Plantar heel pain is a common presentation to the healthcare practitioner dealing with musculoskeletal pain. Distance runners incur a high incidence of lower limb injuries. Falling into this category is plantar heel pain. A lengthy discussion has already been put forward in a recent blog, however it is important to consider other causative factors involved with the onset and treatment of plantar heel pain. This article will consider the tibial nerve (it’s branches) as a source of pain in the heel often mimicking plantar fascia-itis (fascia-oses)
The Tibial nerve actually makes a portion of the infamous sciatic nerve in the posterior thigh (along with the common peroneal nerve). It becomes superficial in the posterior knee before going deep as it descends to supply most of the calf musculature. The nerve then becomes superficial again, medial to the ankle before branching as it exits the tarsal tunnel*
The nerve we are most concerned with clinically is the medial calcaneal branch in close proximity to the attachment of the plantar fascia on the inside of the calcaneus (heel). If compressed, tensioned or irritated it can be a source of pain presenting as plantar fascia-itis.
Due to it’s proximity to the calcaneus it is often considered that the attachment point for the plantar fascia, (what runners might discuss as ‘heel spurs’) is the culprit. Clinically, the medial calcaneal nerve can be seen to be playing a role as the source of pain.
Fig 1. Location of medial calcaneal nerve
So how do we differentiate between nerve involvement and the plantar fascia?
Assessment in conjunction with symptoms should guide the thought process. On assessment you will usually find reproduction of pain/symptoms, the same location or a difference from one side to the other. Symptoms may include pain at the plantar fascia attachment (calcaneus), pain extending across to the lateral side of the heel, pain in the medial ankle (tarsal tunnel). Taking the nerves through their range of motion and performing a tensioning type movement will usually elicit a response that is close to ‘their pain’. Pain reproduction is a clinical pearl when it comes to musculoskeletal assessment.
Further, there is less involvement with the connective tissue as a source of pain often resulting in less morning stiffness than would be expected if plantar fascia were directly involved. There may also be neural symptoms further up the chain behind the knee and into the glutes, eluding to neural pathology. This kind of pathology may also warm up during the course of a session
What might be occurring?
Nervous tissue likes to move and slide within the surrounding tissues (known as the mechanical interface). When nerves become compressed or ‘tensioned’ they generally receive a decreased blood flow and/or become inflamed causing pain.
Altered biomechanics, old injuries (scar tissue) and areas of increased muscle tone are common culprits. Treatment needs to focus on factors ‘driving’ the neural irritation (causative factors) whilst helping to calm the down the nervous system.
Posture as a Factor
Posture is commonly talked about but often not addressed. Efficient running posture is essential in allowing the nervous system to transmit impulses and slide within the adjacent tissues. For example if a distance runner has a seated work place job usually placing increased ‘tension’ on the nervous system as they slump down and then assumes a similar (kyphotic) position whilst running an enormous load will be placed on the nervous system.
Efficient running posture is less costly from an injury point of view. Because the nervous system is continuous, the site of pain may not always be the focus of treatment. If we go back to our seated runner we can consider limited mobility (kyphotic) through the thoracic spine to place increased tension and demands on the lower limbs an. therefore the medial calcaneal nerve!
Fig 3. mobilising the tibial and sciatic tract may give rise to increased medial calcaneal mobility. Angling the foot towards the outside will further stretch the target area
Further to this a tight nervous system will play a significant role especially in activities that are repetitive in nature!
Treatment needs to address the nervous system as a whole - this may include;
- Running posture
- Seated postural options (for those in a poor seated position)
- Neural tightness
- Pronation (rate and amount)
- Pelvic stability (as a factor in foot control)
- Programming factors – recovery, volume, intensity
Fig 2. Kyphosis of the thoracic spine from seated to running posture places a large stress (tension) on the thoracic spine
Do nerve conduction studies play a role?
In subclinical states and acute nerve pathologies, nerve conduction studies are generally not indicated (or useful) as they do not detect nervous system dysfunction at this level. They may be useful for failure of a nerve to activate or chronic pathologies where encroachment of a nerve will lead to total dysfunction of an area.
In chronic cases, where previous soft tissue injury around the ankle/foot has been a problem this may be a valuable adjunct. Ultrasound is able to detect if neural tissue is compressing on certain neural structures, in this case the medial calcaneal nerve. As previously discussed nerves like to slide and move through the adjacent tissue
· The tarsal tunnel is a tunnel formed by the underlying bone (calcaneus) and the retinaculum (connective tissue). Structure’s traversing through this area are vulnerable to compression and reduced mobility
For a full list of neural mobilisation visit the NOI website www.NOI.com
There are also numerous sites on Youtube and social media devoted to this (sift through the not so good sites!!)
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