In vitro biomechanical comparison of a modified 5.5 mm locking compression plate fixation with a 5.5 mm locking compression plate fixation of osteotomized equine third metacarpal bones.
OBJECTIVE
To compare number of cycles to failure for palmarodorsal 4-point bending of a modified 5.5 mm broad locking compression plate (M5.5-LCP) fixation with a 5.5 mm broad LCP (5.5-LCP) fixation used to repair osteotomized equine third metacarpal (MC3) bones.


METHODS
In vitro biomechanical testing.


METHODS
Adult equine cadaveric MC3 bones (n=6 pairs).


METHODS
An 8-hole, M5.5-LCP, obtained by having a 1.0 mm thickness removed from the bone contact portion of the 5.5-LCP, was applied to the dorsal surface of 1 randomly selected MC3 from each pair, and an 8-hole, 5.5-LCP was applied dorsally to the contralateral bone from each pair using a combination of cortical and locking screws. Plates and screws were applied using standard ASIF techniques to MC3 bones with a mid-diaphyseal osteotomy. MC3 constructs had palmarodorsal 4-point bending cyclic fatigue testing. Mean cycles to failure for each method were compared using a paired t-test within each group. Significance was set at P<.05.


RESULTS
Mean±SD cycles to failure of the M5.5-LCP fixation (188,641±17,971) was significantly greater than that of the 5.5-LCP fixation (166,497±15,539).


CONCLUSIONS
M5.5-LCP fixation was superior to 5.5-LCP fixation of osteotomized equine MC3 bones in resisting cyclic fatigue under palmarodorsal 4-point bending.


CONCLUSIONS
This suggests that biological plate fixation is not the ideal choice for osteotomized equine MC3 bones.
Sod
Gary A
GA
Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA. gsod@vetmed.lsu.edu
Riggs
Laura M
LM
Mitchell
Colin F
CF
Martin
George S
GS
Gill
Marjorie S
MS
D000818:Animals; D001696:Biomechanical Phenomena; D001860:Bone Plates / Q000662:veterinary*; D019245:Compressive Strength; D005593:Fracture Fixation, Internal / Q000379:methods / Q000662:veterinary*; D006736:Horses / Q000601:surgery*; D016268:Internal Fixators / Q000662:veterinary*; D008422:Materials Testing / Q000662:veterinary; D050279:Metacarpal Bones / Q000601:surgery*; D010027:Osteotomy / Q000662:veterinary