Tibial stress fractures are common in runners. However, it is unclear what
factors are associated with tibial stress fractures. This study aimed to investigate 1)
magnitudes of bone contact forces occurring while running 2) whether or not repeated
application of running loads is sufficient to explain tibial stress fractures and 3)
whether or not muscle fatigue alters the potential of tibial stress fractures. Tibial stress
fractures were predicted through an estimation of the minimum number of cycles to
failure (Nfail) using an integrated experimental and mathematical modeling approach.
Short running trials within a speed range of 3.5-4 m/s of ten male runners were
evaluated with a coupled force plate and 3 dimensional motion analysis system. The
collected data were used to estimate joint reaction forces (JRF) and joint moments.
Using these JRF and muscle forces predicted from optimization, 2-D bone contact
forces at the distal end of the tibia were determined. Next, tibial stresses were
estimated by applying these bone contact forces to a tibial model, which were then
used to predict the Nfail. All procedures were repeated after plantarflexors fatigued
from prolonged running. This study found that peaks of compressive and posterior
shear forces occurred during mid stance, and these peaks equaled 8.91 ± 1.14 BW and
-0.53 ± 0.16 BW, respectively. These bone contact forces led to a backward bending
of the tibia during most of the stance phase and resulted in the maximum stresses of -
43.4 ± 10.3 MPa on the posterior face of the tibia. These maximum stresses predicted
the group mean of Nfail as being 5.28*10⁶ cycles. However, 2.5% to 56% of
population of runners have a chance of getting tibial stress fractures within 1 million
cycles of a repeated foot impact. Within the context of muscle force and stress
estimation procedures used in this study, Nfail appeared to increase after fatigue, not
decrease as we hypothesized. / Graduation date: 2005
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29003 |
| Date | 25 August 2004 |
| Creators | Sasimontonkul, Siriporn |
| Contributors | Bay, Brian K. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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