Investigating carpal kinematics after Four Corner Arthrodesis by new developed 4-dimensional Rotational X-ray imaging - A pilot study

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 [5]. 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% [6]. Injuries to hand and wrist account for 28.6% of all
attendances at the accident and emergency department [7].

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.


An accepted salvage procedure for the treatment of specific wrist disorders
such as scapholunate advanced collapse and scaphoid non-union advanced
collapse, is four corner arthrodesis.
This procedure, fixing the lunatum, capitatum, triquetrum and hamatum is also
called LCTH fusion. By fusion of these carpalia a decrease in the range of
motion is taken for granted. However the distribution of the remaining range of
motions concerning flexion, extension, ulnary- and radiairy deviations strongly
depends on the position in which the lunatum has been fixed in this bone-block.
In practice, subsequent arthrosis of the radio-ulnair joint is common. A
dyscongruency of the joint surfaces of the radius and the lunatum during
movement is, besides pre-existing articular damage in the radio-ulnairy joint,
a possible explanation. The locally developing high pressures on the articulair
surfaces result in damage of the cartilage.

Osteoarthritis is a wellknown cause of wrist complaints. Four Corner
Arthrodesis is an accepted salvage procedure for the treatment of specific
wrist disorders such as Scapholunate advanced collapse and scaphoid non-union
advanced collapse.
This procedure, fixing the lunatum, capitatum, Triquetrum and Hamate is also
called LCTH fusion. By fusion of these carpal bones a decrease in the range of
motion is taken for granted. However the distribution of the remaining range of
motions concerning flexion, extension, radiol-ulnar deviations strongly depends
on the position in which the lunate has been fixed in this bone-block. In
practice, subsequent osteoarthritis of the radio-ulnar joint is common. A
dyscongruency of the joint surfaces of the radius and the lunate during
movement is, besides pre-existing articular damage in the radio-ulnar joint, a
possible explanation. The locally developing high pressures on the articular
surfaces result in damage of the cartilage.
The aim of this study is to study radio-lunate interaction in patients who have
undergone a FCA procedure in the past.
We hypothesize that the radiolunate rotation angle is of great importance for
developing osteoarthritis of the radiocarpal joint after FCA. The main question
of this study is whether the radiolunate rotation angle and joint congruency
correlate with developing severe osteoarthritis of the radio-lunate joint
surface in patients who have undergone FCA in the past.

This experiment is a Pilot study. The aim is to gain information of the outcome
of FCA on the wrist movements and stability. Both wrists of all patients will
be scanned by our 4D-RX method during flexion/extension, radioulnar deviation.
The scans of the healthy and operated wrists will be compared to eveluate and
study the effects of FCA.
CT scans of both wrists are made previous to 4D-RX scans. The scans are
categorized by the degree of radio-lunate osteoarthritis in to mild, moderate
and severe.

A group of patients with unilateral FCA in the history who*s healthy and
affected wrist will be scanned. First a regular dose CT scan will be obtained
to acquire volume reconstructions of carpal bones. Hereafter both wrists will
be scanned by our 4D-RX method during flexion/extension motion (FEM) and
radioulnar deviation (RUD). The total radiation exposure of the experiments is
about 0.25 mSv which is comparable to 5 weeks natural background exposure in
the Netherlands.