title: Evaluation of risk for secondary fracture after removal of a new femoral neck plate for intracapsular hip fractures.
abstract: OBJECTIVE
  To determine whether a new femoral neck plate has a higher risk for secondary fracture after implant removal than the current standard treatment for intracapsular hip fractures.
  
  
  METHODS
  Six pairs of human cadaver femora (age, 56 ± 5.6 years; range, 48-64 years; two female and four male donors) were instrumented with the femoral neck plate (FNP) or the compression hip screw combined with an antirotation screw (CHS) in a paired study design. After removal of the implants, axial compression tests to failure of the bones were conducted. Maximum force to failure of the bones after implant removal was determined. Axial stiffness of the bones before surgery and after implant removal was determined.
  
  
  RESULTS
  The FNP resulted in a mean failure load of 4687 ± 1743 N (mean ± standard deviation) and the CHS resulted in a mean failure load of 4892 ± 1608 N with no significant difference between the two implant groups (P = 0.405). There was no significant difference in stiffness (P = 0.214) between the FNP (1240 ± 362 N/mm) and the CHS (1293 ± 304 N/mm). The cavities left by the surgery had no effect on the bone stiffness (P > 0.05). The mean failure load of all specimens correlated with the bone mineral density in the proximal part of the femurs by R² = 0.715 (P = 0.001).
  
  
  CONCLUSIONS
  The FNP demonstrated a similar failure load after implant removal compared with the CHS, although the FNP left a 39% larger cavity in the bone.
authors.affiliation: Institute of Biomechanics, Trauma Center Murnau, Murnau, Germany. sebastian.eberle@bgu-murnau.de
authors.forename: Sebastian
authors.initials: S
authors.lastname: Eberle
authors.forename: Christof
authors.initials: C
authors.lastname: Wutte
authors.forename: Christoph
authors.initials: C
authors.lastname: Bauer
authors.forename: Geert
authors.initials: G
authors.lastname: von Oldenburg
authors.forename: Stephanie
authors.initials: S
authors.lastname: Panzer
authors.forename: Peter
authors.initials: P
authors.lastname: Augat
mesh_terms: D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D004548:Elasticity / Q000502:physiology; D019544:Equipment Failure Analysis; D005260:Female; D005265:Femoral Neck Fractures / Q000209:etiology*; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000295:instrumentation; D006620:Hip Fractures / Q000601:surgery*; D006801:Humans; D057072:Intra-Articular Fractures / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012086:Reoperation / Q000009:adverse effects; D013314:Stress, Mechanical