title: Metaphyseal screw augmentation of the LISS-PLT plate with polymethylmethacrylate improves angular stability in osteoporotic proximal third tibial fractures: a biomechanical study in human cadaveric tibiae.
abstract: OBJECTIVE
  The incidence of osteoporotic proximal tibial fractures has increased during the last 2 decades. A promising approach in osteoporotic fracture fixation is polymethylmethacrylate-based cement augmentation of implants to gain better implant purchase in the bone. This study investigates the biomechanical benefits of screw augmentation in less invasive stabilization system-proximal lateral tibial (LISS-PLT) plates in cadaveric extraarticular comminuted proximal tibial fractures (OTA-41-A3.3).
  
  
  METHODS
  Standardized extraarticular proximal tibial fractures were stabilized with the LISS-PLT plate in 6 paired osteoporotic cadaveric tibiae. Bone mineral density was measured with high-resolution, quantitative computed tomography scans to identify bone quality. In the augmented group, the 5 proximal screws of the LISS-PLT plate were augmented with 1 mL of bone cement each, whereas the contralateral tibia was instrumented conventionally as the control. Cyclic axial loading was applied to each specimen with a starting load of 150 N, using a ramp of 0.05 N per cycle to 10-mm axial displacement. Varus displacement was identified from anterior-posterior radiographs.
  
  
  RESULTS
  Bone mineral density showed no significant difference between the 2 groups (P = 0.47). The nonaugmented group reached 9417 load cycles (SD 753) until failure, compared with 14,792 load cycles (SD 2088) in the augmented group (P = 0.002). In the early-onset failure (deformation at 8250 load cycles), varus displacement was significantly smaller in the augmented group (0.46 degrees, SD 0.6) than in the nonaugmented group (3.23 degrees, SD 1.7) (P = 0.01).
  
  
  CONCLUSIONS
  This biomechanical study showed that cement augmentation of the LISS-PLT plate screws in osteoporotic proximal extraarticular tibial fractures significantly lowers the propensity toward screw migration and secondary varus displacement.
authors.affiliation: *Biomedical Services, AO Research Institute Davos, Davos, Switzerland; and †Department of Trauma Surgery, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Goetzen
authors.forename: Tomas
authors.initials: T
authors.lastname: Nicolino
authors.forename: Ladina
authors.initials: L
authors.lastname: Hofmann-Fliri
authors.forename: Michael
authors.initials: M
authors.lastname: Blauth
authors.forename: Markus
authors.initials: M
authors.lastname: Windolf
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000627:therapeutic use*; D017760:Bone Malalignment / Q000517:prevention & control; D001860:Bone Plates; D001863:Bone Screws / Q000009:adverse effects; D002102:Cadaver; D005592:Fracture Fixation / Q000379:methods; D006801:Humans; D058866:Osteoporotic Fractures / Q000503:physiopathology / Q000601:surgery*; D019904:Polymethyl Methacrylate / Q000627:therapeutic use*; D011475:Prosthesis Failure; D013978:Tibial Fractures / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome
chemical_list: D001843:Bone Cements; D019904:Polymethyl Methacrylate