In general, blood supply of the long bones contributes three ways-nutrient, metaphyseal and periosteal vessels.

Its vascular damage is caused by major trauma or extensive soft tissue det-achment. When the diaphysis of long bone is reamed, endosteal blood supply is eliminated.

In our hospital, 23 selected cases of the diaphyseal fracture of tibla have been treated by manipulative reduction, unlearning of the medullary canal and fixation of fracture fragments with an Interlocking intramedullary nail for preserration its vascularity as possible.

We analized the patients from Jan. 1992 to May 1993, who were followed up for a mean 12 months.

Most of cases were acute, 18 of these cases were open fracture and main cause of the injury was traffic accidents.

Overall, 90% of the patients were judged to have good or excellent result based on both clinical and radiological parameters, and the average bony union time was 17 weeks.

The complications were mainly infection(3 cases), loosening or breakage of the locking screws(3 cases) and delayed union(1 case).

The merits of unlearned interlocking nailing were relatively easy procedure, short operation time, decreased complcations, rigid fixation and early rehabilitation.

We concluded that unlearned intramedullary interlocking nailing is a useful method to treat the tibia shaft fractures, especially open type.