title: The dynamisation of locking plate osteosynthesis by means of dynamic locking screws (DLS)-an experimental study in sheep.
abstract: In this in vivo study a new generation of locking screws was tested. The design of the dynamic locking screw (DLS) enables the dynamisation of the cortex underneath the plate (cis-cortex) and, therefore, allows almost parallel interfragmentary closure of the fracture gap. A 45° angle osteotomy was performed unilaterally on the tibia of 37 sheep. Groups of 12 sheep were formed and in each group a different osteotomy gap (0, 1 and 3mm) was fixed using a locking compression plate (LCP) in combination with the DLS. The healing process was monitored radiographically every 3 weeks for 6, respectively 12 weeks. After this time the sheep were sacrificed, the bones harvested and the implants removed. The isolated bones were evaluated in the micro-computed tomography unit, tested biomechanically and evaluated histologically. The best results of interfragmentary movement (IFM) were shown in the 0mm configuration. The bones of this group demonstrated histomorphometrically the most distinct callus formation on the cis-cortex and the highest torsional stiffness relative to the untreated limb at 12 weeks after surgery. This animal study showed that IFM stimulated the synthesis of new bone matrix, especially underneath the plate and thus, could solve a current limitation in normal human bone healing. The DLS will be a valuable addition to the locking screw technology and improve fracture healing.
authors.affiliation: Trauma Hospital Graz, Austria. michael.plecko@inode.at
authors.forename: Michael
authors.initials: M
authors.lastname: Plecko
authors.forename: Nico
authors.initials: N
authors.lastname: Lagerpusch
authors.forename: Daniel
authors.initials: D
authors.lastname: Andermatt
authors.forename: Robert
authors.initials: R
authors.lastname: Frigg
authors.forename: Rudolf
authors.initials: R
authors.lastname: Koch
authors.forename: Michèle
authors.initials: M
authors.lastname: Sidler
authors.forename: Peter
authors.initials: P
authors.lastname: Kronen
authors.forename: Karina
authors.initials: K
authors.lastname: Klein
authors.forename: Katja
authors.initials: K
authors.lastname: Nuss
authors.forename: Alexander
authors.initials: A
authors.lastname: Bürki
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ferguson
authors.forename: Ulrich
authors.initials: U
authors.lastname: Stoeckle
authors.forename: Jörg A
authors.initials: JA
authors.lastname: Auer
authors.forename: Brigitte
authors.initials: B
authors.lastname: von Rechenberg
mesh_terms: D000818:Animals; D001860:Bone Plates; D001863:Bone Screws; D002146:Bony Callus / Q000254:growth & development; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods*; D017102:Fracture Healing; D010012:Osteogenesis / Q000502:physiology*; D010027:Osteotomy; D012756:Sheep