Introduction

People with inflammatory arthritis, including lupus, commonly report foot complaints that include pain, impairment and disability. Foot problems in lupus can involve any of the tissue structures in the foot/ankle. These may include, but are not limited to, joint pain and swelling, skin lesions causing additional pain, tenderness and vascular and/or neurological manifestations in the lower limbs. Foot deformities may not be regularly reported since they may be hidden by footwear. Moreover, foot complaints cannot always be attributed to lupus since they are also widespread in the general population. That said, there is a higher prevalence of foot complaints in the elderly population, which does not reflect the usual age range of the population with lupus. Significant joint deformity is rarely attributed directly to the disease processes seen in lupus. ] However, there are certain conditions seen within subgroups of lupus where synovitis, deformity and subluxation are common, for example, when associated with Jaccoud’s arthropathy. Importantly, foot problems in lupus may be compounded by systemic comorbidities. Pharmacological interventions including long-term corticosteroid therapy,disease modifying medication and, increasingly, biologic therapy, further increase the risk of infection and peripheral ulceration and so people with lupus warrant ‘high risk’ podiatry care.

The range of foot complaints seen in lupus

As indicated previously in this book, lupus is a chronic, heterogeneous disorder with a relapsing and remitting course and foot complaints should be seen in this context. The prevalence of foot complaints in lupus is high, with over three-quarters of those with this condition reporting having experienced pain in their feet during the course of their disease both in the forefoot and, more commonly, in the hindfoot. This pain is generally thought to be multi factorial in origin with contributions from both articular and soft tissue musculoskeletal disorders. Foot pain in lupus can be further complicated by dermatological complications of the condition as well as neurological and circulatory problems such as secondary Raynaud’s phenomenon. Additionally, there is a higher incidence of vasculitis with possibly serious consequences such as ulceration and digital gangrene.

Musculoskeletal foot problems in lupus

Some two-thirds of lupus patients complain of having arthritis in their feet. Additionally, tenosynovitis and tendonitis often coexist, leading to widespread foot and ankle pain, causing considerable disability. Imaging studies have found considerable inflammatory foot joint abnormalities (a greater proportion than hand involvement) and these pathologies include joint effusion, synovial hypertrophy and neoangiogenesis. The ankle and metatarsophalangeal joints appear most commonly affected, which is particularly significant as these joints are key to a smooth progressive gait. Those with lupus report overall reduced function in the feet which, in turn, leads to a reduced ability to undertake normal activities of daily living in a pain free manner. Interestingly, it is suggested that those measures of disease activity frequently used in lupus may not be sufficiently sensitive to identify these issues. Moreover, there is a tendency for non-disclosure of foot problems, particularly if foot examination does not form part of the routine medical examination. Consequently, there is a need for appropriate referral pathways as recommended by groups such as the Arthritis and Musculoskeletal Health Alliance (ARMA).

Dermatological complaints in the feet and lower limbs

In general, dermatological complaints are second only to musculoskeletal-based pain in those with lupus. In the foot/leg the photosensitive discoid rash typically associated with lupus is less frequently seen, perhaps because these areas are more easily covered up. However, a range of dermatological problems commonly arise in the feet. Corns and calluses are the most frequently reported skin problems, affecting almost three quarters of those with lupus. While frequently seen in older individuals within the general population, these lesions appear to present earlier in people with lupus. This increased prevalence is most likely to be caused by a combination of mechanical stresses where abnormal loading due to foot dysfunction causes lesions. However, joint subluxations and toe deformities may also lead to lesions from footwear. While comparatively few people with lupus report foot ulceration, this is a particular concern given the added complications of vascular disease and/or neurological damage placing foot health at particular risk - especially when coupled with immunosuppressive medication.

Immunosuppressive treatment may also hasten skin infections such as fungal infections of both skin and nails and viral infections such as verrucae. Particular care should be taken when managing these lesions as medication combinations may limit the treatment options available and clinicians should be mindful of the increased infection risk and potential for longer healing time associated with some immunosuppressive medications.

Circulatory health in the lower limb

People with lupus are reported to be at greater risk of presenting with complications due to vascular pathology secondary to accelerated atherosclerosis; which may not always be related to traditional risk factors. Research has found peripheral vascular disease (PVD) to be widespread among those with lupus. In the lower limb especially, low ankle brachial pressure indices (a key indicator of PVD) have been reported in the literature as have vasospastic disease such as Raynaud’s phenomenon. Of greater concern are critical ischaemia, foot ulceration and digital gangrene all of which have been reported in retrospective studies. These more serious vascular pathologies may require pharmacological or surgical intervention to prevent progression to gangrene. People with lupus frequently complain of a range of circulatory related complaints including cold feet, chilblains, Raynaud’s phenomenon and pain emanating from intermittent claudication and reinforce the need for appropriate vascular assessment by clinicians and the need for management of cardiovascular co-morbidity.

Nerve function of the foot and lower limb

Neurological deficit has been reported in lupus with both sensorimotor polyneuropathy and axonal degeneration known to affect the lower limbs. Additionally, abnormal nerve conduction studies are reported in people with lupus and, notably, clinical signs of neuropathy are also recorded. While sensory neuropathy affecting the foot is well recognised as a complication in diabetes, it may be less frequently associated with inflammatory arthritis. This highlights the need to include neurological assessment of patients presenting with foot and leg pathology. People with lupus complain of neurological symptoms less frequently than musculoskeletal, dermatological or vascular manifestations. Nevertheless, numbness and loss of balance are reported, which may alert the clinician to an increased risk of falls. There is also a possibility that neurological deficit such as small fibre neuropathy may lead to altered gait patterns and consequently have a further negative impact on musculoskeletal foot impairments, particularly where there are changes in foot shape that may increase the risk of rubbing on footwear.

Management of the foot in lupus

The assessment and management of foot complaints in lupus have received relatively little attention in the literature and the limited evidence base means that a more pragmatic approach to management is required. As with all patients with high risk feet, the potential for foot ulceration is increased by impaired circulation, neurological deficit and co-existing foot deformities. Problems with shoe fitting and increased pressure on the feet due to musculoskeletal dysfunction exacerbates these risks and regular assessment of the feet is essential. This assessment should capture not only the musculoskeletal pathology but also vascular, neurological and dermatological manifestations with due regard for the wider disease management where patients may be taking a range of medications some with powerful immunosuppressive action. Recognising these features and understanding their impact is key to developing a management strategy. Overall, the key aims in the treatment of the feet of any high-risk patient are to prevent serious complications (such as ulceration), reduce pain and increase mobility, particularly where activities of daily living are limited by foot pain. Interventions may include conservative podiatry care such as the reduction of corns and calluses with padding or trapping to off-load mechanical stress on the affected area. Subsequent prescription of foot orthoses and/or footwear to aid with biomechanical control is important to reduce symptoms. Equally, advice to patients about daily foot hygiene, foot inspection and footwear are important. Appropriate footwear choices are essential and can be challenging given the combination of increased foot pain and the demographic profile of the population with lupus, where seemingly unattractive footwear can have a profoundly negative psychosocial impact. People with lupus often have a range of unanswered questions about foot health, which is to be expected given the range of symptoms commonly reported. While limited evidence currently exists to quantify the effectiveness of these interventions in lupus, people with the disease report a need for professional foot care and, regrettably, barriers to accessing such care. Service provision for people with rheumatic disease is known to be problematic despite a range of guidelines about the importance of foot health. It is recommended that those managing patients with lupus should recognise the need for specialist foot care, as serious problems can be avoided by appropriate referral, early examination, preventative treatment and education about foot health.