Author/Authors :
Miyakoshi, Naohisa Department of Orthopedic Surgery - Akita University Graduate School of Medicine - 1-1-1 Hondo, Japan , Iwamoto, Yosuke Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Kijima, Hiroaki Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Tazawa, Hiroshi Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Konishi, Natsuo Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Kubota, Hitoshi Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Yamada, Shin Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Tani, Takayuki Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Kamo, Keiji Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Suzuki, Norio Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Okudera, Yoshihiko Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Fujii, Masashi Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Sasaki, Ken Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Kawano, Tetsuya Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Nagahata, Itsuki Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan , Shimada, Yoichi Akita Hip Research Group - 1-1-1 Hondo - Akita , Japan
Abstract :
Because the tapered wedge-shaped type cementless stem has a small anteroposterior width and a low occupation ratein the medullary space, postoperative rotational instability and stem subsidence due to inadequate proximal fixation are concerns.+e purpose of this study was to clarify the relationship between the rotational instability of the tapered wedge-shaped typecementless stem and femoral canal shape.Methods. A total of 61 primary total hip arthroplasties with the tapered wedge-shapedtype cementless stem Accolade®TMZF (11 males, 50 females; mean age 60 years) from January 2012 to June 2015 who underwentcomputed tomography before surgery and within 4 weeks and 1 year after surgery were evaluated. +e preoperative femoral neckanteversion angle, preoperative femoral canal flair index, the degree of postoperative stem subsidence within 1 year after op-eration, and the degree of rotational change in the stem setting angle within 1 year after operation were investigated.Results. +emean preoperative femoral neck anteversion angle was 32.2°±17.8°(0°–69°), and the mean preoperative canal flair index was3.68±0.58 (2.44–5.55). +ere were no stem subsidence cases within 1 year after operation. +e mean degree of rotational changein the stem from immediately to 1 year after surgery was−0.4°±1.7°(−3°–3°). +ere was no significant correlation between thecanal flair index and the rotational change in the stem. In addition, the mean difference between the preoperative femoral neckanteversion angle and the stem rotational angle immediately after surgery was only 1.3°±5.3°(−29°–15°).Conclusions. In all cases,including stove-pipe cases, the degree of rotational change in the Accolade®TMZF stem from immediately to 1 year after surgerywas within 3°. In other words, regardless of femoral canal shape, the tapered wedge-shaped type cementless stem has little initialrotational instability
