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Evaluation of cast creep occurring during simulated clubfoot correction. Proc Inst Mech Eng H 2013 Aug;227(8):919-27

Date

05/03/2013

Pubmed ID

23636764

Pubmed Central ID

PMC4991776

DOI

10.1177/0954411913485044

Scopus ID

2-s2.0-84884571779   4 Citations

Abstract

The Ponseti method is a widely accepted and highly successful conservative treatment of pediatric clubfoot involving weekly manipulations and cast applications. Qualitative assessments have indicated the potential success of the technique with cast materials other than standard plaster of Paris. However, guidelines for clubfoot correction based on the mechanical response of these materials have yet to be investigated. The current study sought to characterize and compare the ability of three standard cast materials to maintain the Ponseti-corrected foot position by evaluating cast creep response. A dynamic cast testing device, built to model clubfoot correction, was wrapped in plaster of Paris, semi-rigid fiberglass, and rigid fiberglass. Three-dimensional motion responses to two joint stiffnesses were recorded. Rotational creep displacement and linearity of the limb-cast composite were analyzed. Minimal change in position over time was found for all materials. Among cast materials, the rotational creep displacement was significantly different (p < 0.0001). The most creep displacement occurred in the plaster of Paris (2.0°), then the semi-rigid fiberglass (1.0°), and then the rigid fiberglass (0.4°). Torque magnitude did not affect creep displacement response. Analysis of normalized rotation showed quasi-linear viscoelastic behavior. This study provided a mechanical evaluation of cast material performance as used for clubfoot correction. Creep displacement dependence on cast material and insensitivity to torque were discovered. This information may provide a quantitative and mechanical basis for future innovations for clubfoot care.

Author List

Cohen TL, Altiok H, Wang M, McGrady LM, Krzak J, Graf A, Tarima S, Smith PA, Harris GF

Authors

Gerald Harris PhD Director in the Orthopaedic Research Engineering Center (OREC) department at Marquette University
Sergey S. Tarima PhD Associate Professor in the Institute for Health and Equity department at Medical College of Wisconsin
Mei Wang PhD Associate Professor in the Orthopaedic Surgery department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Biomechanical Phenomena
Casts, Surgical
Clubfoot
Humans
Materials Testing
Models, Biological
Torque
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