What causes stress fractures to occur? A stress fracture is an extremely common condition that happens to 1 out of 5 runners (1). This is a question asked by as many as 1,920,000 runners in the US alone that develop stress fractures (2). There are two primary areas that stress fractures occur in runners. One is in the foot bones or metatarsals and the other is in the shin bone or tibia. On occasion, there could be stress fractures that occur in the hip and femur, but this is not nearly as common as the first two.
Medial Tibial Stress Syndrome / Stress Fractures
The classic sign of medial tibial stress syndrome is extreme tenderness over the inner side of the shin bone just above the ankle and spanning over a 4-6cm distance. The pain will worsen as the run goes on and typically goes away after the run is over. This is an early sign and one that should not be ignored. The initial belief is that the stress fracture is caused by periosteal fractioning from the soleus and flexor digitorum longus. More recently, we have found through research that this is not true, as the stress fracture or syndrome involves cortical bone. One commonality that is found as a possible cause of stress syndrome or stress fracture is a smaller tibial cross sectional area. A study was performed by Franklin et al that confirmed that runners with smaller tibial cross sectional areas had a greater chance of developing the syndrome compared to their uninjured counterparts (3). This finding was supported with the work that was done by Magnusson et al. who found that subjects suffering from medial tibial stress syndrome had a tibia that was more porous then the athletic non-pain control subjects (4). This means that in the group that had pain from a fracture in their tibia bone was due to it being less dense in bone material making it more prone to fractures. All bones have a porous internal structure which is why there is testing to determine bone density as people get older to find if people at are at risk for fractures. In runners, this injury is the number one most common injury according to an online survey. The survey took a poll of 748 high school track and field athletes. The results of the study showed that 41 percent of females and 34 percent of males were suffering from medial tibial stress syndrome. This injury is 4 to 6 times more common than achilles tendinitis, illiotibial band syndrome, and plantar fascial injuries. According to the survey, the best predictor in the development of medial tibial stress injury is higher weekly mileage and faster running times. Another study performed by Burne et al. discovered that after a 12 month training program, the only factor that showed to have any value among males in the study was having greater ranges of hip internal and external rotation and lower lean calf girth (5). The authors of the study showed that a 10mm decrease in calf circumference resulted in a 4 fold increase in the incidence of tibial stress fractures. Another study performed on Israeli military recruits showed that males with greater than 65 degrees of hip external rotation were more likely to develop stress fractures (6). Out of all the studies, none were able to find a link to biomechanics creating stress fractures and stress reactions in the tibia. The only study that found a stress fracture correlation was done by Agosta and Morarity, whereby they found that decreased dorsiflexion (ability to bring your toes and foot to shin) led to navicular stress fractures. The study concluded that the tightness in the gastroc caused jamming to occur in the talus into the navicular. If you end up getting a navicular stress fracture, there is a poor prognosis in getting back onto the field anytime soon, as only 45% of individuals suffering from navicular stress fractures return to sport (7).
Action Steps to Eliminate Stress Fractures and Shin Splints of Tibia
The main areas to work on, as confirmed by the research, are hip internal and external rotation and also calf hypertrophy to absorb the increase in vibrational forces when running. We can also add external applications that will help to dampen the pressure placed on the bones.
- Strengthening your hip internal and external rotators. This stabilization will limit excessive motion in the hip and lead to decreased risk in developing stress fractures in the future.
- Run in shoes that minimize the force on the legs like Hoka Shoes. Such shoes will decrease the vibrational forces on the bone and lead to less osteoclast breakdown, which will subsequently even the rate of bone breakdown and bone formation. One brand of shoes that has created a new trend in the running world is Hoka.
- Noene is an excellent way to minimize the vibrational forces that are placed on the bones while running. The Noene that was originally aired on shark tank had applications for force absorption. This application is perfect for runners that are worried about the force of running over time destroying the bone.
- Work on getting calves to increase in circumference. This can be done by performing weight calf raises both seated and standing. This, along with some plyometrics, can increase the size of the gastroc and soleus muscle, which will in turn increase the calf circumference and help absorb some of the vibrational forces placed on the tissue when running. The calf muscle will act as a buffer allowing the vibration to get dampened and diminish in force.
- Break up your runs with Alter G running. The Alter G treadmill is a unique technology designed to help athletes continue to run when injured if there were wanting to prevent injury. The Alter G allow someone to run at a reduced body weight to minimize the effects that gravity has on your bones when running. With the Alter G, you can run at 20 percent of your normal body weight. The treadmill allows you to take off 80 percent of your weight in 1% increments. This will allow your bones a chance to recover from the impact of running.
- Laser Therapy- Lightforce lasers are the choice of the USA track and field team. This laser has been shown to increase production of ATP, increase Nitric Oxide production and also bone growth. This is a great therapy for serious runners and athletes looking into prevention therapy, as well as a performance enhancement as the nitric oxide production acts a vasodialator which opens up the blood vessels of the legs getting greater blood flow to the muscles that need the blood for optimal muscle performance.
1. Bennell K, Malcolm S, Thomas S, et al. The incidence and distribution of stress fractures in competitive track and field athletes. A twelve-month prospective study. Am J Sports Med. 1996;24:211-217.
2. Crowell H, Milner C, Hamill J, Davis I. Reducing impact loading during running with the use of real-time visual feedback. J Orthop Sports Phys There. 2010;40:206.
3. Franklin M, Oakes B, Field B, et al. Section modulus is the optimum geometric predictor for stress fractures and medial tibial stress syndrome in both males and female athletes. Am J Sports Med. 2008;36:1179.
4. Magnusson H, Westlin N, Nyqvist F, et al. Abnormally decreased regional bone density in athletes with medial tibial stress syndrome. Am J Sports Med. 2001;29:712-715.
5. Burne S, Khan, Boudville P, et al. Risk associated with exertion medial tibial pain: a 12 prospective clinical study. Br J Sports Med. 2004;38:441-445.
6. Agosta J, Morarty R. Biomechanical analysis of athletes with stress fracture of tarsal navicular bone: a pilot study. J Australasian Podiatry Med. 1999.
7. Burne S, Mahoney C, Forster B, et al. Tarsal navicular stress injury: long-term outcome and clinical radiological correlation using both computed tomography and magnetic resonance imaging. Am J Sports Med. 2005;33;1875-1881.