A new assembly of locking compression plate for treatment of comminuted femoral fracture: a three-dimensional finite element analysis

Abstract

Objective To explore the stress distributions on a new assembly of locking compression plate (NALCP) in 3 schemes of sliding plate by finite element analysis (FEA) in the treatment of comminuted femoral fracture. Methods A male volunteer received CT scanning with a slice thickness of 0.625 mm. The CT data were converted to FEA models of comminuted femoral fracture by software Mimics 10.0 and Geomagic Studio 12.0. The femoral fracture was fixated by NALCP in 3 schemes of sliding plate respectively. The sliding plate contacted the main plate by a mini arc plane in scheme A, by an inside groove in scheme B, and by a middle groove in scheme C. Loads were applied on NALCP in the 3 schemes when a person slowly walking by one leg and torsion were simulated. The stress distributions on NALCP and the femur were analyzed in the 3 schemes. Results Under the slowly walking and torsion loads, the 3 schemes led to similar change tendency in the stress distribution. The stress centered around the fracture ends. The maximum stress was situated at the lateral border of NO.5 countersink of the plate. The maximum stress of the main plate was the smallest in scheme A(529.20 MPa & 617.20 MPa). The maximum stress of the sliding plate was the smallest in scheme C (372.10 MPa & 814.70 MPa) and the second in scheme A (938.80 MPa & 1, 059.00 MPa). The maximum stress and the maximum displacement of bone blocks were the smallest in scheme A (28.68 MPa & 2.411 mm under slowly walking load; 34.52 MPa & 3.209 mm under torsion load). Conclusions Scheme A of NALCP in which the sliding plate contacts the main plate by a mini arc plane may provide adequate mechanical stability for comminuted femoral fracture and reduce stress concentration on plates, promoting fixation and thus bone union. Key words: Femoral fractures; Fracture fixation, internal; Bone plates; Finite element analysis; Biomechanics