Abstract
BackgroundLittle is known about subchondral perfusion physiology. We developed a 3Rs (Replace, Reduce, Refine) compliant in vitro calf foot model to explore perfusion and intraosseous pressure (IOP).MethodsCalf feet were catheterised and perfused with serum. IOP was measured at three sites, the metacarpal diaphysis (MCD), metacarpal subchondral epiphysis (MCS) and proximal phalanx diaphysis (PPD) using intraosseous needles with pressure transducers and digital recorders. Fresh (< 4 h post mortem) and old feet (> 4 h post mortem) were perfused at different pressures, with and without a proximal tourniquet.ResultsThere was a wide range in basal IOP with a mean IOP of 30.0 mmHg, SD 14.4, range 7.6 mmHg to 52.7 mmHg (n = 40 records) in 15 subjects. There was no significant difference between the three sites tested (p = 0.54, 0.12 and 0.051). At each individual site IOP correlated with perfusion pressure (r = 0.993). With a proximal venous tourniquet, IOP increased from 15.1 mmHg (SD 11.3 mmHg) to 44.9 mmHg (SD 24 mmHg), p < 0.0001, n = 9. Filling and emptying curves during perfusion and with using a tourniquet were similar, indicating that the model behaves in an elastic hydrodynamic manner. In fresh feet IOP peaked after about 1 min irrespective of perfusion pressure, possibly due to auto regulation. Older feet showed a continuously rising IOP and became oedematous. There was no significant difference in IOP between fresh and old feet perfused with serum at 150 cms pressure for 1 min.ConclusionThough basal intraosseous pressure varies, IOP behaves predictably. IOP measurements reflect the perfusion microclimate at the individual needle tip. This 3Rs compliant model will be used for further exploration of subchondral perfusion physiology with loading.
Highlights
Little is known about subchondral perfusion physiology
Perfusion pressure range Using the same methods and under a constant perfusion pressure of 150 cm water for 60 s there was a wide range of basal intraosseous pressure (IOP)
Site differences There was no significant difference in IOP between the sites tested
Summary
We developed a 3Rs (Replace, Reduce, Refine) compliant in vitro calf foot model to explore perfusion and intraosseous pressure (IOP). IOP has generally been found to be raised in bone diseases such as osteonecrosis and after steroid use. Steroid induced models of avascular necrosis have been developed in order to study IOP and its treatments (Drescher et al 2001; Miyanishi et al 2005). More recently there has been interest in IOP during exsanguination in a porcine model used to study intraosseous perfusion in emergency resuscitation situations (Frascone et al 2015). The model would be used to study the IOP and perfusion physiology of cancellous bone by altering perfusion pressures and by use of a tourniquet
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
