Achievement of optimal implant alignment using taper wedge stems with cup-first THA through the MIS antero-lateral approach

Purpose Combined anteversion (CA) technique (stem-first procedure) has become generally accepted as an ideal means to achieve optimal CA value in THA. However, we hypothesized that CA technique for patients with various native femoral anteversions could pose a risk of anterior or posterior cup protr...

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Bibliographic Details
Published in:European journal of orthopaedic surgery & traumatology 2020-12, Vol.30 (8), p.1505-1514
Main Authors: Okada, Taishi, Fukunishi, Shigeo, Yoshiya, Shinichi, Tachibana, Toshiya, Fujihara, Yuki, Masumoto, Yoshinobu, Kanto, Makoto, Takeda, Yu
Format: Article
Language:English
Subjects:
Hip joint
Joint replacement surgery
Medicine
Medicine & Public Health
Original Article
Orthopedics
Surgical Orthopedics
Surgical techniques
Traumatic Surgery
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Summary:Purpose Combined anteversion (CA) technique (stem-first procedure) has become generally accepted as an ideal means to achieve optimal CA value in THA. However, we hypothesized that CA technique for patients with various native femoral anteversions could pose a risk of anterior or posterior cup protrusion. In the present study, we examined whether it is possible to use the taper wedge stem to change the stem version to achieve optimal CA while avoiding cup protrusions with the cup-first procedure through minimally invasive (MIS) antero-lateral approach. Methods Eighty-one patients underwent cup-first THA with a taper wedge stem. The acetabular cup was placed following the preoperative planning of the cup alignment to avoid anterior cup protrusions using CT-based navigation. Following the CA theory, anteversion of the taper wedge stem was changed to the target anteversion from the patient’s native femoral anteversion. The native femoral anteversion, the change in version angle of the stem, postoperative CA and the length of anterior cup protrusions were evaluated in postoperative CT measurements. Results The native femoral anteversion averaged 25.7° ± 8.9° (range 8°–45°). Cases with increased and decreased stem anteversion were observed in 42 hips (51.8%) and 33 hips (40.7%), respectively. The amount of increased and decreased version angles averaged 7.7° ± 4.8° (range 2°–21°) and 7.8° ± 5.1° (range 2°–20°), respectively. Postoperative CA values averaged 36.7° ± 3.4° (range 29.4°–44.2°) and anterior cup protrusion length averaged 2.0 mm ± 2.6 mm (0 ~ 8.8 mm) in axial view and 0.4 mm ± 1.0 mm (0 ~ 3.6 mm) in sagittal view. Anterior cup protrusion of more than 10 mm was not observed in any hips. Conclusion This procedure can be considered as an option to achieve optimal CA anteversion while avoiding anterior cup protrusion in THA.
ISSN:1633-8065
1432-1068
DOI:10.1007/s00590-020-02696-1