Safe zones of half-pin insertion in lumbar vertebrae cadaveric study

Purpose This experimental study is to know what the safe zones and angles of half-pin insertion in lumbar vertebrae are, and if there are other new sites for half-pin insertion. Materials and methods A cadaver study using two bony and four cadaveric specimens was undertaken to examine the safe sites for half-pin insertion in the lumbar vertebrae. Half pins were inserted into specific demarcated sites. Results From our study we suggest that the pedicle of the lumbar vertebrae is a safe and strong region for the insertion of the half pins with 10°–40° divergence from the midline, where the new site of half-pin insertion in the vertebral body anteriorly and at the level of transverse process is safe at an angle that lies between 50° and 60° from the sagittal plane in L4 and L5. Conclusion We concluded that the application of external fixators in the lumbar spine is valuable with good safety margins of half-pin introduction in both the pedicle and the vertebral body.