Deshpande Shreeram V
Department of Orthopaedics, Wrexham Maelor Hospital, Wrexham, UK.
Injury. 2005 Sep;36(9):1067-74. doi: 10.1016/j.injury.2005.02.003. Epub 2005 Apr 18.
Casting materials are commonly used in a trauma and post-operative setting in orthopaedic practice. Swelling after trauma or surgery is universal, hence, the importance of understanding the pressure-volume dynamics of various materials commonly used for casting. This study attempts to define the pressure response of casts made from three commonly used materials to increasing volume, using a cylindrical model cast. Plaster of Paris (PoP), rigid fibreglass and semi-rigid non-fibreglass (Softcast) were chosen for comparison. Softcast had the best compliance and rate dependency characteristics, accommodating significantly more volume of fluid compared to plaster of Paris or Rigid fibreglass material. The latter two had similar compliance. All three materials demonstrated stress-relaxation which is of advantage in reducing peak pressures for a given volume change. This study shows that the casting materials behave in a viscoelastic manner, which allows them to accommodate more volume change than would otherwise be possible. The use of semi-rigid material may be safer than other materials as far as response to swelling (volume expansion) is concerned.
在骨科实践中，铸造材料常用于创伤和术后情况。创伤或手术后肿胀是普遍存在的，因此，了解常用于铸造的各种材料的压力-容积动态变化非常重要。本研究试图使用圆柱形模型铸件来确定由三种常用材料制成的铸件对容积增加的压力反应。选择了巴黎石膏（PoP）、刚性玻璃纤维和半刚性非玻璃纤维（Softcast）进行比较。Softcast具有最佳的顺应性和速率依赖性特征，与巴黎石膏或刚性玻璃纤维材料相比，能容纳更多体积的液体。后两者具有相似的顺应性。所有三种材料都表现出应力松弛，这有利于在给定的体积变化下降低峰值压力。本研究表明，铸造材料表现出粘弹性，这使它们能够比其他情况容纳更多的体积变化。就对肿胀（体积膨胀）的反应而言，使用半刚性材料可能比其他材料更安全。
