Strategies in Trauma and Limb Reconstruction

Register      Login

VOLUME 15 , ISSUE 3 ( September-December, 2020 ) > List of Articles

Original Article

Reducing the Risk of Ring Breakage in Taylor Spatial Frames: The Effect of Frame Configuration on Strain at the Half-ring Junction

Alexios D Iliadis, Roland Bebja, Katherine Wang, Mehran Moazen, Jonathan Wright, Peter Calder, David Goodier

Keywords : Circular external fixator, Complication, Deformity correction, Taylor spatial frame

Citation Information : Iliadis AD, Bebja R, Wang K, Moazen M, Wright J, Calder P, Goodier D. Reducing the Risk of Ring Breakage in Taylor Spatial Frames: The Effect of Frame Configuration on Strain at the Half-ring Junction. 2020; 15 (3):146-150.

DOI: 10.5005/jp-journals-10080-1508

License: CC BY-NC-SA 4.0

Published Online: 01-12-2020

Copyright Statement:  Copyright © 2020; The Author(s).


Aim: We have encountered four cases with Taylor spatial frames (TSF) (Smith & Nephew, Memphis, TN, USA) with breakage at the half-ring junction of the distal ring. This study examines the strain produced on different locations of the distal ring during loading and the effects on the strain of altering the frame construct. Materials and methods: We mounted two ring TSF constructs on tibia saw bone models. The proximal ring was the same in all constructs and consisted of a 2/3 180 mm ring attached with three wires. Construct 1 is reproducing the configuration of cases where failure was seen. The distal 155 mm ring is attached with three half pins. The half-ring junction is located in the midline. Construct 2 has a different half pin placement and an additional wire on the distal ring. Constructs 3 and 4 have the same half pin configuration to construct 1 but the distal ring is rotated 60° internally and externally, respectively. Strain gauges were attached to different locations and measurements recorded during loading. Statistical analysis was performed. Results: Highest strain values were recorded at the half-ring junction of constructs 1 and 2 (>600 microstrains (με) in tension). Rotating the ring 60° internally significantly reduces the strain at the half-ring junction (<300 με) whilst external rotation by 60° further reduces the strain (<180 με). Ring strain is higher in areas close to half pin attachments. Conclusions: The highest strain is in the half-ring junction as the half rings are subjected to different loading modes. The thickness of the half-ring is halved and the second moment of area reduced further increasing breakage risk. Placing this junction close to the half pin–frame interface, as dictated by the anatomical safe zone further increases the strain. Rotating the distal ring 60° significantly reduces the strain at the half-ring junction. Clinical significance: Ring breakage is a rare but significant complication. This is the first study to address this potential mode of TSF failure. Insights and technical tips from this study can help reduce this.

  1. Fragomen AT, Rozbruch SR. The mechanics of external fixation. HSS J 2007;3(1):13–29. DOI: 10.1007/s11420-006-9025-0.
  2. Dammerer D, Kirschbichler K, Donnan L, et al. Clinical value of the Taylor spatial frame: a comparison with the Ilizarov and Orthofix fixators. J Child Orthop 2011;5(5):343–349. DOI: 10.1007/s11832-011-0361-3.
  3. Henderson DJ, Rushbrook JL, Harwood PJ, et al. What are the biomechanical properties of the Taylor Spatial Frame™? Clin Orthop Relat Res 2017;475:1472–1482. DOI: 10.1007/s11999-016-5182-8.
  4. Khurana A, Byrne C, Evans S, et al. Comparison of transverse wires and half pins in Taylor spatial frame: a biomechanical study. J Orthop Surg Res 2010;5(1):23. DOI: 10.1186/1749-799X-5-23.
  5. Basiaga M, Pawlik M. Numerical analysis of Taylor-type external fixator by means of FEM. In: Advances in Intelligent Systems and Computing, vol 284. Information Technologies in Biomedicine;2014;4:387–394.
  6. Chavoshnejad P, Ayati M, Abbasspour A, et al. Optimization of Taylor spatial frame half-pins diameter for bone deformity correction: application to femur. Proc Inst Mech Eng H 2018;232(7):673–681. DOI: 10.1177/0954411918783782.
  7. Henderson DJ, Rushbrook JL, Stewart TD, et al. What are the biomechanical effects of half-pin and fine-wire configurations on fracture site movement in circular frames? Clin Orthop Relat Res 2016;474(4):1041–1049. DOI: 10.1007/s11999-015-4652-8.
  8. Moazen M, Calder P, Koroma P, et al. An experimental evaluation of fracture movement in two alternative tibial fracture fixation models using a vibrating platform. Proc Inst Mech Eng H 2019;233(5):595–599. DOI: 10.1177/0954411919837304.
  9. Parameswaran AD, Roberts CS, Seligson D, et al. Pin tract infection with contemporary external fixation: how much of a problem? J Orthop Trauma 2003;17(7):503–507. DOI: 10.1097/00005131-200308000-00005.
  10. Kazmers NH, Fragomen AT, Rozbruch SR. Prevention of pin site infection in external fixation: a review of the literature. Strategies Trauma Limb Reconstr 2016;11(2):75–85. DOI: 10.1007/s11751-016-0256-4.
  11. Clint SA, Eastwood DM, Chasseaud M, et al. The “Good, Bad and Ugly” pin site grading system: a reliable and memorable method for documenting and monitoring ring fixator pin sites. Injury 2010;41(2):147–150. DOI: 10.1016/j.injury.2009.07.001.
  12. Lethaby A, Temple J, Santy J. Pin site care for preventing infections associated with external bone fixators and pins. Cochrane Database Syst Rev 2008;8(4):CD004551. DOI: 10.1002/14651858.CD004551.pub2.
  13. Nayagam S. Safe corridors in external fixation: the lower leg (tibia, fibula, hindfoot and forefoot). Strategies Trauma Limb Reconstr 2007;2(2–3):105–110. DOI: 10.1007/s11751-007-0023-7.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.