ANZIAM  J.  48 (2006), 199-210

Drainage after total knee replacement

G. Sterling   Department of Orthopaedics   Townsville General Hospital   Townsville   QLD   Australia   G. D. McBain   School of Aerospace   Mechanical   and Mechatronic Engineering   The University of Sydney   NSW   Australia   J. A. Harris   Maunsell Australia Pty Ltd   21 Stokes St   Townsville QLD   Australia

and M. Boland   Department of Orthopaedics   Townsville General Hospital   Townsville   QLD   Australia

Abstract

A simple lumped hydraulic model of knee drainage following arthroplasty is developed incorporating a pressure-volume equation of state for the knee capsule and a wound healing rate dynamically retarded by the blood flow-induced shear stress. The resulting second-order nonlinear ordinary differential system is examined numerically and qualitatively to map the parameter space. In the model, moderate suction or a slight back-pressure promotes gradual drainage and healing whereas excessive suction can lead to a bifurcation in which healing is retarded or even prevented. Guided, then, by the model, the literature, and experience, continuous drainage with a small constant back-pressure appeared beneficial so we prospectively evaluated a series of ten patients. The results are consistent with the model and promising.

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