The biomechanical parameters of
distraction can be divided into three categories: 1) extrinsic
or fixator-related factors, 2) intrinsic or tissue-related
factors, and 3) device orientation (Samchukov et al., 1998c, Cope et al., 1998). Numerous extrinsic
parameters affect the mechanical properties of the distraction appliance and
stability of bone segment fixation. These parameters include the number, length, and
diameter of fixation pins, the rigidity of the distraction device, material properties of
the device, etc. Intrinsic parameters are also important factors
that affect the quality of the forming distraction regenerate. They include the geometric
shape, cross-sectional area, and density of the distracted bone segments; the length of
the distraction regenerate; as well as the tension developing within the soft tissue
envelope, which includes muscles, ligaments, and fascia. Another critically important biomechanical parameter
affecting the successful application of distraction osteogenesis is the orientation
of the distraction device, and consequently the distraction
vector, relative to the anatomical axis of the bone segments to be
distracted.
