What are shin splints?
The term shin splints has been widely used as a catch-all term referring to a collection of different conditions that cause lower leg pain.
The term medial tibial stress syndrome (MTSS) better defines the injury and separates it from injuries such as stress fractures or compartment syndrome.
MTSS is caused by chronic strain, overuse, and microtrauma of the soleus (calf) muscle at its origin on the inside of the shinbone (posteromedial tibia), or deep inflammation of the periosteum, which is the connective tissue that covers the bone, of the tibia beneath the posterior tibialis muscle.
MTSS usually occurs in unconditioned people who begin a new running or jumping activity or conditioned runners who change or increase their speed or distance or change their type of shoe or running terrain.
MTSS also affects individuals who have flat feet because the mechanics of the foot increase stress on the soleus muscle.
Differential diagnosis – MTSS vs compartment syndrome vs stress fracture
MTSS
Medial tibial stress syndrome is the most common presentation of lower leg pain, with pain localised to the inner portion of the tibia in the middle/lower thirds of the lower leg and in the surrounding soft tissue.
With MTSS, pain usually disappears once the activity that causes the pain is reduced or stopped.
An x-Ray sometimes shows chronic cases of MTSS, where there is a mild thickening of the tissue surrounding the tibia (periosteum) or an uneven edge at the end of the tibia in the back.
Despite being the most common of lower leg complaints, MTSS is often a common misdiagnosis for similar conditions such as stress fractures and compartment syndrome.
Stress fracture
Stress fractures are hairline cracks in the bone.
This often follows as a result of shin-splints that have not been managed correctly or when patient tries to ‘run-through’ the problem.
A patient with a stress fracture usually experiences severe pain that does not always go away with rest.
The pain often persists with walking and increases when walking up steps or during similar moderate activity.
A patient with a stress fracture feels pain around the upper outside portion of the tibia.
The patient commonly complains of pain at night.
X-rays are often required to rule out a stress fracture.
However, x-rays may not show a fracture line or a healing stress fracture until several weeks after injury, so a bone scan, CT scan or MRI may be used instead.
Compartment syndrome
There are four divisions of muscles in the lower leg (anterior, lateral, posterior – superficial/deep).
Each of these are surrounded by a thick tissue called fascia that surrounds the muscles completely.
During exercise muscle volume generally increases by 20% increasing pressure within each compartment. Excessive pressure can affect supply to blood vessels and nerves in the leg.
Compartment syndrome is a painful condition that results when pressure within the muscles of the lower leg builds to dangerous levels, preventing nourishment from reaching nerve and muscle cells.
This diffuse widespread lower leg pain typically comes on 5–10 minutes after beginning a bout of exercise, and rapidly builds to such a severity exercise needs to be ceased.
Pain usually settles rapidly on stopping exercise.
The increased severity of pain reflects the fact that it is caused by restriction of oxygen and blood to the involved muscle compartment.
Causes of MTSS
Excessive pronation of the feet.
Pronation is a normal movement of the foot that allows the arch to flatten which helps the body to absorb shock and adapt to different surfaces.
If the arch flattens more than normal is it called excessive pronation.
This places increased pressure on the arch and upon repetitive movement such as running will greatly increase the stress placed on the lower leg.
Tightness in the posterior muscles, which propel the body forward, places additional strain on the muscles in the front part of the lower leg, which work to lift the foot upward and also prepare the foot to strike the running surface.
- Insufficient shock absorption – hard surface running, or worn or improper shoes increases the stress on the anterior leg muscles. Softer surfaces and shoe cushioning materials absorb more shock and less is transferred to the shins.
- Poor lower limb biomechanics/improper foot positioning – the lower leg muscles suffer a tremendous amount of stress when a runner lands only on the balls of the feet (toe running), without the normal heel contact.
The muscles of the foot and leg overwork in an attempt to stabilize the over-pronated foot and the repeated stress can cause the muscles to tear where they attach to the tibia.
Rapid increase of speed or distance
Signs and symptoms of MTSS
- Aching along the front of the shin with activity
- The pain may begin as a dull aching sensation after running
- The aching may become more intense, even during walking, if ignored
- Pain along the inside (medial) part of the lower leg
- Generally, develops gradually over weeks/months
- May have swelling in lower leg
- Tender areas are often felt as one or more small bumps along either side of the shin bone
Treatment
MTSS is an inflammatory disorder, that can be best managed initially with rest, ice and anti-inflammatories (i.e. Nurofen, Voltaren).
Physiotherapy at this stage will involve ultrasound, light massage, and education with guidelines into exercise intensity and frequency.
This aims to settle and relieve the inflammatory process thereby relieving symptoms.
More intense physiotherapy can then be commenced. It usually involves, deep tissue massage, myofascial releases, muscle frictions, structure rehab programs to increase flexibility, strength and endurance and gradual recommencement to normal activities.
Throughout rehabilitation your physiotherapist will advise you on continuing aerobic fitness activity, however it will likely be modified to reduce lower limb impact (i.e. swimming, orbital training, beach walking/running)
Prevention
MTSS can be painful but is usually easily resolved.
- If you experience pain in your shin, thoroughly stretch before exercising, reduce your activity level, and check your footwear.
- If you run on a hard surface, find some softer ground to train on.
- Avoid training errors (‘start low and go slow’). Introduce gradual changes in intensity, activity, and terrain.
- Maintain adequate calf and anterior tibial flexibility, strength, and endurance.
When do you see someone for help?
Your Lifecare practitioner will be able to provide an accurate diagnosis and an appropriate management plan. Often this problem can require a sports medicine doctor, physiotherapist, and/or podiatrist to assist.
Click here to find your closest Lifecare clinic.
