Pediatric supracondylar humerus fractures: Effect of bone–implant interface conditions on fracture stability

Background Closed reduction and percutaneous fixation with Kirschner wires (KWs) is the standard of care of pediatric supra-condylar humerus fractures (SCHFs). Failure modes leading to loss of reduction are not clear and have not been quantified. Multiple factors may weaken the KW–bone interface bon...

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Bibliographic Details
Published in:Journal of children's orthopaedics 2013-12, Vol.7 (6), p.565-569
Main Authors: Lamdan, Ron, Liebergall, Meir, Gefen, Amit, Symanovsky, Naum, Peleg, Eran
Format: Article
Language:English
Subjects:
Fractures
Friction
Medicine
Medicine & Public Health
Orthopedics
Pediatrics
Technical Note
Traumatic Surgery
Wire
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Summary:Background Closed reduction and percutaneous fixation with Kirschner wires (KWs) is the standard of care of pediatric supra-condylar humerus fractures (SCHFs). Failure modes leading to loss of reduction are not clear and have not been quantified. Multiple factors may weaken the KW–bone interface bonding conditions. To the best of our knowledge, the possible effect of this decrease on different KW configurations and fracture stability has never been studied. Purpose To investigate the effect of bone–KW friction conditions on SCHF post-operative mechanical stability and to formulate clinical guidelines for KW configuration under different conditions. Methods Finite element-based model of a fixated SCHF was used to simulate structure stability for two lateral divergent versus crossed lateral and medial KW configurations under varying KW–bone friction conditions. Results Finite element simulations demonstrated that crossed KWs provide superior stability compared with the divergent configuration when KW–bone bonding is compromised. When KW–bone bonding conditions are adequate, crossed and divergent KW configurations provide similar, sufficient fracture stability. Conclusions Under normal bone–implant interface conditions, the two diverging lateral KW configuration offers satisfactory mechanical stability and may be the preferred choice of SCHF fixation. When KW–bone bonding is suboptimal, as when one or more of the lateral KWs are re-drilled, addition of a medial KW should be considered in order to improve stability despite risk to ulnar nerve.
ISSN:1863-2521
1863-2548
DOI:10.1007/s11832-013-0533-4