title: Hydroxyapatite-coated pins versus titanium alloy pins in external fixation at the wrist: a controlled cohort study.
abstract: BACKGROUND
  The purpose of this study was to analyze whether the prevalence of pin-related complications can be reduced by the use of hydroxyapatite (HA)-coated pins in external fixators applied for unstable wrist fractures.
  
  
  METHODS
  Forty patients (160 pins) were randomized for standard uniplanar fixator treatment with the use of identically designed pins either composed of titanium-alloy (Ti6Al4V) (n = 20) or coated by HA (n = 20). Each pin site was clinically evaluated with regard to erythema, drainage, pain value, and radiologically assessed concerning loosening at T1 (mean, 9 days), T2 (mean, 43 days), and T3 (mean, 56 days). In case of pin-track complication, the patient was followed continuously. The need for antibiotics or additional surgery was documented. Bone mineral density was analyzed by Dual Energy X-ray Absorptiometry. At fixator removal (T2), the pin-extraction strength was measured by the use of a digital-torque-wrench.
  
  
  RESULTS
  Two minor pin-track infections requiring oral antibiotics occurred in the HA-pin group (2.7%) (p > 0.05). The vast majority of clinical pin-site parameters were comparable in both groups. At the end of the fixator therapy, there were 16 loose pins (n(Ti6AL4V-group) = 10; n(HA-group) = 6). The rate of loose pins was correlated to patient's age (p < 0.05) but not to bone mineral density values or the occurrence of pin-site infection. Finally, no significant difference between the two groups was detected with regard to the prevalence of clinical relevant pin-site complications (p = 0.80).
  
  
  CONCLUSIONS
  In external fixation of the wrist, the use of HA-coated pins yields no clinical advantages: there is a trend toward a superior pin-bone anchorage, but a tendency of increased susceptibility for minor pin-track infections.
authors.affiliation: Department of Trauma Surgery, University Hospital of Munich, Marchioninistraße, Munich, Germany. Oliver.Pieske@med.uni-muenchen.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Pieske
authors.forename: Leopold
authors.initials: L
authors.lastname: Pichlmaier
authors.forename: Felicitas
authors.initials: F
authors.lastname: Kaltenhauser
authors.forename: Nicolai
authors.initials: N
authors.lastname: Schramm
authors.forename: Bianka
authors.initials: B
authors.lastname: Rubenbauer
authors.forename: Axel
authors.initials: A
authors.lastname: Greiner
authors.forename: Stefan
authors.initials: S
authors.lastname: Piltz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys; D001858:Bone Nails; D020099:Coated Materials, Biocompatible; D017886:Durapatite; D005260:Female; D005592:Fracture Fixation / Q000295:instrumentation*; D050723:Fractures, Bone / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D016896:Treatment Outcome; D014954:Wrist Injuries / Q000175:diagnosis / Q000601:surgery*; D055815:Young Adult
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; C528635:titanium aluminum alloy; D017886:Durapatite