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research-article

Hip joint contact pressure distribution during Pavlik harness treatment of an infant hip: a patient-specific finite element model

[+] Author and Article Information
Behzad Vafaeian

Postdoctoral fellow, Department of Civil & Environmental Engineering, University of Alberta, 7-203 Donadeo Innovation Centre for Engineering, 9211 - 116 Street, Edmonton, Alberta, T6G 1H9, Canada
vafaeian@ualberta.ca

Samer Adeeb

Associate Professor, Department of Civil & Environmental Engineering, University of Alberta, 7-203 Donadeo Innovation Centre for Engineering, 9211 - 116 Street, Edmonton, Alberta, T6G 1H9, Canada
adeeb@ualberta.cahttp://sameradeeb.srv.ualberta.ca

Marwan El-Rich

Assistant Professor, Department of Civil & Environmental Engineering, University of Alberta, 7-203 Donadeo Innovation Centre for Engineering, 9211 - 116 Street, Edmonton, Alberta, T6G 1H9, Canada
elrich@ualberta.ca

Dornoosh Zonoobi

Department of Radiology and Diagnostic Imaging, University of Alberta, 2A2.41 WMC, 8440-112 Street, Edmonton, Alberta, T6G 2B7, Canada
zonoobi@ualberta.ca

Abhilash R. Hareendranathan

Department of Radiology and Diagnostic Imaging, University of Alberta, 2A2.41 WMC, 8440-112 Street, Edmonton, Alberta, T6G 2B7, Canada
hareendr@ualberta.ca

Jacob L. Jaremko

Assistant Professor, Department of Radiology and Diagnostic Imaging, University of Alberta, 2A2.41 WMC, 8440-112 Street, Edmonton, Alberta, T6G 2B7, Canada
jjaremko@ualberta.ca

1Corresponding author.

ASME doi:10.1115/1.4039827 History: Received November 03, 2017; Revised March 26, 2018

Abstract

Developmental dysplasia of the hip (DDH) in infants under 6 months of age is typically treated by the Pavlik harness (PH). During successful PH treatment, a subluxed/dislocated hip is spontaneously reduced into the acetabulum, and DDH undergoes self-correction. PH treatment may fail due to avascular necrosis (AVN) of the femoral head. An improved understanding of mechanical factors accounting for the success/failure of PH treatment may arise from investigating articular cartilage contact pressure (CCP) within a hip during treatment. In this study, CCP in a cartilaginous infant hip was investigated through patient-specific finite element (FE) modeling. We simulated CCP of the hip equilibrated at 90° flexion at abduction angles of 40°, 60° and 80°. We found that CCP was predominantly distributed on the anterior and posterior acetabulum, leaving the superior acetabulum (mainly superolateral) unloaded. From a mechanobiological perspective, hypothesizing that excessive pressure inhibits growth, our results qualitatively predicted increased obliquity and deepening of the acetabulum under such CCP distribution. This is the desired and observed therapeutic effect in successful PH treatment. The results also demonstrated increase in CCP as abduction increased. In particular, the simulation predicted large magnitude and concentrated CCP on the posterior wall of the acetabulum and the adjacent lateral femoral head at extreme abduction (80°). This CCP on lateral femoral head may reduce blood flow in femoral head vessels and contribute to AVN. Hence, this study provides insight into biomechanical factors potentially responsible for PH treatment success and complications.

Copyright (c) 2018 by ASME
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