Clin Orthop Surg.  2022 Jun;14(2):184-190. 10.4055/cios21042.

The Relationship between Femoral Stem Tilt and Stem Length in Total Hip Arthroplasty: A Retrospective Case-Control Study

• Yoon JY
• Seo WY
• Kim HJ
• Yoo JJ

• KMID: 2529751
• DOI: http://doi.org/10.4055/cios21042

Abstract

Background
The current trend of using short femoral stems in total hip arthroplasty (THA) is associated with angular deviation of the femoral stem towards the native femoral axis. The purpose of this study was to compare the difference in stem tilt angle between two different stems with a similar design except for the stem length.
Methods
This is a retrospective review of 66 patients who underwent primary THA between April 2012 and May 2016, using a trans-gluteal direct lateral approach by a single surgeon. We evaluated the femoral stem tilt angle in both the coronal and sagittal planes and performed multivariate logistic regression analysis to evaluate possible risk factors. We also simulated the range of motion (ROM) of the hip joint using three-dimensional computer-aided design software (SolidWorks, 2016) to examine the clinical significance of femoral stem tilt.
Results
The mean coronal tilt angle was 1.8° ± 1.0° in the conventional stem group and 1.6° ± 1.1° in the short stem group, showing no statistically significant difference between the groups (p = 0.570). However, the mean sagittal tilt angle was 4.0° ± 2.0° in the conventional stem group and 7.8° ± 2.0° in the short stem group (p < 0.001). The stem type and stem length had a linear correlation with the sagittal tilt angle (p < 0.001) in multivariate regression analysis. A simulated hip ROM demonstrated a 3.8° decrease in extension in proportion to a 3.8° increase in the mean sagittal stem tilt angle of the short femoral stem.
Conclusions
Anterior femoral stem tilting in the sagittal plane was prominent when the shorter stem was used, and anterior tilting was responsible for decreased ROM in hip extension.

Keyword

Hip joint; Total hip arthroplasty; Prosthesis design; Sagittal stem alignment; Combined anteversion