title: Reverse hybrid and cemented hip replacement compared using radiostereometry and dual-energy X-ray absorptiometry: 43 hips followed for 2 years in a prospective trial.
abstract: OBJECTIVE
  Total hip replacement (THR) with a reverse hybrid (RH), a combination of a cemented polyethylene cup and a cementless femoral stem, has been increasingly used in Scandinavia. In a randomized trial, we compared an RH THR with a proximal hydroxyapatite- (HA-) coated stem to a conventional cemented THR. Both groups received the same polyethylene cup.
  
  
  METHODS
  51 patients (52 hips) were included. Radiostereometry (RSA) and dual-energy X-ray absorptiometry (DEXA) were performed postoperatively and after 6, 12, and 24 months. 42 patients (43 hips) were followed for 2 years.
  
  
  RESULTS
  Mean cup rotation around the x-axis was 0.13° for the cemented group and -0.24° for the RH group (p = 0.03). Cup migration in the other axes, and stem migration and wear were similar between the 2 study groups. Bone remodeling around the cup was also similar between the groups. Bone loss in Gruen zone 1 was 18% for the cementless stems, as compared to an increase of 1.4% for the cemented ones (p < 0.001). Bone loss was similar in the other Gruen zones. Harris hip score and Oxford hip score were similar pre- and postoperatively in the 2 groups.
  
  
  CONCLUSIONS
  In the present study, RH THR with a cementless hydroxyapatite-coated stem and conventional cemented THR did not show any major differences regarding stem migration and bone loss after 2 years of follow-up.
authors.affiliation: Department of Orthopaedics, Lovisenberg Deaconal Hospital, Oslo, Norway. eli@lds.no
authors.forename: Einar
authors.initials: E
authors.lastname: Lindalen
authors.forename: Jon
authors.initials: J
authors.lastname: Dahl
authors.forename: Lars
authors.initials: L
authors.lastname: Nordsletten
authors.forename: Finnur
authors.initials: F
authors.lastname: Snorrason
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Høvik
authors.forename: Stephan
authors.initials: S
authors.lastname: Röhrl
mesh_terms: D015502:Absorptiometry, Photon; D000367:Age Factors; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D001843:Bone Cements; D015519:Bone Density; D002484:Cementation / Q000009:adverse effects / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D059869:Radiostereometric Analysis; D012016:Reference Values; D018570:Risk Assessment; D012737:Sex Factors; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D001843:Bone Cements