Part 4: Vascular and Neural related shin splints: A right pain in the……SHIN!

This next article will detail the vascular and neural type of shin splints. Basically this type relates to compression or damage of the blood vessels or nerves that pass through the lower leg area causing pain in the shin area.

The most common type is Compartment syndrome:

The lower leg has four compartments, which are separated by inelastic fascial layers, essentially causing confined and compressed space. In these compartments are the muscles, blood vessels and nerves. Below shows what structures are in each compartment:

Anterior:

Muscles: Extensor hallucis longus, Extensor digitorum, Tibialis anterior and Peroneus tertius

Nerves: Deep peroneal nerve

Blood vessels: Anterior tibial artery

Lateral:

Muscles: Peroneus brevis and longus

Nerves: Superficial peroneal nerve and proximal portion of deep peroneal nerve

Blood Vessels: Peroneal artery

Superficial posterior:

Muscles: Gastrocnemius, Soleus, Plantaris

Nerves: Tibial nerve branches

Blood Vessels: Posterior tibial, popliteal, peroneal and sural arteries

Deep posterior:

Muscles: Popliteus, Tibialis posterior, flexor hallucis longus and flexor digitorum longus

Nerves: Tibial nerve

Blood vessels: Posterior tibial and peroneal arteries

Compartment syndrome can be either traumatic or non-traumatic in origin. Traumatic is when there is a direct impact on the area, like being kicked in the shin. The damage causes bleeding in the area creating a haematoma and therefore less space. Non traumatic is called exertional compartment syndrome and relates to activity and exercise.

What are the symptoms of traumatic compartment syndrome?

The symptoms are the 5 P's:

Pale

Painful

Pulseless

Paresthesia

Paralysed

Obviously these are the text book symptoms but it’s not always that obvious.

If the bleeding is small then the body can resolve the problem by itself but if there is a large haematoma then they will need to do a Compartmental fasciotomy, which is surgery to cut open the compartment to relieve the pressure. If pressure isn’t relieved quickly then tissue will start to die and worst case scenario you could lose your leg and even die from sepsis!

Exertional Compartment Syndrome (ECS):

This accounts for 33% of shin splints (Clanton & Solcher 1994). The cause of ECS is primarily from exercise. Normally during exercise, there is an increase in blood volume within the exercising muscles, which makes the muscle bigger. Obviously the space in each compartment is limited so there is an increased compartmental pressure. Obviously the body is not daft and can cope with this well in normal circumstances. Roscoe et al (2014) found that in normal subjects, the increase in compartment pressure goes from 23.8 mm Hg at rest to 68.7 mm Hg during exercise but in ECS it goes from 35.5 mm Hg at rest to 114 mm Hg during exercise. This increased pressure causes cramping, burning and tightness in the area of the compartment affected. The foot and ankle can also become numb and weak if the pressure is very high. The symptoms can stop after exercise but if the pressure is high then it may continue for some time even afterwards!

So what causes the pressure to be higher in ECS sufferers?

As per usual it is generally to do with overload. If you train a muscle then you get muscle hypertrophy, which is an increase in muscle size. This will take up more space and then under exercise it will engorge and restrict space even more.

Okay so doesn’t this happen in everyone?

Well yes, but some more than others. Some people can pack on muscle very easily and others not so much. Other factors will relate to technique, body weight, abnormal movement, biomechanics, (essentially the same causes as other forms of shin splints), which will all alter the load on differing structures.

Diagnosis:

Apart from clinical assessment, the standard test is a compartmental pressure study, which is inserting needles into the compartment to measure the pressure at rest and under exercise.

Treatment:

Evidence is not great for non-surgical treatment but surgery is a big step so you should try conservative treatment first. The evidence supports one thing quite strongly, which is activity modification and rest but alongside this, generally the common treatments are a combination of massage and stretching according to Blackman et al (2014). Other authors have found that taping, orthotics and nonsteroidal anti-inflammatory drugs can be beneficial too. But remember in all injuries getting to the root cause is the only option for long term success. So just like the other previously discussed shin splints, you may need to look at the following:

Orthotics, strengthening the weak muscles, stretching the tight muscles, gait/ running re-training and footwear.

If all of this fails then surgery is the only option. This will be a compartmental fasciotomy, which is the same as for a traumatic compartment syndrome.

What is the success rate of surgery?

An anterior or a lateral ECS does best with a greater than 80% success rate. The deep posterior ECS is only about 50%.

What happens post op?

You will need to partake in a 12-week rehabilitation program, which generally builds your mobility, strength and function back to full fitness again.

Now that obviously covers the most common type of vascular and neural shin splints but we will now cover briefly the other potential causes:

Nerve entrapment syndromes:

Overall this accounts for 10% of this type of shin splints (Clanton & Solcher 1994).

Typically burning pain brought about by activity and pins and needles, numbness and weakness can be present locally too. As you can see the symptoms are not much different to other conditions, which makes it difficult to diagnose. The common peroneal, superficial peroneal, and saphenous nerves are most commonly at risk for entrapment and the most common cause is trauma.

Diagnosis:

A clinical neurological examination can help to diagnose but it can’t be conclusive. However, electromyography and nerve conduction studies are the most accurate for diagnosis but the condition must be present for at least 3 to 4 weeks otherwise they may be negative.

Treatments:

Usually conservative management is effective. Generally this includes modifying activities, biomechanical correction, joint mobilisation, neural mobilisation, massage, and nonsteroidal anti-inflammatory drugs. Only occasionally is surgery required for nerve entrapment syndromes.

Here are the nerves affected:

 

Saphenous nerve:

Commonly injured in the adductor canal by local trauma, infection, or inflammation. It is possible that the nerve may also be injured at the knee due to arthroscopy, trauma, or pes anserine bursitis. Symptoms are medial knee or leg pain.

Tibial nerve:

This could be caused by a minor compartment syndrome in the posterior compartment which is where the tibial nerve passes. It could be purely structural, meaning that in the acute phase the nerve becomes inflamed and deoxygenated causing chemical pain and ischemic pain. In the chronic phase, when the problem has been there for a long period of time the nerve can become tighter and shorter and can even scar and tether but as with lots of chronic problems, pain becomes hypersensitised in the central nervous system, which makes the individual’s perception of the symptoms exaggerate. Accessory soleal muscles have also been implicated causing tarsal tunnel syndrome.  The muscle can extend more distally into the inner portion of the ankle.  It would take up space into the tarsal tunnel and during activity and fill with blood, causing compression of the posterior tibial nerve.  MRIs are definitive in diagnosing accessory soleal muscle related problems and if symptoms persist, removal of the accessory muscle will eliminate the underlying problem to the tarsal tunnel.

Sural nerve:

Compression can be from mass lesions, scar tissue, ganglia, surgical trauma, or extrinsic compression from plaster of Paris or ski boots. Symptoms are commonly shooting pains in the cutaneous distribution of the nerve, which is the lateral aspect of ankle/foot.

Common peroneal nerve:

Compression at the peroneal tunnel from sources such as casts, surgery, osteophytes, and cysts can cause this but you can also get it by sitting in a prolonged crossed-legged position. Symptoms are sensory disturbances in the lateral lower leg and foot with possible foot drop and pain at site of compression.

Superficial peroneal nerve:

Local trauma or compression is the most common underlying cause, for example being kicked playing football. Non-traumatic causes are commonly due to fascial defects with or without muscle herniation that then compress the nerve. Symptoms are commonly numbness or paraesthesia in the distribution of the nerve or lateral leg pain. The pain is usually vague pain over the dorsum of the foot and symptoms increase with activity.

L4/5 Lumbar radiculopathy:

Now this one is a curve ball as the problem is in the lower back. However you can have shin pain with no pain anywhere else and the cause can be from a L4/5 Lumbar radiculopathy problem. Most commonly this can be a disc prolapse but other reasons can be stenosis or rarely, more serious pathologies. It is worth considering this as a potential cause, otherwise you may be treating the wrong area!

Vascular syndromes:

Popliteal artery entrapment syndrome (PAES):

Luckily exercise related arterial entrapment syndromes of the lower extremity are rare. The most common is PAES and interestingly the symptoms can be very similar to ECS. It is commonly caused by a compression of the popliteal artery by structures around the popliteal fossa. For example an accessory medial head of the gastrocnemius that passes behind the popliteal artery can compress the artery. Obviously there is no such thing as anatomically correct so popliteal compression can also be caused by fibrous bands of the gastrocnemius or the popliteus muscle or even an unusual course of the popliteal artery

Diagnosis:

Ankle-brachial index, which is checking the ratio of the blood pressure in the lower legs to the blood pressure in the arms is often the first test done. It is recommended that the ankle-brachial index be done with the ankle in only the neutral, forced dorsiflexion, and forced plantarflexion positions. An ankle-brachial index of less than 0.9 is abnormal. This test is considered very accurate but the gold standard is angiography.

Treatment:

Basically this is surgery and is essentially removal of the compressing structure or creating an alternative route for the artery with a bypass graft.

Peripheral vascular disease:

This is basically when you get narrowing of the arteries in the legs from atherosclerosis. It should be considered especially when sensory or motor loss is present in association with exertional lower leg pain. The type of pain is often cramp like and will come on with exertion and stops soon after with rest. This is actually called intermittent claudication. If this is found to be the issue then graded, gradual exercise significantly benefits the leg pain & improves walking time & distance (Watson et al 2009). However if the symptoms continue to worsen then a surgical bypass graft will be needed to restore adequate blood flow.

Deep Vein Thrombosis (DVT):

This is a blood clot in a deep vein, most commonly the symptoms are in the calf but can radiate to the shin area. The symptoms are similar to compartment syndrome due to the fact that blood flow is restricted. A Doppler scan is best for diagnosis and if it is positive then anti-coagulants are needed. If you suspect this then seek medical advice as the worst case scenario is a pulmonary embolism and death!

So overall this Shin splints thing is very complex and varied. So if you suspect that you have a form of shin splints then get booked in for an assessment.

If you need any further information or would like to book an appointment then call Hawkes Physiotherapy on 01782 771861 or 07866195914

WWW.HAWKESPHYSIOTHERAPY.CO.UK