title: Is there a benefit of proximal locking screws in osteoporotic distal radius fractures? - A biomechanical study.
abstract: BACKGROUND
  The distal radial fracture is a common fracture and frequently seen in geriatric patients. During the last years, volar plating has become a popular treatment option. While the application of locking screws at the distal fragment is widely accepted, there is no evidence for their use at the radial shaft.
  
  
  METHODS
  In six osteoporotic pairs of matched human cadaver radii an extra-articular model creating an AO 23-A2.1 fracture was employed. Osteosynthesis were performed using the APTUS 2.5 Adaptive TriLock Distal Radius System (Medartis AG) with locking (LS) or non-locking screws (NLS) for proximal fixation. Biomechanical testing was performed in a staircase fashion: starting with 50 cycles at 200N, the load was continuously increased by 50N every 80 cycles up to a maximum force of 400N. Finally, load to failure was analyzed with failure defined as sudden loss of force measured (20%) or major deformation of the radii (10mm).
  
  
  RESULTS
  At 200N, 250N, 300N, 400N and load to failure, the NLS group showed a higher degree of elastic modulus. In contrast, the LS group showed higher elastic modulus at 350N. Maximum force was higher in the LS group without reaching statistical significance. Reasons for loss of fixation were longitudinal shaft fractures, horizontal peri-implant fractures and distal cutting out. No difference was seen between the two groups concerning the development of the above mentioned complications.
  
  
  CONCLUSIONS
  Our study did not show biomechanical superiority for distal radius fracture fixation by using locking screws in the proximal holes in an osteoporotic cadaver study. At load to failure, longitudinal shaft fractures and peri-implant fractures seemed to be a more relevant problem rather than failure of the proximal fixation.
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bockmann
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Can
authors.initials: C
authors.lastname: Budak
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Figiel
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Lechler
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Bliemel
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Debus
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Schwarting
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Oberkircher
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University Hospital Gießen and Marburg, Location Marburg, Baldingerstr., 35043 Marburg, Germany. Electronic address: michaelfrink@web.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Frink
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008297:Male; D008422:Materials Testing / Q000379:methods*; D058866:Osteoporotic Fractures / Q000601:surgery*; D011885:Radius Fractures / Q000601:surgery*; D013314:Stress, Mechanical
keywords: Biomechanics; Distal radius fractures; Locking screws