title: Development of a technique for cement augmentation of nailed tibiotalocalcaneal arthrodesis constructs.
abstract: BACKGROUND
  Tibiotalocalcaneal arthrodesis with a retrograde nail is an established procedure. Many patients considered for this arthrodesis have poor bone stock, which may make it difficult to obtain construct stability. This study was undertaken to determine whether stability could be enhanced by the cement augmentation of the calcaneal locking screws.
  
  
  METHODS
  A cannulated and perforated screw, and a technique for cement augmentation via this screw, were developed. Eight pairs of human cadaver bones were instrumented with a retrograde intramedullary device (Expert Hindfoot Arthrodesis Nail, Synthes AG, Solothurn, Switzerland). Within each pair, one specimen was randomized to have the nail interlocked in the calcaneus with two conventional screws; while the other specimen was similarly instrumented with the use of two cement-augmented screws. The bone mineral density was determined. In quasi-static tests, the neutral zone and the range of motion of the constructs were determined. Subsequently the specimens were tested in dorsiflexion/plantar flexion until failure occurred. The neutral zone and the range of motion of the constructs were determined every 200 cycles.
  
  
  RESULTS
  Augmentation resulted in significantly greater stiffness and a significantly smaller range of motion in the quasi-static dorsiflexion/plantar flexion test, and in a significantly smaller neutral zone in all quasi-static tests. With cyclic loading, the number of cycles to failure was significantly larger in the augmented group. In both groups, bone mineral density was significantly correlated with the number of cycles to failure. Two augmented screws broke.
  
  
  CONCLUSIONS
  Cement augmentation confers significant mechanical benefit in hindfoot arthrodesis and therefore can be used as a salvage procedure. Further development should be performed to validate the concept.
authors.affiliation: AO Research Institute, AO Foundation, Clavadelerstrasse, Davos Platz, Switzerland. Kajetan.Klos@med.uni-jena.de
authors.forename: Kajetan
authors.initials: K
authors.lastname: Klos
authors.forename: Dirk
authors.initials: D
authors.lastname: Wähnert
authors.forename: Boyko
authors.initials: B
authors.lastname: Gueorguiev
authors.forename: Karsten
authors.initials: K
authors.lastname: Schwieger
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; D001174:Arthrodesis / Q000295:instrumentation* / Q000379:methods; D001696:Biomechanical Phenomena; D001843:Bone Cements; D015519:Bone Density; D001858:Bone Nails; D004867:Equipment Design; D005260:Female; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D013314:Stress, Mechanical; D013977:Tibia / Q000503:physiopathology
chemical_list: D001843:Bone Cements