Shin Splints to Stress Fractures: A Continuum

Description

Shin splints are typically an overuse injury in which the muscles of the lower leg are exerting too much pulling on the point where the muscles insert into the bone (the periosteum). Pain may be located at the inside or front of the shin depending on which muscle group is contributing to the problem. This issue is commonly seen in runners, basketball players, and other athletes.

General Causes

Poor mechanics at the foot and ankle or poor stability and function at the hips and core can create excessive stress on the muscles of the lower leg. Training errors, such as increasing mileage too quickly (>10%/week), not allowing sufficient rest/recovery days, and using old or worn-out shoes (>250-500 miles of use) are also common contributing factors for shin splints. 

Specific Causes

A) Anterior Pain (front of the shin): When the muscles at the front of the shin (anterior) are producing the pain, a heel strike with a quick foot slap creates excessive tension on the Tibialis Anterior muscle too quickly and too forcefully. This running style is also typically associated with running with an upright torso which decreases gluteal muscle activation and requires the Tibialis Anterior muscle to function as a braking mechanism for the foot more than running with the torso leaning slightly forward.

B) Medial Pain (inside of the shin): Often the pain on the inside of the shin (medial) is produced by the Tibialis Posterior and/or Soleus muscle(s). The Tibialis Posterior muscle supports the arch of the foot and it’s normal for the foot to pronate (collapsing of the arch of the foot) slightly in the landing/loading phase of running. Oftentimes when this motion is excessive and too quick this creates excessive pulling on the Tibialis Posterior muscle, increasing the pull on the periosteum, and creating edema and pain. Improving hip strength (specifically of the abductors and external rotators of the hip) can help control the pronation motion at the foot. 

Additional Causes

Abnormal stiffness or looseness of the joints at the foot and ankle can also create abnormal stress on the muscles at the foot and lower leg. Joint stiffness is something that can be assessed by your physical therapist.

With pain at both the front and inside of the shin, tightness in the respective muscles can create a pulling on the point where the muscles insert into the bone even when you’re not running. This is why some runners will take time off from running to rest, but their pain returns quickly once they start running again. This is because the muscle tightness was creating tension on the insertion point even at rest. Your therapist can help reduce muscle and fascial tightness with soft tissue techniques such as hands-on massage, cupping, or the use of a massage gun. You can then use these techniques on yourself to address muscle and fascial tightness as part of your regular routine. Stretching can also be helpful to keep flexibility in the responsible muscles.

It’s important to address the muscle tightness contributing to the symptoms as well as the running or walking mechanics that originally created the muscle tightness.

The Role of Orthotics

Depending on the movement and mobility of the joints in your foot and ankle, your muscle strength, and mechanics with walking and running you may benefit from over-the-counter (OTC) or custom orthotics. There are some great OTC options such as Super Feet orthotics that provide different levels of arch support and stability without breaking the bank.

Orthotics can provide more support, height adjustments, or even a slight tilt to the arch, rearfoot (heel), and forefoot (ball of the foot). 

With 26 bones and many joints in between it’s helpful for a physical therapist to assess how your joints and muscles function at your foot while you’re moving and assess how you improve with physical therapy to determine if you’ll need any orthotic, an OTC orthotic, or something custom. While some people are able to make great gains in therapy and avoid needing a custom orthotic, others may benefit from having an orthotic to improve muscle activation that may desperately be needed to reach your goals.

Stress Fractures of the Tibia

The Continuum From Shin Splint to Stress Fracture

If the issues seen with shin splints are not addressed and the athlete continues to create a high-tension load on the muscles at the foot and ankle, the excessive pull on the Tibia (the large bone of the lower leg) can create a stress reaction in the bone itself that may progress to a stress fracture. 

The Impact of Nutrition on Bone Health

In the event of a stress fracture, it’s also important to assess the athlete’s nutritional intake as a lack of calories can impact bone strength. For female athletes, a lack of calorie intake versus expenditure can lead to the Female Athlete Triad which consists of decreased bone density (increasing the chance of fracturing a bone), irregular or absent menses, and abnormal fatigue. Similar consequences of decreased bone density and abnormal fatigue can also be seen in males experiencing a calorie deficit as well.

How to Identify a Stress Fracture

X-rays are a good starting place to look at bone health. Stress fractures may be obvious or unidentifiable on X-ray depending on the intensity of the injury and the position of the leg when the X-ray is taken. 

Ultrasound imaging can also be used to identify a stress fracture that shows a break in the outer layer of the bone (the cortex) and, in some cases, detect edema at the surface of the Tibia (Grade 1 on the Fredericson Classification System). Ultrasound imaging is somewhat superficial and may not be able to detect changes within the deeper layers of the bone (bone marrow and intracortical area). 

MRI imaging is another option to view the health of the bone and provides information about the health of all layers of the bone.

What To Do If You Have a Stress Fracture

Oftentimes the advice you’ll get on how to heal a stress fracture is to simply rest. While decreasing the amount of intense weight bearing is helpful, there are still forms of exercise that can keep you strong while waiting for the stress fracture to heal. For example, if your stress fracture is on the smaller side you can do some lightweight strength training with Blood Flow Restriction (BFR) and achieve strength gains as if you were pushing heavier weights. 

Depending on the location and causes of the stress fracture, cupping (away from the site of the fracture) but along the muscles that create tension on the fracture site can be helpful.

Get Help That’s Specific To You - Even if you have the same type of shin splints as someone else, your mechanics, strength, etc may not be the same. To get advice that’s specific to you, schedule a physical therapy evaluation.