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Medial Tibial Stress Syndrome (shin splints)

What is it?

Medial Tibial Stress Syndrome (MTSS) is a broad term for an overuse/overtraining injury to the posterior medial portion of the tibia (Inside of the shin).  It is still debated as to the true cause, but many believe MTSS is a result of inflammation to the periosteum (The most outer portion of the bone) due to excessive traction or pull from muscles where they attach along the inside portion of the lower leg.  If training continues, the body will not have enough time to heal, resulting in a possible cascade of impairments including muscle dysfunction (Specifically tibialis posterior, tibialis anterior, and soleus), and further bone degradation.  The most recent thought is that a continuum exists for these bone stress injuries in which MTSS can progress to a stress reaction, and ultimately to a stress fracture if training continues.

This diagnosis is most commonly seen in athletes who regularly participate in high intensity, weight-bearing activities, but other common characteristics include female gender, previous lower extremity injury, a higher BMI, and history of lower activity level.  Females are much more likely to be diagnosed with this condition and it is important to assess for the presence of the female athlete triad (Osteoporosis, amenorrhea, and disordered eating), which predisposes the athlete to recurrent bony injuries if not addressed.  Other specific populations who appear to be at higher risk for MTSS include runners, aerobic dancers, and military personnel given the high lower extremity load and hard surfaces (The latter especially true for military personnel) encountered during training.  Increased loading rate (impact force) at initial contact (when the foot hits the ground) is associated with increased risk for MTSS and thus running style (Excessive hip drop and rotation at the foot) as well as worn or ill-fitting shoes have been associated with the development of this diagnosis.

How is it diagnosed?

Clinical diagnosis is considered the gold standard for MTSS with a focus on patient history and palpation.  As mentioned previously, the patient will likely report a high-level of training on weight-bearing surfaces or possibly a recent significant increase in training frequency, duration, or intensity.  The symptoms are often reported bilaterally.  The patient will generally describe pain during the weight-bearing activity (May not occur immediately) that progressively becomes worse and generally improves with rest.  If the patient describes pain that persists with rest and is bothersome while sleeping, the bony injury may have progressed to a stress fracture.  In terms of palpation, the patient will describe a diffuse (>5cm) area of pain along the posterior-medial tibia.  A stress fracture will present with a more focal area of pain and maybe located along the back of the inside of the shin or the front of the shin.  Radiographs, bone scans, and MRI may be useful imaging tools in ruling out other possible diagnoses but may not illustrate significant findings with MTSS.  MTSS is considered a grade I stress fracture with the presence of periosteal edema (Swelling of the outermost layer of bone) that may or may not be visible with an MRI.  A hop test is a clinical test that is often used for the diagnosis of a stress fracture and maybe also be used for MTSS in order to assess response to high impact forces.

How can a physical therapist help?

Rest is the most important factor regarding treatment for MTSS.  The goal of rest is to allow the body to re-establish normal bone integrity so that it can tolerate the demands placed upon it without recurring incidence of pain and disability.  Now, rest does not mean the patient is unable to participate in an activity; most patients with MTSS are high-level athletes and many may be training for a competition and thus relative rest is an appropriate option.  Relative rest includes non-weight-bearing activities such as swimming and biking that allow the patient to maintain their fitness level while giving the bones and associated muscle and fascia time to heal and repair.  Relative rest may last for up to 4 months, likely without a walking boot, which is used more commonly for bony injuries that have progressed to a stress reaction or a stress fracture.  Once the patient is pain-free with all daily activities, a gradual return to previous weight-bearing activity is initiated.  The patient should look to the physical therapist in order to determine when and how (intensity, duration, frequency) to resume prior to the level of activity.  

For More Information:

Check out this APTA sponsored articleCheck out the Physio Edge podcast on this topic related to runners (specifically minutes 53-60)