What is Medial Tibial Stress Syndrome (MTSS)?

Running is one of the most widely practiced physical activities around the world and the popularity in recent times has increased drastically. However, although the health benefits of running for physically inactive subjects have been demonstrated novice and recreational runners are often affected by running-related injuries. The lower leg is one of the most frequently damaged areas and medial tibial stress syndrome (MTSS) is the main injury affecting 4-20% of the population and has increased prevalence (35%) in athletes. 1,2

MTSS, commonly known as shin splints, is a condition characterised by exercise-induced pain along the inner border of the shinbone (tibia). It primarily affects runners, dancers, military personnel and high impact activities. MTSS occurs when the muscles, tendons and bone tissue in the shin undergo repetitive stress resulting in inflammation and microtears in the periosteum (connective tissue covering the bone). The repetitive stress placed on the area generates microdamage beyond the ability for the body to repair. 2,3

It is important for there to be a differentiation between stress response on the bone and medial tibial stress. Medial stress is described by a diffuse area of pain along the medial border of the tibia whereas stress fracture is focal tenderness over the anterior cortex of the tibia (front of the shin). 

WHAT CAUSES MTSS?  

MTSS is influenced and caused by an interplay of biomechanical, structural, and training-related factors. There isn’t generally one cause in particular, however, it is most commonly seen with a change in running volumes. 1,2,3

The major contributions to MTSS include:

1. Repetitive microtrauma: as you are running, jumping, dancing or completing physical activity you are exposed to repetitive stress on the tibia leading to microscopic damage to the periosteum (membrane around the bone) and underlying bone. Over time the load stimulates osteoclast activity leading to bone resorption and remodelling. Chronic stress induces periosteal thickening and new bone formation along the medial aspect of the tibia. As a response to tissue injury pain and inflammation occurs in the affected region on the medial tibia.

2. Muscle Imbalances: weakness or tightness in the muscles around the lower leg, particularly the gastrocnemius, soleus and tibialis posterior disrupts the normal distribution of forces. When running the calf needs to absorb a large amount of force. If there is weakness in these muscles the tibia has a higher load as the muscles aren’t able to dissipate the forces.

3. Biomechanical Abnormalities: structural abnormalities can influence the load on the medial tibia such as flat feet (pronation) or high arches (supination) which alters the alignment of the lower limb. This also changes the capacity of the foot and ankle to absorb the shock during weight bearing activities.

4. Training related factors: abrupt changes in training volume, intensity or frequency without adequate rest and recovery can lead to more stress placed on the tibia. These changes overwhelm the body’s adaptive mechanisms, exacerbating tissue damage and inflammation. The muscles, ligaments and tendons around the lower limb don’t have enough time to repair after the previous load placed upon these structures. As such if the muscles aren’t able to work effectively this places more pressure on the tibia.

5. Inadequate footwear: poor fitting footwear, worn out shoes or by training on hard surfaces the impact forces transmitted to the lower limb are increased. Therefore, without adequate shock absorption, the stress on the tibia is increased.

RISK FACTORS OF MTSS: 2,3,4

• Increased BMI

• Prior history of MTSS

• Limited running experience

• Smoking 

• Relative Energy Deficiency or one component of the athlete triad (disordered eating, irregular menstruation and bone loss)

• Biomechanical Abnormalities

• Muscle weakness of the calf muscles 

• Poor footwear

• Large amounts of high impact exercises 

SYMPTOMS OF MTSS: 1,2,3

• Pain along the inner side of the shinbone, especially during or after exercise

• Painful to touch the inner side of the shinbone

• Swelling or inflammation in the affected area

• Pain that improves with rest but returns upon resuming activity

• Pain that may worsen when the toes or foot are flexed downwards or upwards

Over time these symptoms may get worse and also result in pain when walking, at rest and/or at night time. 

If activities are continued when these symptoms are felt it may lead to stress reactions on the inner shin bone. Stress reactions are normally felt with pain at the front of the shin. At this stage any impact exercises, such as running or jumping should be avoided otherwise a stress fracture may occur.

DIAGNOSIS OF MTSS:

MTSS is typically diagnosed through a combination of a subjective history including onset of symptoms and activity levels. After this a physical examination will take place with a thorough examination of the area and can potentially require imaging to diagnose as well.3,5

1. The subjective history will involve a history of the patient’s symptoms including the location, severity, duration, pattern and aggravating factors of the pain. It will also include enquiring about the patient’s exercise routine, training intensity, training loads, footwear and any recent changes. This history provides a detailed understanding and indication of what may be occurring before the physical examination takes place.

2. The physical examination is performed to assess the affected area to rule in or out specific diagnoses. A series of tests may be included such as range of motion of the joints, strength assessment, location of any tenderness to touch, observing any swelling and assessing biomechanical factors.

While not always necessary, imaging tests or a sports doctor referral may be required. These may include looking at blood test results, MRI, bone scan or other tests to examine the extent of the injury and rule out the potential for other contributing factors. MTSS has similar symptoms to other conditions which can be rule out with some of these tests.

1. Once a diagnosis of MTSS is confirmed, a treatment plan will be tailored to the individual person. This includes rest, strengthening exercises, footwear recommendations as required, plyometric exercise progressions and a running plan to be developed when returning. 4

GRADING OF MTSS:

MTSS can be classified in grades via MRI imaging. The Fredericson classification system is most commonly used and can guide treatment for the health professionals with time frames for returning to sport or impact activities.5

Periosteal oedema refers to inflammation around the tissues surrounding the bone impacting the outer layer of the bone known as the periosteum. If severe, this inflammation can transfer into the bone and cause some bone marrow abnormalities which impacts the grade classification of MTSS. MRI has both a T1 and T2 weighted images which refer to the method used which highlights different areas of inflammation present.5

The grading system has 4 grades as below:

Grade 1 – periosteal oedema with no associated bone marrow abnormalities

Grade 2 – periosteal oedema with mild bone marrow oedema visible only on fat suppressed T2 weighted MRI images

Grade 3 – periosteal oedema with extensive bone marrow oedema visible on T1 and fat suppressed T2 weighted MRI images

Grade 4a – periosteal oedema with extensive bone marrow oedema visible on T1 weighted MRI images and fat suppressed T2 weighted MRI images. It shows focal areas of intracortical signal changes.

Grade 4b – periosteal oedema with extensive bone marrow oedema visible on T1 weighted MRI images and fat suppressed T2 weighted MRI images. It shows a linear region of intracortical signal change (fracture line).

MANAGEMENT OF MTSS:

The management of MTSS centres on a multidimensional approach aimed at alleviating symptoms, addressing underlying risk factors, facilitating tissue healing and strength progressions.3,4

The management of MTSS will be guided based on the Fredericson grade and the symptoms the individual is experiencing. The initial management will involve a period of offloading the legs from any high impact activities to reduce strain on the affected tibia.6,7 Activity modifications can also be completed such as bike and swimming for cardiovascular fitness.

During the period of offloading, modalities such as anti-inflammatories, ice, compression, massage or dry needling may also be recommended for symptom relief. A referral to a podiatrist may also be beneficial based on the individual for footwear opinions and orthotics to enhance the biomechanics.

Each step you take with running the calf is responsible for absorbing 8-11 times your bodyweight. Therefore, it is crucial that the calf has the strength and control to absorb this force rather than the load going onto the passive structures. Therefore, strengthening of the calf muscles is a key part of recovery from medial tibial stress syndrome.

Before returning to impact, targeted muscle strengthening around the calf and lower limb is imperative for the individual. This will allow for greater strength in the muscles and enhance the ability for the muscles to dissipate the forces through the muscles rather than the tibia. These exercises are can be continually progressed via various exercises and early stage plyometrics.3,7 

The progression of these plyometrics and impact tasks will need to be carefully progressed and altered as running is introduced. The plyometrics allow for the calf and tendons to have the response in the muscle to respond and adapt to the running and strength loads. Once the control on the plyometrics and landing is adequate, returning to running is the next step. When returning to running it is important to have a gradual plan and manage the loads well by not doing too much too quickly. The loads need to be balanced when adapting with the sport and strengthening exercises.

If you suspect you have MTSS or if your symptoms persist despite conservative measures, it's crucial to consult a physiotherapist. At Fortis we can help by providing a thorough evaluation, provide an accurate diagnosis, and recommend appropriate treatment options.

REFERENCES: 

1. Deshmukh, N. S., & Phansopkar, P. (2022). Medial Tibial Stress Syndrome: A Review Article. Cureus, 14(7). DOI: https://doi.org/10.7759/cureus.26641 

2.  Menéndez, C., Batalla, L., Prieto, A., Rodríguez, M. Á., Crespo, I., & Olmedillas, H. (2020). Medial Tibial Stress Syndrome in Novice and Recreational Runners: A Systematic Review. International Journal of Environmental Research and Public Health, 17(20), 7457. DOI: https://doi.org/10.3390/ijerph17207457 

3.  Galbraith, R. M., & Lavallee, M. E. (2009). Medial tibial stress syndrome: conservative treatment options. Current Reviews in Musculoskeletal Medicine, 2(3), 127–133. DOI: https://doi.org/10.1007/s12178-009-9055-6

4.  Kuwabara, A., Dyrek, P., Olson, E. M., & Kraus, E. (2021). Evidence-Based Management of Medial Tibial Stress Syndrome in Runners. Current Physical Medicine and Rehabilitation Reports, 9, 177–185. DOI: https://doi.org/10.1007/s40141-021-00326-3 

5.  Fredericson, M., Bergman, A. G., Hoffman, K. L., & Dillingham, M. S. (1995). Tibial Stress Reaction in Runners. The American Journal of Sports Medicine, 23(4), 472–481. DOI: https://doi.org/10.1177/036354659502300418 

6.  McNamara, W. J., Longworth, T., Sunwoo, J. Y., Syed MT Rizvi, Knee, C. J., & Cole, B. F. (2023). Treatment of medial tibial stress syndrome using an investigational lower leg brace. A pilot for a randomised controlled trial. BMJ Innovations, 9(4), 257–263. DOI: https://doi.org/10.1136/bmjinnov-2022-001054 

7.  Milgrom, C., Zloczower, E., Fleischmann, C., Spitzer, E., Landau, R., Bader, T., & Finestone, A. S. (2021). Medial tibial stress fracture diagnosis and treatment guidelines. Journal of Science and Medicine in Sport, 24(6), 526–530. DOI: https://doi.org/10.1016/j.jsams.2020.11.015