Shin splits are the most common lower leg injury, yet they’re also one of the least understood. The term was first used in the 1950s and typically refers to a diffuse pain around the lower third of the tibia, the larger of the two bones in the lower leg. The exact cause and structures affected are not yet entirely certain, but after decades of conflicting theories, new research has brought us closer to finally solving this medical mystery.

My soon-to-be-completed PhD focuses on shin splits, or, to give it its proper name, medial tibial stress syndrome (MTSS). Through studying the current literature and conducting our own research, we found that MTSS is primarily a bony overload injury, which has important implications for how it should be diagnosed and treated.

How do bones become overloaded?

Bones are constantly shedding old or damaged tissue and replacing it with fresh tissue through a process known as bone remodelling. This occurs constantly at a low rate, but running or other high-impact activities can accelerate this process by constantly subjecting the bone to small amounts of damage which then needs to be healed.

If more bone tissue is being shed than is being replaced, then the bone will lose density. This can occur either because the rate of repair has slowed down, which occurs naturally as we age, or because the amount of damage being done to the bone outpaces its ability to repair itself.

It’s the latter that causes overload, and recent evidence suggests that this is what causes the pain felt in those who suffer from MTSS. If this pain is ignored, the MTSS may become prolonged and more difficult to treat.

Why is MTSS so common?

If you have even a casual interest in fitness, you’re probably aware of the tear-and-repair process of strengthening your muscles, where, much like with bones, tissue damaged by overloading is replaced by fresh tissue. Taken at a gradual, controlled pace, this can be manipulated to promote muscle growth and strength.

Unfortunately, far less people are aware that their bones do the same, even amongst professional athletes. Perhaps it’s because they can’t see their bones or because bones have little impact on athletic performance unless they’re damaged, but, whatever the reason, fitness hobbyists and athletes alike rarely take their bone health into consideration.

This lack of understanding leads to unrealistic expectations in how quickly MTSS can be treated. There’s a very hard limit to the speed at which bones can repair, so if you’ve had MTSS for 18 months before you report it (which was the average amongst those in our studies), you simply aren’t going to be able to recover in a few weeks. Even if the pain subsides relatively soon, you still may be susceptible to shin pains when you return to loading activities.

Unfortunately, the only way you tend to know your bones are becoming overloaded is through pain. X-rays, MRI, DEXA, CT and bone scans all yield high rates of both false positives and false negatives, so diagnosis is best made clinically, as we demonstrated in a study that showed clinical diagnosis to be the most reliable method. Everyone has their own threshold to the symptoms of MTSS, and diagnosis and treatment needs to be provided on a case by case basis.

The good news is, now that we know the likely cause of MTSS, we can improve the quality of our treatment. Click here to find out the best way to treat MTSS based on this new evidence.

If you’re concerned about pain in your shin or any other part of your body, don’t hesitate to get in touch with us by emailing enquiries@physiolondon.co.uk or by calling us on 020 7093 3499.

 

Marinus Winters

Sports and Spinal Physiotherapist