FRACTURE OF DISTAL
RADIUS
Approximately 80% of fractures of the forearm involve the distal radius
and the DRUJ. Fractures of the distal radius are common injuries in children,
adults, and elderly persons, usually resulting from a fall on the outstretched hand. Significantly more force
is required to fracture this part of the radius in adolescents and young adults
than in older adults with severe osteoporosis. Fractures that involve the joint
are usually caused by high impact.
Evaluation of any injury in the
distal radius must include radiographs of the wrist, forearm, and elbow. True anteroposterior,
lateral, and sometimes oblique views are required to determine the extent of
the injury. If intra-articular involvement is suspected, computed tomography
can be performed to determine the degree of joint displacement and guide
management. Fractures of the distal radius may be stable or unstable, depending
on the degree of comminution and initial fracture displacement. Associated
injuries to the carpal bones and/or ligaments of the wrist must be evaluated
for and managed appropriately.
FRACTURE TYPES
Extension/Compression
The precipitating injury of the
extension/compression, or Colles, fracture is a fall on the outstretched hand.
The deformity is caused by dorsal displacement of the distal radius and
swelling of the distal portion of the forearm and is referred to as a “silver
fork” deformity. Successful treatment involves restoration of (1) the radius to
its proper length, (2) the radial inclination and volar tilt of the distal
radius, and (3) the congruity of the articular surface of the distal radioulnar
and radiocarpal joints. Loss of more than 5 mm of radial length (easily
measured by using the styloid process of the ulna as a reference point) may
result in disability. Restoration of the volar tilt of the distal radius is
critical to long-term outcomes and diminishes the risk of altered carpal
kinematics, which would lead to degenerative changes of both the radiocarpal
and midcarpal joints.
If more than 50% of the metaphysis
of the distal radius is comminuted, the fracture is probably
unstable and reduction is difficult to maintain in a plaster cast alone. This
type of fracture is best visualized on the lateral radiograph. Definitive
treatment is determined not only by the injury but also by the patient’s age
and occupation. Anatomic restoration is more important in younger, working
patients, whereas some loss of radial length and tilt may be more acceptable in
sedentary patients.
Fracture of Articular Margin
of Distal Radius
Fractures of the articular margin,
called Barton fractures, represent a small percentage of fractures of the distal
radius. This type of fracture is best described as a fracture-dislocation of
the wrist. Correct diagnosis of Barton fracture is very important because it is
an inherently unstable injury and therefore difficult to manage with the
traditional closed method. The injury is further defined by the direction of
the dislocation. If the dorsal aspect of the articular margin, or rim, is
fractured and the carpus is displaced dorsally, the injury is termed a dorsal
Barton fracture; conversely, the more common volar
Barton fracture refers to a
fracture in which the dislocation is displaced volarly. In many cases, however,
the Barton fracture is nondisplaced and can be treated with immobilization in a
plaster cast with weekly follow-up and repeat radiographs.
A fall on the outstretched hand is
the most common cause of the Barton fracture. The impact wedges the lunate
against either the dorsal or the volar margin of the articular surface of the
radius. The lunate acts as a lever against the articular surface, causing it to
fracture. The carpus is then dislocated along with the fragment of the
articular margin of the radius.
The stability of the closed
reduction depends on the integrity of the radiocarpal ligament on the side
opposite the injury. For example, the stability of the reduction of a dorsal
Barton fracture is best preserved by positioning the wrist in extension to take
advantage of the intact volar carpal ligament.
Reduction of a Barton fracture is
difficult to maintain with an external fixator or with pins and plaster;
there-fore, treatment with open reduction and internal fixation (ORIF) is
usually indicated for fracture-dislocations that have large fragments. Barton
fractures that involve a significant portion of the articular surface are
usually unstable and must be treated with ORIF, using a small buttress plate to
maintain the reduction. Buttressing the distal fragment maintains joint
congruity. It is not absolutely necessary to insert screws into the distal
fragment (which may be significantly comminuted) to maintain the reduction.
Fracture of Styloid Process
of Radius
Most nondisplaced fractures of the
styloid process of the radius can be treated with immobilization in a plaster
cast. Displaced fractures must be anatomically reduced and held with either a
pin or a screw. Often, treatment with closed reduction and percutaneous pin
fixation is sufficient. Fractures of the styloid process are frequently
accompanied by dislocations of the lunate. Thus, with any fracture of the
styloid process, the carpus should be examined for other injuries. Some
surgeons are utilizing wrist arthroscopy to aid in the treatment of these
injuries. Advantages of arthroscopy include direct inspection of the articular
reduction, as well as the ability to identify associated
ligamentous injuries that commonly occur with this injury pattern. Closed
reduction and immobilization in a plaster cast constitute a dependable
treatment for many fractures of the distal radius, but after satisfactory
manipulative reduction some fractures (particularly unstable injuries in young,
active adults) require operative fixation. Current fixation options include
closed reduction and percutaneous pin fixation, external fixation,
or ORIF with a recent trend toward volar locked plating.
TREATMENT
The best determinants of how to
treat fractures of the distal radius are the character of the fracture, whether
it is stable or unstable or intra-articular or extra-articular; the life
style and age of the patient; and the experience of the treating surgeon.
Closed Reduction and Plaster
Cast Immobilization
Colles fractures can often be
reduced using manipulation or traction. After a sterile preparation of the
forearm, local infiltration of lidocaine into the hematoma at the fracture site
often provides adequate anesthesia for manipulating the fracture. Regional
anesthesia, either an axillary or a Bier block, is also commonly used; but if
the patient is very apprehensive or a more extensive procedure is needed, then
general anesthesia may be required.
Traction using fingertraps and
weights is an effective method of reducing Colles fractures. The fingertraps
are secured to the middle and index fingers and the thumb to suspend the arm;
10- to 15-lb weights are attached by a sling to the upper arm to provide
countertraction. Gentle manual manipulation is often needed to fully reduce the
fracture. Hyperextension or re-creation of the deformity should be avoided, if
possible.
If the surgeon decides to
manipulate the fracture without using fingertraps, an assistant is needed to
hold the proximal forearm and provide countertraction. The fracture is then
reduced with gentle longitudinal traction. A sugar tong splint or a long-arm
circular cast is applied after reduction. The sugar tong splint is easier to
apply than the long-arm cast and can be tightened on follow-up visits. To
maintain the reduction, it is important to mold the plaster snugly to the
forearm using three-point molding. The final position of the wrist within the
splint/cast must avoid extreme positions (especially wrist flexion) because
these can exacerbate nerve compression, specifically the median nerve within
the carpal tunnel. Patients must be monitored on a weekly basis for the first 3
weeks with radiographs at each visit confirming maintained reduction. Six weeks
of immobilization is the standard length of immobilization, followed by
protected motion and progressive strengthening.
Closed Reduction and Pin
Fixation
Fractures that do not remain in acceptable
alignment after closed reduction require operative fixation. Patients with
excellent bone quality and an intact (i.e., noncomminuted) volar cortex are
candidates for closed reduction and pin fixation. The most common method is
“intrafocal” pinning and utilizes Kirschner wires that are placed distal to
proximal both through the radial styloid as well as dorsally into the fracture
site and then engaging the volar cortex. This method is not acceptable for
fractures with metaphyseal comminution or intra-articular involvement. The pins
can be removed at 4 weeks, and protected motion is started. The most common
complication with this treatment method is pin site infection requiring
antibiotic treatment or early removal
of the pins. The most feared complication is complex regional pain syndrome
arising from injury to the superficial radial nerve braches during placement of
the Kirschner wire.
External Fixation
Fractured associated with severe,
open soft tissue injuries or fractures that undergo either pin or plate
fixation that is tenuous benefit from external fixation. The most common method
of external fixation is a spanning wrist fixator. Threaded pins are placed into
both the second metacarpal as well as the distal third of the radius and
connected with clamps and bars to maintain length and neutralize forces. Newer
devices have been developed that do not cross the wrist and show promise in the
treatment of complex distal radius fractures. Pin track infections are common.
Complex regional pain syndrome is also a risk from both sensory nerve injury
and overdistraction of the wrist.
Open Reduction and Internal
Fixation ORIF is arguably
the current treatment of choice for most unstable, displaced distal radius
fractures. Traditionally, plates and screws were placed dorsally along the
distal radius, acting as a buttress plate. The intimate relationship of the
extensor tendons to the bone led to high rates of extensor tendon complication
requiring either hardware removal secondary to extensor tenosynovitis or tendon
repair/reconstruction secondary to frank extensor tendon rupture. Locked
plating technology, in which the screw heads are threaded into the plate,
allows placement of the hardware along the volar cortex of the distal radius.
The overlying flexor tendons are protected from the implants by both distance
and the pronator quadratus muscle. The “fixed angle construct” buttresses the
articular surface with screws/pegs or tines placed immediately subchondral to
the articular surface, and then the plate is fixed to the shaft of the radius.
Excellent reduction can be obtained, and the rigid constructs allow early
mobilization and therapy. Soft tissue irritation and injury from the hardware
remain a concern and can be diminished by appropriate position along the bone
and avoiding dorsal screw penetration (bicortical fixation is not required with
these implants). More complex injuries with comminution of the articular
surface or significant volar and dorsal involvement may require ORIF with
multiple plates and screws. Fragment-specific fixation is the concept to applying
smaller implants to individual fracture fragments, leading to stable fixation
and anatomic restoration of complex articular injuries.
COMPLICATIONS
The short-term complications
associated with all fractures of the distal radius are significant and demand
early treatment to prevent long-term residual disability.
To control edema after fracture
reduction and casting, the arm is elevated on pillows or in a sling above the
level of the patient’s heart and ice bags are applied over the cast. Severe
swelling may necessitate splitting the cast, and the cast may need to be
trimmed to prevent skin irritation. The physician should encourage frequent and
full active range of motion of all the finger and thumb joints to prevent
stiffness, which is common, and to reduce swelling. Any persistent pain under
the cast should be investigated with the plaster removed entirely.
Acute injury of the median nerve
after fractures of the distal radius is an uncommon but debilitating problem.
After injury, fracture displacement combined with swelling occasionally
distorts and compresses the median nerve, causing pain or numbness. The
symptoms of median nerve compression usually subside or disappear when the
fracture is reduced. If symptoms persist after reduction particularly
if the patient experiences burning pain in the median nerve distribution prompt
surgical decompression of the nerve in the carpal tunnel may be necessary. Mild
residual numbness and tingling in the median nerve distribution usually subside
with time or can be relieved after fracture healing with a carpal tunnel
release. Sometimes, acute compartment syndrome of the forearm is associated
with fractures of the distal radius. The characteristic symptom is excessive
pain combined with numbness and pain on passive movement of the thumb and
fingers. Compartment syndromes must be recognized promptly and should be
treated with fasciotomy.
Long-term complications develop in
30% to 35% of patients. Loss of the reduction is the most common problem, which
can be minimized or corrected by early identification of the displacement with
radiographs taken at weekly intervals in the first 3 weeks after injury. Repeat
closed reduction and casting may be needed; unstable fractures may require ORIF
or application of an external fixator to restore and maintain alignment. After
3 weeks of healing, fractures of the distal radius have stabilized and will
rarely settle with further loss of radial length. If the fracture heals with a
residual deformity (usually a dorsiflexion deformity), this can be corrected
with surgery. Radiocarpal and carpal instability are also associated with
injuries of the distal radius. Osteoarthritis of the distal radioulnar joint
may produce persistent pain. Fortunately, nonunion is rare, but if it occurs,
treatment comprises ORIF and bone grafting.
Rupture of an extensor tendon, most
commonly of the thumb, is seen following fractures of the distal radius,
as is stenosing tenosynovitis of the first dorsal compartment (de Quervain
disease). Reflex sympathetic dystrophy is a very debilitating complication of
any musculoskeletal injury. It is frequently a result of hand and wrist
fractures, but it develops most often after treatment of unstable fractures with
pin fixation, external fixation, or pin and plaster fixation. The early
recognition and treatment of reflex sympathetic dystrophy is
essential to restore good function.
