title: Minimally invasive stabilization of distal humerus fractures: a pilot study with biomechanical evaluation.
abstract: BACKGROUND
  Fracture of the distal humerus is a fairly rare injury and makes high demands on the treating surgeon. Prerequisites for a good outcome are anatomical reconstruction and osteosynthesis stable enough for exercises. A method permitting early restoration of function is especially important for patients with osteoporosis. The extensive surgical approach necessary for open reduction is associated with a high number of wound healing disorders and infections with a frequency of 11% being reported in the literature. Although open reduction and internal fixation in double-plating technique is unavoidable for complex intraarticular fractures, an alternative, minimally invasive and, consequently, tissue-preserving procedure is desirable for simpler fractures.
  
  
  OBJECTIVE
  To investigate this issue further an angular stable nail system developed for the distal radius was implanted as a stabilizer and the construct tested biomechanically as part of a feasibility study.
  
  
  METHODS
  Distal humerus fractures were stabilized by insertion of a distal radius nail, namely, the Targon DR (Aesculap, Tuttlingen) and a K-wire. To test the hypothesis six cadaveric bones fixed in formalin were tested biomechanically for displacement, implant failure, and stiffness. Displacement was determined by means of an ultrasound-based system.
  
  
  RESULTS
  An average displacement of 1.6 mm ± 0.7 was recorded at a maximum compression force of 100 N in extension and an average displacement of 1.4 mm ± 0.9 in flexion. Implant failure was not observed for any of the constructs.
  
  
  CONCLUSIONS
  The study presented here permits the conclusion that a minimally invasive procedure is possible at the distal humerus and does ensure adequate stability. Although the nail was not specifically designed for the humerus, current findings form the basis for a promising approach that will be pursued further after modification of the nail design.
authors.affiliation: Department of Surgery, Clinic for Orthopedic and Trauma Surgery, Freiburg University Hospital, Freiberg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Reising
authors.affiliation: Department of Surgery, Clinic for Orthopedic and Trauma Surgery, Freiburg University Hospital, Freiberg, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Konstantinidis
authors.affiliation: Department of Surgery, Clinic for Orthopedic and Trauma Surgery, Freiburg University Hospital, Freiberg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Helwig
authors.affiliation: Department of Surgery, Clinic for Orthopedic and Trauma Surgery, Freiburg University Hospital, Freiberg, Germany.
authors.forename: F C L
authors.initials: FC
authors.lastname: Wagner
authors.affiliation: Department of Surgery, Clinic for Orthopedic and Trauma Surgery, Freiburg University Hospital, Freiberg, Germany.
authors.forename: N P
authors.initials: NP
authors.lastname: Südkamp
authors.affiliation: Department of Surgery, Clinic for Orthopedic and Trauma Surgery, Freiburg University Hospital, Freiberg, Germany.
authors.forename: P C
authors.initials: PC
authors.lastname: Strohm
mesh_terms: D001858:Bone Nails; D001864:Bone Wires; D005240:Feasibility Studies; D005594:Fracture Fixation, Intramedullary / Q000379:methods*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D006811:Humerus / Q000293:injuries*; D055595:Mechanical Phenomena; D019060:Minimally Invasive Surgical Procedures; D010865:Pilot Projects
keywords: Distal humerus fracture; angular stable; minimal invasive; nail osteosynthesis