|
Clinical Relevance of Pull-out Strength Testing of Pedicle Screws Pages: 10 Published: Jan 2003
Download this paper for $25
PDF (208K)
View License Agreement Source: STP1431-EB Abstract Pull-out strength testing is described in many published manuscripts and is specially treated in ASTM F1692-96, Standard Test Method for Determining Axial Pull-Out Strength of Medical Bone Screws. Extensive biomechanics are reported on the importance of variables like hole preparation and cement augmentation. In this study, the pull-out strengths of variously-shaped, titanium pedicle screws were tested and the literature was searched for cited incidences of pull-out. The screws were extracted from polyurethane foam that modeled weak, moderate, and strong cancellous bone. Testing revealed significantly different pull-out strengths depending upon screw design and substrate strength. However, the literature search yielded few citations of screw pull-out. Screw loosening and hardware failure are sometimes mentioned in clinical reports but rarely is pull-out documented as a failure mechanism. Standardized testing is useful in comparing various designs but may have little relationship to performance.
| ||
