[Wristing -- a new opportunity in digital migration analysis of uncemented total hip arthroplasty]

The aim of this study was to evaluate a computer program (Wristing) for digital migration analysis in hip endoprotheses and to assess the most accurate landmarks in hip-alone radiographs.

Conventional radiographs of 52 patients with a minimum follow-up period of seven years and five consecutive radiographs were digitised and different landmarks were compared. The parameters with the greatest accuracy were analysed to calculate inter- and intra-observer variability in 30 radiographs. Digital and manual measurement techniques were compared with each other.

The obtained accuracy (95 % confidence interval) was 1.7 to 2.2 mm and 2.8 degrees to 3.2 degrees for the most accurate landmarks. The intra-observer variability was 0.12-0.3 mm; 0.28 degrees and the inter-observer variability ranged from 0.14 to 0.45 mm and 0.5 degrees to 0.53 degrees . In comparison to the migration measurement with pencil and ruler (precision: 0.24-0.67 mm; 0.57-0.74 degrees ) the new software (precision: 0.12-0.3 mm; 0.28 degrees ) was associated with a superior accuracy (t test: p < 0.001).

With the program "Wristing" migration in hip-alone radiographs could be recorded with high precision. The integrated sketch, zooming and the current possibility of comparing radiographs and patient data with previous follow-ups and examples leads to a high inter- and intra-observer accuracy and is very useful in day-to-day clinical practice.