title: The effect of stem design on the prevalence of squeaking following ceramic-on-ceramic bearing total hip arthroplasty.
abstract: BACKGROUND
  The ceramic-on-ceramic bearing for total hip arthroplasty has an extremely low wear rate and demonstrates minimal inflammatory response in comparison with other bearing choices. However, acoustic emissions such as squeaking and clicking are being reported as annoying complications related to its use. The cause or causes of this phenomenon have not been determined. The purpose of the present study was to evaluate the possibility that design aspects of the femoral component may be a contributing factor to the etiology of squeaking associated with the ceramic-on-ceramic bearing total hip arthroplasty.
  
  
  METHODS
  We retrospectively reviewed 266 consecutive patients (304 hips) who had undergone total hip arthroplasty with use of ceramic-on-ceramic bearings. The first 131 consecutive patients (152 hips) (Group 1) received a hydroxyapatite-coated stem composed of titanium-aluminum-vanadium alloy with a C-taper neck geometry and robust midsection with an anteroposterior diameter of 13 mm. The second 135 consecutive patients (152 hips) (Group 2) also received a hydroxyapatite-coated stem, but in that group the stem was composed of titanium-molybdenum-zirconium-iron alloy, with a V-40 neck geometry and a midsection with an anteroposterior thickness of only 10 mm. All 304 hips received the same cup, composed of titanium-aluminum-vanadium alloy. Demographic characteristics, such as age, sex, height, weight, and body mass index, were similar in both groups. Data regarding the presence of squeaking were obtained prospectively. Patients who were seen for clinical follow-up either expressed the squeaking phenomenon themselves or were asked about it by the physician. Patients who were not seen at a recent clinical follow-up visit were contacted by telephone and were asked specifically about squeaking that might be associated with the hip replacement. Only patients with confirmed squeaking noise were included in the present study. Postoperative radiographs, the Short Form-36 health survey, the Harris hip score, and office or telephone interviews of the patient were used to determine the overall outcome of the procedure.
  
  
  RESULTS
  The prevalence of squeaking was seven times higher for patients who received the titanium-molybdenum-zirconium-iron-alloy stem (twenty-seven patients, twenty-eight hips [18.4%]) than in those who received the titanium-aluminum-vanadium-alloy stem (three patients, four hips [2.6%]); this difference was significant (p < 0.0001).
  
  
  CONCLUSIONS
  Our study suggests that different stem alloys, stem geometries, or neck geometries can have an impact on the frequency of squeaking following a ceramic-on-ceramic total hip arthroplasty.
authors.affiliation: Department of Orthopaedic Surgery, Thomas Jefferson University Hospital, Rothman Institute, 925 Chestnut Street, 5th Floor, Philadelphia, PA 19107, USA.
authors.forename: Camilo
authors.initials: C
authors.lastname: Restrepo
authors.forename: Zachary D
authors.initials: ZD
authors.lastname: Post
authors.forename: Brandon
authors.initials: B
authors.lastname: Kai
authors.forename: William J
authors.initials: WJ
authors.lastname: Hozack
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000497:Alloys; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002516:Ceramics; D020099:Coated Materials, Biocompatible; D017886:Durapatite; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009622:Noise; D011474:Prosthesis Design; D012189:Retrospective Studies; D014639:Vanadium
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; C528635:titanium aluminum alloy; D014639:Vanadium; D017886:Durapatite