title: Extra-articular step osteotomy of the olecranon: A biomechanical assessment.
abstract: BACKGROUND
  Trans-olecranon chevron osteotomies (COs) remain the gold standard surgical approach to type C fractures of the distal humerus. This technique is associated with a high complication rate and development of an extra-articular olecranon osteotomy may be advantageous. The aim of this study was to compare the load to failure of COs with extra-articular oblique osteotomies (OOs) as well as modified, extra-articular step osteotomies (SOs).
  
  
  METHODS
  These three osteotomies and their subsequent fixation utilizing a standardized tension band wiring technique were tested in 42 composite analog ulnae models at 20° and 70° of flexion. Triceps loading was simulated with a servo hydraulic testing machine. All specimens were isometrically loaded until failure. Kinematic and force data, as well as interfragmentary motion were recorded.
  
  
  RESULTS
  At 70°, CO failed at a mean load of 963 N (SD 104 N), the OO at 1512 N (SD 208 N) and the SO at 1484 N (SD 153 N), (P<0.001). At 20°, CO failed at a mean load of 707 N (SD 104 N) and OO at 1009 N (SD 85 N) (P=0.006). The highest load to failure was observed for the SO, which was 1277 N (SD 172 N). The load to failure of the SO was significantly higher than the CO as well as the OO.
  
  
  CONCLUSIONS
  Extra-articular osteotomies showed a significantly higher load to failure in comparison to traditional CO. At near full extension (20° of flexion), this biomechanical advantage was further enhanced by a step-cut modification of the extra-articular oblique osteotomy.
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, University of Bern, Insel Hospital, Switzerland. Electronic address: m.zumstein10@gmail.com.
authors.forename: Matthias A
authors.initials: MA
authors.lastname: Zumstein
authors.affiliation: Institute for Surgical Technology and Biomechanics, University of Berne, Stauffacherstrasse 78, Bern, Switzerland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Bürki
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, University of Bern, Insel Hospital, Switzerland.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Massy
authors.affiliation: Institute for Surgical Technology and Biomechanics, University of Berne, Stauffacherstrasse 78, Bern, Switzerland.
authors.forename: Philippe
authors.initials: P
authors.lastname: Zysset
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, University of Bern, Insel Hospital, Switzerland.
authors.forename: Beat K
authors.initials: BK
authors.lastname: Moor
mesh_terms: D001696:Biomechanical Phenomena; D004551:Elbow Joint / Q000503:physiopathology / Q000601:surgery; D019544:Equipment Failure Analysis; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D006810:Humeral Fractures / Q000503:physiopathology / Q000601:surgery*; D008954:Models, Biological; D056740:Olecranon Process / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology; D014457:Ulna / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery
keywords: Elbow; Extensor mechanism; Olecranon osteotomy; Posterior approach; Triceps insertion