The several features which are outstanding on the basis of our microscopic examination are:
1. The simplicity of and the rapid progress made by the healing process.
2. The absence of cartilage from the healing process at the fracture site.
3. The absence of subperiosteal reaction or peripheral callus.
4. The minimal evidence of trauma inflicted by the insertion of the pin.
5. The minimal reaction of the tissues to the presence of the pin.
6. The absence of significant osteoporosis, and the apposition of new bone on trabecular surfaces at such an early period after fracture.
It is quite clear from a study of our specimen that any method of internal fixation which meets mechanical requirements—such as good reduction, elimination of shearing stress at the fracture site, and adequate fixation of fragments which are and remain in an excellent state of nutrition—will result in bony union much sooner than has been generally appreciated in the past. These fundamentals should be borne in mind, since the prominence of technical detail has tended to subordinate some basic pathological and clinical aspects of the problem as a whole.