Lower limb intracast pressures generated by different types of immobilisation casts

Abstract

AIMTo determine if complete, split casts and backslabs [plaster of Paris (POP) and fiberglass] generate different intracast pressures and pain.METHODSIncreased swelling within casts was modeled by a closed water system attached to an expandable bag placed directly under different types of casts applied to a healthy lower limb. Complete fiberglass and POP casts, split casts and backslabs were applied. Twenty-five milliliter aliquots of saline were injected into the system and the generated intracast pressures were measured using a sphygmomanometer. The subject was blinded to the pressure scores to avoid bias. All casts were applied to the same right limb on the same subject to avoid the effects of variations in anatomy or physiology on intracast pressures. Pain levels were evaluated using the Visual Analogue Score after each sequential saline injection. Each type of cast was reapplied four times and the measurements were repeated on four separate occasions. Sample sizes were determined by a pre-study 90% power calculation to detect a 20% difference in intracast pressures between cast groups.RESULTSA significant difference between the various types of casts was noted when the saline volume was greater than 100 mL (P = 0.009). The greatest intracast pressure was generated by complete fiberglass casts, which were significantly higher than complete POP casts or backslabs (P = 0.018 and P = 0.008 respectively) at intracast saline volumes of 100 mL and higher. Backslabs produced a significantly lower intracast pressure compared to complete POP only once the saline volume within casts exceeded 225 mL (P = 0.009). Intracast pressures were significantly lower in split casts (P = 0.003). Split POP and fiberglass casts produced the lowest intracast pressures, even compared to backslabs (P = 0.009). Complete fiberglass casts generated the highest pain levels at manometer pressures of 75 mmHg and greater (P = 0.001). Split fiberglass casts had significantly reduced pain levels (P = 0.001). In contrast, a split complete POP cast did not produce significantly reduced pain levels at pressures between 25-150 mmHg. There was no difference in pain generated by complete POP and backslabs at manometer pressures of 200 mmHg and lower.CONCLUSIONFibreglass casts generate significantly higher intracast pressures and pain than POP casts. Split casts cause lower intracast pressures regardless of material, than complete casts and backslabs.

An Expanding Foam‐Fabric Orthopedic Cast

“…The pressure applied by an orthopedic cast should be minimized (under 30 mmHg) to prevent the constriction of blood flow. [ 32 ] Other thermoplastic casts have been shown to exert mean pressures of 31 ± 3 mmHg without occluding the microcirculation of the skin. [ 33 ]…”

“…The pressure applied by an orthopedic cast should be minimized (under 30 mmHg) to prevent the constriction of blood flow. [32] Other thermoplastic casts have been shown to exert mean pressures of 31 ± 3 mmHg without occluding the microcirculation of the skin. [33] In our experiments, the pressure was measured as a function of time using a capacitive sensing sleeve worn on the wrist of the subject underneath the cast, containing two co-facially arranged electrodes of conductive silver fabric heat-bonded to the opposite sides of the red spacer knit (Figure 1c), which served as the compressible dielectric layer for the capacitive sensing mechanism.…”

Impact of Casting and Splinting Manipulations on Below-Dressing Pressures: An Experimental Model

“…4 In particular, tightly applied dressings can increase the patient’s perception of pain especially in the acute setting secondary to swelling. 3 A study that analyzed patients who presented to the emergency department secondary to cast concerns concluded that 23% of visits were due to tight casts and another 10% were due to pain. 6 Furthermore, anecdotally in the senior author’s upper extremity practice, patients will sometimes complain of pain associated with tight splint dressings.…”

“…The implication is that the pain may be secondary to increased below-dressing pressure between the dressing and the patient's skin. 3 In the extreme circumstance, an especially rigid or noncompliant circumferential dressing will not accommodate severe swelling, resulting in skin necrosis or even limb-threatening compartment syndrome. 4 One method to reduce the below-dressing pressure under circumferential dressings is to split the dressing longitudinally.…”

Shape memory polymer smart plaster for orthopaedic treatments

“…Garfin et al, on the other hand, discovered that univalve splitting decreased cast pressure by 65%, whereas bivalve splitting reduced cast pressure by 47% and 33% in the anterior and posterior compartments, respectively [8]. The lower limb intercast pressures measured in backslab, full POP, split POP, fibreglass and split fibreglass were 47.05 ± 31.8, 72.28 ± 60.3, 17.15 ± 7.53, 82.73 ± 67.0 and 26.58 ± 21.33 mmHg, respectively [9]. In another study, Marson and Keenan found that POP and fibreglass had mean casting pressures of 61.10 and 30.35 mmHg respectively, thus, fibreglass casting produces significantly higher pressure than POP casts [10].…”