title: A novel digital templating methodology for arthroplasty: experience from patients with osteonecrosis of the femoral head.
abstract: OBJECTIVE
  To assess the accuracy of a novel digital templating methodology for total hip arthroplasty (THA) in patients with osteonecrosis of the femoral head (ONFH).
  
  
  METHODS
  A retrospective study was carried out on 77 hips in 58 patients who had undergone uncemented THA for ONFH. Preoperative radiographs were templated using a 2-step procedure: (i) calculation of basic cup and stem sizes based on the anatomical morphology; (ii) adjustment of the basic sizes to account for variables such as femoral external rotation, osteoporotic changes in the femur, osteosclerotic changes in the acetabulum, and the type of stem. Basic and adjusted sizes were compared with the actual sizes of the implants used.
  
  
  RESULTS
  Before adjustment, the overall accuracy was 69% and 70% for stem size and the cup respectively. Among all the cases, 31 femoral components (40%) and 17 acetabular components (22%) required adjustment. After adjustment, the accuracy of templating for stem and cup sizes in these adjusted cases improved from 52% to 87% (p = 0.002), and 41% to 82%, respectively (p = 0.032). And the overall templating accuracy improved to 83% on the stem side (p = 0.038) and 79% on the cup side (p = 0.195).
  
  
  CONCLUSIONS
  Preoperative digital templating was useful in predicting cup and stem sizes in patients with ONFH. Radiographic signs of femoral rotation or osteoporotic changes call for appropriate adjustment to improve the accuracy of templating for THA.
authors.affiliation: Department of Orthopaedics, The First Hospital of Jilin University, Jilin University, Jilin - China.
authors.forename: Ning
authors.initials: N
authors.lastname: Dong
authors.affiliation: Department of Orthopaedics, The First Hospital of Jilin University, Jilin University, Jilin - China.
authors.forename: Chen
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Orthopaedics, The First Hospital of Jilin University, Jilin University, Jilin - China.
authors.forename: Shu-Qiang
authors.initials: SQ
authors.lastname: Li
authors.affiliation: Department of Orthopaedics, The First Hospital of Jilin University, Jilin University, Jilin - China.
authors.forename: Yu-Hang
authors.initials: YH
authors.lastname: Gao
authors.affiliation: Department of Orthopaedics, The First Hospital of Jilin University, Jilin University, Jilin - China.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, The First Hospital of Jilin University, Jilin University, Jilin - China.
authors.forename: Xin
authors.initials: X
authors.lastname: Qi
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D016009:Chi-Square Distribution; D015331:Cohort Studies; D005260:Female; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging* / Q000601:surgery*; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011300:Preoperative Care / Q000379:methods; D011474:Prosthesis Design / Q000379:methods*; D011859:Radiography / Q000379:methods*; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D016896:Treatment Outcome; D055815:Young Adult