R_Bibb_Medical_Modelling_The_Application_of_Adv.pdf

140 Medical modelling
long-standing arthritis and subsequent disuse, or possibly due to the inadvertent
cortical contact of one of the trephines used to prepare the proximal
tibia.
The authors recognise that, although it is still small, there is an increased
radiation dose to the patient associated with the use of a CT scan in this
technique when compared to the plain radiographs normally used. A scan
of the knee, being an extremity, does not put any other radiosensitive
structures in the fi eld. Although, in addition to the images produced, there
is also the opportunity, as was done in this case, for three-dimensional
reconstruction both virtually, and now as a physical model, which can be
compared to the proposed prosthesis pre-operatively.
The technique can be used on any tissue that can be clearly distinguished
in either CT or MR images. Whilst we do not suggest that this technique
is required for any joint replacement which is anything other than ‘straightforward’,
however; this case has demonstrated its value in knee arthroplasty
(surgical knee joint repair) in cases with complex anatomy where the bone
shape and quality was diffi cult to predict from plain fi lms. The creation of
a three-dimensional model facilitates pre-operative planning in diffi cult
cases and provided valuable information prior to surgery.
6.4.6 References
1. Gautsch T L, Johnson E E, Seeger L L (1994), ‘True three-dimensional stereographic
display of 3-D reconstructed CT scans of the pelvis and acetabulum’,
Clinical Orthopaedics, 305, 138–51.
2. Barmeir E, Dubowitz B, Roffman M (1982), ‘Computed tomography in the
assessment and planning of complicated total hip replacement’, Acta
Orthopaedica Scandinavica, 53, 597–604.
3. Roach J W, Hobatho M C, Baker K J, Ashman R B (1997), ‘Three-dimensional
computer analysis of complex acetabular insuffi ciency’, Journal of Pediatric
Orthopedics, 17, 158–64.
4. Migaud H, Cortet B, Assaker C, Kulik J F, Fontaine C, Duquennoy A
(1997),‘Value of a synthetic osseus model obtained by stereo-lithography for
preoperative planning: correction of a complex femoral deformity caused by
fi brous dysplasia’, Revue d’orthopedie et de chirurgie de l’appareil moteur, 83,
(2), 156–9.
5. van Dijk M, Smit T H, Jiya T U, Wuisman P I (2001), ‘Polyurethane real-size
models used in planning complex spinal surgery’, Spine, 26 (17), 1920–26.
6. Munjal S, Leopold S S, Kornreich D, Shott S, Finn H A (2000),‘CT-generated
3-dimensional models for complex acetabular reconstruction’, Journal of
Arthroplasty, 15, 644–53.
7. McCarthy J C, Bono J V, O’Donnell P J (1997), ‘Custom and modular components
in primary total hip replacement’, Clinical Orthopaedics, 344, 162–71.
8. Bert J M (1996), ‘Custom total hip arthroplasty’, Journal of Arthroplasty, 11,
905–15.