Diagnostic performance of dynamic four-dimensional computed tomography (4D CT) compared to arthroscopy for analyzing scapholunate instability.

The wrist is a complex joint, consisting of different separate joints with
intricate inter- and intra-osseous kinematics and stabilisation by different
ligaments. Carpal instabilities based on ligament tears are a relatively common
pathology, especially the one between the scaphoid and lunatum (SLIL). Tears of
SLIL leads to scapholunate instability (SLI) which leads to pain and eventually
to wrist osteoarthritis when untreated. Due to the importance of the wrist and
hand in daily life and in most modern workplaces, this imposes a substantial
morbidity on patients and a considerable societal cost. Patients with an early
diagnosis of ligament tears may benefit from less-invasive treatment options
and have a better prognosis. In the beginning (dynamic) SLI only demonstrates
abnormalities during motion. This would explain the frequent lack of observable
pathologies in static radiographic like X-rays, MRI and CT scans. Because of
its high sensitivity and specificity, wrist arthroscopy still is the gold
standard for diagnosing ligament tears of the wrist. The disadvantage is that
arthroscopy is an invasive technique with operational risks (2%) and that the
function of ligaments cannot be assessed dynamically. Studies have shown that
with the promising new imaging method of 4D CT scanning dynamic imaging of
wrist motions is possible with higher diagnostic performance. More knowledge of
the kinematics of the normal wrist can be obtained by 4D CT. Besides, by
visualizing carpal dynamics in 3 dimensions, it holds the promise of increasing
the understanding of the impact of dynamic SLI on the complex wrist kinematics,
and creates an opportunity to quantitatively and non-invasively follow-up
patients with subtle SL lesions in a prospective manner, potentially forming a
basis for further research that could increase the efficacy of treatments for
this condition.
This would decrease the need for diagnostic arthroscopy dramatically, meaning
less costs and less patient burden.
Radiation exposure is a drawback in 4D CT. Research in the orthopaedic research
lab of the Radboud University Medical Center has demonstrated the feasibility
of 4D CT for use in imaging the moving knee joint at very low radiation doses.
In accordance with this protocol, we want to investigate the feasibility of the
4D CT for the moving wrist joint to visualize the displacement of the bones of
the wrist with the lowest dose possible in a pilot study on healthy volunteers.
Hereafter, we want to perform a diagnostic clinical stud yin which we want to
determine the sensitivity and specificity of the 4D CT to analyse SLI in
comparison with arthroscopy (gold standard).

It is currently common practice to perform diagnostic wrist arthroscopy in
patients suspected of scapholunate instability (SLI). This is an invasive,
relatively expensive and non-dynamic approach. Small lesions or dynamic
dysfunction of the scapholunate interosseous ligament (SLIL) are difficult to
diagnose. Improvements in CT scanning technique have recently made
higher-speed dynamic imaging at lower dose possible, allowing accurate imaging
of the wrist bones in motion, but this method requires validation.

The primary objective of the presented study is to determine the diagnostic
performance (sensitivity and specificity) of the 4D CT scan in the diagnosis of
SLI in comparison with arthroscopic findings (gold standard), after
determination of optimal radiological settings of the 4D CT scan (pilot study).

Hypotheses:
1) Differences in 4D CT parameters (radioscaphoid angle (RSA), lunatecapitate
angle (LCA), scapholunate angle (SLA), radiolunate angle (RLA), scapholunate
distance (SLD)) will be found in patients with and without SLI tears (verified
by arthroscopy).
2) SLD (measured on 4D CT) will be correlated with the arthroscopic Geissler
classification; a larger SL lesion will give a larger SL distance.
3) The more extensive the SL lesion on 4D CT, the more the carpal angles of SLI
wrists will differ from angles measured for the non-SLI wrists
4) 4D CT parameters are more sensitive to arthroscopy-proven SLI than standard
3D CT and conventional radiography.

We hypothesize that 4D CT can be used as a first-choice non-invasive imaging
modality to diagnose SLI and to discriminate SLI from other causes of wrist
pain. Arthroscopy can then be reserved for those patients with inconclusive 4D
CT scans or as a therapeutic procedure.

Study design: pilot study and single center clinical diagnostic study
Pilot study: 15 healthy volunteers undergo a bilateral 3D CT scan and a
bilateral dynamic 4D CT scan while moving the wrist.
Clinical diagnostic study: 30 patients suspect for scapholunar instability
(SLI), a plain bilateral wrist radiograph, a static bilateral CT scan, a
bilateral 4D CT scan and a unilateral arthroscopy of the SLI wrist will be
performed. Both the plain radiographs as the arthroscopy concerns normal
diagnostic work-up of patients suspect for SLI.
Plain radiographs: acquisitions of both wrists in a neutral position
(posterior-anterior, lateral, ulnar-radial deviated and clenched fist
positions). Parameters to be measured are: scapholunate diastasis, carpal
angles (scapholunate, radiolunate, radioscaphoid, and lunocapitate), presence
of dorsal or ventral intercalated segment instability, and scaphoid *signet
ring sign*.
4D CT scan:. First, a full-dose static CT of both wrists will be acquired.
Then, a dynamic 4D CT scan will be performed while the participant moves both
wrists actively in flexion-extension and ulnar-radial deviation according to a
protocol. One cycle of movements last roughly 10 seconds. Total exposure to
radiation will be 30 seconds in total. In the pilot study optimal radiological
settings will be determined by a computerized low-dose simulation to find the
minimal dose able to reliably yield usable imaging data.
Arthroscopy (gold standard): Each patient will undergo a wrist arthroscopy. The
surgeon will be blinded for the 4D CT results. Further treatment of the patient
depends on the findings during the arthroscopy as in standard clinical
practice. Arthroscopy will be performed according to the current standards and
all relevant structures will be assessed and scored using the generally
accepted classification systems. With regard to the SLIL, lesions will be
classified according to the Geissler classification.
4D CT data wil be analyzed, Each wrist will be rated separately in a randomized
order and raters will be blinded to each other, to clinical findings and to
X-ray findings.. Arthroscopy will be seen as the reference standard for
diagnosing SLI. This will lead to three groups: 1) a group in which a SLIL
lesion is found during arthroscopy, considered proven SLI (group 1).2) no SLIL
lesion is found during arthroscopy, SLI will be considered not-proven, despite
the clinical suspicion (group 2), and 3) asymptomatic contralateral wrists
(group 3).
The 4D CT values from these three groups will be compared with each other.

The dynamic 4D CT scan of the wrist has an estimated total effective radiation
dose of approximately 0.03 mSv. In the clinical study, patients will
complementary undergo a dynamic 4D CT of the wrists with a dose below this, the
exact dose will be determined after interim evaluation of the first 10
volunteers (pilot study). This will burden a trivial risk compared to the
natural background radiation in the Netherlands (2mSv).

Volunteers will receive information by teleohone or a visit depending on the
wishes of the volunteer.
iom patient ingepland. Het verdere verloop van de diagnostiek (artroscopie) en
eventuele therapie wordt niet nadelig beinvloed door deelname aan de studie
(dus er vindt geen verlenging van de wachttijd plaats). Het kost de patient 1
maal een extra bezoek aan het RAdboudumc met minimale tijdsbela Vrijwilligers
krijgen van te voren een gesprek met uitleg (poliklinische of telefonisch
afhankelijk van de wens van de vrijwilliger) waarna twee weken bedenktijd voor
het al of niet tekenen van het informed consent. Na ontvangst van het informed
consent zal de 4D CT scan worden ingepland iom de vrijwilliger. De belasting
vergt 1 tot maximaal twee bezoeken aan het Radboudumc met minimale
tijdsbelasting.
Patient verdacht voor SLI krijgen ten tijde van het poliklinische bezoek reeds
de mogelijkheid aangeboden om deel te nemen aan de studie. Dit is geen extra
bezoek. Eveneens wordt een bedenktijd van twee weken ingelast en wordt het 4D
CT scan onderzoek sting.

There is no personal benifit for participation in the study but we expect that
the results of this study will benefit future patients with wrist sprain.
Future research of patients with wrist pathology, pre- and postoperative, will
provide the surgeon with information where to aim for during surgery.

If 4D CT scan is proven to be an accurate tool for diagnosis of SLI in patients
suspected of SLI, it will have significant impact on daily practice of the hand
surgeon by decreasing the need for performing arthroscopy.

Fluoroscopy, the only imaging modality to detect dynamic abnormalities until
now, will be replaced by 4D CT, as it provides more accurate and quantifiable
information of wrist dynamics with comparable radiation exposure when using
modern scanners.
Besides aiding in better diagnosis of SLI, if surgical intervention of SLI is
deemed appropriate, the source of the instability might be more precisely
identified and allow clinicians to offer more specific and appropriate surgery
for each patient. Following from this, the effect of different surgical
interventions on wrist kinematics can be non-invasively and thoroughly
investigated, helping to guide and shape further knowledge of wrist kinematics
and improve clinical treatment.

In summary, 4D CT can potentially lower the cost and improve the efficacy of
care for the patient and open up a new domain of knowledge that can aid the
diagnosis, and treatment of wrist pathology.


iom patient ingepland. Het verdere verloop van de diagnostiek (artroscopie) en
eventuele therapie wordt niet nadelig beinvloed door deelname aan de studie
(dus er vindt geen verlenging van de wachttijd plaats). Het kost de patient 1
maal een extra bezoek aan het RAdboudumc met minimale tijdsbelaVrijwilligers
krijgen van te voren een gesprek met uitleg (poliklinische of telefonisch
afhankelijk van de wens van de vrijwilliger) waarna twee weken bedenktijd voor
het al of niet tekenen van het informed consent. Na ontvangst van het informed
consent zal de 4D CT scan worden ingepland iom de vrijwilliger. De belasting
vergt 1 tot maximaal twee bezoeken aan het Radboudumc met minimale
tijdsbelasting.
Patient verdacht voor SLI krijgen ten tijde van het poliklinische bezoek reeds
de mogelijkheid aangeboden om deel te nemen aan de studie. Dit is geen extra
bezoek. Eveneens wordt een bedenktijd van twee weken ingelast en wordt het 4D
CT scan onderzoek sting.

Er is geen persoonlijke winst voor de deelnemer aan de studie. Maar de
verwachting is dat indien middels 4D CT scan nauwkeurige diagnostiek kan
plaatsvinden van patienten met een SL lesie en eventuele andere polspathologie,
dat de behoefte aan arthroscopie van de pols enorm afneemt aangezien deze vorm
van diagnostiek een belangrijk onderdeel is geworden van de dagelijks praktijk
voor analyse van chronische polsklachten. Dit zou maatschappelijk een grote
kostenbesparing zijn en voor de patiëntengroep met chronische polsklachten een
veel mindere belasting daar de 4D CT niet invasief is en geen anesthesie
behoeft.