Shin Splints – Causes, Complications and Prevention

Definition

Shin splints is the common term for medial tibial stress syndrome. It refers to pain felt anywhere along the shinbone from knee to ankle. People who play sports that involve a lot of running are particularly prone to this injury. One of the most common reasons for this pain is overuse, such as trying to exercise beyond your current level of fitness. The exact cause of the pain is unknown. It may be caused by the tendons and muscles that run the length of the shin pulling on the bone and creating inflammation. More recent research suggests it is more likely a stress reaction from the bone.

Pain felt on the inner side of the shinbone is called ‘medial shin splints’, while the term ‘anterior shin splints’ refers to pain felt on the outer side. While medial shin splints are more common, pain may be felt on both sides of the shinbone in severe cases. Treatment options include rest, the regular use of icepacks on the affected area, and anti-inflammatory medication such as aspirin.

What are the types of shin splints?

It does not have specific types but rather describe a common condition characterized by pain along the shinbone (tibia) during physical activity. However, there are some terms or classifications used to describe different aspects of shin splints. Here are a few related terms or classifications:

Anterior shin splints

This term is sometimes used to describe shin splints when the pain is primarily felt on the front part of the lower leg. It may be associated with stress on the muscles and tendons in the front of the shin.

Posterior shin splints

This term refers when the pain is located on the inner side of the shin. It is typically associated with stress on the muscles and tendons in the posterior (back) portion of the lower leg.

Medial tibial stress syndrome (MTSS)

MTSS refers to the pain along the shinbone caused by repetitive stress and overuse during physical activity. It’s important to note that these terms are often used interchangeably, and the treatment approaches for shin splints are generally similar regardless of the specific location of the pain.

Epidemiology

The incidence of MTSS ranges between 13.6% to 20% in runners and up to 35% in military recruits. In dancers it is present in 20% of the population and up to 35% of the new recruits of runners and dancers will develop it. Large increase in load, volume and high impact exercise can put at risk individuals to MTSS.  Risk factors include being a female, previous history of MTSS, high BMI, navicular drop, reduced hip external rotation range of motion, muscle imbalance and inflexibility of the triceps surae), muscle weakness of the triceps surae (prone to muscle fatigue leading to altered running mechanics, and strain on the tibia), running on a hard or uneven surface and bad running shoes.

Pathophysiology

While the exact mechanism 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 help shock absorption properly, forcing the tibia to absorb most of the impact. Lack of cushioning footwear, especially on hard surfaces, does not absorb transmitting forces while running or jumping. 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 fibres 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.

Symptoms of Shin splints

It is common in people who do a lot of running or other activities that involve repeatedly putting weight on the legs, such as tennis or basketball.

They aren’t usually serious, but can stop you from exercising. They may get worse if you ignore them. It’s important not to run through the pain.

The main symptom is pain in the shin bones, which run down the front of your lower legs.

The pain tends to:

• Begin soon after starting exercise
• Gradually improve when resting sometimes the pain may fade while you’re still exercising, but it can eventually become constant and continue even when resting
• Be dull and achy to begin with, but may become increasingly sharp or severe and stop you exercising
• Affect both shins
• Be felt over a large part of the shin (an area over 5cm across) pain in a small area may be caused by a stress fracture instead

Sometimes, there may also be some swelling.

Causes of Shin splints

Experts do not all agree on the cause of shin splints and the exact cause is not known. They are thought to be caused by overuse or overactivity and typically occur in runners. There are certain things that have been suggested that may make shin splints more likely. These include:

• A sudden increase in training frequency or intensity.
• A lack of calcium.
• Hard running surfaces.
• Running up an incline
• Previous leg injury.
• Poorly fitted or inadequate running shoes that do not support the foot and ankle.
• Various problems with leg muscles such as the lower leg and in foot position, including over-pronation of the foot. (The foot (and ankle) normally rolls slightly inwards when we move. In over-pronation, the foot rolls inwards more than normal.)
• Flat feet. These are a cause of over-pronation as well.

Some experts suggest that it is caused by small tears in the structure of the membrane between the two bones of the leg below the knee (the tibia and fibula). This structure is called the interosseous membrane.

Others suggest that they may also be caused by:

• Overuse injury of tendons (tendinopathy).
• Muscle sprains.
• Inflammation of the membrane surrounding the tibia and fibula bones (periostitis).

Tiny fractures (microfractures) in the surface of the tibia have also been suggested as a cause.

The relationship between shin splints and compartment syndrome is not clear. Some experts consider it to be a form of compartment syndrome, whereas others believe that compartment syndrome is a separate condition that can cause shin splints.

Risk factors

Some risk factors include:

• A sudden increase in the level of intensity of your workout or sport
• Over training
• Runners, both beginners and seasoned
• Running on hard, flat surfaces such as concrete or asphalt
• Having flat feet or high arches
• Being in military training

Complications

While shin splints themselves are not typically serious, if left untreated or if the underlying causes persist, several complications can arise. Here are some potential complications associated with shin splints:

1. Stress fractures: It can lead to tiny cracks in the bone if not treated properly.
2. Chronic pain and disability: If shin splints are not taken care of, they can cause long-term pain and difficulty in doing daily activities.
3. Compartment syndrome: In rare cases, shin splints can result in a condition called compartment syndrome, causing pain, numbness, and potential muscle and nerve damage.
4. Muscle imbalances and biomechanical issues: It can be caused by problems with how your muscles work or how you move. If not addressed, this can lead to other injuries in your lower legs or knees.
5. Delayed recovery: Without proper rest and treatment, shin splints can take longer to heal, keeping you away from activities you enjoy for a longer time.

Remember, it’s important to get proper care and rest if you have shin splints to avoid these complications.

Diagnosis

While a healthcare professional is best suited to diagnose accurately, there are common methods and assessments they may use to diagnose this condition. Here are some approaches used in diagnosing shin splints:

Medical history: The doctor will ask about your symptoms and activities that might have caused the pain.

Physical examination: The doctor will check your legs for tenderness, swelling, or redness. They may also observe your movements and how you walk or run.

Imaging tests: In some cases, the doctor may order X-rays, bone scans, or MRI to look for any fractures or other possible causes of the pain.

Additional tests: Sometimes, the doctor may suggest additional tests, like blood tests, to rule out other conditions that could be causing the leg pain.

Remember, it’s important to see a doctor for an accurate diagnosis of shin splints. They will ask you questions, examine your legs, and may order tests to determine the cause of your pain.

Treatment

To relieve your symptoms, you need to give your bones and muscles time to heal. Shin splints treatment usually includes a combination of:

• Rest: Take a break from sports, running and other activities to give your muscles and bones a chance to recover. You may need to rest and take it easy for a few weeks or longer.
• Ice: Apply a cold compress to your shins every 10 to 20 minutes, three to four times a day, for a few days. Ice helps relieve the swelling and pain of shin splints.
• Pain relievers: Over-the-counter (OTC) nonsteroidal anti-inflammatory drugs (NSAIDs) can ease pain and swelling.
• Supplements: A vitamin D3 supplement (1000 to 2000 IU daily) may help. Discuss supplements with your healthcare provider.
• Shin splint stretches: Gently stretching and flexing your lower leg muscles may be helpful.
• Slow increase in activity level: When you do become active again, start slowly. Increase your activities gradually to reduce the risk of shin splints returning.
• Supportive shoes and shoe inserts: For people who have flat feet, shoe inserts (orthotics) can be effective at relieving the pain of shin splints. Orthotics support your arches and reduce stress on the muscles and bones in your lower legs.
• Physical therapy: Physical therapy can help you get moving again by strengthening your legs and reducing your chance of repeated injury.

Prevention of Shin splints

• To the extent that it is an overuse injury, shin splints can be prevented by gradually increasing exercise activities.
• Footwear that provides proper support to your feet can also help to prevent shin splints.
• Cross-train in sports such as swimming or cycling, which have a lower impact on the shins, to balance out the workout.
• Add strength training to workouts to develop the muscles that can prevent shin splints.
• Don’t overdo it. Runners, and athletes in general, have a habit of pushing through pain, but this could just cause more injury and keep them down for longer periods.
• Poor foot mechanics and weak muscles tend to contribute to shin splints. To prevent it these people will need physiotherapy or wear custom orthotics.