Dear Caitlin,
I write to you a junior trainee sonographer, at the
beginning of my musculoskeltal training. I work
rurally without the support of any sonographers in my
practice and I do not have an on-site radiologist.
I hope you don’t mind, but Anna Graves has passed on
your details because she thought you might be able to
assist me with the basic ultrasound prinicples and
understandings before undertaking a plantar fascia
assessment.
No worries if you cant, but I look forward to your
response.
Thank-you kindly,
Jonathon Chidley
Jonathon Chidley
Dear Jonathon,
Thank-you for your email. I would be happy to assist you in
your studies. Performing an ultrasound examination of the
plantar fascia is a relatively straight-forward examination.
As will all sonographic assessments, the priority is to
understand the anatomy. The plantar fascia is a flattened
tendinous aponeurosis spanning from the calcaneal tubercle,
or posterior postion of the calcaneous and the proximal
phalanges of the toes. The structure is largely composed of
longitudinal collagen fibres into three structural divisions,
the medial, central and lateral component. A continuous
fascial connection exists between the plantar fascia and the
Achilles tendon and the paratendon, which decreases with
age (Stecco et al, 2013 and Arherakis et al, 2015). The plantar
fascia role involves supports the longitudinal arch of the foot,
aiding proprioception and peripheral motor coordination
(Stecco et al, 2013). The following is a diagram to aid your
visual understanding.
To undertake a plantar fascia assessment, position the
pateint prone, either with the foot flexed and toes on the bed
or with the feet hanging off the edge of the bed. Place the
probe over the midline heel with the probe in a longitidinal
position.
It is important to understand normal sonographic
appearances of the plantar fascia. The following image
demonstrates the medial plantar fascia insertion at the
calcaneous of the right foot. The fascia will present as a flat,
homogenous fibrillar structure with no particular
vascualrity generally detectable. Below is an image I have
taken of a normal plantar fascia insertion measuring 32mm
at the widest point. There is no significant bulging, loss of
fibrillar patern, it is homogenous (as apposed to being
heterogenous and hypechoic) and therefore oresents
normally on US. Be certain the assess both the medial and
lateral origin aspects and follow them down in longitudinal
and transverse to assess the structure entirely. Refer to the
diagram above to recall how large the area is you will need
to assess.
With a good understanding of the normal anatomy of the
plantar fascia, you will begin to notice any anamolies.
Plantar fasciitis is an inflammatory condition that affects
up to 10% of the general population during their lifetime,
typically during middle age. Pain typically presents
tenderness on dorsiflexion on the medial heel, usually in the
morning or at the beginning of activity. Risk factors
ineclude biomechanical factors, obesitiy, excess stnadning,
ealking and running in inappropriate footwear. Ultrasound
provides an ideal modality to assess the plantar fascia
demonsrating thickness and heterogenicity in inflammed
fascias (Mohseni-Bandpei et al, 2014). The following image is
an image I have taken over the semester of a thickened
plantar fascia. The fascia measures 7mm and appears
hypoechoic and bulges in comparison to a normal plantar
fascia (refer back to the image above).
Plantar fibromatosis, also known as Ledderhose disease, is a
hyperproloferative disease of the plantar fascia resulting in
nodule formations. Presentation is typically slow growing
palpable nodules which demonstrate pain and swelling after
extended exercise, with a predilation to men. Bilateral
disease exists in 25% of cases. (Veith et al, 2013). The next
image I have included for you is an image I have recently
taken of a patient who presented with a area of focal pain
and tenderess. The clinical area revealed a focal bulging of
the plantar fascia, without any significant increase in
vasculairty.
A recent ultrasound study has shown that 73% of
participants with clinical plantar pain demonstrates plantar
fascitis and 51% demonstrates a plantar fibroma. Keep in
mind that the two pathologies, therefore, are not mutually
exclusive, with 36% of patients demonstrated to have both
plantar fibromatosis with platar fascitis (Argerakis et al,
2015).
Though less common, it is likely you may also encounter
plantar fascia tears or calcaneal spurs in patients presenting
with plantar pain.
You will also need to understand how to assist in a cortisone
injection of the plantar fascia. It will your responsibility to
source the equipment for the radiologist, explain the
proceedure to the patient, gain informed consent and
position the patient appropriately. Position the patient prone
with their feet resting off the edge of the bed. Increase the
height of the bed and move the ultrasound machine closer
towards the patients feet and rotate the screen to allow easy
injection and visualisation of the screen for the radiologist.
Injections are typically composed of 1mL of 4mg/mL
dexamethasone sodium phosphate after an initial 2%
lignocaine (McMillan et al, 2012). You will need to have
2*2mL syringes, a drawing up needle, an injection needle
(length based on the patient’s individual injection depth),
lignocaine, marcaine, cortisone, cholorhexidine, a sterile
dressing pack and sterile gloves readily available. Each
radiologist has a slightly different protocol for injections, but
typically be prepared to sterilise the area with
chlorohexidine as the radiologist prepares the injections. My
radiologists will inject the initial anaesthatic without US
guidance, injection from the posterior heel, with the needle
parallell to the sole of the foot. You will simply need to locate
the needle once it is in place. The aim in to inject the needle
slightly superficial to the plantar fascia origin allowing it to
tract distally. Given the ultrasound beam is typically
perpendicular to the needle, it is usually visualised well but
can be improved with a significant decrease in frequency,
appropriate focus and gain. Here is an annotated image of
an injection I have performed recently.
I hope my correspondance will assist you in you ultrasound
assessments. Please, Jonathon, feel free to contact me with
any concerns. It has been a pleasure to help.
Thank you,
CaitGardiner
Caitlin Gardiner
References
Arherakis NG, Positano RG, Positano CJ et al, 2015. Ultrasound Diagnosis and
Evaluation of Plantar Heel Pain. JAPMA; 105(2): 135-140.
Mohseni-Bandpei MA, Nakhaee M, Mousavi ME, Shakourirad A et al, 2014. Application
of Ultrasound in the Assessment of Plantar Fascia in Patients with Plantar Fasciitis: A
systemic review. Ultrasound in Medicine and Biology; 40(8): 1737-1754.
McMillan AM, Landorf KB, Gilheany et al, 2012. Ultrasound Guided corticosteroid
injection for plantar fasciitis randomised controlled trial. BMJ; 344
Stecco C, Corradin M, Macchi V, Morra A, Porzionato A, Biz C and De Caro R, 2013.
Plantar fascia anatomy and its relationship with Achilles tendon and paratendon.
Journal of Anatomy; 223(6): 665-676.
Veith NT, Tschernig T, Histing T and Madry H, 2013. Plantar Fibromatosis- Topical
Review. FAI; 34(12): 1742-1746.