Distal radial fracture is one of the most common injuries treated
by orthopaedic surgeons, and one-sixth of all fractures encountered
in emergency rooms involve the distal part of the radius. Although
various surgical treatments of unstable, comminuted distal radial
fractures have demonstrated satisfactory results, closed reduction
and cast immobilization has remained the standard for most relatively
low-energy fractures1,2. Even
when a distal radial fracture requires surgery, a successful initial
closed reduction is valuable for controlling pain before the surgery
and for facilitating the open reduction. Therefore, accurate primary
closed reduction of a distal radial fracture is an important orthopaedic
procedure, and an effective technique for monitoring the reduction
is needed. Postoperative radiography (and, where available, intraoperative fluoroscopy)
is essential for evaluation of closed reduction of all fractures,
including distal radial fractures. For the past fifteen to twenty
years, fluoroscopic technology (available in the United States and,
to a limited extent, in the developing world) has provided high-resolution
real-time images and low radiation levels while allowing the surgeon
to monitor the reduction process. Radiation-free ultrasonography,
however, is widely available and can provide both real-time and dynamic
multiple-plane images with a small and simple-to-use transducer
that can be operated with only one hand, a major advantage in the
acute trauma setting. Sonography has traditionally been used to
evaluate soft tissue because bone is a natural barrier to echo.
However, because bone has high impedance and reflects strong echoic
signals, sonography can clearly illustrate bone alignment. It can
also provide continuous information that will allow the surgeon
to monitor the reduction in real time.
In this prospective study, we attempted to determine whether the
real-time and dynamic multiple-plane observation capabilities of
ultrasonography would allow an orthopaedic surgeon to perform a
closed reduction without multiple attempts, as are frequently needed
when only conventional radiographic techniques are employed. We
also evaluated the reliability and accuracy of sonography in comparison
with that of conventional radiography.
Sonographic monitoring was performed on twenty-seven wrists with
an acute displaced distal radial fracture in twenty-five consecutive
patients (fourteen male and eleven female) ranging in age from eight
to eighty-six years (median age, 48.4 years). All patients underwent
immediate closed reduction and cast immobilization between December
1999 and April 2000 in the emergency center of our hospital. These reductions
and sonographic monitoring procedures were performed by a qualified
orthopaedic surgeon (T.-C.C. or I-M.J.) with the assistance of a
resident. Sixteen patients sustained the injury when they stumbled,
slipped, or fell; five, in a traffic accident; and four, in a sports
accident.
All fractures were classified, with use of the Frykman3 and AO/ASIF systems4, on posteroanterior and lateral radiographs
of the wrist made before and after the reduction. There were six
Frykman type-I fractures, thirteen type-II, two type-V, five type-VII,
and one type-VIII. According to the AO/ASIF classification,
fifteen fractures were type A2, six were type A3, two were type
B3, and four were type C1. In summary, there were twenty-one displaced
extra-articular fractures, four displaced extra-articular and nondisplaced
intra-articular fractures, and two displaced intra-articular fractures.
Fractures were defined as displaced when there was >3 mm
of radial shortening, dorsal or volar angulation, or >2
mm of radial displacement of the distal fragments. We did not perform
any detailed bone-mineral assessment, but on the basis of the demographic
information and plain radiographs we believed that fourteen patients had
a fracture in osteoporotic bone.
Reduction and Immobilization Procedure
The reduction was performed with use of established procedures.
Briefly, patients were in a supine position under local anesthesia
or under anesthesia induced with intravenous methohexital (Brevital;
Eli Lilly, Indianapolis, Indiana; 1 mg/kg). There were
some minor variations in the reduction technique, but in general
we used traction on the fingers and continuous countertraction on
the arm with the elbow flexed 90°. The wrist was then carefully
manipulated while the manipulation was monitored sonographically.
When a patient had a severely displaced fracture, we released the
traction and manipulated the wrist and forearm, using sonographic
monitoring to help us to find the best position for alignment of
the fracture. Once the reduction of the fracture was confirmed by continuous
sonographic observation, an above-the-elbow plaster-of-Paris cast
was applied.
Sonographic Examination and Measurements
All sonographic examinations in this study were performed with
a commercially available real-time scanner (SSD-620; Aloka, Tokyo,
Japan) with a 7.5-MHz linear-array transducer. The surgeon viewed
the fracture radiographs before performing the fracture reduction,
but the surgeon measuring the parameters for the final comparison
was blinded to all prior radiographs and sonograms. For comparison
of anatomic alignment, the contralateral (uninjured) wrist was also
examined in the twenty-three patients without bilateral involvement.
The technique that we used for the sonographic monitoring was
simple. After adequate anesthesia administration and positioning
of the injured upper extremity, ultrasound coupling gel is placed
on the skin over the positions for the dorsal, volar, and radial
sections (Fig. 1, a,
b, and c). For the dorsal section, because
the center of the distal part of the radius falls along the longitudinal
line between the index and long fingers, the transducer is placed
on the dorsal side of the radius in the parallel space between the
index and long fingers. For the volar section, the transducer is
placed on the volar side of the radius in the parallel space between
the index and long fingers. For the radial section, the transducer
is placed near the snuffbox area.
For a detailed comparison of the sonographic and radiographic
examinations of these three sections, a pilot study was conducted
on the right wrist of one of the authors (T.-C.C.). At the center
of each of these three sections, a fine acupuncture needle was inserted
perpendicular to the surface and down to the underlying bone surface.
Lateral radiographs were then made to verify the cortical surfaces
observed on sonographic examination of these sections (Fig. 1, d and e).
The dorsal, volar, and radial cortices observed on sonographic examination
of these sections proved to be identical to those observed on conventional
radiographs (Fig. 1, f,
g, and h).
The alignment of the fracture was shown by the reflection of ultrasound
from the volar, radial, and dorsal cortical surfaces of the radius
and the corresponding carpal bones. The distance of the displacement
and the angulation between the proximal and distal fragments was
used to quantify the displacement and to monitor the reduction.
When the fracture was too distal or too comminuted, the corresponding
carpal bones were used in place of the distal fragment.
After completion of the sonographic monitoring and the recording
of the three standard sections before and after the reduction of
every fracture, four parameters in each of the three sections were
measured. The parameters included the (1) radial displacement distance,
(2) volar displacement distance, and (3) dorsal displacement distance,
which are the displacement distances between the proximal and distal fragments
observed in the standardized radial, volar, and dorsal sections,
respectively, and (4) the volar fracture angle, which is formed
by a line parallel to the volar cortex of the proximal fragment
and a second line along the distal fragment (Fig. 2, a,
b, and c).
Radiographic Examination and Measurements
We made plain posteroanterior and lateral radiographs of the injured
wrist, with a calibration marker, before and after the reduction
and cast immobilization. Because the acutely injured wrist and the
long arm cast occasionally interfered with the standard projection
directions, one of the authors (T.-C.C.) achieved standardization
and consistency of every radiograph by using different projection
techniques in different situations, as described previously5,6. The posteroanterior and lateral
radiographs were made with the elbow flexed 90° (or, for some patients
wearing a long arm cast, with the elbow in a fixed reduced position
of nearly 90°) and the humerus abducted 90°, so that the elbow was
at the same height as the shoulder. The posteroanterior radiograph was
made with the palm of the hand flat on the film cassette, and the
lateral radiograph was made at a right angle to the posteroanterior
radiograph.
The surgeon performing the measurements was blinded to the previous
radiographs and the sonograms. The assessment of the radiographs
included measurement of the four parameters (radial, volar, and
dorsal displacement distances and volar fracture angle), identical
to those measured on the sonographic studies. The three conventional
measurements of accurate treatment and sufficient radiographic follow-up (radial
shortening distance, radial inclination angle, and palmar tilting
angle)5,6, which could not be
determined with the sonography (one of the limitations of a sonographic
examination), were also evaluated (Fig. 2, d) and correlated
with the sonographic changes.
Statistical Analysis
Data were analyzed statistically with a Student paired t test, with
p < 0.05 considered significant. In addition to the data obtained
by the authors of the present study, the data obtained by an invited
observer blinded to the patients’ previous radiographs
and sonographic images were analyzed.
Characteristic Sonographic Findings
All sonographic and radiographic images were evaluated by three
orthopaedic surgeons and a radiologist who had experience with ultrasonography.
Distinct presentation of homogeneous, strong, bright reflective
echoes with dorsal acoustic shadowing was the characteristic feature
of the bone border in all patients. A longitudinal examination across
the fracture site revealed a clear disruption of the continuous
reflection of the radius; furthermore, the displacement between
the fracture fragments and the angle formed by the fracture fragments could
be observed and measured easily in every case (Figs. 3 and 4). If the fracture
was located in a juxta-articular or intra-articular area, the corresponding
carpal bone (usually the scaphoid or lunate) could be used in place
of the distal radial fragment (Figs. 5 and 6).
Adequacy of Reduction
Traction and manipulation monitored by sonographic examination
successfully reduced all of the fractures to normal or nearly normal
anatomic alignment. Despite successful primary treatment, surgical
intervention with various methods of internal and/or external
fixation was indicated, and was performed within one week, in six
wrists with an unstable fracture pattern.
Results of Measurements
Sonographic and Radiographic Measurements at
the Fracture Site
A comparison of the sonographic and radiographic measurements
of the volar, dorsal, and radial displacement distances as well
as of the volar fracture angle is shown in Table I. Both modalities
showed a significant decrease in the displacement distances and
a significant correction of the fracture angle (p < 0.05).
Anatomic or nearly anatomic alignment of both fragments was achieved
in every reduction, as demonstrated by the almost completely reduced
translation in all three planes and the correction of the volar
fracture angle to a value comparable with that on the normal, contralateral
side. In addition, the paired t test analysis showed a close and
significant association between the sonographic and radiographic
measurements of all of these parameters both before and after the
reduction (p < 0.05).
Radiographic Measurements of Conventional Parameters
of Reduction
Table II shows
the means and standard deviations for the palmar tilting angle,
radial inclination angle, and radial shortening distance, before
and after the reduction and cast immobilization, as measured on
the radiographic studies. The palmar tilting angle averaged -18.5°
(range, 25° of volar tilt to -67° of dorsal tilt) on the initial
lateral radiographs. The angle was significantly decreased, to an
average of 6.1° (range, 20° of volar tilt to -5° of dorsal tilt),
on the radiographs made immediately after the reduction and cast
application (p < 0.05). There was also a significant increase
in radial inclination (p < 0.05), from 14.8° (range, -5°
to 45°) on the initial radiographs to 24.6° (range, 18° to 30°)
on the postreduction radiographs, and a significant decrease in
the radial shortening (p < 0.05), from 3.4 mm (range, 0
to 12 mm) to 0.0 mm (range, -2 to 1 mm). Overall, the results of
the closed reductions in this series were successful according to
generally accepted criteria6:
a palmar tilting angle between 0° and 22°, a radial inclination
angle between 16° and 28°, and radial shortening of <2 mm.
This study was a prospective review of the findings in twenty-seven
consecutive wrists with various types of acute displaced distal
radial fractures treated primarily with sonographically guided closed
reduction and cast immobilization. With the real-time guidance and
confirmation of the sonographic examination, we were able to achieve
anatomic or nearly anatomic alignment in every closed reduction
in this study. These results were verified by radiographs made immediately
after each reduction and cast application. A comparison of radiographs
made before and after the reduction and immobilization revealed
the restoration of normal bone alignment, normal radial inclination
and palmar tilting angles, and preservation of radial length in
every wrist immediately after treatment. The sonographic observations
were identical to the radiographic findings. This similarity supports
the hypothesis that sonographic monitoring can provide real-time
observation that can guide and confirm the closed reduction of extra-articular
distal radial fractures.
Sonography for the diagnosis of disorders in the musculoskeletal
system has been found to be especially useful for the detection
and characterization of soft-tissue abnormalities7.
Only a few studies have shown that sonography can be a useful adjunct
to routine radiography for the diagnosis of fractures—e.g.,
the early diagnosis of stress fractures8;
the detection of occult fractures in children9,10;
and the identification of some fractures, including those of the
scaphoid, sternum, rib, greater tuberosity of the humerus, orbital
floor, and radial neck, that are poorly delineated by conventional
radiographs8,9,11-18. Sonography,
however, is not yet frequently used. All of the above reports also
concluded that sonography is not the method of choice for detecting
and diagnosing bone fractures. One major reason for this conclusion
is the basic technical difficulty of detecting subtle changes caused
by the fracture on the sonographic image. If, however, advances
in technology allow sufficiently high-resolution sonographic images, this
difficulty might be overcome. In contrast, cortical discontinuities
in fractures of tubular bone—shown by the distinct interruption
of the strong echo—were not difficult to observe on the
sonograms in our study. One report19 of
an experimental study on cadaveric long bones also advocated the
use of sonography for documenting fractures, concluding that a high-resolution
transducer, if not placed parallel to the fracture line or the zone
of osseous impaction, can detect a cortical discontinuity of 1 mm.
Another study20 showed the successful use of sonography instead
of fluoroscopy during closed reductions and for monitoring the passing of
a guide-wire in nine of ten patients who underwent femoral nailing.
Sonography has also been used intraoperatively to monitor the reduction
and stabilization of thoracolumbar burst fractures21,22. Recently,
Durston and Swartzentruber23 reported successful ultrasound-guided
reduction of forearm shaft fractures in three children. We therefore
believe that sonographic monitoring might be an easy, convenient,
practical, and reliable tool for monitoring reduction of displaced fractures.
Restoration of normal or nearly normal anatomic alignment is acknowledged
as a key component of the treatment of distal radial fractures.
Radiographic imaging is essential for objective evaluation of the
quality of the closed reduction. During the reduction procedure,
fluoroscopy can be used to monitor the reduction in a timely fashion,
and repeated radiographs can be used to confirm the final reduction
status. For a variety of reasons, neither of these technologies
is optimal in the treatment of distal radial fractures. Conventional
radiography cannot provide real-time or dynamic multiple-plane monitoring
of the reduction. Instead, the radiographs are made after the closed
reduction and with an above-the-elbow cast in place. Therefore,
correction of an unsatisfactory reduction requires removal of the
cast followed by remanipulation of the fracture. For the past fifteen
to twenty years, low-radiation fluoroscopic technology that can
provide real-time monitoring of closed reductions has been available
in many places in the United States, but, unlike sonographic technology,
it is not yet commonly available in the developing world. Fluoroscopy can
provide relatively rapid but not dynamic, instantaneous multiple-plane
observation.
Noninvasive, radiation-free sonography is available in both the
developed and the developing worlds, in most, if not all, emergency
rooms to facilitate many procedures in general surgery, gynecology
and obstetrics, and internal medicine. In addition to distinct delineation
of the alignment of the fracture, sonography offers a number of
advantages that make it a reliable, convenient, and useful means
of monitoring closed reductions of extra-articular distal radial
fractures. First, sonography allows the orthopaedist to observe
the dynamic changes of the alignment of the fracture during reduction
in real time and at any time-point during the reduction, providing
immediate feedback with which to improve the reduction. Second,
unlike conventional static radiography and even the most up-to-date
fluoroscopy, sonography allows the surgeon to rapidly monitor the
bone in as many planes as needed19 merely by moving a small handheld
transducer. Third, dynamic visualization of the fracture, both during
and after reduction attempts, allows immediate recognition of any
position of instability. This might enable the orthopaedic surgeon to
better control the reduction with use of specific splinting techniques.
Fourth, a splint or cast can be applied after the reduction with
greater confidence that it will not have to be removed and reapplied
because of a less-than-adequate fracture alignment. Fifth, because
use of sonography should decrease the number of reduction attempts,
there should be less trauma to the surrounding soft tissues. Finally,
whereas it is necessary to wait for conventional radiographic images
to be developed, a sonographic scanner can quickly print an image
on thermal paper. This ability is important because the sonogram
can depict up to three-quarters of the circumference of the distal
part of the radius, providing sufficient topographic information
for the surgeon to align the fracture.
Sonography does, however, have some limitations because of its
inherent inability to penetrate bone. Observation of the articular
surface and the sigmoid notch is thus limited because of their deep-seated
position. Furthermore, the articular surface is blocked by carpal
components, and the sigmoid notch is blocked by the ulna. Also,
sonography cannot be used instead of radiographs to assess or confirm
the quality of the reduction of intra-articular displacement of
distal radial fractures, which is not uncommon. Another limitation
of sonography is that it cannot measure three useful conventional radiographic
parameters: radial shortening, radial inclination, and palmar tilting.
If, however, as demonstrated by the present study, anatomic or nearly
anatomic alignment is achieved with use of sonographic monitoring,
one may anticipate that these parameters will be acceptably restored.
In summary, sonography is an effective tool for real-time monitoring
of the reduction of distal radial fractures. It is noninvasive,
produces no morbidity, is highly accurate, is easy to use, and can
sometimes be more useful in closed reduction than conventional radiography.
While sonography has some limitations that prevent it from completely
replacing conventional radiography, it can facilitate the reduction
and prevent repeated reduction attempts.
Note: The authors are grateful to Hong-Ming Tsai, MD, Department
of Radiology, National Cheng Kung University Hospital, for his help
in interpreting our sonographic and radiographic results. They also
thank Bill Franke for proofreading and revising the English in this
article.