Metatarsal Strains Are Sufficient to Cause Fatigue Fracture During Cyclic Overloading

Abstract

Human in vivo tibial strains during vigorous walking have not been found to exceed 1200 microstrains. These values are below those found in ex vivo studies (>3000 microstrains) to cause cortical bone fatigue failure, suggesting that an intermediate bone remodeling response may be associated with tibial stress fractures. Metatarsal stress fractures, however, often develop before there is time for such a response to occur. Simultaneous in vivo axial strains were measured at the mid diaphysis of the second metatarsal and the tibia in two subjects. Peak axial metatarsal compression strains and strain rates were significantly higher than those of the tibia during treadmill walking and jogging both barefoot and with running shoes and during simple calisthenics. During barefoot treadmill walking metatarsal compression strains were greater than 2500 microstrains. During one- and two-leg vertical jumps and broad jumping, both metatarsal compression and tension strains were >3000 microstrains. Compression and tension strains in the metatarsus unlike those of the tibia may be sufficiently high even during moderate exertional activities to cause fatigue failure of bone secondary to the number of loading cycles without an intermediate bone remodeling response.

Direct in vivo strain measurements in human bone—A systematic literature review

“…Moreover, it is not clear whether running maintains or increases bone strength. This is due to the fact that among the studies, which measured tibial strains during running, five studies (Lanyon et al, 1975;Burr et al, 1996;Milgrom et al, 1996Milgrom et al, , 2002Ekenman et al, 1998) reported strain magnitudes between 277 and 1583 me all of which fall in the physiological loading zone. Playing basketball decreased tibial stress fracture risk in infantry recruits who played basketball regularly for at least 2 years before basic training (Milgrom et al, 2000c).…”

“…To better understand metatarsal stress fracture etiology, in vivo strain measurements were conducted at the dorsal surface of the second metatarsal diaphysis. Milgrom et al (2002) investigated strains and strain rates at medial tibia and second metatarsal simultaneously during different activities. They found that second metatarsal experienced higher strain and strain rates than medial tibia particularly in the compression direction.…”

Use of bisphosphonates for the treatment of stress fractures in athletes

“…Stress fractures in athletes and military recruits are the result of either fatigue failure secondary to high strains or strain rates or mediated through bone remodeling response by attempting to strengthen itself when subjected to high strains or strain rates or new strain patterns. Milgrom et al [49] have shown in their in vivo human bone strain gauge study that tibial stress fractures are likely to be remodeling mediated while metatarsal stress fractures are caused by cyclic overloading alone.…”

Do not use bisphosphonates without scientific evidence, neither in treatment nor prophylactic, in the treatment of stress fractures

“…In military recruits, especially in basic training, it has led to modification of the type of training, the time for the repetitions and the load [9,10]. The researchers are trying hard to get a solution to the problem, not only with different types of surgery but also by medical treatment [4,11].…”

“…A stress fracture is an overuse injury and the mechanism depends on the load of the bone and if the load gives more strain and strain rate than the bone can stand, then a stress fracture occur [10].…”