title: High hip center technique using a biconical threaded Zweymüller cup in osteoarthritis secondary to congenital hip disease.
abstract: BACKGROUND
  The high hip center technique used for a deficient acetabulum is reconstruction of the hip at a high center of rotation. In the literature, there is no consensus regarding the value of this technique.
  
  
  OBJECTIVE
  We investigated whether the new-generation biconical threaded Zweymüller cup fixed in a high nonanatomic position in patients with arthritis secondary to congenital hip disease experienced different rates of polyethylene wear and long-term survivorship when compared with anatomically positioned cups.
  
  
  METHODS
  We studied the polyethylene wear rate and Kaplan-Meier survivorship of 104 titanium threaded Zweymüller cups in 88 patients (81 females), placed in 70 hips at near-normal hip center and in 34 hips at a high hip center position at a distance of 31.1 to 60 mm (mean, 39.7 mm) from the interteardrop line. Minimum followup was 2 years (mean +/- SD, 8.6 +/- 3.5 years; range, 2-15 years).
  
  
  RESULTS
  The mean linear polyethylene wear rates in the near-normal and high hip center groups were not different (0.110 +/- 0.050 mm and 0.113 +/- 0.057 mm, respectively). The Kaplan-Meier 15-year cup survivorship rates with revision for any reason as an event of interest in the near-normal and high hip center groups also were not different (97.2% [95% confidence interval, 88.5%-99.3%] and 97.1% [95% confidence interval, 73.8%-99.3%], respectively).
  
  
  CONCLUSIONS
  The high hip center technique using a biconical threaded Zweymüller cup in patients with arthritis secondary to congenital hip disease results in a polyethylene wear rate and long-term cup survivorship comparable to those observed in anatomically positioned cups.
  
  
  METHODS
  Level III, therapeutic study. See the Guidelines for Authors for a complete description of level of evidence.
authors.affiliation: Department of Orthopaedics, Karpenissi General Hospital, 2 P Mpakoyanni Street, Karpenissi, 36100, Greece, chnortho@yahoo.gr.
authors.forename: Nikolaos A
authors.initials: NA
authors.lastname: Christodoulou
authors.forename: Konstantinos P
authors.initials: KP
authors.lastname: Dialetis
authors.forename: Athanasios N
authors.initials: AN
authors.lastname: Christodoulou
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D006618:Hip Dislocation, Congenital / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D020959:Polyethylene; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D014025:Titanium
chemical_list: D020959:Polyethylene; D014025:Titanium