Differential Diagnosis of Kienböck's
Disease by Magnetic Resonance Imaging
U. Bartelmann1, K. Kalb1,
S. Hollenberg1, B. Landsleitner1, S. Fröhner2
and R. Schmitt2
1Klinik
für Handchirurgie
2Institut
für diagnostische und interventionelle Radiologie der Herz- und Gefäßklinik
GmbH, Bad Neustadt/Saale Germany
Most topics and problems consider
the therapeutic consequences of Kienböck’s disease depending on its
stage; there is little in the literature about the differential diagnosis
of Kienböck’s disease. Because of technical developments in
radiological imaging we now possess very detailed pictures. However there
are many radiological findings within the lunate bone that can falsely
appear to be Kienböck’s disease. We were particularly interested in
similarities and how we could differentiate these findings from Kienböck’s
disease.
We collected pathological findings
of the lunate bone, which are not Kienböck’s disease, by conventional
x-rays, computer tomography including computer-animated images and
magnetic resonance imaging (MRI) using contrast-enhanced sequences of
highest quality. These findings were compared with the different stages of
Kienböck’s disease and identified.
Stages I and II of Kienböck’s
disease (Lichtman classification) show changes especially in the MRI,
which are very similar to synovitis, the ulnar impaction syndrome, a
transient vascular compromise of the lunate bone as well as a small
fracture. Cystic changes, such as an intraosseous ganglion, can imitate
stages II and III. Even in stage IV it can be difficult to differentiate
it from pseudarthrosis of the lunate bone.
The differentiation between
Kienböck’s disease and other pathological findings was sometimes only
possible with MRI, including contrast-enhanced sequences. We therefore
suggest that Kienböck’s disease must be correctly diagnosed with help
of the MRI before engaging in any therapeutic steps. The MRI also permits
more detailed differentiation and possibly a new additional classification
of the formerly known radiological stages, which should be included in
planning therapeutic measures.
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The Usefulness of MRI in the
Diagnosis of the Cause of Carpal Tunnel Syndrome
J. Brüske 1, M. Bednarski
1, K. Krzyslak 2, A. Zyluk1, P. Prowans1
1 Department
of General and Hand Surgery
2 Department
of Radiology, Pomeranian Medical University,
Szczecin, Poland
Diagnosis of the carpal tunnel
syndrome (CTS) is based mainly on the clinical examination; however, nerve
conduction studies are commonly used to confirm the clinical impression.
The results of both examinations confirm the presence of compression of
the median nerve at the level of the carpal tunnel, but the cause of
entrapment usually remains unknown. This paper presents the results of a
prospective trial set up to examine the usefulness of magnetic resonance
imaging (MRI) in preoperative diagnosis of the cause of carpal tunnel
syndrome.
Patients and Methods -
From January 1998 to January 1999, 32 patients with signs and symptoms of
CTS were identified in the department. The patients included 29 women and
3 men ranging in the age from 24 to 72 years. Diagnosis of the syndrome
was based on clinical examination and nerve conduction studies. Magnetic
resonance studies were performed on a 0.3 T or 1.0 T imager (Ultimate
Fonar) equipped with knee coil. All patients were operated, and operative
findings were compared with results of the preoperative MRI.
Results -
Preoperative scans showed flattening of the median nerve at the level of
the hook of hamate with simultaneous thickening of the nerve at the level
of the pisiform bone, barrel-shaped extension of the carpal tunnel with
palmar relief of the flexor retinaculum, increased signal intensity around
the tendons on T2-weighted images, thickening of the flexor retinaculum
and intraneural tumors. The following findings : tenosynovitis in 20
patients, thickening of the flexor retinaculum in 8, intraneural tumors
(neurofibroma) in 2 and no visible cause of compression in the remaining 2
cases were revealed by the operations. Analysis of the results of MRI
studies showed good correlation with operative findings. Barrel-shaped
extension of the carpal tunnel with palmar relief of the flexor
retinaculum as well as increased signal intensity around the tendons on
T2-weighted images correlated well with the presence of tenosynovitis.
Thickening of the flexor retinaculum and intraneural tumors were also
identified on preoperative MRI scans. The results of this study suggest
that MRI studies may be useful in the preoperative diagnosis of the cause
of carpal tunnel syndrome.
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Optimizing the Imaging Parameters for
3D-Gradient Echo Imaging of the Wrist
J.L. Hobby, P.W. Bearcroft
Department of Radiology and
Orthopaedic Research Unit, University of Cambridge and Addenbrooke’s NHS
Trust, Cambridge, United Kingdom
Objectives - To
identify a set of parameters which produced the optimum image quality for
3D- gradient echo imaging of the wrist (the highest spatial resolution
compatible with an acceptable signal- to-noise ratio, and appropriate soft
tissue contrast) with a maximum acquisition time of six minutes.
Methods - Images
were acquired on a GE Signa LX-MR Scanner operating at 1.5 Tesla. Series
of coronal gradient echo images were obtained of a volunteer. Varying
time-to-repetition (TR), time-to- echo (TE) and the flip angle were used
to determine which set of parameters yielded the optimum soft tissue
contrast. Throughout each imaging session the central frequency,
transmitter and receiver gains were held constant to minimize the
variation between images. We also acquired a series of images using
different numbers of phase encoding steps and fields of view to determine
the impact of increasing spatial resolution on the signal-to-noise ratio
and imaging time. We assessed the effect of increasing the number of
signals averaged upon image quality and acquisition time. We assessed the
effects of reciever bandwidth on signal-to-noise ratio and chemical shift
and susceptibility artefacts. As part of this evaluation we compared two
different receiving coils, a phased array extremity coil and a dedicated
wrist coil (Medical Advances).
Results - The
best compromise of soft tissue contrast, signal-to-noise ratio, spatial
resolution, reducing artefacts and imaging time was achieved with the
following parameters : TR 40 msec, TE 18 msec, flip angle 25 degrees FOV
10 x 10cm, 30 x 1 mm contiguous slices, receiver bandwidth 16 MHz. We will
present graphs and examples of the effect of varying imaging parameters on
soft tissue contrast and signal-to-noise ratio.
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Tumors of the Hand
L. De Smet
Department of Orthopaedics, KUL
Leuven, Leuven, Belgium
All tissues of the hand can be
involved in a tumoral process; benign, pseudobenign or malignant. However,
for the majority of hand surgeons, tumors comprise only 1 to 10% of their
activity. There are some differences in occurrence and clinical or
radiological presentation of common tumors found elsewhere in the body.
Some tumors are rather rare in the hand :
- metastases, chondrosarcoma and lymphoma;
- some tumors have a predilection for localization
in the hand : glomus, giant cell or tendon sheath tumors.
We are also frequently confronted
with pathological processes which mimic a tumor or vice versa.
The imaging of soft tissue tumors
with plain radiographs rarely discloses the probable diagnosis. The
radiolucency of a lipoma and soft tissue calcifications in hemangiomas are
the exceptions. But calcifications can be seen in other pathological
situations (calcifying tendinitis). There is a group of tumoral or
pseudotumoral processes with soft tissue ossification : Turret's
exostosis, pseudomalignant myositis ossificans and bizarre paraosteal
chondromatous proliferation. For the correct diagnosis, comparison of
clinical, radiological and histological features is required.
Most bone tumors are benign.
Osteolytical lesions, especially in the terminal phalanges are a
diagnostic challenge, but histology reveals the answers. Osteoid osteomas
are probably not as rare as previously thought, and their clinical and
radiological appearances are peculiar. They are the great simulators of
other pathologies, and the first rule for the diagnosis is to be aware of
the possibility. Chronic or subacute infections of bone remains difficult
to differentiate from tumors.
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Finite Element Modelling of Wrist
Contact Pressures based on Wrist X-Rays
P. Ledoux1, F. Schuind2,
D. Lamblin1
1
Department of Surgery, Clinique du Parc Léopold, Brussels, Belgium
2
Department of Orthopedics and Traumatology, Cliniques Universitaires de
Bruxelles, Hôpital Erasme, Brussels,
Belgium
In order to explain the mechanical
behaviour of the normal wrist and in particular conditions, we set up a
model of the wrist in two dimensions using a finite element software. This
type of software provides a means of modelizing complex structures and
defining mechanical properties for each of the components of the model. We
traced the bone geometry based on an x-ray of a healthy wrist face on in a
neutral position. In this paper we present two pathological situations :
Kienböck’s disease and scaphoïd nonunion.
The aetiology of Kienböck's disease
remains unclear, but is likely to be multifactorial. The necrosis could
result from traumatic interruption of the bone blood flow in a patient
with insufficient vascular collaterals. Alternatively, Kienböck's disease
could result from microfractures sustained by the lunate through exposure
to abnormal mechanical stresses, with progressive collapse. Kienböck's
disease is statistically associated with negative ulnar variance.
Lunatomalacia is almost never seen with an ulnar plus variance. Most
patients report the history of an initial trauma to the wrist, and on CT
scans, 82% of the collapsed lunates appear to be fragmented. Experimental
and mathematical studies have demonstrated that the lunate is submitted to
high compressive pressures at the radiocarpal joint. On the ulnar side,
the lunate lies on the soft triangular fibrocartilage, and the peak
pressures are much lower. Palmer has demonstrated that the radio-lunate to
ulno-lunate peak pressures ratio depends on the relative lengths of the
radius and ulna. The hypothesis of the present study was that, in poor
mechanical conditions related to negative Ulnar Variance
(UV) or to increased uncovering of the lunate, the bone would be submitted
to high internal stresses, causing microfractures and progressive
collapse. The results of our study supports the theory that in certain
anatomical situations, the lunate is submitted to high cancellous stresses
that may lead to progressive collapse. The risk of fracture is especially
high in the case of thick or angulated trabeculae, with high uncovering of
the lunate and with negative ulnar variance. A positive ulnar variance
seems to protect the bone. An initial fracture could in many cases
initiate the lunate collapse. The fracture line propagates proximally, as
seen in clinical practice.
Although based on their long-term
clinical development there appeared to be no doubt that fractures of the
scaphoid modify the mechanical behaviour of the carpus, the mechanisms of
these modifications had not yet been described. This study based on finite
element analysis provides insight into the sequence behind the onset of
arthritis at the level of the wrist, highlighting the existence of
pressure peaks at the level of nonunion (between the scaphoid and the
radius) and at the level of midcarpal interface (scaphoid-capitatum and
lunate capitatum). This evidence explains the clinical development of
nonunions of the scaphoid and is in good concordance with data of clinical
series founded in the literature. Our study indirectly demonstrates the
role played by the scaphoid within the wrist as an effort transmission
column.
The use of finite element analysis
for the modelization of simple or complex osteo-articular systems may
prove to be a highly useful tool for the understanding of these
mechanisms.
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