title: Bone density and functional results after femoral revision with a cementless press-fit stem.
abstract: BACKGROUND
  The influence of radiographic bone density changes in the area surrounding a total hip arthroplasty (THA) revision with a cementless press-fit stem is unknown, notably in terms of functional results. We have therefore conducted a study aiming to (1) propose a radiographic method to assess bone density, (2) measure the functional effects of reduced bone density, and (3) determine the factors contributing to these modifications.
  
  
  OBJECTIVE
  A reduction in radiographic bone density has a negative influence on the functional result after revision using a cementless press-fit stem.
  
  
  METHODS
  We retrospectively assessed 150 THA revisions at a mean follow-up of 6.3 ± 3.2 years (range, 2-15 years). The clinical assessment was based on the Harris Hip Score. Bone density modifications were measured radiographically and the method was evaluated. The change in bone density was classified into two groups: (1) bone density not reduced or < 2 Gruen zones (118 cases [79%]); (2) bone density reduced ≥ 2 zones (32 cases [21%]). The variables showing a potential influence were the Cortical Index (CI), the type of primary stability with the press-fit system, and the femoral implant length.
  
  
  RESULTS
  Inter- and intraobserver reliability of radiographic bone density measurement was evaluated as moderate or good (Kappa, 0.58; 0.60 and 0.67, respectively). For the Harris Hip Score at follow-up, there was a borderline statistical relation between stages 1 and 2: for the 118 stage 1 patients, this score was 83.62 ± 11.54 (range, 27-99) versus 78.34 ± 15.98 (range, 62-91) for stage 2 patients (P = 0.09). A CI ≤ 0.44 showed mediocre bone quality contributing to decreased bone density (P < 0.02). On the other hand, there was no statistically significant relation with the type of primary fixation (P = 0.34) or the length of the implant (P = 0.23).
  
  
  CONCLUSIONS
  A cementless revision femoral stem can induce a reduction in bone density with possible functional effects. The negative role played by bone scarcity on the functional score is confirmed, and even though the difference is not statistically significant, we suggest using a short stem when this is possible.
authors: Département de chirurgie orthopédique, unité de chirurgie du membre inférieur, hôpital Lapeyronie, CHU de Montpellier, 371, avenue du Doyen-Gaston-Giraud, 34295 Montpellier cedex, France. Electronic address: f-canovas@chu-montpellier.fr.
authors: F
authors: F
authors: Canovas
authors: Centre chirurgical Emile-Gallé, 49, rue Hermite, 54000 Nancy, France.
authors: O
authors: O
authors: Roche
authors: Hôpital Roger-Salengro, CHU de Lille, 2, avenue Oscar-Lambret, 59037 Lille cedex, France.
authors: J
authors: J
authors: Girard
authors: Hôpital de Hautepierre, CHU de Strasbourg, avenue Molière, 67098 Strasbourg cedex, France.
authors: F
authors: F
authors: Bonnomet
authors: Polyclinique Sévigné, rue du Chêne-Germain - Z.A.C.-de-Coësmes, BP 67, 35512 Cesson-Sévigné cedex, France.
authors: M
authors: M
authors: Goldschild
authors: 11, Galeries du théâtre, 35000 Rennes, France.
authors: P
authors: P
authors: Le Béguec
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D015519:Bone Density; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D005500:Follow-Up Studies; D006615:Hip / Q000503:physiopathology*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation / Q000295:instrumentation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: Bone density; Cementless stem; Femoral implant; Press-fit; Review