In vitro biomechanical comparison of 3.5 mm LC-DCP/intramedullary rod and 5 mm clamp-rod internal fixator (CRIF)/intramedullary rod fixation in a canine femoral gap model.
OBJECTIVE
To compare the biomechanical properties of clamp rod internal fixation (CRIF)/rod and LC-DCP/rod constructs in a canine femoral gap model.


METHODS
Cadaveric biomechanical study.


METHODS
Canine femora (n = 10 pair).


METHODS
Femora with 40 mm ostectomies were assigned to LC-DCP/rod or CRIF/rod treatment groups. Five construct pairs had 4-point bending and 5 pairs had torsional loading. Construct stiffness, strength, and bending angle at failure or permanent angular deformation (torsional loading) were determined. Statistical comparisons were performed using Student t tests; significance was set at P ≤ .05.


RESULTS
There was significantly greater permanent angular deformation, or residual twist, in the CRIF/rod constructs (23.1 ± 0.89°) compared with LC-DCP/rod constructs (7.47 ± 2.08°). Whereas there was no significant difference in torsional stiffness of these constructs at torsional loads <4.92 N m (P = .819), LC-DCP/rod constructs had significantly greater torsional stiffness (0.303 ± 0.079 N m/°) and strength (11.546 ± 2.79 N m) than CRIF/rod construct stiffness (0.06 ± 0.013 N m/°) and strength (6.078 ± 0.527 N m) at torsional loads >4.92 N m. Differences in stiffness and strength in 4-point bending were not statistically significant.


CONCLUSIONS
LC-DCP/rod constructs had significantly less permanent angular deformation than CRIF/rod constructs. CRIF/rod constructs became less stiff as torsional load was increased, thus the LC-DCP/rod constructs had significantly greater torsional stiffness and strength under high torsional loads. LC-DCP/rod and CRIF/rod constructs performed similarly under 4-point bend loading conditions.
Department of Veterinary Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas.
Glen A
GA
Bonin
Sean T
ST
Baker
Caleb A
CA
Davis
Christie M
CM
Bergerson
Aubrey A
AA
Hildebrandt
Don A
DA
Hulse
Sharon C
SC
Kerwin
Michael R
MR
Moreno
W Brian
WB
Saunders
D000818:Animals; D001696:Biomechanical Phenomena; D002102:Cadaver; D004283:Dog Diseases / Q000601:surgery*; D004285:Dogs; D005269:Femur / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000662:veterinary*; D066298:In Vitro Techniques; D007593:Joint Instability / Q000601:surgery / Q000662:veterinary*