Friday, 20 July 2012

Plantar Fascia Pain

This is one of the most common clinical presentations when it comes to distance runners. These cases are often long and drawn out, with patients often bouncing from one health care professional to the next.  One of the most vital pieces of information I can give to the patient is that of education on the possible causes, management and treatment. Education allows the patient to become active in the rehabilitation protocol.

Brief Anatomy

The plantar fascia is a thick band of connective tissue with investing layers from the calcaneal (heel) tuberosity to the base of the metatarsals, creating a mobile yet stable soft tissue foundation for the medial and transverse arches of the foot.

The plantar fascia is composed of type 1 collagen  (a thick protein arranged in parallel bundles) with the ability to resist high loads of tensile stress. It is considered a non-contractile tissue responding to the mechanical loads placed upon it. It has poor ability to stretch much beyond 4% of its resting length. The plantar fascia is prone to degenerative changes in response to chronic overuse and increasing with age related changes in the connective tissues.

There are 3 nerves that travel through the various layers of the plantar fascia from the medial (inside) portion of the ankle. The medial calcaneal nerve, the lateral plantar nerve and the medial plantar nerve all arise from the larger tibial nerve. These often play a role in plantar fascia pain with the medial calcaneal nerve often commonly involved as it wraps around the tuberosity. 

Anatomy of the plantar fascia

Function

The plantar fascia maintains the longitudinal and transverse arches of the foot and also serves to dampen pronation. As the foot contacts the ground and continues through to mid stance the plantar fascia lengthens under load almost causing a breaking effect, thus absorbing load. This sets the stage for the foot to then supinate creating a more rigid structure for toe off.

If the plantar fascia undergoes degenerative changes (collagen disarray, neovessel in growth, fibrosis etc) the structure become less mobile and less resistant to tensile load. This creates further overload on already compromised structure.

Onset

Plantar fascia pain usually appears with a gradual onset. Initially there is stiffness (and pain) on arising only to warm up 5 minutes later. The pain gradually progresses to pain on warm up and sometimes warm down. There is often a period of weeks to months where the patient does not seem to regress. Often this is where the running athlete does not present for treatment thinking “it’s not getting worse!”. Despite no notable regression the connective tissue may still degenerate under repetitive loads.

Over time if the athlete continues to run there will be a point where pain is constant through out the run. This is usually the first time a clinician will see the runner often months into the process.

Causes

The causes are likely multifactorial:
  • Increase in volume
  • Increase in intensity
  • Change in training surface
  • Change in footwear (or lack of)
  • Reduced dorsiflexion
  • Excessive pronation
  • Reduced great toe extension

Pronation – a possible causative factor


Prognosis

The prognosis for plantar fascia pain is less reliable than for a straight - forward muscle tear. The quicker the injury is addressed the better the outcome. Plantar fascia pain is similar to a tendinopathy in nature, with degeneration of the connective tissue a classical finding under ultrasound. Depending on the location within the plantar fascia, will depend on the type of tissue you are dealing with. For example, a degenerative enthesopathy (insertion onto the tuberosity of the heel) will involve various connective tissues, possibly fat pad and underlying soft tissues. If the focus is in the body of the plantar fascia it may be a case of the connective tissue composition (type 1 collagen).

If addressed early, clinical evidence would suggest you may be looking at 6-12 weeks recovery.

Chronic ongoing plantar heel pain injuries can be as long as 6 months to 2 years with high re-occurrence rates.

“The Doc says I have heel spurs!”

A basic understanding of the anatomy helps to understand the pathogenesis. As stated, the plantar fascia attaches to the calcaneal (heel) tuberosity. In some cases abnormal mechanics may place an increased demand upon the attachment leading to an increase in bone loading, hence, size of the tuberosity.

There is no evidence to suggest that an increase in bone (the so-called heel spurs) is a causative factor in pain. In fact some asymptomatic patients (no symptoms) have enlarged calcaneal tuberosities. It is therefore important to look to the causative factors and ways of managing plantar fascia heel pain. A ‘spur’ is not a sign of plantar fascia pain. The painful site is usually close to the attachment and may be involved in some cases.

Treatment

Plantar fascia pain presents in a similar fashion to a tendinopathy and as such should be treated as one. There is little evidence to suggest inflammation to be a factor in plantar fascia heel pain. In this case the treatment protocol will be lengthy. Addressing the causative factor(s) is paramount.

Treatment options include:

Soft tissue therapy to focal areas of thickening especially in the posterior lower limb if reduced dorsiflexion is a factor.  Joint mobilisation and local stretching may improve the outcome. Clinically local soft tissue work to mobilise thickened areas within the plantar fascia may be warranted.

Controlling excessive pronation with strengthening of tibialis posterior (inside of calf) and gluteus medius (lateral hip) or with the use of orthoses. Biomechanics during the gait cycle may have an important role to play. Overall reducing load on the plantar fascia. Low dye taping may help in the short term as a means of gaining proprioception and further reducing load

Further soft tissue treatment may help with overloaded structures (areas of increased tone) that alter gait as a compensatory mechanism or as a cause of the injury itself.

Address footwear* (or lack of – think barefoot running) - this is a hot topic at the moment! Whichever way you decide to go, make it a slow transition and be sure to use progressive over load and recovery techniques in your training program.

Consider consequences further up the chain eg; reduced torso rotation can create compensation through increase rotation of the femur, tibia and pronation. The net effect is loading of the plantar fascia. Consider the whole kinetic chain.

Low dye taping may help

What about rolling on a golf ball?

This may work to minimise the symptoms temporarily, however it will do little to help with the driving factors. Very rarely do we find in clinical practice the plantar fascia to be tight. It is important to consider the anatomy and function when considering the goal of any treatment. The plantar fascia is a thick piece of connective tissue with very little stretch – do we really need to try and stretch it?

Is it always plantar fascia involvement?

This discussion has focused on pain in the plantar fascia. There are numerous causes of pain in the plantar surface of the foot, the location will be a key to further possibilities such as:
  • Fat pad contusion (heel)
  • Plantar fascia tear (grade?)
  • Sesamoiditis
  • Morton’s neuroma
  • Stress fracture of the cuboid
  • Stress fracture of the calcaneus
  • Medial calcaneal nerve compression (common)

Summary

Plantar fascia pain is common in runners and often lengthy to treat. By the time the running athlete has presented to healthcare professionals there is usually a long history. Plantar fascia pain is degenerative in nature thus occurring over time. An earlier treatment program will likely give a better prognosis.

·       If you would like to read some great articles on the science for and against bare foot running go to the science of sport website www.sportsscientists.com

For those interested in further reading Clinical Sports Medicine, Brukner and Khan, 2007, have some excellent information and practical tips

For now,
Jimmy

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