Contact Pressures of the Posterior Heel in Lower Extremity Splints: A Biomechanical Study

Category: Basic Sciences/Biologics; Trauma Introduction/Purpose: Immobilization using lower extremity splints is a ubiquitous tool in orthopaedic care in the emergency department, operating room, and outpatient clinic settings. Prolonged use of these splints may result in skin changes or ulceration of the heel if not padded or positioned correctly. There is currently no biomechanical study in the literature measuring posterior heel contact pressure in lower extremity splints. The purpose of our study is to measure the contact pressure differences in the posterior heel with increasing layers of cotton padding, with and without the heel floating. We hypothesize that increased layers of padding will decrease contact pressure, but improvement will plateau. We predict that floating the heel will also considerably offload contact pressure. Methods: Short leg splints were applied to six limbs in three healthy subjects with an underlying pressure transducer (Tekscan I-Scan system) on the skin surface of the posterior heel. Peak contact pressures were measured after 0, 2, 4, and 6 layers of cotton padding were applied behind the heel in positions both with and without the heel freely floating. Each limb served as their own control, as pressure changes were compared to each limb’s baseline measurement (splint applied with all padding removed). Results: Over a 3-fold decrease in peak contact pressure was observed after the application of 4 or 6 layers of cotton padding. This escalated to over a 6-fold decrease with 2, 4, or 6 layers of padding while the splint was positioned with the heel freely floating. Splints with 4 and 6 layers of padding decreased heel contact pressure similarly (reduced to 29% and 28% from baseline, respectively), improved from 2 layers of padding (51% decrease from baseline). The mean contact pressure with 6 layers of padding (28% from baseline) remained higher than the mean contact pressure with 0 layers of padding with the heel floating (21% from baseline). Conclusion: Lower extremity splints with 4 or 6 layers of cotton padding provided a meaningful decrease in peak posterior heel contact pressure. The greatest decrease in heel contact pressure was observed in splints with the heel floating, even with all layers of cotton padding removed. This was more optimal than all layers of cotton padding tested. This study emphasizes the critical nature of patient counseling regarding the importance of proper splint positioning with the heel floating when at rest. Neglecting to do so may put the patient at increased risk for posterior heel skin complications.