Article

A high accuracy was recently reported for the three-dimensional
(3D) computerised planning of total hip arthroplasty (THA), comparing well with
navigation regarding leg length and femoral offset. However, there is no
randomised study comparing 3D preoperative planning with conventional 2D
templating in terms of accuracy and clinical relevance. HYPOTHESIS: The 3D
preoperative planning has a higher accuracy than the conventional 2D preoperative
templating regarding the implants size and their positioning. METHODS: A prospective comparative randomised study was carried out from 2008 to
2009, including two groups of 30 patients who underwent THA for primary
osteoarthritis. One surgeon performed all the surgical procedures using a
minimally invasive direct anterior approach. In one group, the planning was made
on calibrated X-rays using 2D templates. In the other group, a CT-scan based 3D
computerised planning was performed with dedicated software. The reconstructed
hip final anatomy was compared postoperatively to the preoperative planning and
the accuracy was expressed as the mean difference (+/-SD) between the planned
positioning and the final positioning of the implants. RESULTS: The prediction
rate for the stem and the cup sizes were respectively of 100% and 96% in the 3D
group versus 43% for both components in the 2D group. When combining both
components, the prediction rate was 96% in the 3D group versus 16% in the 2D
group. In the 3D group, a high accuracy was achieved for the planning of the leg
length (-1.8+/-3.6mm ranging from -8 to+4mm) and the femoral offset
(-0.07+/-2.7mm ranging from -5 to+4mm) versus 1.37+/-6.4mm ranging from -9 to
13mm and 0.33+/-5.7mm (-16 to 11mm) in the 2D templating group (P<0.0001).
DISCUSSION: The 3D planning gives a higher accuracy than conventional 2D
templating in forecasting the size of cup and the stem. This contributes to the
prediction for leg length and offset that is more reliable with the 3D technique.
This study suggests that 3D planning CT-scan data is an attractive alternative to
navigation to restore these parameters. The high accuracy achieved by a
low-experience surgeon suggests that 3D planning may help shorten the learning
curve when using the minimally invasive direct anterior approach. LEVEL OF EVIDENCE: Level III low-powered prospective randomized trial.
CI - Copyright (c) 2012 Elsevier Masson SAS. All rights reserved.

Langue : ANGLAIS

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