title: Tailor-made Surgical Guide Reduces Incidence of Outliers of Cup Placement.
abstract: Malalignment of the cup in total hip arthroplasty (THA) increases the risks of postoperative complications such as neck cup impingement, dislocation, and wear. We asked whether a tailor-made surgical guide based on CT images would reduce the incidence of outliers beyond 10 degrees from preoperatively planned alignment of the cup compared with those without the surgical guide. We prospectively followed 38 patients (38 hips, Group 1) having primary THA with the conventional technique and 31 patients (31 hips, Group 2) using the surgical guide. We designed the guide for Group 2 based on CT images and fixed it to the acetabular edge with a Kirschner wire to indicate the planned cup direction. Postoperative CT images showed the guide reduced the number of outliers compared with the conventional method (Group 1, 23.7%; Group 2, 0%). The surgical guide provided more reliable cup insertion compared with conventional techniques.
  
  
  METHODS
  Level II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, 565-0871, Osaka, Japan. hana-osaka@umin.net
authors.forename: Takehito
authors.initials: T
authors.lastname: Hananouchi
authors.forename: Masanobu
authors.initials: M
authors.lastname: Saito
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Koyama
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Sugano
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
mesh_terms: D001172:Arthritis, Rheumatoid / Q000601:surgery; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D016063:Blood Loss, Surgical; D004867:Equipment Design; D005260:Female; D005271:Femur Head Necrosis / Q000601:surgery; D006615:Hip / Q000000981:diagnostic imaging / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D011183:Postoperative Complications / Q000209:etiology; D011446:Prospective Studies; D015203:Reproducibility of Results; D012371:Robotics / Q000379:methods; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D014057:Tomography, X-Ray Computed