Cannulated versus non-cannulated cancellous screw fixation for femoral neck fractures: a synthetic bone biomechanical study.
OBJECTIVE
To compare the compressive strength of cannulated versus non-cannulated cancellous screws for undisplaced femoral neck fractures in synthetic bones.


METHODS
18 synthetic proximal femurs simulating an AO B1 valgus impacted femoral neck fracture in osteoporotic bone were used. The fracture angles were between 55º and 63º (Pauwels grade 2). Fixation was made using 6.5-mm non-cannulated screws (n=6), 6.5-mm cannulated screws (n=6), or 7.3-mm cannulated screws (n=6). A custom-built jig was designed to guide the insertion of the screws in an identical triangular configuration. Screws were tightened by a single operator using a torque-measuring screwdriver. The femoral head was subjected to progressive axial loading at 5 mm/min. The load to failure and displacement were recorded.


RESULTS
The 3 groups did not differ significantly except that the load to failure was higher in the construct with 6.5-mm non-cannulated screws than that with 6.5-mm cannulated screws (1222 N vs 1008 N, p=0.003).


CONCLUSIONS
The compressive strength of a synthetic bone hip fracture model fixed with non-cannulated screws was higher than that of cannulated screws of the same diameter.
Department of Orthopaedic Surgery, Jurong Health Services, Alexandra Hospital, Singapore.
A W
AW
Gardner
School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
M Z
MZ
Toh
Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.
K S A
KS
Yew
Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.
D T T
DT
Lie
School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
S M
SM
Chou
D001696:Biomechanical Phenomena; D001863:Bone Screws; D019245:Compressive Strength; D005265:Femoral Neck Fractures / Q000503:physiopathology / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D008953:Models, Anatomic
bone screws; compressive strength; femoral neck fractures