Effect of a modular neck hip prosthesis on anteversion and hip rotation in total hip arthroplasty for developmental dysplasia of the hip

• Published in: Journal of artificial organs Vol. 23; no. 3; pp. 255 - 261
• Main Authors: Nakahara, Ema, Uemura, Keisuke, Ando, Wataru, Hamada, Hidetoshi, Takao, Masaki, Sugano, Nobuhiko
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.09.2020; Springer Nature B.V
• Subjects: Aged; Arthroplasty, Replacement, Hip - instrumentation; Arthroplasty, Replacement, Hip - methods; Biomedical Engineering and Bioengineering; Biomedical materials; Body mass; Body mass index; Body size; Bone Anteversion - etiology; Bone Anteversion - physiopathology; Bone Anteversion - surgery; Cardiac Surgery; Computed tomography; Developmental Dysplasia of the Hip - complications; Developmental Dysplasia of the Hip - physiopathology; Developmental Dysplasia of the Hip - surgery; Dysplasia; Female; Femur; Hip; Hip Prosthesis; Humans; Image acquisition; Joint replacement surgery; Joint surgery; Male; Medicine; Medicine & Public Health; Middle Aged; Modular systems; Musculoskeletal diseases; Nephrology; Original Article; Prostheses; Prosthesis Design; Range of Motion, Articular - physiology; Recreational vehicles; Retrospective Studies; Rotation; Surgical implants; Total hip arthroplasty; Functional femoral anteversion; Version control; Hip rotation; Antetorsion; Modular neck
• ISSN: 1434-7229; 1619-0904
• DOI: 10.1007/s10047-020-01162-3

Total hip arthroplasty (THA) is often required to decrease the excessive anatomical femoral anteversion (AA) in developmental dysplasia of the hip. Studies have recommended decreasing the AA via the use of a retroverted modular neck. However, hip rotation after THA may strengthen or weaken the effect of changing the AA. Thus, the present study analyzed the effect of a retroverted neck on AA and hip rotation. Patients who underwent THA using a straight neck (ST group) or a 15° retroverted neck (RV group) in a version changeable dual modular system (Mainstay stem, Kyocera, Kyoto, Japan) were retrospectively reviewed. After matching for age, body mass index, and surgical approach, 44 patients were included in each group. The AA and hip rotation (femoral rotational angle: FRA) were measured on CT images acquired preoperatively and 1 month after THA, and were compared between the groups. The mean ± standard deviation preoperative AA of the ST group (26.1 ± 10.7°) was significantly smaller than that of the RV group (44.2 ± 7.8°) ( p  < 0.001). In contrast, the postoperative AA did not significantly differ between the groups (ST group 27.5 ± 9.8°, RV group 25.1 ± 8.3°, p  = 0.406). The change in FRA after THA did not significantly differ between the groups (ST group − 3.8 ± 9.9°, RV group − 3.5 ± 9.1°, p  = 0.841). In conclusion, a 15° retroverted neck was useful in controlling AA in hips with excessive AA, and the change in FRA after THA did not differ between the ST group and the RV group.