title: The effect of antegrade femoral nailing on femoral head perfusion: a comparison of piriformis fossa and trochanteric entry points.
abstract: BACKGROUND
  Piriformis fossa entry antegrade femoral nailing is a common method for stabilizing diaphyseal femur fractures. However, clinically significant complications such as chronic hip pain, hip abductor weakness, heterotopic ossification and femoral head osteonecrosis have been reported. A recent cadaveric study found that piriformis entry nailing damaged either the deep branch of the medial femoral circumflex artery (MFCA) or its distal superior retinacular artery branches in 100% of specimens and therefore recommended against its use. However, no study has quantitatively assessed the effect of different femoral entry points on femoral head perfusion.
  
  
  METHODS
  Twelve fresh-frozen cadaveric lower extremity specimens were randomly allocated to either piriformis fossa or trochanteric entry nailing using a 13-mm reamer. The contralateral hip served as an internal matched control. All specimens subsequently underwent gadolinium-enhanced fat-suppressed gradient-echo sequence MRI to assess femoral head perfusion. Gross dissection was also performed to assess MFCA integrity and distance to the opening reamer path.
  
  
  RESULTS
  MRI quantification analysis revealed near full femoral head perfusion with no significant difference between the piriformis and trochanteric starting points (95 vs. 97%, p = 0.94). There was no observed damage to the deep MFCA in either group. The mean distance from the reamer path to the deep MFCA was 3.2 mm in the piriformis group compared to 18.5 mm in the trochanteric group (p = 0.001). Additionally, there was a significantly greater number of mean terminal superior retinacular vessels damaged by the opening reamer in the piriformis cohort (1 vs. 0; p = 0.007).
  
  
  CONCLUSIONS
  No statistically significant difference in femoral head perfusion was found between the two groups. Therefore, we cannot recommend against the use of piriformis entry femoral nails. However, we caution against multiple errant starting point attempts and recommend meticulous soft tissue protection during the procedure.
authors.affiliation: Orthopaedic Trauma Service, Memorial Hermann Hospital, University of Texas Health Science Center at Houston, 6400 Fannin St, Suite 1700, Houston, TX, 77030, USA, Patrick.C.Schottel@uth.tmc.edu.
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Schottel
authors.forename: Richard M
authors.initials: RM
authors.lastname: Hinds
authors.forename: Lionel E
authors.initials: LE
authors.lastname: Lazaro
authors.forename: Craig
authors.initials: C
authors.lastname: Klinger
authors.forename: Amelia
authors.initials: A
authors.lastname: Ni
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Dyke
authors.forename: David L
authors.initials: DL
authors.lastname: Helfet
authors.forename: Dean G
authors.initials: DG
authors.lastname: Lorich
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D005263:Femoral Artery; D005264:Femoral Fractures / Q000175:diagnosis / Q000628:therapy*; D005270:Femur Head / Q000098:blood supply / Q000601:surgery*; D005594:Fracture Fixation, Intramedullary / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010477:Perfusion / Q000379:methods*