Page 172 - ASOP ROT Study Guide

8. HOW FRACTURES HEAL

Bone tissue can be regenerated after injury, unlike other connective tissues which heal with fibrous
tissue, forming a scar. This remarkable process remains poorly understood but we can glean
enough information to help us in planning and understanding the various treatment regimens
described above. The process of bone healing is outlined in Figure 29.

FIGURE. A DIAGRAMMATIC REPRESENTATION OF THE HEALING http://www.apsubiology.org/anatomy/2010/2010_Exam_Re
views/Exam_2_Review/Ch_6_Bone_Fractures.htm
PROCESS OF FRACTURED BONE.

Bones heal in the presence of some movement. This is clear from the example of broken ribs
which unite efficiently (albeit painfully) with prodigious external callus formation. It appears that
movement stimulates union but the movement must be small and only in certain directions. Bones
are stimulated to heal by micro movement directed along the long axis of the bone at right angles
to the break. They heal least efficiently if subjected to shearing forces or large movements.

The converse also holds true. Although bones will heal if there is no movement, they do so very
slowly and by a different process which does not involve natural external callus formation. This
method of fracture healing is also not fully understood.

All bone healing is highly dependent on a good blood supply and so we again come to appreciate
the importance of the surrounding soft tissues and of the essential need to respect bone as a
living, as well as a structurally important, material.

Bearing these points in mind we can conclude that bones which are allowed to heal with optimal
movement will do so efficiently and with no long term adverse consequences, provided alignment
may be maintained. However, if bones are fixed rigidly (using internal fixation techniques) then
they will unite in accurate alignment (provided the surgeon has been able to be accurate!), but will
do so slowly. This will be most marked in long bones and less problematical in cancellous bone,
which tends to heal fairly quickly.