The influence of screw omission on construction stiffness and bone surfacestrain in the application of bone plates to cadaveric bone

Biological fracture repair is becoming an increasingly popular means of fra cture fixation. This technique involves a reduction in the amount of surgic al trauma thereby preserving vascular supply and soft-tissue integrity comb ined with the implantation of less hardware. The aim is the stimulation of callus formation as the means by which fracture union occurs. This paper describes the mechanical effect of the symmetrical omission of s crews on construction stiffness and bone surface strain following the appli cation of bone plates to cadaveric bone. The influence of the pattern of sc rew omission was evaluated in both intact and osteotomized bone specimens. The application of bone plates using certain patterns of screw omission did not significantly effect the stiffness of the final construction whilst in herent bone surface strain was increased. It was concluded that the omission of screws in certain defined patterns fo r a given plate-bone construction may meet the criteria for 'biological fix ation'. There was no apparent deleterious effect on structural stiffness fo llowing the omission of 40% of the total screw complement from a plate-bone construction. (C) 1999 Elsevier Science Ltd. All rights reserved.