Mechanics of hip dysplasia reductions in infants using the Pavlik harness: A physics-based computational model

Orlando J. Ardila, Eduardo A. Divo, Faissal A. Moslehy, George T Rab, Alain J. Kassab, Charles T. Price

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Biomechanical factors influencing the reduction of dislocated hips with the Pavlik harness in patients of Developmental Dysplasia of the Hip (DDH) were studied using a three-dimensional computer model simulating hip reduction dynamics in (1) subluxated and (2) fully dislocated hip joints. Five hip adductor muscles were identified as key mediators of DDH prognosis, and the non-dimensional force contribution of each in the direction necessary to achieve concentric hip reductions was determined. Results point to the adductor muscles as mediators of subluxated hip reductions, as their mechanical action is a function of the degree of hip dislocation. For subluxated hips in abduction and flexion, the Pectineus, Adductor Brevis, Adductor Longus, and proximal Adductor Magnus contribute positively to reduction, while the rest of the Adductor Magnus contributes negatively. In full dislocations all muscles contribute detrimentally to reduction, elucidating the need for traction to reduce Graf IV type dislocations. Reduction of dysplastic hips was found to occur in two distinct phases: (a) release phase and (b) reduction phase.

Original languageEnglish (US)
Pages (from-to)1501-1507
Number of pages7
JournalJournal of Biomechanics
Volume46
Issue number9
DOIs
StatePublished - May 31 2013

Keywords

  • Dynamical analysis
  • Hip dysplasia
  • Non-linear muscle model
  • Passive reduction
  • Pavlik harness

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Rehabilitation
  • Biophysics
  • Biomedical Engineering

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