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. 2018 Mar 27;15(3):787-791.
doi: 10.1016/j.jor.2018.03.027. eCollection 2018 Sep.

The 3-dot circle: A reliable method for safe and efficient digital templating of the acetabular component

Firas Arnaout  1 , Varun Dewan  1 , Christos Paliobeis  1
Affiliations

The 3-dot circle: A reliable method for safe and efficient digital templating of the acetabular component

Firas Arnaout et al. J Orthop. .

Abstract

Background: Templating for preoperative planning of joint arthroplasty has followed the evolution of digital templating software.

Objective: This study aims to provide a safe, reliable and reproducible method for prediction of acetabular component size based on measurement of the radiographic femoral head diameter, with the aid of templating software.

Methods: A defined methodology for femoral head measurement was applied to 97 consecutive, calibrated digital pelvic radiographs. Based on radiographic femoral head diameter, the minimum acetabular shell diameter was calculated and then compared to the size of the implanted acetabular shells.

Results: This method predicted safe minimum acetabular component size with an accuracy of 95.9% with a high inter-observer reliability of 97.6%.

Conclusions: This study presents a simple, reproducible and accurate method for templating of the minimum safest acetabular component diameter.

Keywords: Hip replacement; Preoperative planning; Preoperative templating; THR.

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Figures

Fig. 1
Fig. 1
KingMark® calibration device.
Fig. 2
Fig. 2
Anteroposterior pelvic radiograph showing adequately aligned KingMark®.
Fig. 3
Fig. 3
Anteroposterior pelvic radiograph demonstrating the ‘three-dot circle’ technique of femoral head measurement with blue circles pointing to the three-dot allocation.
Fig. 4
Fig. 4
Flow chart of patients included.
Fig. 5
Fig. 5
Results of cup size minus femoral head measurements in the two assessors) C—H: cup minus head measurement.
See this image and copyright information in PMC

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