The Effect of Immobilization Devices on Contact Pressures of the Ankle and Hindfoot

Category: Ankle, Hindfoot Introduction/Purpose: The tall Controlled Ankle Motion (CAM) boot and the short CAM boot are commonly used devices to immobilize the foot and ankle. These devices are preferably used instead of casts and splints as they are easily removed, allowing possible wound examinatio...

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Main Authors: Niall A. Smyth MD, Pooyan Abbasi, Cesar de Cesar Netto MD, PhD, Stuart M. Michnick MD, Nicholas D. Casscells MD, Brent G. Parks MSc, Lew C. Schon MD
Format: Article
Language:English
Published: SAGE Publishing 2019-10-01
Series:Foot & Ankle Orthopaedics
Online Access:https://doi.org/10.1177/2473011419S00401
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author Niall A. Smyth MD
Pooyan Abbasi
Cesar de Cesar Netto MD, PhD
Stuart M. Michnick MD
Nicholas D. Casscells MD
Brent G. Parks MSc
Lew C. Schon MD
author_facet Niall A. Smyth MD
Pooyan Abbasi
Cesar de Cesar Netto MD, PhD
Stuart M. Michnick MD
Nicholas D. Casscells MD
Brent G. Parks MSc
Lew C. Schon MD
author_sort Niall A. Smyth MD
collection DOAJ
description Category: Ankle, Hindfoot Introduction/Purpose: The tall Controlled Ankle Motion (CAM) boot and the short CAM boot are commonly used devices to immobilize the foot and ankle. These devices are preferably used instead of casts and splints as they are easily removed, allowing possible wound examination, personal hygiene, and therapeutic exercises. However, the effect of these devices on joint contact pressures is unknown. The aim of this study is to assess the effect of the tall CAM boot and short CAM boot on contact pressures of the ankle, subtalar, talonavicular, and calcaneocuboid joints. We hypothesize that both the tall CAM boot and short CAM boot will reduce contact pressures of the ankle and hindfoot joints, with the tall CAM boot having the greatest effect. Methods: Eight lower extremity cadaver specimens were mounted on a servohydraulic test frame. The specimens were loaded to 700 N at a cyclical frequency of 1 Hz with the posterior tibial, peroneus longus, peroneus brevis, flexor hallucis longus, flexor digitorum longus, and Achilles tendon physiologically tensioned. TekScan (TekScan, Boston, MA) pressure sensors were placed in the ankle, subtalar, talonavicular, and calcaneocuboid joints. In the sagittal plane, the specimens were loaded on a neutral surface, followed by 20o of dorsiflexion. Each specimen served as its own control, with contact pressures measured with no immobilization (control), followed by placement in a short CAM boot and tall CAM boot. In addition, contact pressures in the immobilized limbs were measured at muscle loads both equal to and half of the load applied to the control in order to account for decreased muscle activation during immobilization. Results: There was no difference in the average and peak contact pressures of the ankle, subtalar, talonavicular and calcaneocuboid joints when comparing the short CAM boot to no immobilization at equal tendon loads. The tall CAM boot significantly decreased average and peak contact pressures of the ankle, subtalar, and talonavicular joints when compared to no immobilization. The reduction in contact pressures was accentuated when the load applied to the tendons was decreased in accordance with diminished muscle activation during immobilization. Neither immobilization device decreased the contact pressures of the calcaneocuboid joint at equal tendon loads. Conclusion: Immobilization in a tall CAM boot decreases contact pressures of the ankle and hindfoot in both a neutral position and in dorsiflexion. A tall CAM boot should be used clinically if the goal of its use is to maximally reduce contact pressures of the ankle and hindfoot.
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spelling doaj.art-dc1b7f872578424a9a7c4918a910966c2022-12-21T17:24:46ZengSAGE PublishingFoot & Ankle Orthopaedics2473-01142019-10-01410.1177/2473011419S00401The Effect of Immobilization Devices on Contact Pressures of the Ankle and HindfootNiall A. Smyth MDPooyan AbbasiCesar de Cesar Netto MD, PhDStuart M. Michnick MDNicholas D. Casscells MDBrent G. Parks MScLew C. Schon MDCategory: Ankle, Hindfoot Introduction/Purpose: The tall Controlled Ankle Motion (CAM) boot and the short CAM boot are commonly used devices to immobilize the foot and ankle. These devices are preferably used instead of casts and splints as they are easily removed, allowing possible wound examination, personal hygiene, and therapeutic exercises. However, the effect of these devices on joint contact pressures is unknown. The aim of this study is to assess the effect of the tall CAM boot and short CAM boot on contact pressures of the ankle, subtalar, talonavicular, and calcaneocuboid joints. We hypothesize that both the tall CAM boot and short CAM boot will reduce contact pressures of the ankle and hindfoot joints, with the tall CAM boot having the greatest effect. Methods: Eight lower extremity cadaver specimens were mounted on a servohydraulic test frame. The specimens were loaded to 700 N at a cyclical frequency of 1 Hz with the posterior tibial, peroneus longus, peroneus brevis, flexor hallucis longus, flexor digitorum longus, and Achilles tendon physiologically tensioned. TekScan (TekScan, Boston, MA) pressure sensors were placed in the ankle, subtalar, talonavicular, and calcaneocuboid joints. In the sagittal plane, the specimens were loaded on a neutral surface, followed by 20o of dorsiflexion. Each specimen served as its own control, with contact pressures measured with no immobilization (control), followed by placement in a short CAM boot and tall CAM boot. In addition, contact pressures in the immobilized limbs were measured at muscle loads both equal to and half of the load applied to the control in order to account for decreased muscle activation during immobilization. Results: There was no difference in the average and peak contact pressures of the ankle, subtalar, talonavicular and calcaneocuboid joints when comparing the short CAM boot to no immobilization at equal tendon loads. The tall CAM boot significantly decreased average and peak contact pressures of the ankle, subtalar, and talonavicular joints when compared to no immobilization. The reduction in contact pressures was accentuated when the load applied to the tendons was decreased in accordance with diminished muscle activation during immobilization. Neither immobilization device decreased the contact pressures of the calcaneocuboid joint at equal tendon loads. Conclusion: Immobilization in a tall CAM boot decreases contact pressures of the ankle and hindfoot in both a neutral position and in dorsiflexion. A tall CAM boot should be used clinically if the goal of its use is to maximally reduce contact pressures of the ankle and hindfoot.https://doi.org/10.1177/2473011419S00401
spellingShingle Niall A. Smyth MD
Pooyan Abbasi
Cesar de Cesar Netto MD, PhD
Stuart M. Michnick MD
Nicholas D. Casscells MD
Brent G. Parks MSc
Lew C. Schon MD
The Effect of Immobilization Devices on Contact Pressures of the Ankle and Hindfoot
Foot & Ankle Orthopaedics
title The Effect of Immobilization Devices on Contact Pressures of the Ankle and Hindfoot
title_full The Effect of Immobilization Devices on Contact Pressures of the Ankle and Hindfoot
title_fullStr The Effect of Immobilization Devices on Contact Pressures of the Ankle and Hindfoot
title_full_unstemmed The Effect of Immobilization Devices on Contact Pressures of the Ankle and Hindfoot
title_short The Effect of Immobilization Devices on Contact Pressures of the Ankle and Hindfoot
title_sort effect of immobilization devices on contact pressures of the ankle and hindfoot
url https://doi.org/10.1177/2473011419S00401
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