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


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Schönrath
F
F
Universitätsklinik und Poliklinik für Orthopädie und Physikalische Medizin, Klinikum der Medizinischen Fakultät der Martin-Luther-Universität Halle-Wittenberg.
Hein
W
W
Klima
S
S
Bach
A
A
D000077:Acetabulum / Q000000981:diagnostic imaging; D016001:Confidence Intervals; D019544:Equipment Failure Analysis; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008432:Mathematical Computing; D015588:Observer Variation; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011859:Radiography; D012680:Sensitivity and Specificity; D012984:Software