Davids J R, Frick S L, Skewes E, Blackhurst D W
Motion Analysis Laboratory, Shriners Hospital for Children, Greenville, South Carolina 29605, USA.
J Bone Joint Surg Am. 1997 Apr;79(4):565-9. doi: 10.2106/00004623-199704000-00013.
Complications related to immobilization in a cast after an injury or an operation may be related to the materials used for the cast or to the techniques of application, or to both. To evaluate the widely held clinical opinion that the use of a fiberglass cast is dangerous and inappropriate when subsequent swelling of the extremity is anticipated, we studied the skin surface pressures that were generated beneath above-the-knee casts made with different materials and applied with different techniques. A prosthetic model of the lower extremity was designed with an expandable calf compartment to simulate swelling after an injury or an operation. With use of this model, we measured the skin surface pressure beneath a plaster-of-Paris cast, a fiberglass cast that had been applied with a standard technique, and a fiberglass cast that had been applied with a stretch-relax technique. The highest mean skin surface pressure after application of the cast (p < 0.001) and after simulated swelling of the limb (p = 0.04) was generated by the fiberglass cast that had been applied with a standard technique. The lowest mean skin surface pressure after application of the cast (p = 0.006), simulated swelling of the limb (p < 0.001), and all subsequent steps of the experimental protocol (p < 0.001) was generated by the fiberglass cast that had been applied with the stretch-relax technique. The mean skin surface pressure generated by the plaster cast and by the fiberglass cast applied with the standard technique did not return to the value before application of the cast until anterior and posterior longitudinal cuts had been made in the cast and the cast had been spread at those cuts. When the fiber-glass cast had been applied with the stretch-relax technique, the mean pressure returned to the baseline value after only an anterior longitudinal cut and spreading at that cut. The principal pitfall of the use of a fiberglass cast is related to the technique of application. When the fiberglass cast had been applied with the standard technique, it generated a mean skin surface pressure that was higher than that associated with the plaster cast and it accommodated simulated swelling poorly. When the fiberglass cast had been properly applied, with the stretch-relax technique, it generated a mean skin surface pressure that was significantly lower (p = 0.006) than that associated with the plaster cast and it better accommodated simulated swelling without the need to sacrifice the structural integrity of the cast.
受伤或手术后使用石膏固定所引发的并发症，可能与石膏所用材料、应用技术或两者皆有关。为评估一种广泛存在的临床观点，即当预期肢体随后会肿胀时，使用玻璃纤维石膏是危险且不合适的，我们研究了用不同材料并采用不同技术制作的膝上石膏下方所产生的皮肤表面压力。设计了一个下肢假体模型，其小腿部分可扩张，以模拟受伤或手术后的肿胀情况。利用这个模型，我们测量了巴黎石膏、采用标准技术应用的玻璃纤维石膏以及采用拉伸 - 松弛技术应用的玻璃纤维石膏下方的皮肤表面压力。采用标准技术应用的玻璃纤维石膏在石膏应用后（p < 0.001）以及肢体模拟肿胀后（p = 0.04）产生的平均皮肤表面压力最高。采用拉伸 - 松弛技术应用的玻璃纤维石膏在石膏应用后（p = 0.006）、肢体模拟肿胀后（p < 0.001）以及实验方案的所有后续步骤中（p < 0.001）产生的平均皮肤表面压力最低。巴黎石膏和采用标准技术应用的玻璃纤维石膏所产生的平均皮肤表面压力，直到在石膏上进行前后纵向切割并在这些切口处撑开石膏后，才恢复到应用石膏前的值。当采用拉伸 - 松弛技术应用玻璃纤维石膏时，仅进行一次前纵向切割并在该切口处撑开后，平均压力就恢复到了基线值。使用玻璃纤维石膏的主要问题与应用技术有关。当采用标准技术应用玻璃纤维石膏时，它产生的平均皮肤表面压力高于巴黎石膏，并且对模拟肿胀的适应性较差。当采用拉伸 - 松弛技术正确应用玻璃纤维石膏时，它产生的平均皮肤表面压力显著低于（p = 0.006）巴黎石膏，并且能更好地适应模拟肿胀，而无需牺牲石膏的结构完整性。
