Background
Radiographic outcomes after total hip arthroplasty (THA) have been linked to clinical outcomes. The direct-anterior approach (DAA) for THA has been criticized by some for providing limited exposure and compromised implant position, but allows for routine use of intra-operative fluoroscopy. We sought to determine whether radiographic measurements differed by THA approach using prospective cohorts.
Methods
Two reviewers blinded to surgical approach examined 194 radiographs, obtained 4–6 weeks after primary THA, and obtained measurements for acetabular inclination angle, acetabular anteversion, radiographic limb length discrepancy (LLD), and femoral offset. All surgeries were performed at a tertiary academic medical center in rural New England by an experienced fellowship-trained arthroplasty surgeon. Measurements for inclination angle, anteversion, LLD, and offset were made into binary yes/no responses based on whether the mean measurement (between the two reviewers) was acceptable or not based on established criteria. Multivariate logistic regression analyses were performed using pre-operative and intra-operative characteristics to identify predictors of acceptability for each measurement.
Results
The DAA group had higher rates of acceptable acetabular angle (96 vs. 85%, P=0.005), and was protective against an unacceptable angle in an adjusted predictive model (OR 0.16, P=0.005). There were no significant differences between approaches for acceptable anteversion, LLD, or offset. Body mass index of 30–34 was associated with higher odds of unacceptable inclination angle compared to the non-obese group (aOR 6.82, P=0.013).
Conclusion
DAA for THA was associated with lower odds of unacceptable inclination angle compared to the posterior approach, with no differences in anteversion, LLD, or offset.