Biomechanical study of various pedicle screw revision techniques
- VernacularTitle:椎弓根螺钉不同翻修方法的生物力学研究
- Author:
Xisheng WENG
;
Guixing QIU
;
Weidong ZHAO
- Publication Type:Journal Article
- Keywords:
Bone screws;
Reoperation;
Biomechanics
- From:
Chinese Journal of Orthopaedics
1996;0(10):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective To determine the best method of revision for failed pedicle screw by investigating the change in maximum insertional torque and axial pullout strength after placing a larger diameter and/or longer screw or augmenting the failed hole with bone shims or PMMA. Methods Six fresh male adult cadaveric spines from T10-L5 were harvested. These specimens, aging from 23 to 51 years with an average of 36.7 years, were divided into six groups: 1)Using a larger diameter screw; 2)Using a longer screw; 3)Using a larger and longer screw; 4)Augmenting with bone shims; 5)Augmenting with PMMA; and 6)Reinsertion after being backed out. The first three groups were subdivided into two groups. Maximum insertional torque and axial pullout strength of each original screw were recorded as control data. Change of maximum insertional torque and axial pullout strength between original and corresponding revision screws were noted. Measurements were analyzed using one-way ANOVA statistically by SPSS10.0. Insertional torque change after simply removing and replacing a 5.0 mm?40 mm screw was also measured. Results Among the changes in pedicle dimensions, the greatest improvement in peak insertional torque and axial pullout strength occurred when using a 2 mm larger and 10 mm longer screw, with an increase of 37.06% and 18.22%; a 2 mm larger screw increased peak insertional torque and axial pullout strength by 20.15% and 19.99% respectively, while a 1 mm larger and 5 mm longer screw increased by 19.23% and 10.07% respectively; use of a 5 mm or 10 mm longer screw decreased peak insertional torque by 32.80% and 14.02% respectively, with axial pullout strength down by 27.36% and up by 43.25% respectively. Use of bone shims caused a decrease of the insertional torque and axial pullout strength by 14.99% and 29.34% respectively. Hole augmentation with PMMA lead to a significant increase in insertional torque but a decrease in axial pullout strength by 37.40%. Simply removing and replacing an original screw resulted in a decrease in insertional torque by 34.22%. Conclusion Revision for pedicle screw is most effective when using a 2 mm larger diameter screw, next by using a 1 mm larger diameter and 5 mm longer screw. Use of a bone shim should be avoided. The efficacy of hole augmentation with PMMA need to be further investigated.
