(Medial Tibial Stress Syndrome)

Medial Tibial Stress Syndrome (MTSS) commonly known as “Shin splints” is a common cause of lower leg pain and is generally seen in athletes or other individual including army recruits performing high intensity and stress athletic activity

The lower leg is comprised of the tibia and fibula. These two bones contribute to the ankle joint as well as the knee joint. The tibia transfers most of the load bearing stresses during walking with the fibula accounting for 5-8% of the weight bearing load during walking.  The tibia has muscular attachments from the deep flexor muscles in the calf. These muscles include the flexor digitorum longs and the posterior tibial muscle in the deep leg compartment as well as the soleus muscle which is one of the two muscles forming the Achilles tendon. 

The cause of this injury is generally related to abnormal stresses placed on the tibia or excessive motion from the muscular fascial attachments to the tibia.  Poor training techniques as well as excessive foot motion called pronation are contributing features to this problem. Women generally more than men have a higher incidence of this injury which may be partially related to different load characteristics placed on the tibia bone with differing bony anatomy as well as angulation of the leg bones from the hip to the ground.

The pain encountered from MTSS is experienced on the medial or inside aspect of the tibia 4-6 cm above the ankle joint. Pain is generally dull and aching and is noted during warm up for the specific sporting activity and then generally improves into the activity. As the injury progresses pain can become constant and can extend into non athletic activity. Swelling is generally not seen early in the course of the injury but may be present in more advance cases.

MTSS is thought to be a continuum of injury to the leg related to stress that may advance on to the development of tibial stress fracture (TSF). Pain associated with stress fracture can mirror that of advanced MTSS with pain at all times in the tibia with the potential inclusion of swelling at the location of the stress fracture site.  Palpable pain from MTSS and TSF occur at the same region of the tibia but generally pain from a TSF occurs directly over the tibia.

There are generally two theories about the cause with no clear consensus on causation of the injury.  The first theory suggests that abnormal load bearing stresses occur at the region of pain at the tibia bone leading to a reaction to the vascular lining of the bone called the periosteum causing pain. This periosteal reaction may lead to bone remodeling at the tibia. The second theory suggests that excessive stresses on the muscular attachments at this region of the tibial can create an inflammation to the muscle fascia causing a fascitis.  MRI  and bone scan studies have been performed that make arguments for both possible causations.

Treatment is geared primarily at rest. Temporary cessation of the offending athletic activity with a focus on low impact activity including bike riding and swimming is an important tool in recovery. Early symptoms may require backing off of the intensity and duration of the activity as well as focusing on running on softer surfaces as well as the using ice and oral ant inflammatory medications. Supportive athletic shoes that help to control abnormal foot pronation as well as the use of orthotics may also be helpful.

The diagnosis is usually made with a strong history and physical exam. Diagnostic imaging including the use of x-rays, bone scan or MRI is generally not required unless the suspicion for TSF is high. MRI has replaced bone scans as a diagnostic tool in most instances.

Return to athletic activity should be guarded and taken slowly with a reduction in the overall base running mileage and intensity with 10-15% increase per week until full return to activity