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.

The research compared two types of plates used to fix bone fractures in horses, finding that the modified 5.5 mm locking compression plate provided better resistance to bending and fatigue than the standard version.

Objective of the Study

• The purpose of this study was to compare the fatigue resistance and fixation strength of two types of plates, a 5.5 mm broad locking compression plate (5.5-LCP) and a modified version (M5.5-LCP), in repairing osteotomized (cut) equine third metacarpal (MC3) bones.

Methodology

• The study was conducted in vitro using adult equine cadaveric MC3 bones.
• Each pair of bones was fixed with either an 8-hole M5.5-LCP or an 8-hole 5.5-LCP.
• The M5.5-LCP was modified by removing a 1.0 mm thickness from the bone contact portion of the 5.5-LCP
• Plates and screws were applied using standard ASIF techniques to MC3 bones with a mid-diaphyseal osteotomy, a surgical fracturing technique.
• The repaired MC3 bone constructs were subjected to a palmarodorsal 4-point bending cyclic fatigue test, a method of testing the resistance of the constructs to repeated bending stresses.
• The number of cycles to failure for each method was then statistically compared using a paired t-test.

Results

• The results showed the M5.5-LCP fixation (188,641±17,971 cycles) outperformed the standard 5.5-LCP fixation (166,497±15,539 cycles) in terms of cycles to failure, indicating it had better resistance to cyclic fatigue.

Conclusions

• The study concluded that the M5.5-LCP fixation was superior to 5.5-LCP fixation in repairing osteotomized equine MC3 bones, indicating that it may be a better choice in clinical practice.
• The findings also suggested that biological plate fixation, which is represented by the 5.5-LCP, is likely not the optimal choice for osteotomized equine MC3 bones due to its lesser resistance to fatigue.