title: Comparison of calcaneal fixation of a retrograde intramedullary nail with a fixed-angle spiral blade versus a fixed-angle screw.
abstract: BACKGROUND
  Retrograde intramedullary nailing is an established technique for tibiotalocalcaneal arthrodesis (TTCA). In poor bone stock (osteoporosis, neuroarthropathy), device fixation in the hindfoot remains a problem. Fixed-angle spiral-blade fixation of the nail in the calcaneus could be useful.
  
  
  METHODS
  In seven matched pairs of human below-knee specimens, bone mineral density (BMD) was determined, and TTCA was performed with an intramedullary nail (Synthes Hindfoot Arthrodesis Nail HAN Expert Nailing System), using a conventional screw plus a fixed-angle spiral blade versus a conventional screw plus a fixed-angle screw, in the calcaneus. The constructs were subjected to quasi-static loading (dorsiflexion/plantarflexion, varus/valgus, rotation) and to cyclic loading to failure. Parameters studied were construct neutral zone (NZ) and range of motion (ROM), and number of cycles to failure.
  
  
  RESULTS
  With dorsiflexion/plantarflexion loading, the screw-plus-spiral-blade constructs had a significantly smaller ROM in the quasi-static test (p = 0.028) and early in the cyclic test (p = 0.02); differences in the other parameters were not significant. There was a significant correlation between BMD and cycles to failure for the two-screw constructs (r = 0.94; p = 0.002) and for the screw-plus-spiral-blade constructs (r = 0.86; p = 0.014).
  
  
  CONCLUSIONS
  In TTCA with a HAN Expert Nailing System, the use of a calcaneal spiral blade can further reduce motion within the construct. This may be especially useful in poor bone stock.
  
  
  CONCLUSIONS
  Results obtained in this study could be used to guide the operating surgeon's TTCA strategy.
authors.affiliation: AO Foundation, Clavadelerstrasse 8, 7270 Davos Platz, Switzerland. kajetan.klos@aofoundation.org
authors.forename: Kajetan
authors.initials: K
authors.lastname: Klos
authors.forename: Boyko
authors.initials: B
authors.lastname: Gueorguiev
authors.forename: Karsten
authors.initials: K
authors.lastname: Schwieger
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Fröber
authors.forename: Steffen
authors.initials: S
authors.lastname: Brodt
authors.forename: Gunther O
authors.initials: GO
authors.lastname: Hofmann
authors.forename: Markus
authors.initials: M
authors.lastname: Windolf
authors.forename: Thomas
authors.initials: T
authors.lastname: Mückley
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000601:surgery*; D001174:Arthrodesis / Q000295:instrumentation*; D015519:Bone Density; D001858:Bone Nails; D002102:Cadaver; D002111:Calcaneus / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008422:Materials Testing; D011474:Prosthesis Design; D013314:Stress, Mechanical; D013628:Talus / Q000601:surgery; D013640:Tarsal Joints / Q000601:surgery*; D013977:Tibia / Q000601:surgery