a biomechanical study of torque and accuracy of halo pin insertional devices* by michael d. smith,...

A Biomechanical Study of Torque and Accuracy of Halo Pin Insertional Devices*

by MICHAEL D. SMITH, LINDA J. JOHNSON, JOSEPH H. PERRA, and BERNARD A. RAWLINS

J Bone Joint Surg AmVolume 78(2):231-8

February 1, 1996

©1996 by The Journal of Bone and Joint Surgery, Inc.

Devices A (PMT, Chanhassen, Minnesota), B (Ace Medical, Los Angeles, California), and C (Bremer Medical, Jacksonville, Florida) were single-use, shear-off devices that were designed to

measure 0.90 newton-meter (eight inch-pounds) of torque.

MICHAEL D. SMITH et al. J Bone Joint Surg Am 1996;78:231-8


Devices D (Jerome Medical, Mount Laurel, New Jersey), E (PMT), and F (Bremer Medical) were fully adjustable devices that were tested at both 0.68 and 0.90 newton-meter (six and eight inch-

pounds) of torque.



Devices G (Levtech, Dallas, Texas) and H (Jerome Medical) were fixed spring-loaded devices that were designed to measure 0.68 newton-meter (six inch-pounds) of torque.



Devices I (Bremer Medical) and J-new (Ace Medical) were partially adjustable spring-loaded devices.



Box plots of the distributions of achieved torque across all trials in which the target torque was 0.68 newton-meter (six inch-pounds) compared with that across all trials in which the target

torque was 0.90 newton-meter (eight inch-pounds).



Graph showing the proportion of accurate trials and mean percentage deviation from the target torque for all devices tested.



Figs. 7-A and 7-B: One cause of error for the spring-loaded and fully adjustable devices was inaccurate placement of the calibration marks that guide the application of torque.



To obtain 0.90 newton-meter (eight inch-pounds) of achieved torque, the calibration dot was placed far beyond the correct marking.



a biomechanical study of torque and accuracy of halo pin insertional devices* by michael d. smith,...

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