Clinical evaluation of wrist*s scapholunate ligament injury by new developed 4-dimensional Rotational X-ray imaging

Wrist problems are responsible for a significant social-economic problem for
the employers and the community as they are responsible for the longest absence
period from work with substantial financial consequences due to workers'
compensation, medical expenses, and productivity losses. Malfunctioning of the
wrist often leads to reduced quality of life and has profound consequences for
the patients involved. Due to the complex anatomy, diagnosis of wrist injuries
is hampered by the various levels of trauma severity and the large number of
possible trauma locations. Therefore it is of great importance for the patient
and the medical doctor to recognize and properly diagnose problems in the wrist
at an early stage.

The year-prevalence of wrist complaints among Dutch adults in 1998 was
estimated by the Dutch Institute for public health and environment (RIVM) at
approximately 17.5%. Injuries to hand and wrist account for 28.6% of all
attendances at the accident and emergency department. Since ligament injury is
believed to be present in 5-25% of wrist traumas it is of great importance to
diagnose a ligamentous injury at an early stage in order to avoid progression
of wrist pathology. Scapholunate ligament (SLL) injury is the most common form
of ligamentous injury of the wrist seen in 60% of the cases . If undiagnosed,
SLL injury leads to progressive limitation of movement, chronic pain and other
irreversible changes within the joint. If Untreated, SLL injury is by far the
most frequent cause of degenerative osteoarthritis of the wrist.

The wrist is the most complex joint in the human body. It consists of 8 wrist
bones, 26 ligaments and numerous articular surfaces. The complex movements of
these bones during wrist motion are still poorly understood. Diagnosis is
sometimes difficult owing to poor understanding of carpal kinematics;
inconsistencies in the physical examination and limited value of imaging
methods Treatment outcomes are variable by lack of quantitative data.
In order to functionally stabilize the wrist, numerous strong ligaments
interconnect the wrist bones together and to other surrounding structures
allowing them to function cohesively. Wrist stability can be described as the
ability of the wrist to maintain a normal balance between the articulating
bones under physiologic loads and movements without overloading or loss of
motion control. However, the functional balance between the articulating bones
may be disturbed due to ligament dysfunction. This can be observed as a loss of
joint integrity and malfunctioning of the wrist during movements which is
manifestated as pain, typical snaps, painful clicks and the sense of loss of
control and strength during hand use.

In the current diagnostic practice, plain radiographs are acquired for the
evaluation of the wrist after a trauma. Although for skeletal pathology static
imaging modalities are in most cases sufficient to diagnose fractures and
dislocations of bony structures, for dynamic abnormalities, static images are
insufficient. Unless there is an obvious gap between wrist bones, ligamentous
injury and its related abnormal wrist movements are missed. Current static
diagnostic modalities have shown to have limited value in detection of wrist
ligament injuries. (Arthrography: sensitivity 60-67%, specificity 70%-100% CT:
53% false negatives, MRI: sensitivity 33.3% and specificity of 48% ).

Currently it is only possible to diagnose isolated injuries of ligaments with
invasive methods such as arthroscopy which is now seen as the "gold standard".
Beside the fact that it is a surgical procedure, it has also the disadvantage
of being laborious, time consuming, and too expensive to use as a standard
diagnostic tool. Consequently, SLL injury frequently goes undiagnosed and
untreated, often being passed off as a simple sprain. As a result, late
recognition of SLL injuries often leads to damage of the joint that cannot be
treated without residual problems in joint function. In these cases, the
instability has progressed so much that the chances for success after surgical
reconstruction are strongly diminished. Unfortunately this is a frequently
observed situation for many patients seen in the clinic [12]. In this light the
specific clinical problem that is addressed in the study is:

*Due to lack of a validated non-invasive diagnostic tool, scapholunate ligament
injuries in the wrist are currently not diagnosed after a wrist trauma. This
makes an early intervention impossible causing irreversible damage to the
wrist*.

Previous cadaver studies have proven that total SLL ruptures result in
detectible alterations of wrist kinematics. Since dynamic abnormalities are
believed to be of greater value for detecting of partial and total ligamentous
injuries, various authors have pleaded for a diagnostic technique that is both
noninvasive and capable of documenting abnormal kinematics. Concomitant to
these expectations we hypothesize that ligamentous injury of the wrist will be
better detectible by dynamic diagnostic methods, implying that the wrist
kinematics will be indicative for ligament function. By providing us
quantitative data such tool enables us to diagnose ligament injuries and
evaluate the benefits of such interventions afterwards.
We developed a new method for the acquisition of dynamic 3D images of a moving
joint . In our method a 3D-rotational x-ray system is used to image a cyclic
moving joint during a period of time. This results in multiple sets of
projection images, which are reconstructed to a series of time resolved 3D
images i.e. 4D-rotational X-ray. In this way we are able to investigate dynamic
wrist behavior in a non-invasive way (figure 3). The resulting data are
processed whereby movements can be quantified, and studied. By using these
quantitative data we will be able to differentiate between normal and abnormal
wrist kinematics which occur after ligament disruption. After describing these
differences we expect to investigate the benefits of a reconstructive operation
which we expect to be measurable in the terms of improved carpal kinematics.

The aim is to gain basic dynamic information for an upcoming accuracy studies
whereby the diagnostic value of 4D-RX will be determined. By comparing healthy
individuals with those with scapholunate ligament dissociation we expect to
detect abnormal motion patterns which we will quantify in measurable values.
Delineation of specific motion patterns and discriminative values will enable
us to set up new definitions for diagnosing ligamentous wrist pathologies. By
Rescanning patients with scapholunate ligament rupture after a reconstructive
procedure we expect to show the benefits of such interventions.

This study is a Pilot comparative case-control study. The aim is to gain
information for upcoming accuracy studies whereby the diagnostic value of 4D-RX
will be determined.
In all groups both wrists will be scanned by our 4D-RX method during
flexion/extension, radioulnar deviation. Same scans are obtained once again
while axial loading is extended during flexion/extension, radioulnar deviation.
3 months after a reconstructive procedure the operated wrist is scanned again
to evaluate and study the effects of such operations. Scans are obtained during
flexion/extension and radioulnar deviation.

For healthy individuals this means a net radiation exposure of 0.1-0.15 mSv.
For people with scapholunate ligament dissociation this exposure will be 0.2
mSv.