8Yerby SA, Toh E, Mclain RF. Revision of failed pedicle screws using hydroxyapatite cement :a biomechanical analysis[ J ]. Spine, 1998,23: 1657 - 1661.
9Halvorson T, Kelley L, Thomas K. Effects of bone mineral density on pedicle screw fixation [ J ]. Spine, 1994,19:2415 - 2420.
10Soshi S, Shiba R, Kondo H,et al. An experimental study on transpedicular screw fixation in relation to osteoporosis of the lumbar spine [ ]. Spine, 1991,16 : 1335 - 1341.
