Comminuted talar neck fractures: a mechanical comparison of fixation techniques.
OBJECTIVE
To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fractures.


METHODS
In vitro biomechanical study.


METHODS
Bioengineering research laboratory.


METHODS
Thirty previously frozen human cadaveric tali were osteotomized across the talar neck. A wedge of bone 2 cm long and extending 50% of the medial to lateral and superior to inferior dimension of the talus was removed to create an unstable, comminuted fracture.


METHODS
The specimens were randomized to one of 3 fixation groups. The first group was fixed with 3 anterior-to-posterior screws. The second group was fixed with 2 cannulated screws inserted from posterior to anterior. The third group was fixed with 1 screw from anterior to posterior and a medially applied blade plate. Specimens were embedded in acrylic cement and mounted on an Instron mechanical testing machine. Loading was applied in the dorsal-medial direction to failure.


METHODS
For each specimen, the load-displacement curve, yield point, and 3 mm displacement point were recorded in response to controlled dorsal-medial loading to failure. Stiffness was calculated as the linear portion of the slope of the load (kN) versus displacement (mm) curve. Statistical analysis of the data was conducted using analysis of variance.


RESULTS
The mean yield point of each of the fixation techniques tested exceeded 1.4 kN. No statistically significant difference was found between the fixation methods, even when variations in age and sex were considered.


CONCLUSIONS
The mean yield point of the fixation techniques tested exceeds the theoretical stress across the talar neck during active motion. Anterior plate fixation provided equivalent stability to posterior screw fixation.
Attiah
Mohammed
M
Victoria Hospital, University of Western Ontario, London, Ontario, Canada.
Sanders
David W
DW
Valdivia
Gonzalo
G
Cooper
Ian
I
Ferreira
Louis
L
MacLeod
Mark D
MD
Johnson
James A
JA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000379:methods; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D050723:Fractures, Bone / Q000503:physiopathology* / Q000601:surgery*; D018460:Fractures, Comminuted / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D013314:Stress, Mechanical; D013628:Talus / Q000293:injuries* / Q000503:physiopathology* / Q000601:surgery; D013718:Tensile Strength; D016896:Treatment Outcome