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Combined anteversion technique reduced the dislocation in cementless total hip arthroplasty
Yasuharu Nakashima1, Masanobu Hirata, Mio Akiyama
1Department of Orthopaedic Surgery, Kyushu University, Fukuoka, Japan, yasunaka@ortho.med.kyushu-u.ac.jp.
Insights
The combined anteversion (CA) technique in total hip arthroplasty (THA) significantly reduces dislocation rates. This method, where the cup placement matches stem anteversion, proved more effective than manual cup placement.
Area of Science:
- Orthopedic Surgery
- Biomedical Engineering
Background:
- Total hip arthroplasty (THA) aims to restore function and reduce pain.
- Dislocation remains a significant complication following THA.
- Accurate component positioning is crucial for THA success.
Purpose of the Study:
- To evaluate if the combined anteversion (CA) technique reduces dislocation rates in primary cementless THA.
- To assess the accuracy of CA achieved with manual cup placement.
Main Methods:
- Retrospective review of 634 primary cementless THA cases.
- Comparison between CA technique group (n=230) and manual placement group (n=404).
- Post-operative CA measured via CT scans in 111 hips.
Main Results:
- Dislocation rate was 0.4% in the CA group vs. 2.5% in the manual group.
- CA technique was a significant factor in reducing dislocations (OR 5.8).
- 73% of hips achieved intended CA with the CA technique.
Conclusions:
- The combined anteversion technique significantly lowers dislocation risk after primary THA.
- Manual cup placement can lead to outliers from the intended CA.
- CA technique offers improved component alignment and patient outcomes.
Purpose:
The combined anteversion (CA) technique is a method in which the cup is placed according to the stem anteversion in total hip arthroplasty (THA). We examined whether the CA technique reduced the dislocation rate, and the distribution of CA with the manual placement of the cup.
Methods:
We retrospectively reviewed 634 hips in 579 patients with primary cementless THA. In 230 hips using the CA technique [CA(+)], a CA of 50 ± 10° was the aim. In the remaining 404 hips [CA(-)], the cup was first placed targeting 20° of anteversion. The post-operative CA was measured using the computed tomography (CT) images in 111 hips.
Results:
One hip (0.4%) had a dislocation in the CA(+) group, whereas ten hips (2.5%) had a dislocation in the CA(-) group. A multivariate analysis showed that primary diagnosis, head size and CA technique significantly influenced the dislocation rate. Patients in the CA(-) group were 5.8 times more likely to have a dislocation compared to the CA(+) group. In the 111 hips with CT images, 81 hips (73.0%) achieved the intended CA.
Conclusions:
Although the manual placement of the cup resulted in 27% of outliers from the intended CA, the CA technique significantly reduced the dislocation after primary THA.
