A Biomechanical Comparison of Expansive Pedicle Screws for Severe Osteoporosis: The Effects of Screw Design and Cement Augmentation
Fig 2
Photographs that show expansive screws with 6 (left) and 4 (right) separated lengthwise slits (A), and expansive screws with different EELs: (B) 16-mm EEL (with an inner pin of 44-mm in length) and (C) 22-mm EEL (with an inner pin of 38-mm in length).
The insertion pin was inserted into the interior of the screw to open the fins at the tip of the expansive screws. The difference in EEL affects the range of screw expansion following pin insertion.