title: The primary stability of angle-stable versus conventional locked intramedullary nails.
abstract: OBJECTIVE
  The aim of this study was to compare the initial biomechanical characteristics of the angle-stable locking system for intramedullary nails using the new biodegradable sleeve with conventional locking in the treatment of unstable distal tibial fractures.
  
  
  METHODS
  Eight pairs of fresh, frozen porcine tibiae were used for this study. The expert tibial nail (Synthes) was equipped with either conventional locking screws (CL) or the angle-stable locking system (AS). This system consists of a special ASLS screw with a biodegradable sleeve. For this investigation distal tibias (5.5 cm) were used and the nails were locked with three screws in both groups. Biomechanical testing included non-destructive torsional and axial loading.
  
  
  RESULTS
  The AS group showed a significantly higher torsional stiffness (70%) compared to the CL group. The range of motion was 0.5 times smaller for the AS constructs. The neutral zone was eight times higher in the CL group (p < 0.001). In axial loading the AS group also showed a 10% higher axial stiffness and a 12% lower range of motion (p < 0.001).
  
  
  CONCLUSIONS
  The angle-stable locking system (ASLS) using a special screw and sleeve locking for intramedullary nails provides a significantly higher primary stability. The differences determined in this study may have clinical relevance particularly for torsional loads. For the new biodegradable angle-stable sleeve we found a comparable stability to the PEEK-based sleeve system. This system has the potential to decrease complications such as secondary loss of reduction and mal-/non-union.
authors: Department of Trauma-, Hand- and Reconstructive Surgery, Friedrich Schiller University Jena, Erlanger Allee 101, 07747, Jena, Germany. Dirk.Waehnert@ukmuenster.de
authors: Dirk
authors: D
authors: Wähnert
authors: Yves
authors: Y
authors: Stolarczyk
authors: Konrad L
authors: KL
authors: Hoffmeier
authors: Michael J
authors: MJ
authors: Raschke
authors: Gunther O
authors: GO
authors: Hofmann
authors: Thomas
authors: T
authors: Mückley
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001860:Bone Plates; D001863:Bone Screws; D005260:Female; D005594:Fracture Fixation, Intramedullary / Q000379:methods*; D016268:Internal Fixators; D019736:Prostheses and Implants; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D013552:Swine; D013977:Tibia / Q000601:surgery*; D013978:Tibial Fractures / Q000601:surgery*