Clinical orthopaedics and related research
-
Clin. Orthop. Relat. Res. · Oct 1998
Comparative StudyStrain rate and timing of stimulation in mechanical modulation of fracture healing.
Fracture of the long bones results in a repair process that has the potential to restore the anatomic morphology and mechanical integrity of the bone without scar tissue. The repair process can occur in two patterns. In the first, under conditions of rigid stabilization, direct osteonal remodeling of the fracture line can occur with little or no external callus, a process known as direct bone repair. ⋯ The beneficial effect of this particular biophysic stimulus early in the healing period may be related to the viscoelastic nature of the differentiating connective tissues in the early endochondral callus. In the early endochondral callus, high rates of movement induce a greater deformation of the fracture fragments because of the stiffening of the callus. Alternatively, the transduction pathway may involve streaming potentials as a result of the high movement rate.
-
Laboratory and clinical scientists and practicing clinicians need definitions of union, delayed union, and nonunion. Fracture union is a gradual process, so quantitative measures are the most meaningful. However, end point definitions also are useful, but they need empirical validation. ⋯ These observations suggest a more rational approach to the definition of union, delayed union, and nonunion than that provided by the selection of arbitrary times. For conservatively treated fractures at least, delayed union can be defined as the cessation of the periosteal response before the fracture successfully has been bridged. Nonunion is the cessation of both the periosteal and endosteal healing responses without bridging.