Purpose: This experimental study is to know what are the safe zones and angles of half pin insertion in thoracic vertebrae.
Methodology: Simple tools were used, power drill, 4, 5, 6mm halfpins, goniometer, and portable X-rays apparatus.
There were two bony specimens consists of complete lumber thoracic and cervical spine with ribs and sternum attached, three cadaveric specimens preserved in formalin, consists of thorax and abdomen with the back muscle dissected to show the thoracic pedicle.
The methodology was to insert the schanz screw in the thoracic pedicle from T1to T12 by free hand technique in bony skeleton, and then repeated on the cadaveric specimens to evaluate the correct angle of insertion, checking the site of half pin insertion by X-ray for the cadaveric specimen.
Results: The suggested safe angulation of half pins was 20 to 30degrees at T1, while, 15 to 25 degrees at T2,
It was 10 to 15 degrees at T3, while at T4 it was 10 to 15 degrees, where from T5 to T9 the safe angle was from 5 to 15 degrees.In T11 and T12, the safe angle was between 0 and 5 degrees.
the safe angle of half pins insertion in the pedicle of thoracic spine in sagittal plane in all vertebrae from T1to T12 was between 10 to 15 degrees.
Conclusion: It was concluded that the application of the external fixator in thoracic spine is safe provided that better understanding of the anatomical properties of the thoracic spine.
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