INJURY & REHAB
Plantar fasciitis is one of the most common causes of plantar heel pain. Clinical lead podiatrist, Jai Saxelby, provides a technical insight into the condition, and details treatment therapies.
The plantar fascia, also known as the plantar aponeurosis, is a visco-elastic structure that spans the underside of the foot (from the heel to the toes) and plays a significant role in the weight-bearing foot, both statically and dynamically. Its design is equipped to resist elongation under tensile load, resulting in the storage of elastic energy. Working synergistically with the Achilles tendon, it absorbs energy during initial weight-bearing, then returns the energy during propulsion, acting like a spring.
Measurement of oxygen consumption during running suggests the storage of elastic energy in muscle and tendons saves about 50% of the metabolic energy that would otherwise be needed. Box 1 explains the foot model known as the ‘windlass mechanism’, which illustrates the relationship between the foot joints and the plantar fascia, and how to test it yourself.
Windlass mechanism and test
The anatomy involved is the medial slip of the plantar fascia and the medial (inside of the foot) arch. The plantar fascia originates from the medial tubercle of the heel and inserts into the base of the proximal phalanx of the first metatarsophalangeal joint (MTPJ). The windlass test requires the big toe to be dorsiflexed (upward movement); this tightens the plantar fascia due to it being wound around the first metatarsal head, effectively drawing the first MTPJ and heel together, thereby ‘shortening’ the arch (see Box 1).
How to use the windlass test
Stand the client on a step, allowing the toes to overhang. Apply an upward force to the big toe and feel the tension in the plantar fascia; approximately 65 degrees is regarded as a normal range of movement (Box 1a). The more restricted the movement, the greater the tension in the plantar fascia – in some cases it may even provoke symptoms. There are various causes that result in this restriction, including: bony deformity (hallux rigidus); excessive foot pronation; and restricted ankle joint movement, e.g., tight calves.
Function of the windlass in the gait cycle
During initial contact, the windlass unwinds, the arch elongates, and the fascia goes taut (Box 1b). Synchronous with this, the foot pronates (heel everts, midfoot pronates and the forefoot inverts).
During propulsion, the windlass tightens and the arch shortens. Synchronous with this, the foot supinates (heel inverts, midfoot supinates and the forefoot everts) (Box 1c).
What is plantar fasciitis?
Plantar fasciitis is one of the most common musculoskeletal foot injuries, but is often used as a cover term for all plantar heel pain. The evidence suggests that the condition is a chronic degenerative/reparative process caused by repetitive micro-trauma to the fascia over time. Due to this, the term plantar fasciopathy is now commonly used. Box 2 details the anatomy, the location of the pain, and the clinical signs and symptoms used to make a clinical diagnosis of plantar fasciitis. Diagnostic imaging, such as an ultrasound or MRI, has been shown to be useful for confirming diagnosis. Plantar fasciitis is prevalent in athletic, military and non-athletic populations and is not gender specific. It affects all age ranges, but most commonly the over 40s.
Anatomy of plantar fasciitis and its signs and symptoms
A diagnosis of plantar fasciitis is confirmed when the client presents with the following signs and symptoms:
- Pain at the medial tubercle of the heel and along the plantar fascia
- Pain upon first weight-bearing after a long period of sitting, and the beginning of weight-bearing activities such as walking*
- As the day progresses, pain can increase and continue after physical activities
- The nature of the pain has been described as burning, aching, and occasionally lancinating
*This is based on the author’s clinical experience only. If the client does not experience pain on first weight-bearing, then I get suspicious that it’s not a typical presentation, so would dig a little more diagnostically in order to get a more precise diagnosis. My advice is, if you have a client with this presentation, then get the client to seek specialist assessment, e.g., a podiatrist, physiotherapist, etc.
Differential diagnosis of plantar heel pain
Other diagnostic considerations for plantar heel pain include: calcaneal stress fracture; rupture of the plantar fascia; and entrapment neuropathy. Some systemic conditions can manifest themselves as plantar heel pain, including seronegative arthropathies, referred lumbar pain, etc.
Causes of plantar fasciitis
There are several theories as to the development of repetitive trauma, including overuse, over-training, excessive bodyweight, biomechanical changes to the properties of soft tissues, and/or altered biomechanics.
Although there is no evidence showing a correlation between plantar fasciitis and excessive foot pronation, Box 1 has already shown that when the foot is elongated, the plantar fascia is under greater tension. The functional relationship between plantar fascia and the Achilles has already been acknowledged; evidence shows a significant association between a tight calf, i.e., restricted ankle dorsiflexion (foot points upward) and plantar fasciitis. Just before heel lift during the gait cycle, ankle dorsiflexion should be at its maximum. If this is restricted, i.e., tight calves, then the windlass mechanism is restricted, the foot continues to elongate (rather than shorten), and tension in the plantar fascia increases.
Other factors to consider when looking for potential causes of plantar fasciitis include occupation. Evidence shows that individuals on their feet for prolonged periods, i.e., shifts in excess of eight hours, are more at risk. Also footwear (shoes that are totally flat and/or with minimal arch support), though this is based on expert consensus only.
Treatment for plantar fasciitis
The treatment options vary greatly, but tend to group into two categories:
- Mechanical therapies that are focused on directly or indirectly reducing the tensile load applied to the plantar fascia
- Therapies that are focused on reducing the symptoms, i.e., pain (in a comprehensive review, 28 different therapies were cited, but almost half were mentioned only once, which suggests their use is not widespread)
- In the first instance, it is agreed among experts that the first-line treatment is self-care advice, focusing on the following:
- Reassurance – most people with plantar fasciitis will make a complete recovery within one year
- Symptom relief – the application of ice is advised (cover the foot with a towel and apply for 15-20 minutes; this is based on expert opinion only) – the use of analgesia, e.g., paracetamol, codeine, and non-steroidal anti-inflammatory drugs such as Ibuprofen is advised (but although they have plausible mechanisms of action, there are no robust clinical trials to support their use)
- Reduce mechanical loading on the plantar fascia (directly or indirectly):
- Rest – avoid standing or walking for long periods where possible, avoid going barefoot or in shoes that offer no support (this is based on expert opinion rather than research studies, with the logic being based on the condition being considered an over-use injury, so resting to allow healing and recovery to take place would be a sensible approach to take)
- Orthoses/insoles – there is some good evidence to support their use and they are recommended on the basis that they benefit foot posture and reduce the strain on the plantar fascia (the jury is still out over which is the most effective type – prefabricated over the counter or customised – but NICE guidelines advise that ‘magnetic’ insoles should be avoided)
- Losing weight – if overweight (to prevent future episodes)
- Stretching – this focuses on specifically stretching the Achilles and plantar fascia (Box 4) but, again, there is a lack of good evidence (although this is a therapy that is perceived by clients as being of the most benefit and is widely advocated by most experts)
How personal trainers can help
The advice is to rest and reduce the loading but, practically speaking, what does that mean and how do you manage it?
Evidence supports that load management is a key component in the rehabilitation process. The Pain Monitoring Model (PMM) shows that monitoring pain levels during rehabilitation makes it possible to continue training, if the pain scores are kept within certain limits, i.e., below 5 on a 0-10 scale.
Both static and dynamic activities will load the plantar fascia; it is often presumed that dynamic activities are more provocative, but is that really the case? Ask the client: when is their condition most painful? What activities set it off? Another option is for you to evaluate this – monitor their training using the PMM and record their response, then use the information to tailor their training.
Additional mechanical-focused therapies
Evidence supports its use in the short term, assisting in off-loading the plantar fascia. It can also be used as a preventive measure, i.e., use when undertaking activities that will place considerable load on the fascia, e.g., running, heavy weight-lifting. Some clinicians trial taping first and, if they get a positive response, will progress to orthoses. Box 3 illustrates how to self-apply.
These have been shown to be effective in the treatment of Achilles tendinopathy; there is a modified version that is effective for plantar fasciitis (Box 4), however, the reader should be mindful that this is a considerable amount of load, so need to consider whether it’s appropriate for their client. This is where the PMM can assist in making a client-centred evaluation. If it’s too much, then consider performing with the upper-body supported, i.e., leaning over a worktop so the loading is reduced, and then evaluate the effect.
Intrinsic foot muscles
These play an integral role in supporting the arches of the foot. Recently, a new theory has been proposed to assist our understanding of intrinsic foot muscle function – the foot core system. The intrinsic foot muscle test evaluates the ability to maintain a neutral foot posture during single leg standing. Box 5 illustrates the test.
Intrinsic foot muscle test
The client’s foot is placed into subtalar joint neutral (palpate either side of the head of the talus, just in front of the ankle until it feels equally prominent on both sides). With the heel and forefoot on the ground, the client lowers their toes to the ground and is asked to maintain this position for 30 seconds. Changes in foot position and over-activity in the extrinsic leg muscles are observed. Early studies suggest this can be used to detect improvements in foot core function. The short foot exercise (Box 6) can isolate the contraction of the intrinsic foot muscles and there is increasing evidence suggesting it can improve foot function. However, this is a prolonged standing exercise (30 seconds in duration), so its impact on the client’s symptoms need to be evaluated. If it aggravates, then a non-weight-bearing alternative should be considered. Over time, the client may be able to progress to the standing exercise. Short foot and non-weight-bearing intrinsic foot exercises Roll the toes over the ball and try and grip the ball, holding for one to two seconds, 15 reps, three times.
If symptoms persist, then it would be wise to refer on for medical advice, where a thorough assessment and diagnosis can be made. Other mechanical therapies include night splints (to stretch the Achilles and plantar fascia) and aircast boot (to off-load and rest the foot). Symptom-focused treatments include: acupuncture (limited evidence); extra corporeal shock wave therapy (safe, with evidence showing short-term benefits; however, the NICE guidelines advise its efficacy is inconsistent); steroid injection (there is evidence to show it is effective in the short term, i.e., one month, but not in the long term, and also there are concerns over repeated use, e.g., risk of rupture); surgery (mixed results and is considered a last option; most surgeons will advocate exhausting conservative measures first).
Plantar fasciitis is a common foot injury, with the majority resolving within 12 months. Most effective treatments can be self-applied, but input and monitoring of load could be of use to the client. If persistent, then refer on for further medical input.
Jai is an enhanced role musculoskeletal podiatrist working for PhysioWorks-Sheffield Teaching Hospitals NHS Foundation Trust. He has 28 years’ clinical experience and has published several papers on plantar fasciitis. As 15-20% of his case load relates to this condition, he’s dealt with a lot of painful heels.