distal radius with dislocation in which the articular surface of the radius remains in contact with the carpus; however, the reverse type involves the volar portion rather than the dorsal aspect of the radius.
• The Colles fracture is a fracture of the distal radius with dorsal angulation/displacement; the key differentiating finding is the lack of intraarticular extension.
• The Smith fracture can be thought of as a reverse Colles fracture with volar rather than dorsal angulation.
• The die-punch fracture is a fracture of the articular surface of the radius with depression of the lunate facet.
• The Chauffer’s fracture is an avulsion fracture of the radial styloid.

Staging

Morphological classification:[22]

1. Typical Barton
2. Radial Barton
3. Ulnar Barton
4. Comminuted Barton

Prognosis

Intraarticular fractures of the distal radius, including the Barton fracture, have a higher risk of post-traumatic arthritis than extraarticular fractures. Any articular step-off of greater than 2 millimeters can increase the likelihood of post-traumatic arthritis by almost 100%. However, most studies indicate this does not significantly affect livelihood. The population with the worst prognosis is the elderly, who tend to have higher mortality than other patients due to the limitations to activities of daily living.[23]

Complications

The treating/managing physician should be aware of the multiple injuries that can occur in association with Barton fractures and other fractures of the distal radius including tears of the triangular fibrocartilage (TFCC), traumatic acute carpal tunnel syndrome, development of compartment syndrome in the forearm at time of initial presentation, and development of complex regional pain syndrome (CRPS) in the subsequent weeks and months following the initial treatment. Range-of-motion exercises for the wrist and fingers should be started as soon as possible to prevent wrist stiffness. [24]

These complications can occur following Barton's fracture: Carpal tunnel syndrome, radial nerve compression, ulnar nerve injury, complex regional pain syndrome (CRPS), post-traumatic arthritis, radiocarpal instability, malunion, distal radioulnar joint instability, flexor tendon adhesions, tendon rupture, tendinitis, tenosynovitis, trigger finger, Dupuytren's contracture, and compartment syndrome.

Surgical site infection, loss of fracture reduction, iatrogenic fracture, tendon injuries, neurovascular compromise, compartment syndrome, painful implant, and wrist stiffness are the common complications postoperatively.[25]