title: No medium-term advantage of electrochemical deposition of hydroxyapatite in cementless femoral stems. 5-year RSA and DXA results from a randomized controlled trial.
abstract: OBJECTIVE
  Hydroxyapatite has been used for a long time as an adjunct to enhance cementless fixation. The benefit of this is still debated, but new methods of hydroxyapatite deposition have emerged, offering possible gains. In order to investigate this further, we compared the migration pattern and periprosthetic bone remodeling in a cementless femoral stem with either electrochemically deposited hydroxyapatite-called Bonemaster (BM)-or a conventional plasma-sprayed hydroxyapatite (HA) coating.
  
  
  METHODS
  55 hips were randomized to either BM or HA cementless femoral stems. Patients were followed with radiostereometry (RSA), dual-energy X-ray absorptiometry (DXA), radiographic measurements, and hip questionnaires for 5 years.
  
  
  RESULTS
  For both stems, migration occurred mainly as subsidence and retroversion during the first 3 months. The BM group had a higher retroversion rate of 0.17° per month during this period, as compared to 0.06° per month for the HA group (p = 0.006). Thereafter, there was almost no movement in any direction for both stem types. Bone resorption occurred mainly during the first year, and subsequently decreased to a rate close to what is seen in normal ageing. The greatest total decrease occurred in Gruen zones 1 and 7, similar in the groups at 5 years. There was a slightly higher resorption rate in Gruen zone 7 from 2 to 5 years in the BM group (1.3% per year; p = 0.04), but in a magnitude that would scarcely affect stem stability or survival.
  
  
  CONCLUSIONS
  There were no clinically relevant differences between the 2 stems regarding stability or periprosthetic bone loss at 5 years. Electrochemically deposited HA does not appear to affect fixation or bone remodeling when compared to conventional plasma spraying at 5 years. Thus, at this point, Bonemaster appears to be safe.
authors.affiliation: a Department of Orthopedic Surgery , Oslo University Hospital Ullevål , Oslo , Norway .
authors.forename: Bernhard
authors.initials: B
authors.lastname: Flatøy
authors.affiliation: a Department of Orthopedic Surgery , Oslo University Hospital Ullevål , Oslo , Norway .
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Röhrl
authors.affiliation: a Department of Orthopedic Surgery , Oslo University Hospital Ullevål , Oslo , Norway .
authors.forename: Berte
authors.initials: B
authors.lastname: Bøe
authors.affiliation: a Department of Orthopedic Surgery , Oslo University Hospital Ullevål , Oslo , Norway .
authors.forename: Lars
authors.initials: L
authors.lastname: Nordsletten
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D001843:Bone Cements / Q000737:chemistry; D015519:Bone Density / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology*; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D016001:Confidence Intervals; D017886:Durapatite / Q000737:chemistry*; D005260:Female; D005269:Femur / Q000601:surgery; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods; D011474:Prosthesis Design; D059869:Radiostereometric Analysis / Q000379:methods; D013499:Surface Properties; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D001843:Bone Cements; D020099:Coated Materials, Biocompatible; D017886:Durapatite