title: Could larger diameter of 4th generation ceramic bearing decrease the rate of dislocation after THA?
abstract: BACKGROUND
  Fourth generation (Delta) ceramic bearing was developed to reduce dislocation after total hip arthroplasty (THA) by increasing the head diameter. We tested a hypothesis that 32/36 mm Delta ceramic bearing decreases the dislocation rate. We also evaluated ceramic-related complications and early outcome of this thin liner-on-large head ceramic bearing.
  
  
  METHODS
  We performed a prospective study on patients who underwent THA with use of 32/36 mm Delta ceramic bearing. The dislocation rate was compared with the historical dislocation rate of third generation 28 mm ceramic bearing. We also evaluated ceramic fracture, squeak, short-term results and survival. Follow-up period was minimum 2 years.
  
  
  RESULTS
  Between April 2010 and February 2012, we enrolled 250 consecutive patients (278 hips). All patients received cementless prostheses. Four patients (4 hips) who received metal shells ≤ 46 mm and 28 mm heads were excluded. Three patients died and 2 patients were lost within 2 years. The remaining 241 patients (269 hips) were followed for 24-46 months. There were 142 men (161 hips) and 99 women (108 hips) with a mean age of 53.7 years (range, 17-75 years) at the index operation. Dislocation occurred in three hips (1.1%). An old age was a risk factor for dislocation. Ceramic fracture and squeaking did not occur in any patient. Mean Harris hip score was 90.3 points at the latest follow-up. All acetabular and femoral components had bone-ingrowth stability. No hip had detectable wear or osteolysis. The survival was 99.3% in the best case scenario and 97.8% in the worst at 48 months.
  
  
  CONCLUSIONS
  Total hip arthroplasty with use of 32/36 mm Delta ceramic bearing showed lower incidence of hip dislocation compared with 28 mm third generation ceramic bearing. A caution should be paid to prevent a fall in senile patients even though a large head is used. The short-term results of THA with this type of ceramic articulation are encouraging and we did not find any ceramic-related complications.
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seongnam, South Korea.
authors.forename: Young-Kyun
authors.initials: YK
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Chung-Ang University College of Medicine, Seoul, South Korea. Electronic address: hayongch@naver.com.
authors.forename: Yong-Chan
authors.initials: YC
authors.lastname: Ha
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seongnam, South Korea.
authors.forename: Woo-Lam
authors.initials: WL
authors.lastname: Jo
authors.affiliation: Department of Orthopaedic Surgery, Hallym University Sacred Heart Hospital, Anyang, South Korea.
authors.forename: Tae-Young
authors.initials: TY
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Murup Hospital, Masan, South Korea.
authors.forename: Woon-Hwa
authors.initials: WH
authors.lastname: Jung
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seongnam, South Korea.
authors.forename: Kyung-Hoi
authors.initials: KH
authors.lastname: Koo
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000379:methods; D001696:Biomechanical Phenomena; D002516:Ceramics; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006617:Hip Dislocation / Q000453:epidemiology* / Q000517:prevention & control / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology / Q000503:physiopathology; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation / Q000379:methods; D056910:Republic of Korea; D017678:Sex Distribution; D016474:Weight-Bearing / Q000502:physiology*