Insertional Torque and Pullout Strength of Pedicle Screws with or without Repositioning: A Porcine Study
Purpose. To evaluate the insertion torque and pullout strength of pedicle screws with or without repositioning. Methods. 20 fresh porcine lumbar vertebrae of similar size were used. The entry point was at the site just lateral and distal to the superior facet joint of the vertebra, and to a depth of...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SAGE Publishing
2014-08-01
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| Series: | Journal of Orthopaedic Surgery |
| Online Access: | https://doi.org/10.1177/230949901402200223 |
| _version_ | 1818328489845063680 |
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| author | Chun Ee Tan Margaret Woon Man Fok Keith Dip Kei Luk Kenneth Man Chee Cheung |
| author_facet | Chun Ee Tan Margaret Woon Man Fok Keith Dip Kei Luk Kenneth Man Chee Cheung |
| author_sort | Chun Ee Tan |
| collection | DOAJ |
| description | Purpose. To evaluate the insertion torque and pullout strength of pedicle screws with or without repositioning. Methods. 20 fresh porcine lumbar vertebrae of similar size were used. The entry point was at the site just lateral and distal to the superior facet joint of the vertebra, and to a depth of 35 mm. A 6.2-mm-diameter, 35-mm-long pedicle screw was inserted parallel to the superior end plate on one side as control. On the other side, an identical screw was first inserted 10° caudal to the superior end plate, and then repositioned parallel to the superior end plate. The insertional torque and pullout strength were measured. Results. Three of the specimens were excluded owing to pedicle fractures during the pullout test. Repositioned pedicle screws were significantly weaker than controls in terms of the maximum insertional torque (3.20±0.28 vs. 2.04±0.28 Nm, 36% difference, p±0.01) and pullout strength (1664±378 vs. 1391±295 N, p±0.01). Conclusion. Repositioning pedicle screws should be avoided, especially when the pedicle wall is breached. If repositioning is deemed necessary, augmentation with polymethyl methacrylate or a screw with a larger diameter should be considered. |
| first_indexed | 2024-12-13T12:32:59Z |
| format | Article |
| id | doaj.art-63f8e19fdf924b139bb4302e97e41f79 |
| institution | Directory Open Access Journal |
| issn | 2309-4990 |
| language | English |
| last_indexed | 2024-12-13T12:32:59Z |
| publishDate | 2014-08-01 |
| publisher | SAGE Publishing |
| record_format | Article |
| series | Journal of Orthopaedic Surgery |
| spelling | doaj.art-63f8e19fdf924b139bb4302e97e41f792022-12-21T23:45:57ZengSAGE PublishingJournal of Orthopaedic Surgery2309-49902014-08-012210.1177/230949901402200223Insertional Torque and Pullout Strength of Pedicle Screws with or without Repositioning: A Porcine StudyChun Ee Tan0Margaret Woon Man Fok1Keith Dip Kei Luk2Kenneth Man Chee Cheung3 Department of Orthopaedics and Traumatology, Penang Hospital, Penang, Malaysia Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong KongPurpose. To evaluate the insertion torque and pullout strength of pedicle screws with or without repositioning. Methods. 20 fresh porcine lumbar vertebrae of similar size were used. The entry point was at the site just lateral and distal to the superior facet joint of the vertebra, and to a depth of 35 mm. A 6.2-mm-diameter, 35-mm-long pedicle screw was inserted parallel to the superior end plate on one side as control. On the other side, an identical screw was first inserted 10° caudal to the superior end plate, and then repositioned parallel to the superior end plate. The insertional torque and pullout strength were measured. Results. Three of the specimens were excluded owing to pedicle fractures during the pullout test. Repositioned pedicle screws were significantly weaker than controls in terms of the maximum insertional torque (3.20±0.28 vs. 2.04±0.28 Nm, 36% difference, p±0.01) and pullout strength (1664±378 vs. 1391±295 N, p±0.01). Conclusion. Repositioning pedicle screws should be avoided, especially when the pedicle wall is breached. If repositioning is deemed necessary, augmentation with polymethyl methacrylate or a screw with a larger diameter should be considered.https://doi.org/10.1177/230949901402200223 |
| spellingShingle | Chun Ee Tan Margaret Woon Man Fok Keith Dip Kei Luk Kenneth Man Chee Cheung Insertional Torque and Pullout Strength of Pedicle Screws with or without Repositioning: A Porcine Study Journal of Orthopaedic Surgery |
| title | Insertional Torque and Pullout Strength of Pedicle Screws with or without Repositioning: A Porcine Study |
| title_full | Insertional Torque and Pullout Strength of Pedicle Screws with or without Repositioning: A Porcine Study |
| title_fullStr | Insertional Torque and Pullout Strength of Pedicle Screws with or without Repositioning: A Porcine Study |
| title_full_unstemmed | Insertional Torque and Pullout Strength of Pedicle Screws with or without Repositioning: A Porcine Study |
| title_short | Insertional Torque and Pullout Strength of Pedicle Screws with or without Repositioning: A Porcine Study |
| title_sort | insertional torque and pullout strength of pedicle screws with or without repositioning a porcine study |
| url | https://doi.org/10.1177/230949901402200223 |
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