TITLE:
Effect of screw position on bone tissue differentiation within a fixed femoral fracture
AUTHORS:
Saghar Nasr, Stephen Hunt, Neil A. Duncan
KEYWORDS:
Femoral Fracture; Internal Fixation; Screw Number; Screw Position; Tissue Differentiation; Finite Element Analysis
JOURNAL NAME:
Journal of Biomedical Science and Engineering,
Vol.6 No.12A,
December
27,
2013
ABSTRACT: Plate
and screw constructs are routinely used in the treatment of long bone
fractures. Despite considerable advancements in technology and techniques,
there can still be complications in the healing of long bone fractures.
Non-unions, delayed unions, and hardware failures are common complications observed
in clinical practice following open reduction and internal fixation of
fractures [1]. Potential causes of these adverse clinical effects may be disruptive
to the periosteal and endosteal blood supply, stress shielding effects, and
inadequate mechanical stability. The goal of the present study was to explore
the effect of screw position on the fracture healing and formation of new bone
tissue with mechanoregulatory algorithms in a computational model. An idealized
poroelastic 3D finite element (FE) model of a femur with a 5 mm fracture gap,
including a plate-screw construct was developed. Nineteen different plate-screw
combinations, created by varying the number and position of screws within the
plate, were created to identify a construct with the most favourable attributes
for fracture healing. The first phase of the study evaluated constructs through
mechanical stress analyses to identify those constructs with high loadsupport
capability. The second phase of the study evaluated healing and bone formation
with a biphasic mechanoregulatory algorithm to simulate tissue differentiation
for fixation within selected constructs. The results of our analysis demonstrated
a 4-screw symmetrical construct with the largest distance between screws to
provide the most favourable balance of stability and optimized conditions to
promote fracture healing.