Journal of Applied Physiology, Vol 78, Issue 5 1977-1984, Copyright © 1995 by American Physiological Society
Pressure-volume relationships in equine midcarpal joint
J. Hardy, A. L. Bertone and W. W. Muir
Department of Veterinary Clinical Sciences, Ohio State University, Columbus 43210, USA.
The effects of joint angle, fluid infusion, history-dependence, and time
dependence on the pressure-volume (PV) relationships of normal equine
midcarpal joints were determined. Horses (n = 24 and 48 midcarpal joints)
were anesthetized and placed in dorsal recumbency, and the four midcarpal
joint pouches were cannulated for intra-articular pressure (IAP)
measurements and recording. Fluid (synovial fluid or saline) was infused or
withdrawn through the dorsal joint capsule. The PV curves were sigmoid and
best described by IAP = A x e(B x volume) - C, where B is the fractional
change in pressure per unit change of volume, and A and C are constants.
Compartmentation was not observed. Elastance was greater at sub- than
supra-atmospheric pressures, at 90 degrees than 135 degrees angles, and
with saline than synovial fluid. Hysteresis was greater at 90 degrees than
135 degrees angle, and with synovial fluid than saline. Elastance
progressively increased with sequential distention at high IAPs. IAP
relaxation was a positive logarithmic relationship of IAP. These findings
suggest an important role of synovial fluid in articular PV relationships
and emphasize the role of joint angle, prior distention cycles, and decay
of IAP with time in future studies investigating these phenomena.
