Locking screw-plate interface stability in carbon-fibre reinforced polyetheretherketone proximal humerus plates

Int Orthop. 2017 Sep;41(9):1735-1739. doi: 10.1007/s00264-017-3562-7. Epub 2017 Jul 13.


Purpose: Carbon-fibre reinforced polyetheretherketone (CFR-PEEK) plates have recently been introduced for proximal humerus fracture treatment. The purpose of this study was to compare the locking screw-plate interface stability in CFR-PEEK versus stainless steel (SS) proximal humerus plates.

Methods: Locking screw mechanical stability was evaluated independently in proximal and shaft plate holes. Stiffness and load to failure were tested for three conditions: (1) on-axis locking screw insertion in CFR-PEEK versus SS plates, (2) on-axis locking screw insertion, removal, and reinsertion in CFR-PEEK plates, and (3) 10-degree off-axis locking screw insertion in CFR-PEEK plates. Cantilever bending at a rate of 1 mm/minute was produced by an Instron machine and load-displacement data recorded.

Results: Shaft locking screw load to failure was significantly greater in CFR-PEEK plates compared to SS plates (746.4 ± 89.7 N versus 596.5 ± 32.6 N, p < 0.001). The stiffness and load to failure of shaft locking screws was significantly decreased when inserted 10 degrees off-axis compared to on-axis in CFR-PEEK plates (p < 0.001). Stiffness and load to failure did not vary significantly following screw reinsertion in CFR-PEEK plates.

Conclusion: The mechanical stability of locking screws in CFR-PEEK plates is comparable or superior to locking screws in SS plates.

Keywords: Biomaterials; Carbon-fiber polyetheretherketone; Proximal humerus fracture.

MeSH terms

  • Benzophenones
  • Biocompatible Materials / adverse effects
  • Biomechanical Phenomena
  • Bone Plates / adverse effects*
  • Bone Screws / adverse effects*
  • Carbon
  • Carbon Fiber
  • Fracture Fixation, Internal / adverse effects
  • Fracture Fixation, Internal / instrumentation*
  • Fracture Fixation, Internal / methods
  • Humans
  • Humerus / surgery
  • Ketones / adverse effects
  • Polyethylene Glycols / adverse effects
  • Polymers
  • Prosthesis Design / adverse effects
  • Prosthesis Failure / etiology*
  • Shoulder Fractures / surgery*
  • Stainless Steel / adverse effects


  • Benzophenones
  • Biocompatible Materials
  • Carbon Fiber
  • Ketones
  • Polymers
  • Stainless Steel
  • polyetheretherketone
  • Polyethylene Glycols
  • Carbon