4DCT, Knee, Femoropatellar Instability Clinical Trial
Official title:
Morphological and Biomechanical Analysis of Knee 4DCT in Femoropatellar Instability
To compare the radiological parameters measured by dynamic four dimensional CT (4DCT) in the
analysis of patellofemoral involvement of subjects (amplitude of patellofemoral tilt angle
variations, coefficient of variation of the same angle, distance of lateral displacement of
the patella ) in patients with patellofemoral clinical syndrome to those free of this
syndrome (= control group).
It is expected that the amplitude of patellofemoral tilt angle changes, its coefficient of
variation, and the patella lateral displacement distance differ between the 2 groups
compared. This result would clarify the potential value of dynamic 4D CT in the diagnosis of
PFI
Patellofemoral instability (PFI) is frequent, causing chronic knee pain, functional impotence
or disability because it is associated with the development of early patellofemoral
osteoarthritis. PFI are classically classified into three types: anterior pain syndrome (SR,
without structural abnormality), potential patellar instability (with structural anomaly
favoring, but no history of patellar dislocation) and objective patellar instability (with
structural abnormality and history of patellar dislocation). Diagnosis of the disease outside
objective patellar instability is difficult at present, and objective criteria are lacking to
determine management and evaluate the rehabilitation program of these patients.
Radiographic assessment of the knee is the diagnostic method of reference to objectify
patellar patellofemoral instability and to look for contributing factors including signs of
trochlear dysplasia, and remains the initial method of exploration of a patellar syndrome.
Static imaging reveals signs of objective instability (patellar luxation, fracture stigmas)
or favorite factors (trochlear dysplasia, increased distance of anterior tibial tuberosity /
trochlear throat).
Nevertheless, some important elements in the pathophysiology of patellofemoral instability
such as patellar tilt and lateral displacement of the patella are essentially dynamic and
vary according to the degree of flexion-extension of the knee. Our hypothesis is that the
variation of these parameters during the movements could make it possible to improve the
diagnosis of patellar instabilities without favoring structural anomaly and the follow-up of
the patients who benefit from a patellofemoral reeducation program.
Some authors propose functional MRI of the knee with static acquisitions during different
movements. Nevertheless, no validated technique allows the study of biodynamic anomalies in
real time. The dynamic knee scanner is not very radiating and the knee is not very
radio-sensitive. This technique could therefore represent an interesting alternative allowing
dynamic analysis of patellar displacements during knee flexion and patellar engagement.
Finally, new methods of post-processing CT images based on registration and automatic
segmentation of bone structures are available for clinical application. This type of tool
allows a semi-automatic quantification of patellar displacements that could provide objective
evaluation criteria for patients with patellofemoral instability. In 2016, a Swedish team
published a study on the feasibility of five patients performing a quantitative
semi-automatic dynamic scanner analysis of patellofemoral flexion-extension joint movement.
This shows the value of evaluating this method in a larger population with a control group
Main objective: To compare the radiological parameters measured by dynamic 4D CT in the
analysis of patellofemoral involvement of subjects (amplitude of patellofemoral tilt angle
variations, coefficient of variation of the same angle, distance of lateral displacement of
the patella ) in patients with patellofemoral clinical syndrome (= Cas group) to those free
of this syndrome (= control group).
It is expected that the amplitude of patellofemoral tilt angle changes, its coefficient of
variation, and the patella lateral displacement distance differ between the 2 groups
compared. This result would clarify the potential value of dynamic 4D CT in the diagnosis of
PFI.
Secondary objectives:
1. compare, in the pathologic group, the radiological parameters measured by 4D dynamic CT
(coefficient of variation, amplitude of the patellofemoral tilt angle and distance of
patella lateral displacement) according to the type of patellofemoral instability (
anterior pain syndrome, potential patellar femoro instability and "objective"
femoro-patellar instability) obtained by conventional imaging (static CT).
2. To estimate the interobserver reproducibility of the radiological parameters measured by
4D dynamic CT during image post-treatment in all patients (measurement of patellofemoral
angle of flap angle and distance of patella lateral displacement)
;