title: The cartilage degeneration and joint motion of bipolar hemiarthroplasty.
abstract: OBJECTIVE
  The outcomes of bipolar hemiarthoplasty for osteonecrosis of femoral head have been disappointing due to cartilage degeneration and osteolysis. We investigated the cartilage degeneration, joint motion, and factors associated with osteolysis.
  
  
  METHODS
  We retrospectively reviewed 134 bipolar hemiarthroplasties. The wear rate of acetabular cartilage was calculated. The ranges of motion of outer bearing and inner bearing were determined, and the ratio (O/I ratio) was calculated.
  
  
  RESULTS
  The mean degeneration rate of acetabular cartilage was 0.34 ± 0.35 mm/year. We could observe that the outer bearing motion was dominant, but decreased over time. In addition, the degeneration rate of cartilage and the decline rate of outer bearing motion of the osteolysis group were significantly higher than those of the control group.
  
  
  CONCLUSIONS
  Close observation is needed in cases of high degeneration rate of cartilage and rapid decline of outer bearing motion due to possibility of osteolysis.
authors.affiliation: Department of Orthopaedic Surgery, Hanyang University Hospital, 17 Haengdang-dong, Seongdong-gu, Seoul, South Korea.
authors.forename: Yee-Suk
authors.initials: YS
authors.lastname: Kim
authors.forename: Young-Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Kyu-Tae
authors.initials: KT
authors.lastname: Hwang
authors.forename: Il-Yong
authors.initials: IY
authors.lastname: Choi
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000368:Aged; D019072:Antibiotic Prophylaxis; D002357:Cartilage Diseases / Q000209:etiology / Q000473:pathology* / Q000534:rehabilitation; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging / Q000601:surgery; D062785:Hemiarthroplasty / Q000009:adverse effects / Q000379:methods*; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000209:etiology / Q000473:pathology; D011183:Postoperative Complications; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D016896:Treatment Outcome