Digital comparison of planned and implanted stem position in total hip replacement using a program form migration analysis

Aim

One main goal in primary total hip replacement is the reconstruction of preoperative biomechanical conditions by adequate implant positioning. Our aim was to compare the planned and effectively implanted stem position in using a program for digital migration measurement.

Patients

We examined 120 cases with this new method based on a modification of the EBRA-FCA program and compared these results to direct plain radiographic methods. In addition, the intra- and inter-observer reliability was determined in 50 cases.

Results

We observed a rate of correct prediction of 80% for the size of the stem. The new method revealed a good correlation (0.95 and 0.64 for the position along the stem axis and 0.84 for the stem angle) to direct plain radiographic methods. Regarding the intraclass correlation coefficient for intra- and inter-observer reliability, the results were superior (0.97 vs. 0.81?C0.84 and 0.90 vs. 0.74?C0.88) compared with direct plain radiographic methods.

Conclusion

We concluded that the comparison of the planned and implanted stem position using a modified EBRA-FCA method is more reproducible than direct radiographic measurements.