Biomedical Engineering Reference
In-Depth Information
is facilitated by the RANK-RANKL-OPG pathway, together with the sys-
temic hormone PTH and transforming growth factor TGF-β. PEMF devices
are used clinically to promote bone healing, especially in nonunion fracture,
but relatively little is known about the mechanisms involved.
Wang and Qin [1] proposed a mathematical model to simulate the effect of
PEMF on bone remodeling at the cellular level, which would help to better
understand the underlying mechanisms. In their analysis, Equations (8.1)-(8.4)
were numerically solved using Matlab and a series of graphs were plotted for
the concentration dynamics of OPG; RANKL; cell populations of OBA, OCA,
and OBP; and bone volume, as shown in Figures 8.2-8.5, respectively. Note that
the parameter values listed in Tables 6.1 and 7.1 have been used in the analysis.
The effects of PEMF on bone remodeling are dependent on its intensity,
frequency, waveform, and application time. According to Hannay et al. [54],
the duration of the PEMF stimulation does not affect bone cell development,
which is different from bone remodeling under mechanical stimulus. In this
numerical investigation, the specific parameter values of PEMF were chosen
from the widely used PEMF devices in clinics [55]; this set of parameter val-
ues is the only one used in this study's model. Consequently, it is assumed
that the effects of PEMF on bone remodeling in this model, specifically OPG
or RANKL, do not change (represented by two different constants,
F
OPG
and
F
RL
, in the model) throughout the simulation (3 months).
OPG
400000
300000
200000
100000
0
10
20
30
40
50
60
70
80
90
Time [days]
FIGURE 8.2
OPG concentration dynamics during 3-month PEMF application.
