The Psoriatic Foot

A positive approach

to psoriasis and

psoriatic arthritis

What are the aims of this leaflet?This leaflet is written to help you understand what canhappen to the feet when affected by psoriasis or psoriaticarthritis.

About psoriasis and psoriaticarthritisPsoriasis (sor-i’ah-sis) is a long-term(chronic) scaling disease of theskin that affects about 2% ofthe UK population. It usuallyappears as red, raised,scaly patches known as plaques. Any part of thes k i n s u r f a c e may b einvolved but the plaquesmost commonly appear on theelbows, knees and scalp. Itcan be itchy but is notusually painful. It is not contagious; you cannot catch itfrom another person.Nail changes, including pitting and ridging, are present

in 40 - 50% of people with psoriasis. 10 - 20% of peoplewith psoriasis will develop psoriatic arthritis. See ourleaflet Nail Psoriasis.There does not seem to be any link between the severity

of the psoriasis affecting the skin and the severity ofpsoriatic arthritis. For more detailed information onpsoriasis and psoriatic arthritis see our leaflets What isPsoriasis? and What is Psoriatic Arthritis?

About the footThe feet are an important part of the human anatomy;each foot has 26 bones, 33 joints and is controlled bymuscles, tendons, and ligaments. The skin on the sole ofthe foot is different to that on the rest of the body, with aparticularly large number of sweat pores.

Plaque psoriasis

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To cope with the weight that is continually placed onthem, the soles of the feet have the thickest layers of skinon the human body. They are, however, very sensitive andact as sensors when walking or standing. Therefore,anything that interferes or affects the feet can have aprofound impact on function and general wellbeing.

Psoriasis on the footMost commonly, psoriasis on the foot looks similar toplaque psoriasis in other locations on the body and iscalled palmoplantar psoriasis. Often the plaques are thickand scaly, which can be painful and bleed if cracksappear. It is important to distinguish psoriasis from otherconditions that affect the foot. Apart from plaque, there are other types of psoriasis

which affect the foot and have a different appearance.Localised pustular psoriasis – also known as

palmoplantar pustular psoriasis (PPP) – affects about5% of people with psoriasis. It occurs most commonlybetween the ages of 20 and 60. It can be painful and ismore common in women than men. About 10-25% ofpeople with PPP have a family history of psoriasis but theprecise reason why some people develop it is not known.PPP causes pustules on the palms and soles. As in all

types of psoriasis, infection and stress are suspectedtrigger factors. PPP is normally recognisable by yellow/white pustules approximately 2-3mm in diameter, appearingon fleshy areas of hands and feet,such as the base of the thumband the sides of the heels. These pustu les are

sterile, which means theya re no t t h e re su l t o finfection. Antibiotics donot affect them. After atime, the pustules dry up andresolve, leaving brown stains onthe skin surface. The natural Pustular psoriasis

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history of the disease is usually cyclical (occurring oftenor repeatedly), with the appearance of new crops ofpustules followed by periods of low activity in which thepustules resolve. See our leaflet Pustular Psoriasis.

Acrodermatitis continua of Hallopeau is a very rareform of localised pustular psoriasis. This looks similar topalmoplantar pustular psoriasis, but is localised to theends of the fingers and, less commonly still, the toes(acropustulosis). It usually starts after some trauma to theskin. It tends to be painful and frequently affects the nails.It may lead to loss of the nails. Bone changes can be seenin severe cases. It is difficult to treat and many therapieshave been tried. Topical treatments are usually not verysuccessful but occasionally systemic medications mayhelp to clear the lesions and restore the nails.

Nail involvement Given they are part of the skin, it is perhaps not surprisingthat nails can be affected by a skin disease such aspsoriasis. Nail psoriasis is very common, yet no oneknows why some people get nail involvement and othersdo not. Nails grow from the nail plate, which is just underthe cuticle. In people who develop psoriasis of the nails,it is involvement of the nail plate that causes pitting,ridging, thickening, lifting and discolouration of the naildue to abnormalities in the growth of tissue in the nail bed.The nail is made of modified skin and, once it has

grown, it can only be altered by filing orclipping. Treatments are usuallydirected at the nail bed or thenail folds that tuck aroundt h e e d g e s . Tr e a t e dinflammation in thesetissues can result in betternail growth with fewerfeatures of psoriasis, buttreatment of nail psoriasis canbe difficult. Nail psoriasis

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Triggers of psoriasisIt is not fully understood what causes psoriasis, but it isan inherited inflammatory disease. It can be triggered byevents, illness or injury to the skin. A particular processknown as Koebner’s phenomenon or Koebnerisation isnamed after the German dermatologist Heinrich Koebner.Koebner found that people with psoriasis whose skinbecame traumatised following an injury, often developeda psoriatic lesion in the area, but where psoriasis had notpreviously been seen; such sites include cuts, bruises,burns, bumps, vaccinations, tattoos and other skinconditions.

DiagnosisIf you think you may have psoriasis on your foot or feet, itis best to get a diagnosis. Visiting your GP or asking yourpharmacist is a good place to start. Alternatively, you maywish to see a local chiropodist (sometimes known as apodiatrist), particularly if your nails have becomethickened and difficult to manage.Psoriasis on a foot or both feet may be diagnosed by

simple examination, but if there is any doubt then referralto a specialist (dermatologist) may be required. It isunlikely that any specific test will be performed unlessthere is a suspicion of a fungal infection, when somesamples may be taken for laboratory analysis.

TreatmentsFor plaque psoriasis on the foot, treatment will generallybe similar to those recommended for other areas of thebody, with the use of topical (applied to the skin) creams,ointment and gels. See our leaflet Treatments forPsoriasis: An overview.The use of phototherapy (ultraviolet light) may be

considered, but availability and access to appropriatecentres can sometimes be limited. It may be possible totreat psoriasis affecting the hands and feet

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with localised phototherapy. See our leaf letPsoriasis and Phototherapy.Palmoplantar pustular psoriasis is often difficult to treat,

although some people do benefit from potent topicalsteroids combined with tar preparations. However, inmost cases treatment with acitretin (a vitamin A derivative)tablets is the most effective.Treating nails can be problematic, as once the nail

changes appear the damage has already occurred. It isimportant to check that other conditions that affect thenail, such as fungal infection, are not present, as thesecan often look similar to nail psoriasis. It is advisable tokeep nails short and clean. See our leaflet Nail Psoriasis.

Psoriatic arthritis in the foot The ankle is a hinge joint between the talus bone of thefoot and the two bones of the lower leg, the tibia andfibula. The ankle joint lets you move your foot up anddown. Other movements, such as tilting and rotation,occur at other joints in the foot itself. Each foot contains26 bones which form joints where they meet. These jointsare all lined with a synovial membrane that produces alubricating oil. Many tendons pass around the ankle toconnect the bones with the muscles that move them.These are also covered in synovial membrane and oiledwith synovial fluid. In psoriatic arthritis, any part of the footcan be affected and become inflamed and painful, whichin turn may lead to permanent disability.

What happens?The synovial membranes that line joints, tendons andconnective tissue become thickened and inflamed(tendonitis and enthesitis). This releases more fluid thannormal so the joints and tendons become tender andswollen, which may result in:

� pain

� tenderness

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� swelling

� stiffness

� difficulty walking

� deformity (such as sausage-shaped toes)

� decreased range of movement

� locked joints

� joints feeling hot.

The pattern of joints that may be involved can vary fromperson to person, and may just affect a small number ofjoints (oligoarthritis) or many joints (polyarthritis). Mostcommonly, psoriatic arthritis is asymmetric in pattern (notidentical on both sides) unlike rheumatoid arthritis, whichis symmetrical.In terms of symptoms, psoriatic arthritis can cause

stiffness in the joints, particularly after a period ofinactivity such as after waking up in the morning. Psoriaticarthritis can also cause swelling of an individual toe so itlooks like a sausage, called dactylitis. Some people alsoexperience heel pain because the Achilles tendon, which

Bones of the foot

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connects the calf muscles to theheel bone, has becomeinflamed. Swelling aroundthe ankle is common inpsoriatic arthritis affectingthe foot. Psoriatic arthritis can lead

to shortening or clawing ofthe toes, hyperextension of thebig toe and some in-rollingof the ankle with flattening ofthe metatarsal arch. Stiffness of the joints, rather thaninstability, also happens quickly and can becomeirreversible within a few months. The occurrence ofcalluses and ulcers on the soles of the foot is lesscommon than in rheumatoid arthritis (RA) but corns overthe interphalangeal joints can be very painful.Symptoms tend to flare up and then die down again. If

the inflammation is persistent andleft untreated, toe joints canfuse together, with the spacebetween the individualjoints being lost.You should always seek

medical adv ice i f youexper ience st i ffness inyour jo ints especially afterinactivity, severe pain, rednessor swelling in one or both feet, whetherthis is mild or severe. It is essential to minimise theinflammation to avoid permanent joint deformity.

Causes and triggersAs with skin psoriasis, the cause of psoriatic arthritis isunknown, with an event or illness often considered atrigger. There is also a theory (hypothesis) of a ‘deepKoebner phenomenon’ which might initiate psoriaticarthritis, although this is yet to be proven.

Dactylitis

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Getting a diagnosis of psoriaticarthritisThe presence of psoriasis may provide an indication ofpsoriatic arthritis when someone develops jointsymptoms. Psoriatic arthritis can develop in people witha lot or a little of psoriasis, and may be more common inpeople with nail psoriasis. As well as joint symptoms,psoriatic arthritis can lead to feeling tired. Many peoplebecome frustrated by a lack of diagnosis; psoriaticarthritis tends to have periods of improvement andworsening, which may also be attributed to mechanicaljoint problems and not inflammatory arthritis. If you have the symptoms of inflammatory arthritis, such

as psoriatic arthritis, your doctor will often refer you to arheumatologist. In some cases, further tests (blood) andimagery (X-ray, ultrasound, MRI) may be sought, althoughthis will depend on the individual circumstances and levelof confidence in the initial diagnosis.

TreatmentIn most instances, specific treatment to the foot isnecessary to some degree. Treating psoriatic arthritis inthe foot will include many of the therapies used inmanaging arthritis elsewhere. The aim of therapy is toreduce inflammation, pain and avoid permanent disability. Initial treatment is likely to include analgesia (pain relief),

often the anti-inflammatory painkillers recommendedsuch as ibuprofen, are those that can be supplied overthe counter (OTC). To treat the inflammation and swellinga prescription-only medicine (POM) may be required andwould only be available from your doctor. Treatments mayinclude corticosteroid injections to the worst involvedareas (painful, but effective for up to 6 months), oral(tablet) corticosteroids, anti-inflammatory gels anddisease-modifying drugs such as methotrexate.Sometimes, in large joints, a procedure calledarthrocentesis is carried out. This involves drawing out

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(aspirating) the fluid for investigation for infection and thediagnosis of inflammatory conditions. The treatmentslisted above may only be prescribed if you have seen arheumatologist. See our leaflet Treatments for PsoriaticArthritis: An overview.

Surgery and the psoriatic footOrthopaedic surgery to correct deformed joints is onlyjustified in the presence of long-standing deformity wherepain is preventing adequate mobility and all alternativemedical treatments have failed. The advancement ofnewer techniques in recent years has seen better resultsin small joint replacement, but such procedures still needcareful consideration and discussion with advice from anappropriate surgeon.

PhysiotherapyIt is always advisable to rest severely inflamed joints, butphysiotherapy and exercise can help to maintain mobilityof your joints so they are less likely to become stiff andseize up. See our leaflet Physiotherapy and Exercise:Psoriatic Arthritis.

How successful are the treatments?Anti-inflammatory drugs can help to reduce pain, swellingand stiffness. Unfortunately, however, they can make skinsymptoms worse in some people. Steroid injections tojoints may give relief. Disease-modifying drugs such asmethotrexate can damp down both skin and jointsymptoms, as can targeted biologic agents. In some cases, surgery to remove a thickened synovial

membrane (synovectomy), realign a joint (osteotomy) orto fuse a joint (arthrodesis) may stop pain which resultsfrom movement. Sometimes it is possible to remove the painful end of a

bone (excision arthroplasty).

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Remember: All treatments may have unwanted sideeffects or require special precautions (eg duringpregnancy). Always make sure you have all theinformation before embarking on any course of therapy;this includes reading the patient information leaflets (PILs)provided with your medicines.

Other common conditionsIf you develop problems with your foot, such as sores,rashes, nail deformities or painful swollen joints, doremember that they may not be caused by psoriasis orpsoriatic arthritis.

Some common skin conditions that affect the feet

include:

� athlete’s foot (tinea pedis) - caused by fungalinfections

� plantar warts (verruccas) - generally appear onthe soles of the foot with a callus appearancebut are caused by the human papollomavirus(HPV)

� calluses - often the result of an ill-fitting shoethat rubs, causing the skin to harden

� corns - similar to calluses, but often found onthe top of a toe

� pitted keratolysis - usually on the soles andcaused by bacteria

� dyshidrotic eczema (dyshidrotic dermatitis) - anitchy rash, the cause of which is unknown, butwhich worsens in warm weather

� ingrown toenails - due to poor nail care, wherethe nail is cut too short and grows into the skin,causing pain and swelling

� diabetic ulcers - due to decreased blood flowand poor circulation in someone with diabetes.

Some common joint conditions that affect the feet

include:

� gout - where crystals of uric acid are depositedin the joints, tendons and skin

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� bunions - swellings and tenderness when thejoints in your big toe no longer fit together asthey should, often caused by ill-fitting shoes

� heel spurs (plantar fasciitis or fasciosis) -inflammation at the site where the fasciaattaches under the heel

� heel burs i t is (subcalcaneal burs i t is ) -inflammation of the fluid-filled sac (bursa)located between the skin of the back of the heeland the Achilles tendon

� Achilles tendinosis - the Achilles tendon isplaced under more pressure than it can copewith and small tears develop, along withinflammation and, in some cases, leading totendon rupture

� chronic inflammation of the heel pad - causedby a heavy heel strike giving rise to a dull achein the heel, which increases during the day.

What can I do to help my feet?The most important action is to seek advice and helpwhen you notice any changes in your foot, whatever theymay be. You can talk to your GP or local pharmacist foradvice. Some problems can be resolved simply. Forissues that are more persistent you may be referred to aspecialist, such as a dermatologist, rheumatologist,physiotherapist, surgeon or chiropodist/podiatrist.For general foot care, personal hygiene is important,

particularly in avoiding fungal and viral infections. Changeshoes and socks regularly, avoid shoes which are ill-fittingor cause bad posture. If you are overweight, losing weightcould relieve the pressure on your joints and improve yourwalking gait.If you are diagnosed with psoriasis, develop a treatment

regime that works for you; often, applying treatment aftera bath or shower, along with the use of an emollient, canmake the process easier. If you have nail involvement, keep nails trimmed and

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clean. If they are thick, try trimming them after soakingthem in a bath or shower, as this makes them softer andeasier to cut. Alternatively, seek an appointment with achiropodist, which is often available via the NHS.If you have psoriatic arthritis, it is important to rest

inflamed joints. Sourcing footwear that supports the footand helps to reduce the pressure on the inflamed areascan help, as can inner soles and orthotic supports. Onceagain, a chiropodist is best placed to advise you.

Useful contacts:For information about health matters in general and howto access services in the UK, the following websitesprovide national and local information.

� NHS Choices (England): www.nhs.uk

� NHS 24 (Scotland): www.nhs24.com

� Health in Wales: www.wales.nhs.uk

� HSCNI Services (Northern Ireland):

http://online.hscni.netThese sites are the official sites for the National Health

Service and provide links and signposting services torecognised organisations and charities.

References:

http://www.nhs.uk/Livewell/foothealth/Pages/Footproblems-podiatrist.aspx - accessed 20/1/16

Gelfand JM, Weinstein R, Porter SB, Neimann AL, BerlinJA, Margolis DJ. Prevalence and treatment of psoriasis inthe United Kingdom: a population-based study. ArchDermatol 2005;141:1537-41.

Cohen MR, Reda DJ, Clegg DO. Baseline relationshipsbetween psoriasis and psoriatic arthritis: analysis of 221patients with active psoriatic arthritis. Department ofVeterans Affairs cooperative study group on seronegativespondyloarthropathies. J Rheumatol 1999;26:1752-6.

Alamanos Y, Voulgari PV, Drosos AA. Incidence andprevalence of psoriatic arthritis: a systematic review.

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J Rheumatol 2008;35:1354-8. 10 Ibrahim G, Waxman R,Helliwell PS. The prevalence of psoriatic arthritis in peoplewith psoriasis. Arthritis Rheum 2009;61:1373-8.

Krueger JG, Bowcock A. Psoriasis pathophysiology:current concepts of pathogenesis. Ann Rheum Dis2005;64 Suppl 2:ii30-6.

Gladman DD, Shuckett R, Russell ML, Thorne JC,Schachter RK. Psoriatic arthritis (PsA) - an analysis of 220patients. Q J Med 1987;62:127-41.

Gladman DD, Antoni C, Mease P, Clegg DO, Nash P.Psoriatic arthritis: epidemiology, clinical features, course,and outcome. Ann Rheum Dis 2005;64 Suppl 2:ii14-7.

Stoll ML, Punaro M. Psoriatic juvenile idiopathic arthritis:a tale of two subgroups. Curr Opin Rheumatol

Alamino RP, Maldonado Cocco JA, Citera G, et al.Differential features between primary ankylosingspondylitis and spondylitis associated with psoriasis andinflammatory bowel disease. J Rheumatol

McHugh NJ, Balachrishnan C, Jones SM. Progression ofperipheral joint disease in psoriatic arthritis: a 5-yrprospective study. Rheumatology (Oxford) 2003;42:778-83.

Ritchlin CT, Kavanaugh A, Gladman DD, et al. Treatmentrecommendations for psoriatic arthritis. Ann Rheum Dis2009;68:1387-94.

Gelfand JM, Gladman DD, Mease PJ, et al. Epidemiologyof psoriatic arthritis in the population of the United States.J Am Acad Dermatol 2005;53:573.

About this informationThis material was produced by PAPAA. Please be awarethat research and development of treatments is ongoing. For the latest information or any amendments to this

material, please contact us or visit our website. The sitecontains information on treatments and includes patientexperiences and case histories.

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The Information Standard scheme was developed by theDepartment of Health to help the public identify trustworthyhealth and social care information easily. At the heart of thescheme is the standard itself – a set of criteria that definesgood quality health or social care information and the methodsneeded to produce it. To achieve the standard, organisationshave to show that their processes and systems produceinformation that is:

� accurate � evidence-based

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� balanced � well-written.

The assessment of information producers is provided byindependent certification bodies accredited by The UnitedKingdom Accreditation Service (UKAS).Organisations that meet TheStandard can place the quality markon their information materials andtheir website - a reliable symbol of

Original text written by PAPAA January 2016.

Reviewed and revised by Dr Ruth Murphy, consultantadult and paediatric dermatology consultant, SheffieldTeaching Hospitals NHS Foundation Trust, Dr EstherBurden-Teh, dermatology registrar and clinical researchfellow, The Centre of Evidence Based Dermatology,University of Nottingham and Dr Satyapal Rangaraj,consultant paediatric and adolescent rheumatologist,Nottingham University Hospitals NHS Trust in April 2016.Following a review in April 2019 minor changes have beenmade by PAPAA.

A lay and peer review panel has provided key feedbackon this leaflet. The panel includes people with or affectedby psoriasis and/or psoriatic arthritis.

Published: April 2019

Review date: November 2021

The charity for peoplewith psoriasis and psoriatic arthritis

PAPAA, the single identity of the Psoriatic Arthropathy Alliance and the

Psoriasis Support Trust.

The organisation is independently funded and is aprincipal source of information and educationalmaterial for people with psoriasis and psoriatic

arthritis in the UK.

PAPAA supports both patients and professionals byproviding material that can be trusted (evidence-

based), which has been approved and contains nobias or agendas.

PAPAA provides positive advice that enablespeople to be involved, as they move through their healthcare journey, in an informed way which is appropriate for their needs and any

changing circumstances.

Psoriasis and Psoriatic Arthritis Alliance is a company limited by guarantee

registered in England and Wales No. 6074887

Registered Charity No. 1118192

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Tel: 01923 672837Fax: 01923 682606

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PF/04/19

ISBN 978 1 906143 32 9