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VOLUME 11 , ISSUE 3 ( November, 2016 ) > List of Articles

Original Article

Stability at the half pin–frame interface on external fixation constructs

Alexios Dimitrios Iliadis, Parag Kumar Jaiswal, Jay Meswania, Gordon Blunn, David Goodier, Peter Calder

Keywords : Half pin–frame interface, External fixation constructs, Grub screws, Bolt screws, Stability

Citation Information : Iliadis AD, Jaiswal PK, Meswania J, Blunn G, Goodier D, Calder P. Stability at the half pin–frame interface on external fixation constructs. 2016; 11 (3):193-198.

DOI: 10.1007/s11751-016-0269-z

License: CC BY-NC-SA 4.0

Published Online: 30-11-2016

Copyright Statement:  Copyright © 2016; Jaypee Brothers Medical Publishers (P) Ltd.


Abstract

A mechanical study investigating the use of two different methods (grub and bolt screws) to secure external fixation half pins to circular frames. A four part experiment: (1) Grub and bolt screws were used to secure half pins in Taylor Spatial frames. Loosening torques were measured using a calibrated torque wrench. (2) Using universal testing machine (UTM), axial loading was applied to establish thresholds for loosening in grub and bolt screw constructs. (3) We established the application torque to produce failure at the head–driver interface using these two methods. (4) Grub and bolt screw constructs were created controlling torque. Using UTM, axial loading was applied to establish thresholds for loosening. Statistical analysis was conducted using SPSS v20.0.0. (1) Higher torque is employed when bolt rather than grub screws is used to secure half pins on Rancho cubes (p < 0.05). (2) Loading threshold for loosening is higher in bolt screw constructs when the torque applied to secure the constructs is not controlled (p < 0.05). (3) Torque required for failure at the head–driver interface was 5.3 Nm for grub screws and 9.9 Nm for bolts. (4) Loading threshold for loosening is higher in grub screw constructs when the same torque was applied to secure them (p < 0.05). Bolt screws can be employed to secure the half pin–frame interface. They offer good stability and reduce failure at the head–driver interface. Further research is needed to determine the mechanical properties of such constructs in vivo.


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  1. Marsh DR, Shah S, Elliot J, Kurdy N (1997) The Ilizarov method in nonunion, malunion and infection of fractures. J Bone Joint Surg Br 79(2):273-279
  2. Noordeen MHH, Lavy CBD, Shergill NS, Tuite JD, Jackson AM (1995) Cyclical micromovement and fracture healing. J Bone Joint Surg Br 77(4):645-648
  3. Bronson DG, Samchukov ML, Birch JG, Browne RH, Ashman RB (1998) Stability of external circular fixation: a multivariable biomechanical analysis. Clin Biomech 13:441-448
  4. Board TN, Yang L, Saleh M (2007) Why fine wire fixators work: an analysis of pressure distribution at the wire-bone interface. J Biomech 40(1):20-25
  5. Green SA, Harris NL, Wall DM, Ishkanian J, Marinow H (1992) The Rancho mounting technique for the Ilizarov method. A preliminary report. Clin Orthop Relat Res 280:104-116
  6. Calhun JH, Li F, Bauford WL, Lehman T, Ledbetter BR, Lowery R (1992) Rigidity of half pins for the Ilizarov external fixator. Bull Hosp Jt Dis 52(1):21-26
  7. Aro HT, Markel MD, Chao EY (1993) Cortical bone reactions at the interface of external fixation half pins under different loading conditions. J Trauma 35(5):776-785
  8. Green SA (1991) The Ilizarov method: Rancho technique. Orthop Clin North Am 22(4):677-688
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