This paper describes a simple method to determine stem orientation after total hip replacement. It is based on standard antero-posterior radiographs and computes the angle between prosthesis and film plane from the shortening of predefined distances in the projection.
The error of the method is less than 5 per cent for the stem orientation and less than 10 per cent for the neck orientation. The method allows accurate control of stem orientation by means of standard equipment in orthopaedic practice.
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