Part 3: Muscle and tendon related shin splints: A right pain in the....SHIN!

This next article will detail the muscle and tendon type of shin splints. If you remember back in the previous article, muscle and tendon often pulled onto the bone causing the bone related shin splints to occur. If the bone is getting overloaded from the pull of the muscle and tendon then there is also a lot of load going through the muscle and tendon too!

So essentially, overload of muscle and tendon are the causes of this type of shin splints. Generally the overload of the muscle causes different levels of muscle injury and the overload of the tendon causes tendinopathy, which includes Tendinitis and Tendinosis.

What are the types of muscle injury?

The following are described by Mueller-Wohlfahrt (2012) and they progress in severity depending on the amount of overload to the muscle.

Type 1A: Fatigue-induced muscle disorder:         

This is characterised by an increased muscle tone caused by overexertion. Symptoms are commonly aching in the entire muscle and increased muscle firmness. As opposed to pain, the athlete will report muscle tightness. Ekstrand et al (2013) found that footballers with fatigue-induced muscle disorder missed just 8 days of sport on average.

Type 1B: Delayed-onset muscle soreness (DOMS):

Click here for an entire article about DOMS: http://mathewhawkesphysiotherapy.blogspot.co.uk/2013/07/muscle-blog-series-part-4-delayed-onset.html

Type 2A: Spine-related neuromuscular muscle disorder:

This is characterised by an increased muscle tone caused by a functional or structural spinal/lumbopelvical disorder. Symptoms are commonly aching in the entire muscle and increased muscle firmness. Pain will increase with continued activity but should go away at rest. There will be discrete oedema between the muscle and fascia and thee can be increased sensitivity to touch and stretch but as this is not a structural injury and a scan will show just oedema.

Type 2B: Muscle-related neuromuscular muscle disorder:

This is characterised by an increased muscle tone but often it will be in a smaller area of the muscle and not the full length. This type of injury often results from dysfunctional neuromuscular control. Like the previous types, there is aching and tension along with Cramp-like pain. Unlike the previous types there will be more obvious oedematous swelling so this will be the only thing seen on a scan.

Type 3A: Minor partial muscle tear:

Now we get to the structural types of muscle injury that most people are aware of and would call a strain. This type of a tear will have a maximum diameter of less than a muscle fascicle/bundle. Symptoms are usually a sharp or stabbing pain at the time of injury. So pain is instant and it will be a localised pain. Sometimes it is possible to palpate the tear in the fibre structure within a firm muscle band and early stretching will exacerbate the symptoms. An MRI would be positive for fibre disruption on high resolution and it would detect intramuscular haematoma also.

Type 3B: Moderate partial muscle tear:

This type is a tear will have a diameter of greater than muscle fascicle/bundle. Symptoms are usually a sharp or stabbing pain, with a tearing sensation at time of injury. So pain is instant and it will be a localised pain. It is common to palpate the tear and early stretching will exacerbate the symptoms. An MRI would be positive for significant fibre disruption, probably including some retraction. There is commonly fascial injury and intermuscular haematoma.

Type 4: (Sub)total muscle tear/tendinous avulsion:

This type is a tear involving the subtotal/complete muscle diameter/tendinous injury. There will be a dull pain at time of injury, with very noticeable tearing.  The athlete will often experience a ‘snap’ followed by a sudden onset of localised pain. There will be a large defect in muscle with significant haematoma and a gap can be palpated due to muscle retraction.

Contusion: Direct injury:

This is caused by direct muscle trauma, caused by a blunt external force. This will lead to a haematoma within the muscle causing pain and loss of motion. Pain will be a dull at the time of injury but will likely increase as the haematoma increases. If the contusion is very large then this can cause compartment syndrome, which will be discussed in the next article.

Overall all types of muscle injury can be the cause of shin splints but types 3A, 3B and 4 are uncommon.

What is Tendinopathy, Tendinosis and Tendinitis?

Tendinopathy:

This is a broad term encompassing painful conditions occurring in and around tendons, which includes tendinitis and tendinosis.

Tendinitis: 

This basically means inflammation of a tendon.

Tendinosis: 

This means degeneration of tendon (meaning cumulative damage).

So what does this mean to me?

For a long time tendinitis was the term used and it was considered that injured tendons were simply inflamed. Then the thinking shifted to the thought that there was little or no inflammation present in these conditions (Andres & Murrell 2008). However as is with research, the thinking is changing again: There may be an inflammatory response associated with chronic tendinopathy, even though recent opinions had decided it to be non-inflammatory (Rees 2013).

It is important to know which type is the issue because the way that you treat each one is different.

So now we generally know what can go wrong in muscle and tendon but what are the specific muscles and tendon affected in shin splints?

Posterior and medial compartment muscles:

Tibialis posterior:

This muscle and its tendon are essentially there to control pronation of the foot and to support the arch of the foot. So the muscle or tendon can be overloaded from the amount of load and the level of load applied directly to them. Overload can obviously be from the following:

Poor training methods:

High mileage (20 miles or more a week) has been found to be a risk factor (Korpelainen et al 2001), which was also supported by Wilder & Sethi (2004).

Not doing enough then doing too much – Under loading of the structure causes weakness of the tissues, which exposes the structure making it easier to overload.

Poor fitness:

Jones et al (2002) found that lower aerobic fitness is a risk factor, likely due to fatigue affecting technique and form.

Not having enough recovery between sessions:

Ristolainen (2014) found that athletes with less than 2 rest days per week have a 5.2 times higher risk of injury!

Vascular and metabolic disturbances:

Diabetes and Peripheral vascular disease will increase the risk due to poor blood flow and therefore slow recovery rate.

Genetics:

As with all things some people have a genetic predisposition to chronic connective tissue disorders.

Age:

Healing was found to be slower with age, so it is easier to overload structures cumulatively if you don’t allow enough recovery between activities (Soybir et al 2013).

Incorrect training surfaces:

Hard surfaces obviously don’t shock absorb well and cambered and uneven surfaces too, can be an issue, as this will alter the stress to the body (Dugan & Weber 2007).

Muscle dysfunction/inflexibility:

Tibialis Posterior can be weak making it easier to overload particularly in people who tend to overpronate.

Athletes with calf muscle weakness and poor endurance are more likely to fatigue, which leads to altered running mechanics (Beck 1998).

Niemuth et al (2005), found that poor core and hip strength/control contributed to overuse injury in the lower limb, in particular the Gluteus medius muscle causes knock on effects such as internal rotation and pronation forces, which makes tibialis posterior work harder.

Shoe design:

Barefoot & minimal footwear had significantly greater eversion & tibial internal rotation in running, which causes more strain to the tibialis posterior (Sinclair et al 2013).

Biomechanics:

Overpronation will cause extra workload for the tibilais posterior.

Weight:

If you are heavier, then the soft tissues have to work harder to control the impact and support the arch of the foot (Hamstra-Wright et al 2014).

The pattern of progression of tibilais posterior issues can vary but remember the muscle and tendon are overloaded together but tendon takes longer to heal. This essentially means that muscle injury is usually less of a problem compared to tendon. The Tibialis posterior can be acutely overloaded by doing way too much in one go, which will almost certainly create a non-structural muscle injury and may develop tendinitis. If you continue to overload the tibialis posterior again and again then you will develop more severe muscle injury or chronic tendinosis.

Soleus:

The soleus & its fascia are anatomically & biomechanically implicated in the production of stress to the medial tibia causing shin splints (Michael & Holder 1985). So overuse of this muscle can cause issues much in the same way that the tibialis posterior can. The difference though is that the soleus is a plantar flexor, not an anti-pronator, so the issue will come from force in this direction. So the common causes are as follows:

Poor training methods, Poor fitness and not enough recovery time:

These are all the same as Tibialis posterior.

Age, genetics and incorrect training surfaces:

These are all the same as Tibialis posterior.

Muscle dysfunction/inflexibility/hypermobility:

If the calf muscles are weak then they are easier to overload particularly if the Gastrocnemius is weak. If the calf muscles are tight then they get overloaded by stretch. Running is about efficiency due to the fact that the Achilles tendon stores elastic energy and the passive recoil propels you forwards. The issue is that if your calf and Achilles are to flexible then you won’t get this as much, which means that you need to contract your calf muscles more to generate the push, making overload easier.

Shoe design and running style:

Forefoot runners are more likely to overload the soleus and over cushioned footwear will dissipate the force into your Achilles, which will lessen the storage of elastic energy and again make the calf work harder to compensate.

Weight:

If you are heavier, then the soft tissues have to work harder to control the impact (Hamstra-Wright et al 2014).

Flexor Digitorum longus and Flexor Hallucis longus:

These two muscles and their tendons can also be at fault. They are located in a similar area to the tibialis posterior but they have a different role. Both muscles help to essentially grip the floor and adjust to the floor surfaces for balance. So if you are running on uneven surfaces or have poor proprioception and balance then these too can be overloaded causing shin splint pain.

Anterior compartment muscles:

Tibialis anterior and extensor halluces longus:

Usually these muscles are overloaded due to the controlling of the foot down to the floor on each heel strike impact, so they are essentially decelerators. More common than not, it affects the muscle and not the tendon and tends to be an acute and short lived problem.

Lateral Compartment muscles:

Peroneus longus and brevis:

The functional roles of these muscles is to support the arch of the foot and to stop the foot from rolling over respectively. They can therefore be overloaded in someone who is flat footed and in someone who is very supinated. If you have an unstable ankle joint from recurrent ankle sprains then it is likely that the peroneals are weak and will be overloaded quite easily.

Treatments:

Treatment will vary dependent on the structures at fault, but here are the common treatments:

In the first 72 hours of symptoms or in the first 72 hours after irritating the injury use P.O.L.I.C.E:

PROTECT from aggravating activities such as running but this will be anything that causes pain to increase during, after or the next day.

OPTIMAL LOADING: Don’t completely rest though. It may be possible to train in other ways for example elliptical training uses less medial hamstring, gastrocnemius, soleus & tibialis anterior muscles compared to walking (Burnfield et al 2010). Obviously swimming and cycling should be okay too due to the lower forces and loads.

ICE: Apply ice in a damp tea towel over the area for 20 minutes and you can re-apply every 2 hours.

COMPRESSION: use something to compress the area, such as tubigrip but make sure it is not too tight.

ELEVATE: In between activity elevate the leg.

Non Steroidal Anti-inflammatories (NSAID’s):

Remember this will only help in acute muscle injury or tendinitis but will be possibly detrimental to tendinosis.

After things have settled down then the following can help:

Orthotics:

Semi rigid orthoses reduced shin splints in military conscripts (Larsen et al 2002).

Custom-made biomechanical insoles may be more effective than no insoles for reducing shin splints (Yeung et al 2011).

Ultrasound:

Ultrasound works best for: Ligament, Tendon, Fascia, Joint capsules & Scar tissue as they absorb it best (Sparrow et al 2005). Basically the denser the soft tissue the better, in fact Dyson (1999) found that the recovery rate of muscle is 50% greater with therapeutic ultrasound.

Massage:

There is an accelerated recovery of muscle function from massage-based therapies (Best et al 2013).

Myofascial Trigger point therapy MTrP:

This can help to reduce the pain in the muscle at fault in the short term but has no long term effect.

Strengthening the weak muscles:

Now just because a muscle is ‘strong’ on a resisted test, doesn’t mean that it works well in function. This can make it difficult to fully evaluate what to target. If the muscle is weak on a resisted test then it is likely to be weak in function. In this case, you should target the muscle but if it is the other way around, then you need to look at how they move and then try to understand if the abnormal motion is caused by weakness or something else. This being said, Niemuth et al (2005) found it beneficial to strengthen around the hip. They looked at hip abductors mostly but found adductor and flexor strengthening was also helpful.

Stretching the tight muscles:

Obviously this will differ in each person so you need to see what structures are tight and stretch them. Common areas tend to be the calf and the hamstrings. (Wilder & Sethi 2004).

Gait/ Running re-training:

Gait analysis can be important because it can highlight any technique issues and see abnormal movements. This can then be targeted by gait and running training and drill work to rectify the issues and lower the risks (Beck 1998).

Footwear:

You should change running shoes every 250–500 miles, because trainers can lose up to 40% of their shock absorption and support after this point (Cook et al 1985).

So this concludes muscle and tendon related shin splints, so keep tuned in for the final installment of the shin splints blog series.

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

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