Shin splints, also known as Medial Tibial Stress Syndrome(MTSS), is defined by the American Academy of Orthopedic Surgeons as “pain along the inner edge of the shinbone (tibia).” Shin splints are usually caused by repeated trauma to the connective muscle tissue surrounding the tibia. They are a common injury affecting athletes who engage in running sports or other forms of physical activity, including running and jumping. They are characterized by general pain in the lower region of the leg between the knee and the ankle. Shin splints injuries are specifically located in the middle to lower thirds of the inside or medial side of the tibia, which is the larger of two bones comprising the lower leg.

Shin-Splints
Red area represents tibia. MTSS pain found on inner and lower 2/3rds of tibia.

Signs and symptoms

Shin splint pain is described as a recurring dull ache along the inner part of the lower two-thirds of the tibia. In contrast, stress fracture pain is localized to the fracture site.

Biomechanically, over-pronation is the common cause for shin splints and action should be taken to offset the biomechanical irregularity. Pronation occurs when the ankle bone moves downward and towards the middle to create a more stable point of contact with the ground. In other words, the ankle rolls inwards so that more of the arch has contact with the ground. This abnormal movement causes muscles to fatigue more quickly and unable to absorb any shock from the foot hitting the ground.

Causes

While the exact cause is unknown, shin splints can be attributed to the overloading of the lower leg due to biomechanical irregularities resulting in an increase in stress exerted on the tibia. A sudden increase in intensity or frequency in activity level fatigues muscles too quickly to properly help absorb shock, forcing the tibia to absorb most of that shock. This stress is associated with the onset of shin splints. Muscle imbalance, including weak core muscles, inflexibility and tightness of lower leg muscles, including the gastrocnemius, soleus, and plantar muscles (commonly the flexor digitorum longus) can increase the possibility of shin splints. The pain associated with shin splints is caused from a disruption of Sharpey’s fibers that connect the medial soleus fascia through the periosteum of the tibia where it inserts into the bone. With repetitive stress, the impact forces eccentrically fatigue the soleus and create repeated tibial bending or bowing, contributing to shin splints. The impact is made worse by running uphill, downhill, on uneven terrain, or on hard surfaces. Improper footwear, including worn-out shoes, can also contribute to shin splints.

Diagnosis

Shin splints can be diagnosed after taking a thorough history and performing a complete physical examination. The physical examination focuses on palpable, or gentle pressure, tenderness over a 4-6 inch section on the lower, inside shin area. The pain has been described as a dull ache to an intense pain that increases during exercise, and some individuals experience swelling in the pain area. Clinical history focuses on an individual’s previous history with shin splints. People who have previously had shin splints are more likely to have it again.
Vascular and neurological examinations produce normal results in patients with shin splints. Radiographies and three-phase bone scans are recommended to differentiate between shin splints and other causes of chronic leg pain. Bone sctintigraphy and MRI scans can be used to differentiate between stress fractures and shin splints.
It is important to differentiate between different lower leg pain injuries, including shin splints, stress fractures, compartment syndrome, nerve entrapment, and popliteal artery entrapment syndrome. These conditions often have many overlapping symptoms which makes a final diagnosis difficult, and correct diagnosis is needed to determine the most appropriate treatment.

Treatment

Treatment for shin splints is not always successful because the exact cause of shin splints is still unknown.
Most Common Treatment

  • Rest
  • Ice
  • Strengthen
  • Gradually returning to activity

Initial treatment for shin splints includes rest and ice. Rest and ice work to allow the tibia to recover from sudden, high levels of stress and reduce inflammation and pain levels. It is important to significantly reduce any pain or swelling before returning to activity. Strengthening exercises should be performed after pain has subsided, focusing on lower leg and hip muscles. Individuals should gradually return to activity, beginning with a short and low-intensity level. Over multiple weeks, they can slowly work up to normal activity level. It is important to decrease activity level if any pain returns. Individuals should consider running on other surfaces besides asphalt, such as grass, to decrease the amount of force the lower leg must absorb. Orthoses and insoles help to offset biomechanical irregularities, like pronation, and help to support the arch of the foot.