Plantar fasciitis is a condition so common in athletes it’s even been called Runner’s Heel. It creates pain in the sole of the foot, where the fascia attaches to the heel bone which is usually aggravated by walking barefoot or sports involving running. This article will explore the pathology of plantar fasciitis and how to treat it.
The plantar fascia is made up of 3 bands of tough fibrous tissue extending from heel bone to multiple attachments in the metatarsals (bones at the base of the toes). Of these 3 bands the central band is considered most important in plantar fasciitis, the lateral band is very variable and not fully formed in many people while the medial band is very thin at its attachment to the heel bone.
I should point out at this stage that I’ve probably got the title wrong! Really we should be calling Plantar Fasciitis ‘Fasciopathy‘ or ‘Fasciosis‘. When a word ends in ‘itis’ it suggests inflammation and research has indicated that Plantar Fasciopathy probably doesn’t involve inflammation (Lemont et al 2003). Lets make it simple and just abbreviate to PF instead!
PF is said to affect more than 1 million people per year (Goff and Crawford 2011) and while it does tend to be self limiting and resolve in 6-18 months (Wearing 2006) it can be a long and frustrating process, especially for an athlete. Understanding the pathology is key to managing the condition but can be complex and challenging to understand (by ‘pathology’ we mean what is actually going on with the tissues). Wearing (2006) describes common tissue changes in PF:
“Collagen degeneration with fibre disorientation, increased mucoid ground substance, angiofibroblastic hyperplasia and calcification are the most frequently reported findings.”
Unless you study histology I doubt that clarifies much! A simplification would be to say there are changes where the plantar fascia attaches to the heel bone (an area known as the enthesis). These changes involve thickening of the tissue and disruption of the fibres which make up the fascia (collagen). In degenerative cases this can involve the development of blood vessels within the fascia in areas that usually have limited blood supply, this is called neovascularisation or angiofibroblastic hyperplasia. Calcification refers to parts of the tissue changing to become more bone like in nature, this can happen in PF with the development of a bony ‘heel spur’ – a small bony projection on the heel bone. However heel spurs can be present in patients without PF so they may not be relevant to the pathology.
These changes share a lot in common with another group of conditions – tendinopathy. In fact the plantar fascia shares a lot of similar features to tendon – both thicken in response to excess load and both show a non-inflammatory reaction that can progress to degenerative change. They also have similar structures and display ‘viscoelastic’ properties during loading.
In recent years the work of Cook, Purdam, Magnusson and co. has advanced our understanding of tendon pathology. This progress has resulted in fundamental changes to how we manage tendinopathy. Plantar Fasciopathy hasn’t enjoyed as much of the lime light and as a result there are still many questions about how best to manage it.
There are certainly many overlaps between tendinopathy and fasciopathy, this begs the question, should we approach PF in a similar way to tendinopathy?
At present I think there can be a ‘one size fits all’ approach to PF. Standard advice and stretches are given, sometimes regardless to the stage of the condition. In fact in an NHS Trust I previously worked in PF was managed with telephone advice and a standardised exercise sheet! I’m hoping that following a similar reasoning process as tendinopathy might improve our management of PF.
So how do we go about dong this? Key features in tendinopathy are determining the stage of the tendinopathy, modifying both tensile and compressive load and promoting tendon adaptation through appropriate loading exercises. Can we apply these to PF?
Identifying PF Stage
Cook and Purdam (2009) highlighted the importance of determining the ‘stage’ of a tendinopathy in determining management. They suggested that clinically 2 broad stages could be used – reactive/ early dysrepair and degenerative/ later dysrepair. In the reactive stage the tendon responds to excessive load by thickening and stiffening which helps act as a stress shield to decrease load. Unfortunately this process usually results in pain but is reversible and settles when the excessive load is removed. In degeneration the tendon structure changes and there is change in the collagen which makes up the tendon. For more on this read staging of tendinopathy.
Scott Wearing is widely published in PF research. He suggests in his excellent 2006 paper that there is similarity between the response of plantar fascia and tendon. This could mean that PF also goes through stages along a similar continuum. All that jargon aside where does it leave us with managing PF?
Well I would suggest it may be helpful to stage PF in a similar way – determine if it is in an acute ‘reactive’ stage or a more chronic ‘degenerative’ stage and vary your management accordingly.
The reactive response usually occurs after a fairly rapid increase in loading so if you’ve not had PF before and it’s developed as you’ve increased your running distance or introduced new training it’s more likely to be reactive.
Degenerative change usually happens after prolonged overloading. If you’ve had grumbly heel pain for a while which has gradually worsened and you’re an older athlete it is more likely a more degenerate picture.
Treatment of different stages
In the reactive stage treatment will largely centre around reducing load on the plantar fascia. This can be achieved by reducing activities that increase pain such as walking barefoot and running. Taping the fascia can also help. Stretching the Achilles is widely recommended for PF but it might be best avoided in the reactive stage as it places greater stress on the fascia. In tendinopathy ‘load management’ is key in the reactive stage and the same is true of PF.
With more chronic degenerate PF load management is still key but can involve a gradual increase in load on the plantar fascia. This will probably involve stretching of the plantar fascia itself as well as the Achilles’ tendon. Strengthening calf muscles and Tibialis Posterior may also help these muscles to manage load associated with impact during running to prevent recurrence. Again if we take the lead from tendinopathy management we have some guidance in terms of pain and exercise. Research on achilles tendinopathy by Silbernagel (2007) found that people could continue sport as long as they aimed to keep their pain below 5 out of 10 (where 0 is no pain and 10 is worst possible pain) and pain had reduced by the next morning. You could apply this idea to plantar fasciopathy, indeed many runners continue to run with their symptoms. However I would urge caution with this – running with pain hasn’t been widely studied in patients with PF.
Types of load
When we consider the stress on a tendon or the plantar fascia with often think of tensile load which places a stretching force on the tissue. Until fairly recently compression has been overlooked but Cook and Purdam (2012) highlight the importance of compressive load.
Tensile load on the plantar fascia is thought to be created by something described as the ‘windlass mechanism’ and can be increased by achilles tendon tightness. However according to Wearing (2006) compressive load has not been fully examined in PF. Perhaps future research will shed light on this.
A number of factors will play a part in loading – your training type, volume and intensity will have a role as will footwear and training surface. There can be a connection between barefoot running and PF as this promotes forefoot striking and increases load on the calf complex. Harder surfaces like road may have a larger ‘ground reaction force’ than grass or off-road training placing more load on the fascia. Try to spot patterns between changes you’ve made and changes in symptoms. This can help you identify a cause to your PF and potential solutions.
Several risk factors have been identified in PF and generally these link to increase load on the fascia;
- Obesity – BMI over 30
- Achilles tendon tightness
- Reduced ankle dorsiflexion (the upward movement)
- Foot posture? High arches and excessive pronation have both been linked to PF and are listed as risk factors by Goff and Crawford (2011). However there is some debate in the literature as few empirical studies have demonstrated a clear connection between plantar fasciopathy and shape of the arch of the foot.
- Excessive load through sport or occupation – especially prolonged standing or distance walking/ running.
Addressing these factors will likely reduce load on the PF allowing it to heal.
Role of stretching
Stretching the calf muscles has been a cornerstone of managing PF for years. Many articles in the literature recommend it alongside traditional exercises like rolling your foot over a frozen bottle of water. Despite its popularity there is a sparsity of quality evidence supporting calf stretches for PF. The theory is that a tight achilles increases load on the fascia so we stretch it to reduce load. The problem is there is some debate whether stretching will actually achieve this. A big question too is why stretch a condition that is usually aggravated by tensile load? Cole et al. (2005) reviewed the evidence base for treatment of PF and reported “the benefits of stretching both the plantar fascia and achilles tendon are unknown”.
That said I do feel achilles stretches have a role in more chronic cases where you are aiming to gradually increase load on the fascia. There is some evidence that stretching the plantar fascia itself may be more effective – DiGiovanni et al. (2003) found fascia specific stretches were superior to achilles stretching in treating chronic PF. Their follow up study (DiGiovanni et al. 2006) revealed marked long term improvement with specific plantar fascia stretching. Whether you can actually ‘stretch’ the fascia remains a subject of debate but this intervention does seem to help symptoms.
Many aspects of plantar fasciopathy have not been extensively studied. My thoughts here come from the perspective of a reasoned way of managing a condition heavily linked to overload with many similarities to tendinopathy. It’s based on general theories on how tissues respond to load and how treatment often involves ‘optimal loading’ of the tissue to stimulate recovery. However without a sound evidence base this can only really be theory and opinion in relation to plantar fasciopathy. Indeed while there are similarities to tendinopathy (which has been used as a framework to guide some of these ideas) there are differences too. The use of isometric and eccentric exercise has become a key factor in managing tendinopathy, this is difficult to achieve with plantar fascia. The pathology of tendinopathy and fasciopathy differ too so questions remain on how much of what we’ve learned from tendon studies can be applied to PF.
It can be helpful to think of plantar fasciopathy as a response to excess load. This can be an acute response that will settle with temporary reduction in load or a more chronic response that requires a gradual re-introduction to loading. Modifying sporting activities to find a level that doesn’t aggravate symptoms is key to management. There are similarities with tendinopathy that might help guide us in some respects but this approach is not evidence based. In 2003 the Cochrane Collaboration did a systematic review of interventions for treating plantar heel pain. The work, by Crawford and Thompson reported,
“At the moment there is limited evidence upon which to base clinical practice”
They updated the review in 2010 but it was later withdrawn as it was substantially out of date! This highlights a big gap in the research for this common and complex condition.
Plantar Fasciopathy is not the only potential cause of heel pain and is frequently misdiagnosed. With any lingering injury it is sensible to seeking a professional opinion to clarify diagnosis and management. As ever with injury management if in doubt get it checked out!