Modeling Hyaluronic Acid Fluid Flow in Manual Therapy
Hans Chaudhry PhD1, Max Roman PhD1, Antonio Stecco MD2, Thomas W. Findley MD
PhD3
1 New Jersey Institute of Technology, Newark NJ
2 Ospedale Civile, Padova, Italy
3 VA New Jersey Health Care System, East Orange NJ and UMDNJ-New Jersey
Medical School, Newark NJ. Thomas.Findley@va.gov 973 676 1000 x 2713
Hyaluronic acid (HA) forms a fluid layer separating deep fascia from muscle.
Practitioners often claim to increase fascial motion, so we investigated whether this could
be due to pressure generated in the HA layer (similar to hydroplaning in a car).
METHOD HA is reported to have constant viscosity between 22 and 31 C, and therefore
is subject to modeling as a newtonian fluid. We modeled fluid pressure distribution
generated by the flow of hyaluronic acid between deep fascia and muscle with loading on
a 25 x 25 mm square of fascia overlying a 100 µm film thickness of HA. We used
models representing three different manual techniques: High loading by the practitioner
with constant shear rate representing Rolfing®, high loading with 5 hertz horizontal
oscillating shear representing Fascial Manipulation®, and no loading with 5, 15 and 60
hertz vertical oscillations representing a mechanical vibrator. We applied the Lubrication
theory in fluid mechanics for flow between two plates (the deep fascia and the
epimysium) to determine pressure contours and pressure distribution.
RESULTS The pressure generated by HA is highly dependent on the film thickness,
velocity, amplitude and frequency of vibration. In general, peak pressures for the
oscillating techniques mechanical massager (1.8, 5.7 and 23 MegaPascals ( mPa) at 5,15
and 60 Hz) and fascial manipulation® techniques (1.3 mPa), were much greater than that
generated in the constant shear technique, Rolfing® (0.16 mPa). The pressures in the
center of the area of load application were far higher than those near the edge of the area.
CONCLUSIONS The differential in pressure may generate fluid flows of HA from the
center of manual therapy toward the periphery. Since HA is a known lubricant, this may
increase motion between deep fascia and muscle and account for clinical observations of
increased mobility. Actual measurement of loading and shear forces during manual
therapy will improve this model.
U
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h0
h1
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Fluid film