Summary
The purpose of this study was to study the effects of pin design and dynamic loading
on the biological response of bone at the pin-bone interface (PBI). An electro-pneumatic
pin-loading device was used to mimic the forces that would be experienced by external
fixator pins, during patient ambulation following repair of a fracture with external
skeletal fixation. The remodelling response was assessed histologically with fluorescence
microscopy of plasticembedded undecalcified pin-bone sections, and surface-stained
histomorphometry.
There were no significant differences between the AO Schanz and Howmedica Apex 5.0
mm diameter self-tapping pin designs when they were inserted in 4.5 mm diameter predrilled
pilot holes. When pin type was controlled for, significant differences (p<0.05) existed
between loaded and control groups as well as between entry (near) and exit (far) cortices.
Less bone resorption was observed in the non-loaded group in comparison to the dynamically
loaded group, and bone resorption in the near cortex consistently exceeded the amount
of bone resorption in the far cortex for both treatment groups.
The purpose of this study was to examine the effects of pin design and dynamic pin
loading on the remodelling response of cortical bone at the pin-bone interface (PBI)
of intact sheep tibiae. No significant differences were demonstrated between pin designs;
however, significant differences (p<0.05) existed between loaded versus control pins,
as well as between entry and exit cortices.
Keywords
External fixator pin-bone interface - dynamic pin loading - bone remodelling
