Factors affecting the pullout strength of self-drilling and self-tapping anterior cervical screws

Patrick W Hitchon; Matthew D Brenton; Justin K Coppes; Aaron M From; James C Torner

doi:10.1097/00007632-200301010-00004

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Factors affecting the pullout strength of self-drilling and self-tapping anterior cervical screws

Journal article

Peer reviewed

Factors affecting the pullout strength of self-drilling and self-tapping anterior cervical screws

Patrick W Hitchon, Matthew D Brenton, Justin K Coppes, Aaron M From and James C Torner

Spine (Philadelphia, Pa. 1976), Vol.28(1), pp.9-13

01/01/2003

DOI: 10.1097/00007632-200301010-00004

PMID: 12544947

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Abstract

A biomechanical comparison of 12-, 14-, and 16-mm self-tapping and self-drilling screws in cadaveric cervical spines was performed. This study compared self-drilling and self-tapping screw designs used in anterior cervical locking plates in terms of insertion torque and pullout strength. In addition to screw design, the effects of screw length (12, 14, and 16 mm) and bone mineral density were examined. A total of 201 screws were implanted and tested. Nineteen cadaver spine specimens (C2 through C7) were radiographed and their bone mineral density measured. In each vertebral level, two screws of the same length were implanted and their insertion torque measured. One of each screw design (self-drilling or self-tapping) was randomly placed in each vertebra for side-by-side comparison. Vertebrae then were individually potted and mounted on an MTS machine for accurate measurement of maximum pullout strength. Pullout strength was strongly related to screw length ( = 0.0002). There was no significant difference in pullout strength between the self-drilling and self-tapping screw designs at any length ( = 0.9352). A significant correlation ( </= 0.0077) exists between insertion torque and bone mineral density for the self-drilling and self-tapping 14- and 16-mm screws. A significant correlation exists between pullout strength and bone mineral density for 14- and 16-mm screw lengths of both screw types ( < 0.0001). It would appear that the longest screw feasible should always be used clinically for maximum pullout strength. There is no difference in pullout strength between self-drilling and self-tapping screws. Bone mineral density significantly influences screw performance.

Torque

Bone Density - physiology

Bone Screws - statistics & numerical data

Cervical Vertebrae - diagnostic imaging

Humans

Middle Aged

Bone Screws - standards

Stress, Mechanical

Male

Spinal Fusion - instrumentation

Radiography

Cervical Vertebrae - surgery

Biomechanical Phenomena

Aged, 80 and over

Adult

Female

Aged

Cadaver

Equipment Failure Analysis

Details

Title: Subtitle: Factors affecting the pullout strength of self-drilling and self-tapping anterior cervical screws
Creators: Patrick W Hitchon - Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive/Room 1847 JPP, Iowa City, IA 52242, USA. patrick-hitchon@uiowa.edu
Matthew D Brenton
Justin K Coppes
Aaron M From
James C Torner
Resource Type: Journal article
Publication Details: Spine (Philadelphia, Pa. 1976), Vol.28(1), pp.9-13
DOI: 10.1097/00007632-200301010-00004
PMID: 12544947
NLM abbreviation: Spine (Phila Pa 1976)
ISSN: 0362-2436
eISSN: 1528-1159
Publisher: Lippincott Williams & Wilkins; United States
Language: English
Date published: 01/01/2003
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Epidemiology; Surgery; Injury Prevention Research Center; Neurosurgery
Record Identifier: 9983995164502771

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