Got Shin Splints? The Low-down on MTSS...

Recently a friend/colleague of mine asked me what she could do about her shin pain. She says that every time she goes for long walks, especially hiking, she develops anterior shin pain. After giving her the quick rundown on what to do, I decided maybe it was time for a blog on medial tibial stress syndrome.

What is it?

Medial tibial stress syndrome is commonly known as shin splints. It is one of the most common causes of exertional leg pain in athletes. MTSS is on the spectrum of repetitive stress injury that ranges from shin splints to actual stress fracture of the tibia (the weight-bearing bone of the lower leg). Stress reaction in the tibia and surrounding musculature results because the body does not have time to heal due to repetitive trauma of the tibia and surrounding musculature. Without rest and proper treatment, this can progress to stress fractures of the tibia.

Pathophysiology – what’s going on in there?

Thought initially to be due to underlying periostitis of the tibia (bone injury), MTSS is now thought to be a spectrum of tibial stress injuries including tendinopathy (when tendons that attached muscle to bone become inflamed), periostitis (inflammation of the periosteum, the outer layer of bone), periosteal remodeling (when bone breaks down and rebuilds), and stress reaction of the tibia. It is also thought to be due to dysfunction of the muscles in the lower limb- the tibialis posterior, tibilais anterior, and soleus muscles.

Physical Exam

For the medical providers out there, on physical exam, the medial ridge of the tibia (origin of the tibialis posterior and soleus muscles) is often tender to palpation, especially at the distal and middle tibial regions. The anterior tibia, however, is usually non-tender. Reassuringly, neurovascular symptoms are usually absent. Sensory or motor loss with associated exertional lower leg pain is more indicative of a diagnosis of acute or chronic exertional compartment syndrome. While ECS can be confused with MTSS, it is different in pathophysiology, diagnosis, and treatment. (Maybe that can be another blog!) 

A thorough musculoskeletal exam should be done to evaluate for associated abnormalities of MTSS including genu varus or valgus, tibial torsion, femoral anteversion, foot arch abnormalities, or leg-length discrepancy. All of these can affect stress on the tibia. Leg-length discrepancy can be evaluated by multiple methods, however, the simplest may be having the patient lie in supine position and evaluating the symmetry (or asymmetry) of the medial malleoli. Also examine flexibility and balance of hamstrings and quadriceps muscles as imbalances and poor flexibility can be associated with lower-extremity stress reaction. These can be a focus for preventative exercises during the treatment phase.

One of the most common risk factors for MTSS is hyperpronataion of the subtalar joint, caused by poor ankle mobility at the tibiofibular joint or limited ankle dorsiflexion. Assess for this by viewing the feet in standing position as below. You can also have the patient perform a one-legged squat in standing position or you can do a gait exam as these can bring out worsening hyperpronation.

Subtalar hyperpronation on (a) medial and (b) anterior view.

Further Work-up

This is usually not indicated, but if the athlete is not improving after conservative treatment (see below), imaging can be done. X-rays typically do not show pathology until 2-3 weeks after initial injury. At this point, you may see periosteal exostoses if the cause is related to periosteal reaction. This is also a time to identify any healing stress fractures that may have been the cause of the pain. MRI can show changes much earlier than 2-3 weeks, demonstrating progression of injury in the tibia, starting with periosteal edema, progressive marrow involvement, and finally cortical stress fracture.

Initial Treatment

MTSS just happens to be one of those nagging injuries that keeps us from doing what we want to do, so many times people ignore their pain, but if you are having pain for more than a week, you should go to your Sports Medicine Physician for an evaluation to ensure that you do not have stress fractures, a more severe complication of medial tibial stress syndrome. Rest, ice, NSAIDs (non-steroidal anti-inflammatories such as ibuprofen), and calf stretching for initial pain symptoms is the first-line treatment. Since initial treatment is what no athlete wants to hear (rest, ice, ibuprofen), modifying the training program to decrease intensity, frequency, and duration of work-outs can be done when full rest is not possible. Decreasing mileage by 50% can help alleviate symptoms without complete cessation of running. Avoiding running on uneven surfaces and on hills is also recommended. When beginning rehabilitation, low-impact and cross-training exercises should be done, in addition to strength and flexibility exercises.

Prevention/Rehabilitation

Fit Feet 

My daughter now owns Stride Rite shoes.
They provide the proper amount of support
for this little lady who is about to go off
exploring the world all on her own two feet.

As we discussed earlier, hyperpronation at the subtalar joint is one of the main risk factors for MTSS.
Orthotics can be helpful to correct this. Another important thing to consider is footwear. Shoes with shock absorbing soles help reduce forces through the lower extremity and prevent repeat MTSS. Shoes should also have the proper fit and be changed every 300 miles to 6 months of wear. Runners who train in extreme climates should consider multiple pairs of shoes to keep on rotation as wet shoes lose 40% of their shock absorbing and support capabilities.

It’s all in the kinetics

An assessment by your Sports Medicine Physician, Physical Therapist, or Strength & Conditioning Coach certified in Functional Movement Screening can help pinpoint abnormalities in kinetic chain movements and help correct these with exercises.

Specific strength and flexibility exercises –
These are for after an initial rest or modified training phase; do not attempt in the acute phase as this can exacerbate symptoms.

Proper footwear is even more
important on uneven terrain!

Stretching and strengthening of the calf muscles, including eccentric calf exercises (up with two legs and down with one on your heel raise, or can go up with non-affected leg and down slowly with affected leg) can prevent muscle fatigue and prevent MTSS. Strengthening of the tibialis anterior and other muscles that control foot inversion and eversion may also be beneficial as these provide increased ankle and foot stability.

Ankle ROM and strength exercises with Thera-Band.

Core hip flexibility and strength are related to almost every injury in Sports Medicine, and MTSS is no different. Thus, strengthening abdominal, gluteal, and hip muscles (See the Mommy-Baby Core Workout from 2014.) can improve running and gait mechanics, thus preventing lower-extremity overuse injuries like MTSS.

Medical treatment

ESWT, extracorporeal shockwave therapy has been shown to be beneficial in some studies; ask your doctor about it! Injections with cortisone, dry-needling, and acupuncture have been used for treatment of MTSS, but there are no conclusive studies proving these treatments work specifically for MTSS.

Surgical treatment

A posterior fasciotomy can be performed in athletes who do not improve with the above measures, and intramedullary nail placement can be done for stress fractures in season. However, these procedures may not be curative and are not the most common treatments. They may improve pain and function, but results vary among individuals.

Prevention!

This is the most important step. Athletes who suffer from MTSS are at high risk for repeat injury. Training errors, poor technique, and abnormal anatomic alignment should be fixed, and focus should be on the strength and flexibility exercises above. If you are having repeat episodes, it is important to have a thorough evaluation and an individualized training/rehab program.

References:

Beck B. Tibial stress injuries: an aetiological review for the purposes of guiding management. Sports Med. 1998;26(4):265–79.

Galbraith R. and Lavallee M. E. Medial tibial stress syndrome: conservative treatment options. Curr Rev Musculoskelet Med (2009) 2:127–133

Moen, Rayer, et al. Shockwave treatment for medial tibial stress syndrome in athletes; a prospective controlled study. Br J Sports Med. 2012 Mar;46(4):253-7.

Sems A, Dimeff R, Iannotti J. Extracorporeal shock wave therapy in the treatment of chronic tendinopathies. J Am Acad Orthop Surg. 2006;14(4):195–204.

Strakowski J, Jamil T. Management of common running injuries. Phys Med Rehabil Clin N Am. 2006;17(3):537–52.

Wilder R, Seth S. Overuse injuries: tendinopathies, stress fractures, compartment syndrome, and shin splints. Clin Sports Med. 2004;23:55–81.

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