Biomechanical Analysis of Tibial Strength After Harvest of Unicortical Tibial Grafts from Two Different Sites

Abstract

Considering that there was no statistically significant difference in torque to failure between the two groups of tibiae, the site for tibial bone graft can be selected based on the shape of the cortical graft necessary for each specific surgery.

Biomechanical Analysis of Tibial Strength After Harvesting Unicortical Tibial Grafts of Two Different Lengths

“…We chose this design to obtain torsional strength data for intact specimens, which was not obtained in a previous study using the same model. 13 We tested the smallest and largest size graft used in practice by the senior author to determine whether strength differed between the graft and intact groups and between the two graft groups. In specimens from which graft was to be taken, a rectangular cortical strut graft randomly assigned measuring 1.5 × 2 cm or 1.5 × 6 cm was obtained from the medial cortex 1 cm dorsal to the tibial crest.…”

“…The drill holes were connected using a high-speed microsagittal saw with precautions taken not to overcut the holes as described previously. 13 Each graft was then lifted out of the tibia using a 0.25-in osteotome. Both ends of each tibia were cross-drilled with Kirschner wires for testing.…”

“…Testing was done as described previously. 13 Both ends of each tibia were mounted in fiberglass resin within PVC pipe sections, and torsional stability was provided by the Kirschner wires. An MTS 858 Mini Bionix servohydraulic test frame (MTS Systems Corp., Eden Prairie, MN) was used for loading (Figure 1).…”

“…1,5,6,8,10,12,16,17,19 In orthopedic surgeries, especially those involving the lower extremity, ease of harvest and availability of a proximal tibial strut graft may offer a useful alternative for cortical autograft. 3,11,13…”

“…A recent biomechanical study noted no difference in torque to failure for tibial specimens used as donor sites for grafts taken from the tibial crest or off the crest. 13 However, there is no point of reference in the literature indicating how much cortex can be safely removed from the tibia and to what degree the removal of cortex weakens the tibia.…”