A biomechanical analysis of the stability of titanium bone fixation systems in proximal phalangeal fractures

Apex bending and torsional loading were utilized to study the effects of different plate design and thickness, and screw size and design on the rigidity and strength of seven different titanium mini- and microplates placed onto osteotomized proximal phalanges. One hundred forty-four fresh frozen human cadaveric proximal phalangeal bones underwent a mid shaft osteotomy followed by application of one of the following plates: (1) Synthes linear 1.5-mm five-hole plates, (2) Leibinger linear 1.2-mm five-hole or (3) 1.7-mm four-hole plates, or (4) Leibinger three-dimensional 1.2-mm four-hole, (5) 1.2-mm eight-hole, (6) 1.7-mm four-hole, or (7) 1.7-mm eight-hole plates. Three-point bending (apex dorsal or apex volar) and torsional loading were utilized for each plating configuration. Analysis of variance models of bone specimen width, depth, cortical thickness, and length revealed that increasing plate thickness was associated with increasing rigidity, but that the three-dimensional design yielded a higher relative rigidity except under apex volar loading.