Fluoroscopic evaluation of the Duracon total knee prosthesis

Three-dimensional (3D) fluoroscopic analysis is the most accurate measurement
technique to examine the in vivo kinematics of TKR (Banks et al., 1997; Dennis
et al., 1996; Dennis et al., 1998a; Garling et al., 2005; Stiehl et al., 1999).
The position and orientation of 3D computer models of total knee components are
manipulated so that their projections on the image match those captured during
the in vivo knee motion (Garling et al., 2002; Kaptein et al., 2006).

Fluoroscopic analysis studies has shown that there is a broad range of
kinematic patterns of the femur with respect to the tibia during dynamic
activities and a significant proportion of implanted knees has abnormal
kinematics (Callaghan et al., 2001; Dennis et al., 1998b; Stiehl et al., 1999).
In the short term, poor kinematics may lead to a feeling of instability and
limits the mobility of the patient. In the long term, abnormal kinematics may
lead to accelerated wear of the articular surfaces (Banks and Hodge, 2004;
Krichen et al., 2006) and excessive stresses in bone-implant interface leading
to aseptic loosening (Taylor and Barrett, 2003).

The kinematics are determined by the design of the implant, particularly the
geometry of the articulating surfaces, the alignment of the components with
respect to the bone and to each other, and of the surrounding soft tissue
(Dennis et al., 1998b; Karrholm et al., 1994). Because of the influences of the
prosthesis design, it is important to asses the in vivo characteristics and
functional adaptations of the design following TKR (Banks and Hodge, 2004;
Banks et al., 1997; Taylor et al., 2003).

The goal of this study is to perform a kinematic evaluation of the Duracon knee
prosthesis (Stryker, USA), by means of fluoroscopy and EMG. The findings of
this study will contribute to improve total knee designs and improve
rehabilitation strategies.

1 year post-operative patients will be evaluated with fluoroscopy and EMG.
Also, patients are asked to fill in several questionnaires.

For fluoroscopy the cumulative effective dose will be 0.02 mSv (3 trials × 2
tasks × 3 seconds of 15 fps imaging). The additional annual radiation dose is
negligible if the natural annual exposure of 2 mSv is considered and will do
the subject no harm.

The International Commission on Radiological Protection categorizes the
corresponding level of risk qualitative due to radiation as *trivial* with a
quantitative risk of about one in a million or less. The required level of
benefit should be related to *only increase knowledge*.
(http://ec.europa.eu/energy/nuclear/radioprotection/publication/099_en.htm)

Other potential risks are risks associated with normal knee replacements such
as infection, migration, bone loss, pain, loosening of components, metal
sensitivity reactions and tromboembolic complications.