In vitro biomechanical comparison of dynamic compression plates with a rough contact surface and a polished contact surface for fixation of osteotomized equine third metacarpal bones.

This research article compares the performance of dynamic compression plates with rough and smooth contact surfaces when used to repair fractures in horse’s metacarpal (limb) bones. The study showed that the plates with rough contact surfaces demonstrated superior resistance to repeated bending stress compared to those with smooth surfaces.

Research Goals

• The objective of this study was to compare the biomechanical performance of dynamic compression plates (DCP) and limited-contact dynamic compression plates (LC-DCP) with rough (R-) versus smooth contact surfaces. This was performed by assessing how long it took for the plates to fail when applied to repair fractures in horse metacarpal bones.

Methodology

• The study used 15 pairs of adult horse metacarpal bones. The bones were divided into three test groups for comparison: rough DCP vs smooth DCP, rough 4.5-LC-DCP vs smooth 4.5-LC-DCP, and rough 5.5-LC-DCP vs smooth 5.5-LC-DCP.
• In each group, an 8-hole plate with a rough contact surface was applied to one randomly chosen bone from each pair, while a similar 8-hole plate with a smooth surface was applied to another bone from the same pair.
• All plates and screws were applied using standard Association for the Study of Internal Fixation (ASIF) techniques. All metacarpal bones had mid-diaphyseal osteotomies, a surgical breaking procedure.
• The team conducted the testing simulating the forces a horse’s limb would face during activity. They then compared the average number of cycles to plate failure for each method within each group. A cycle counts as one period of stress on the bone. The plates were considered to have failed when the bone fracture reopened.

Results

• The study found that the average cycles to failure was significantly higher for all types of plates with rough surfaces than the corresponding ones with smooth surfaces.
• Concretely, the R-DCP fixation lasted 230,025 cycles compared to 103,451 cycles for the traditional DCP. The R-4.5- LC-DCP stayed for 99,237 cycles versus 46,464 cycles for the 4.5-LC-DCP and the R-5.5-LC-DCP lasted for 65,113 cycles compared to 34,224 cycles for the 5.5-LC-DCP.

Conclusions

• The study concluded that, for fracture repair in horse metacarpal bones, constructs using plates with rough contact surfaces performed better than those using plates with smooth surfaces in resisting cyclical bending fatigue.
• This could lead to changes in the materials and techniques used for veterinary orthopedic surgery to improve recovery outcomes.