The effect of acetabular and femoral component version on dislocation in primary total hip arthroplasty
Takaaki Fujishiro1,2, Takafumi Hiranaka3, Shingo Hashimoto4
1Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-Cho Chuo-Ku, Kobe, Hyogo, 650-0017, Japan. taka2446@yg8.so-net.ne.jp.
Insights
Optimizing acetabular component anteversion between 10° and 30° is crucial for reducing total hip arthroplasty (THA) dislocation risk. Deviations in version increase the likelihood of dislocation, with specific associations for anterior and posterior hip instability.
Area of Science:
- Orthopedic Surgery
- Biomedical Engineering
- Radiology
Background:
- Total hip arthroplasty (THA) is a common procedure to alleviate hip pain and restore function.
- Hip dislocation remains a significant complication following THA, impacting patient outcomes.
- Understanding component alignment is critical for preventing THA instability.
Purpose of the Study:
- To analyze the variability of acetabular and femoral component version in primary THA.
- To determine the relationship between component alignment, clinical factors, and hip dislocation after THA.
Main Methods:
- CT scans of 1,555 primary THA patients were analyzed to measure component version.
- Dislocation frequency, direction, and associated factors (femoral head size, posterior tissue repair, prior surgery, gender) were recorded.
Main Results:
- The overall dislocation rate was 3.22%.
- Cup anteversion outside the 10°-30° range increased dislocation risk by 1.9 times.
- Increased combined anteversion correlated with anterior dislocation; smaller combined anteversion correlated with posterior dislocation.
- Previous rotational acetabular osteotomy and small femoral head size (<28 mm) were linked to higher dislocation rates.
Conclusions:
- Maintaining cup anteversion within the 10°-30° range is essential for minimizing THA dislocation risk.
- Component alignment, specifically combined anteversion, plays a role in the direction of dislocation.
- Patient-specific factors like prior surgery and femoral head size influence dislocation risk.
Purpose:
The purpose of the present study was to: (1) investigate the variation of both acetabular and femoral component version in a large series of consecutive primary THA patients, and (2) to better define the associations of acetabular and femoral component alignment and clinical factors with subsequent hip dislocation in those patients.
Methods:
We analyzed CT scans of 1,555 consecutive primary THAs and measured version of the components. We also documented the frequency and direction of subsequent dislocation as well as femoral head size, posterior tissue repair, any history of previous hip surgery, and gender.
Results:
The dislocation rate after THA was 3.22 %. The dislocation risk was 1.9 times higher if cup anteversion was not between 10° and 30°. Compared to hips that did not dislocate, those that experienced anterior dislocation had a significantly greater combined anteversion; those that dislocated posteriorly had a significantly smaller combined anteversion. Hips with previous rotational acetabular osteotomy or head size smaller than 28 mm correlated with an increased dislocation rate.
Conclusion:
The dislocation risk could be higher if cup anteversion was not between 10° and 30°. Greater combined anteversion could be a risk factor of anterior dislocation, and posterior dislocation could be more common in smaller combined anteversion.
