الفهرس | Only 14 pages are availabe for public view |
Abstract Distraction osteogenesis represents the mechanical induction of new bone produced during the gradual separation of two well –stabilized bone segments. The soft tissues are not simply stretched by distraction, they too undergo lengthening. Several mechanisms of muscular adaptation are described, the most important of which is the addition of new sarcomers at the end of muscle fibers. Ultrastructurally, changes at the energy supplying and protein synthesizing systems are recognized. Adaptation of nerves occurs mainly by proliferation of schwann cells. Delay in nerve conduction is well recognized. Nerve injury during distraction may be surgical or as a result of stretch. The most common nerve to be affected is the common peroneal nerve. Distraction also has different effects on joints including decreased range of motion and subluxation. The effect on articular cartilage in the form of fibrillation occurs more with femoral lengthening than tibial lengthening and less with spanning apparatus. Distraction in skeletally immature patients causes reversible alteration in the growth plate in the immediate vicinity of the distraction segment. This leads to a temporary slowing in longitudinal growth of the affected physis evidenced by temporary reduction in thickness and in cell count. |