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Medial Tibial Stress Syndrome

what is MTSS?

Well, the truth be told we are still not entirely sure, and the most current definition we have is ‘Pain felt along the middle or distal third of the posteromedial border of the tibia that occurs during exercise, excluding pain from ischemic origin or signs of stress fracture (Yates & White, 2004). Currently, there are 2 schools of thought: the anatomical and the bone stress biomechanical theories.

Anatomical Theory:

The anatomical theory proposes that certain muscles within the leg contract and pull against the tibia and the surrounding tissue called the periosteum, causing symptoms; although, we are not 100% sure which muscle is to blame. There is research supporting all of the muscles in the deep compartment of the leg being to blame, most probably because we are all different (or technically, have anatomical variation). Whilst many of us conform to ‘normal’ anatomy, variation does exist, and this can make the results of the research appear confusing (Stickley, Hetzler, Kimura, & Lozanoff, 2009).

Bone Stress / Biomechanical Theory:

The next school of thought is the biomechanical principle and which really looks at the amount of stress going through the bone and the bones reaction to this stress. As you apply a force perpendicular to the leg bone (tibia), it will bend at the narrowest point (this is termed a bending moment), and this point tends to be the site at which MTSS symptoms occur, as shown in the picture below.

As bone is living tissue, it responds to stress, and we know that bone needs to be stressed to remodel and grow new bone. Injuries occur when too much stress is applied over a prolonged period of time, and eventually, the bone reaches failure point, which can result in a stress fracture.

There was some thought that if MTSS were left untreated, it would eventually lead to a stress fracture putting MTSS and stress fractures on the same continuum. However, this may not be the case as not everyone with MTSS goes on to develop a stress fracture. Furthermore, there is no clear evidence that people with stress fractures had MTSS prior to the stress fracture.

A mix of both theories:

There is also some thought that actually MTSS is a combination of the anatomical and the bone stress theories. One study demonstrated that as a muscles fatigues, the bone stress increases, as the muscles are unable to oppose the bending moments in the tibia (Milgrom et al., 2007). In my opinion, this would appear to be a reasonable explanation.

How does MTSS present?

The good thing about MTSS is that it has a nice clear presentation which includes:

  • Pain on running (can occur on fast pace walking) which initially does not cause you to stop running; however, this may be the case if symptoms and activity continue.

  • The pain is normally described as an intense ache.

  • On palpation there is pain along the lower inside border of the shinbone (tibia), this is known as the lower medial third of the tibia.

  • After running the pain settles within 48 hours and does not wake you up at night.

What causes MTSS?

There are many risk factors for MTSS, with no one factor regularly to blame. MTSS is known as a multifactorial pathology which means that multiple factors are contributing to the problem. From the research, we can see some of the most common causes are:

  • Too Much Too Soon. Bone takes time to adapt to new stress levels. MTSS is very common in people who have come back from injury or previously did little activity, and try to do too much too soon.

  • The Female Sex. Unfortunately, women are at higher risk of developing bone stress injuries compared to men due to what is known as the female triad, which reduces bone strength. There are 3 elements to the triad: irregular periods, osteoporosis (reduced bone density) and low-energy consumption (poor, low-calorie diet). Clearly, this does not apply to all females, and it is important to remember that men can get stress-related injuries as well.

  • Excessive Foot Pronation is when the foot rolls in (pronates) too much and too quickly, resulting in increased stress going through the tibia and increasing the bending moment, hence increased stress. It may also result in increased muscle activity and thus stress to the bone.

  • Poor Proximal Control is an area that is frequently overlooked and forgotten about when, actually, it is very important. Evaluation of the function at the hips and pelvis when running can reveal areas of poor function: this may be reduced motion, weakness or stiffness. One common weakness is within the gluteal muscles, which results in internal hip/knee rotation and foot pronation. This is where detailed gait analysis comes into its own. The secret to successful management is a clear identification of the cause of the problem. By analysing the pelvis, hip, knee and foot, we can determine where the site of dysfunction is occurring and develop an individual management plan (see below under gait analysis).

  • Calf muscle weakness. We know that in people with MTSS, the functional calf strength is weaker than those without. Whilst focusing on Gastrocnemius strengthening is good, the Soleus muscle should be targeted as well.

  • Tibial Varum is the natural bowing in the leg which is compensated by foot pronation and tends to increase the amount of bending that occurs during running.

How to treat MTSS

No one treatment works for everyone. Due to the multifactorial nature of MTSS, it is common that a range of interventions is required. A successful treatment plan can only be provided once the cause of the pain has been determined. For example, if MTSS is being caused by excessive foot pronation and calf and gluteal weakness, all of these must be addressed to treat and prevent further pain.

Common treatments include:

  • Foot orthoses (insoles) are used to try to reduce bone stress. There is good evidence to support the use of orthoses, although the research is confusing as to which type of orthoses are most appropriate (Craig, 2009; Loudon & Dolphino, 2010; Moen, et al., 2009; Reshef & Guelich, 2012, Rome, et al., 2005; Yeung, Yeung, & Gillespie, 2011). The most likely explanation for this is the variability between individuals and the need for tailored prescriptions-just as eyeglasses will only be effective with the right prescription, foot orthoses are the same.