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11.4 RESULTS 233

FIG. 11.24 Amplitude of axial micromotion (μm), for the “A” study, corresponding to different nail materials: (A) steel intramedullary nail;
(B) titanium intramedullary nail.

gap) to 2.01mm (distal fracture, 20mm gap), whereas the titanium nail yields a higher rate of global movement:
1.62mm (proximal fracture, 0.5mm gap) to 3.14mm (distal fracture, 20mm gap). By calculating the ratio of the global
movement between both materials a pitchfork of 1.22–1.56 is obtained.
However, in the “B” study, global stability of each fixation system follows similar tendencies as the aforemen-
tioned amplitude of micromotion for the steel nail and titanium nail. The global movement at the top of the nail
was measured yielding the most rigid behavior for the fourth interlocking system: 1.75–2.01mm for the steel nail,
whereas for the titanium nail, the first screw combination showed the smallest motion for the first interlocking
system: 2.81 and 2.80mm (3mm and 20mm gap size, respectively). For the smallest gap size, the fourth interlock-
ing system was again the most stable in terms of global movement (2.36mm). Analogously to the analyzed micro-
motions, the second and third fixation systems yield similar results for both materials in the two gaps associated
with comminuted fractures.

I. BIOMECHANICS