[Measurement of acetabular cup inclination in anteroposterior pelvic radiogram : An indicator of quality after primary total hip arthroplasty?].

BACKGROUND AND OBJECTIVE

Acetabular cup orientation, consisting of pelvic positioning, version and inclination, can influence short-term and long-term results after total hip arthroplasty (THA). The radiographic measurement of acetabular cup inclination represents an indicator of quality for the EndoCert certification in Germany. The purpose of this study was to determine the intrarater and interrater reliability of radiographic measurements of acetabular cup inclination after THA.

MATERIAL AND METHODS

In this study four independent investigators with different levels of expertise retrospectively performed measurements on radiograms (anteroposterior pelvic radiogram) from 99 patients. The intraclass correlation coefficient (ICC) and Pearson's correlation coefficient were determined and were considered statistically significant with r > 0.8 and p < 0.05.

RESULTS AND CONCLUSION

A high correlation was found for both intrarater and interrater reliability based on determination of Pearson's correlation coefficient and the ICC with r > 0.9 and p < 0.001 for all measurements. Based on these results the radiographic measurement of acetabular cup inclination can be considered as a simple measuring tool with high intrarater and interrater reliability. As cup orientation consists of inclination, version and positioning, the exclusive measurement of cup inclination for radiological quality assessment needs to be discussed critically.