title: Impact of double-tiered subchondral support procedure with a polyaxial locking plate on the stability of distal radius fractures using fresh cadaveric forearms: Biomechanical and radiographic analyses.
abstract: BACKGROUND
  The present study compared the changes in biomechanical and radiographic properties under cyclic axial loadings between the 'double-tiered subchondral support' (DSS) group (wherein two rows of screws were used) and the 'non-DSS' (NDSS) group (wherein only one row of distal screws was used) using cadaveric forearm models of radius fractures fixed with a polyaxial locking plate.
  
  
  METHODS
  Fifteen fresh cadaveric forearms were surgically operated to generate an Arbeitsgemeinschaft für Osteosynthesefragen (AO) type 23-C2 fracture model with the fixation of polyaxial volar locking plates. The model specimens were randomized into two groups: DSS (n = 7) and NDSS (n = 8). Both the groups received 4 locking screws in the most distal row, as is usually applied, whereas the DSS group received 2 additional screws in the second row inserted at an inclination of about 15° to support the dorsal aspect of the dorsal subchondral bone. Cyclic axial compression test was performed (3000 cycles; 0-250 N; 60 mm/min) to measure absolute rigidity and displacement, after 1, 1000, 2000 and 3000 cycles, and values were normalized relative to cycle 1. These absolute and normalized values were compared between those two groups. Radiographic images were taken before and after the cyclic loading to measure changes in volar tilt (ΔVT) and radial inclination (ΔRI).
  
  
  RESULTS
  The DSS group maintained significantly higher rigidity and lower displacement values than the NDSS group during the entire loading period. Radiographic analysis indicated that the ΔVT values of the DSS group were lower than those of the NDSS group. In contrast, the fixation design did not influence the impact of loading on the ΔRI values.
  
  
  CONCLUSIONS
  Biomechanical and radiographic analyses demonstrated that two rows of distal locking screws in the DSS procedure conferred higher stability than one row of distal locking screws.
authors: Department of Orthopaedic Surgery, Showa University School of Medicine, Tokyo, Japan. Electronic address: sadaaki.tsutsui@gmail.com.
authors: Sadaaki
authors: S
authors: Tsutsui
authors: Department of Orthopaedic Surgery, Showa University School of Medicine, Tokyo, Japan.
authors: Keikichi
authors: K
authors: Kawasaki
authors: Department of Orthopaedic Surgery, Showa University School of Medicine, Tokyo, Japan; College of Science and Engineering, Kanazawa University, Kanazawa, Japan.
authors: Ken-Ichi
authors: K
authors: Yamakoshi
authors: Department of School of Health Sciences, Sapporo Medical University, Sapporo, Japan.
authors: Eiichi
authors: E
authors: Uchiyama
authors: Health Sciences University of Hokkaido, School of Rehabilitation Science, Sapporo, Japan.
authors: Mitsuhiro
authors: M
authors: Aoki
authors: Department of Orthopaedic Surgery, Showa University School of Medicine, Tokyo, Japan.
authors: Katsunori
authors: K
authors: Inagaki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D004838:Epiphyses / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D005542:Forearm; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007593:Joint Instability / Q000517:prevention & control*; D008297:Male; D011859:Radiography / Q000379:methods; D011885:Radius Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D013314:Stress, Mechanical; D014954:Wrist Injuries / Q000000981:diagnostic imaging / Q000601:surgery*