Native Anteversion in the Total Hip Replacement Population.

Presenting Author – Sanjeev Gupta
Introduction Appropriate femoral stem anteversion is an important factor in maintaining stability and maximising the performance of the bearing after total hip replacement (THR). The anteversion of the native femoral neck has been shown to have a significant effect on the final anteversion of the stem, particularly with a uncemented femoral component. The aim of this study was to quantify the variation in native femoral neck anteversion in a population of patients requiring total hip replacement. Methods Pre-operatively, 1215 patients received CT scans as part of their routine planning for THR. Within the 3D planning, each patient’s native femoral neck anteversion, measured in relation to the posterior condyles of the knee, was determined. Patients were separated into eight groups based upon gender and age. Males and females were divided by those under 55 years of age, those aged 55 to 64, 65 to 74 and those 75 or older. Results The median femoral anteversion across all 1215 subjects was 14.4° (-27.1°–54.5°, interquartile range (IQR) 7.4°–20.9°). The median anteversion in males was 12.7° (-27.1°–45.5°, IQR 6.0°–19.1°), compared to female anteversion of 16.0° (-14.0°–54.5°, IQR 9.7°–22.4°). These gender differences were statistically significant, p < 0.0001. Femoral anteversion in young males (75), p=0.002. This age-related difference approached significance in females, p = 0.06. 14% of patients had extreme anteversion (30°) Conclusion
• Native femoral neck anteversion in patients requiring THR is widely variable, with a range of over 80°.
• Females have higher femoral anteversion than males.
• Femoral anteversion in young males was significantly higher than in older males. This age-related difference approached significance in females.
• Having an understanding of 3D patient morphology can greatly assist in pre-operative planning of THR, as post-op stem anteversion is likely influenced by the anteversion of the native femoral neck.