title: Total hip replacement with a cementless acetabular component and a cemented femoral component in patients younger than fifty years of age.
abstract: BACKGROUND
  We have been using hybrid total hip arthroplasty (a cementless acetabular component and a cemented stem) in young patients. The purpose of this study was to determine the prevalence of aseptic loosening, polyethylene wear, and osteolysis after the use of this technique.
  
  
  METHODS
  We studied a prospective consecutive series of sixty-four primary hybrid total hip replacements in fifty-five patients younger than fifty years old. There were forty-three men and twelve women; the average age at the time of the index operation was 43.4 years. The average duration of follow-up was 9.4 years. We used a cementless acetabular component without screw-holes and a cemented femoral component with a 22-mm head in all hips. Clinical follow-up with use of Harris hip ratings and radiographic follow-up were performed at six weeks; at three, six, and twelve months; and yearly thereafter. The sequential annual linear and volumetric wear rates were measured, and bone-remodeling and osteolysis were assessed.
  
  
  RESULTS
  The mean preoperative Harris hip score was 44 points, which increased to 95 points at the time of final follow-up. No hip had aseptic loosening. One hip (2%) was revised because of late infection. The average linear wear (and standard deviation) was 0.96 +/- 0.066 mm, with an average annual rate of 0.096 +/- 0.013 mm. The average volumetric wear was 364.7 +/- 25.2 mm (3), with an average annual rate of 43.4 +/- 3.5 mm (3). Six hips (9%) had an osteolytic lesion of <1 cm in diameter in the calcar femorale (zone 7).
  
  
  CONCLUSIONS
  Our results show that a hybrid arthroplasty with a cementless acetabular component and a smooth cemented femoral component (Ra, 0.6 mm) is effective for primary total hip replacement in young patients. Although there was no aseptic loosening and a low prevalence of osteolysis at the latest follow-up evaluation, the high rates of linear and volumetric wear of the polyethylene liner in these young patients remain a concern.
authors: Joint Replacement Center of Korea, Seoul, Korea. younghookim@netsgo.com
authors: Young-Hoo
authors: YH
authors: Kim
authors: H-K
authors: HK
authors: Kook
authors: J-S
authors: JS
authors: Kim
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D000328:Adult; D000367:Age Factors; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D001843:Bone Cements / Q000009:adverse effects* / Q000627:therapeutic use*; D001847:Bone Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D011183:Postoperative Complications; D011446:Prospective Studies; D011475:Prosthesis Failure; D011859:Radiography; D020127:Recovery of Function / Q000502:physiology; D013997:Time Factors
chemical_list: D001843:Bone Cements