title: Cementless Corail™ femoral stems with laser neck etching: Long-term survival, rupture rate and risk factors in 295 stems.
abstract: BACKGROUND
  Implant neck fracture involving a non-modular femoral stem is rare in primary total hip arthroplasty (THA). Occasional cases have been reported following laser etching of the Corail(tm) stem, but risk factors have not been precisely determined. We therefore performed a retrospective study on a series of Corail(tm) stems with laser neck etching, in order to: (1) determine the exact implant neck fracture rate at 10 years, and (2) identify associated risk factors.
  
  
  OBJECTIVE
  Laser etching increases the rate of implant neck fracture.
  
  
  METHODS
  Between October 2002 and December 2003, 295 THAs were consecutively performed using the Corail(tm) stem with laser neck etching, in 286 patients: 151 male (53%), 135 female (47%); mean age, 63 years (range, 18-89 years); mean weight, 73kg (range, 45-120kg). Stems were standard in 240 cases (81%) and lateralized in 55 (19%). The main assessment criterion was stem replacement for implant neck fracture.
  
  
  RESULTS
  At a mean 10 years' follow-up (range, 1-11 years), 11 patients were lost to follow-up (4%) and 35 had died (12%) (with stem in situ). Overall 10-year stem survival was 91% (95% CI: [87-94%]). Sixteen patients (5.4%) underwent revision surgery for implant neck fracture, 6 (2%) bone and joint infection and in 4 cases (1.3%) the stem was replaced preventively for fracture risk suspected during a revision procedure on the cup. All fractures were of the fatigue type, implicating implant neck laser etching. Mean time to fracture was 4.5 years (range, 1.4-9.8 years). Risk factors comprised: weight>80kg (P=0.002) (OR=5.7; 95% CI: 1.9-17), age<60 years (P=0.02) (OR=3.4; 95% CI: 1.2-9.6), male gender (P=0.01) (OR=14.8; 95% CI: 1.9-113) and lateralized stem (P<0.001) (OR=6.5, 95% CI: 2.3-18).
  
  
  CONCLUSIONS
  The present 5.4% fracture rate was higher than in registry data (<1%). Fracture mechanisms involved excessive stress in an area under tension, leading to fatigue fracture. Male gender, high weight and young age were risk factors, as in the literature for fatigue fracture. Location and depth of laser etching induced fatigue fracture. The study demonstrated that laser etching creates an area of weakness in the implant neck and should therefore be eschewed in this part of the femoral stem.
  
  
  METHODS
  IV, retrospective study.
authors.affiliation: Hospices civils de Lyon, centre hospitalier Lyon-Sud, service de chirurgie orthopedique et traumatologique, 165, chemin Grand-Revoyet, 69495 Pierre-Bénite cedex, France.
authors.forename: A
authors.initials: A
authors.lastname: Merini
authors.affiliation: Hospices civils de Lyon, centre hospitalier Lyon-Sud, service de chirurgie orthopedique et traumatologique, 165, chemin Grand-Revoyet, 69495 Pierre-Bénite cedex, France; Université de Lyon, 69622 Lyon, France; Université Claude-Bernard Lyon 1, 43, boulevard du 11-Novembre, 69100 Villeurbanne, France; IFSTTAR, UMRT 9406, laboratoire de biomécanique et mécanique des chocs, 25, avenue Mitterrand, 69500 Bron, France. Electronic address: anthony.viste@chu-lyon.fr.
authors.forename: A
authors.initials: A
authors.lastname: Viste
authors.affiliation: Hospices civils de Lyon, centre hospitalier Lyon-Sud, service de chirurgie orthopedique et traumatologique, 165, chemin Grand-Revoyet, 69495 Pierre-Bénite cedex, France.
authors.forename: R
authors.initials: R
authors.lastname: Desmarchelier
authors.affiliation: Hospices civils de Lyon, centre hospitalier Lyon-Sud, service de chirurgie orthopedique et traumatologique, 165, chemin Grand-Revoyet, 69495 Pierre-Bénite cedex, France; Université de Lyon, 69622 Lyon, France; Université Claude-Bernard Lyon 1, 43, boulevard du 11-Novembre, 69100 Villeurbanne, France; IFSTTAR, UMRT 9406, laboratoire de biomécanique et mécanique des chocs, 25, avenue Mitterrand, 69500 Bron, France.
authors.forename: M-H
authors.initials: MH
authors.lastname: Fessy
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D001835:Body Weight; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D057068:Periprosthetic Fractures / Q000209:etiology* / Q000601:surgery; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000209:etiology* / Q000601:surgery; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D055815:Young Adult
keywords: Corail(tm) stem; Laser etching; Stem neck fracture; Total hip arthroplasty