Most individuals who exercise have likely experienced the shin splints, in medical terms referred to as Medial Tibial Stress Syndrome (MTSS), at some point in their lives. MTSS is an inflammatory response of the connective tissues of the lower leg that occur due to repetitive loading, like what happens when someone starts to exercise again. This scenario is likely as MTSS occurs more commonly in individuals who suddenly increase their amount of physical activity, or who change the frequency or type of exercise. This usually causes there to be pain located diffusely (all over) the shin bone, which is the Tibia. It is important to recognize the early signs, as rest or modification of activity can prevent further complications. If the overuse continues then MTSS may progress to various stages of a stress fracture.
A Stress Fracture occurs after repeated submaximal loading of normal bone with insufficient rest periods and causes there to be a break in the bone. The repeated stresses on the bone cause there to be microfractures of the bone. This can arise because with insufficient rest periods there is greater osteoclastic activity (breaking bone down), then there is osteoblastic activity (building bone). Therefore, if the repeated submaximal forces on the bone continue the stress reaction can progress to a fracture of the cortex of the bone, which is a stress fracture.
Lower extremity stress fractures are most common among athletes who perform repetitive sessions of running or jumping; with some reports stating that the highest rates of stress fractures occur in Track and Field athletes. Among recreational and competitive runners the incidence of lower extremity stress fractures is 8.3% for men and 13.2% for women. The most common sites for stress fractures to occur at are the tibia, metatarsals, and the fibula. The two highest risk factors for developing a stress fracture are having a history of a previous stress fracture and being of the female gender. Other risk factors are: sudden increase in physical activity, running greater than 25 miles per week, having a reduced caloric intake, having a decreased bone mass, low Vitamin D levels, and being a military recruit going through basic training.
When patients have a stress fracture their initial symptoms are very similar to MTSS. However, with a stress fracture the pain tends to more focal (one point is tender) and the symptoms have been lasting for a longer period of time; like weeks to months rather than a few days. The pain may start to worsen and it may occur while at rest instead of mainly during exercise. The main difference between a stress fracture of the Tibia (the shin bone) and the Fibula (smaller bone on the lateral side of the leg), is the location of the pain. With a stress fracture of the Tibia the pain is most likely on the medial side of the bone, typically on the inferior portion of the bone. A Fibular stress fracture will cause pain more on the lateral side of the lower leg.
Often times a low-risk stress fracture can be diagnosed based on the history the physician obtains from the patient. For there to be a definitive diagnosis of the injury, then imaging studies must be obtained. Initially a regular radiograph (x-ray) of the leg will be obtained. This imaging technique is good when a definitive fracture is present and it is widely available and has a cheaper cost compared to other modalities. However, stress fractures can be in various stages and not all provide a clear break on a regular radiograph. If there continues to be a need for a definitive diagnosis, or to quantify the extent of the injury, then a Magnetic Resonance Image (MRI) should be obtained. An MRI is useful as it can show the various stages of a stress fracture, from the beginning where there is bone marrow edema (swelling) present up to showing the presence of a fracture.
The initial treatment of most stress fractures is rest from physical activity and to provide support to the area. The sooner a patient rests the injured area the sooner they can start to heal, which means the sooner they can get back to their full activity level. A short period of non-weight bearing, or reduced weight bearing, should occur if there is pain with walking. Fibular stress fractures rarely require there to be a period of non-weight-bearing. There can be a gradual resumption of normal activities once there is no longer pain with the previous level of support and activity. The expected time to take for healing to occur for a stress fracture is around 12 weeks. One study demonstrated that an average of 13 weeks was required to be able to return to their sport with reduced intensity and about 19 weeks to be able to participate at full intensity.
Chase King, MS-IV
David Carfagno, D.O., C.A.Q.S.M.
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