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Foot problems in older people

Paul Dearden, Andrew Wines
OPEN ACCESS

Investigation

The diagnosis of hallux valgus is clinical, but imaging can be useful to rule out arthritic processes of the neighbouring joints. Routine weight-bearing anteroposterior and lateral x-rays are all that is required to plan surgical treatment (Figure 4). Concerns about peripheral circulation and sensation should be addressed as for lesser toe deformities (see above).

Management

Initial management of hallux valgus by the GP should involve advice about footwear that accommodates the patient’s deformity. If no suitable shoe can be purchased over the counter then referral to an orthotist may be helpful. The addition of bunion pads, splints and other commercial products may help in relieving symptoms. Simple orthotics that support the medial arch and offload the metatarsals may be considered, but custom orthotics have limited value.

Surgical management should be considered if nonoperative treatment has failed to resolve symptoms or if skin breakdown over bony prominences is imminent. All surgical treatments require the metatarsal and possibly the phalanx of the great toe to be cut and repositioned. There is no role for bunionectomy in the treatment of hallux valgus. Patients can generally bear weight postoperatively in a stiff-soled sandal, which must be worn for six weeks after surgery. In older patients, mobility may be compromised in the immediate postoperative period, and attention should be paid to the patient’s home and support environment before specialist referral.

Fat pad atrophy

With ageing, loss of the normal cushioning effect provided by the plantar fat pad is a common cause of foot pain. Although this occurs often in older people, it has multifactorial causes, including diabetes, rheumatoid arthritis, peripheral vascular disease, trauma and chronic corticosteroid use. The loss of this protective adipose tissue and the surrounding collagen septae can expose the underlying delicate neurovascular structures to excess load and shear forces. In the compromised neuropathic foot often seen in people with diabetes, these excess forces can lead to break down of skin and ulceration exposing bony prominences.

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Investigation

The diagnosis of fat pad atrophy is essentially clinical. Thinning of the plantar fat pads allows the underlying bony structures to be more easily palpated during clinical examination. Fat pad atrophy can be distinguished from plantar fasciitis causing heel pain as the symptoms of fat pad atrophy are often bilateral with central heel pain. In contrast, plantar fasciitis typically causes medial heel pain in one foot. As with most foot pathologies, simple weight-bearing anteroposterior and lateral x-rays are useful and may help to rule out other causes for the patient’s foot pain.

Management

Offloading and cushioning of the affected area should be the mainstay of management. This is done with a variety of pads, orthotic inserts and shoe modifications, which can be obtained from a podiatrist. If imminent ulceration is a concern then the patient should be referred to an orthopaedic surgeon for assessment. Osteotomies or resection of prominent underlying bone are sometimes required.

Morton’s neuroma

Patients with Morton’s neuroma most often complain of a burning sensation in the forefoot and sometimes an associated clicking or catching sensation. The pathogenesis of the condition is poorly understood. The common digital nerve can be entrapped without inflammation in either the third–fourth or second–third web spaces secondary to several potential causes. Discomfort is often poorly localised by the patient, but pain may radiate to corresponding toes and there may be associated altered sensation or numbness. The pain is worsened by wearing enclosed or ill-fitting shoes and is reduced when walking bare foot.

Examination

Examination may reveal a slight fullness over the affected area. Gentle palpation of the affected web space often reproduces the patient’s pain. Mulder’s sign may be positive, with a painful click elicited by compression of the foot with one hand and simultaneous upward thumb pressure under the affected web space (Figure 5).This is caused by subluxation of the neuroma beneath the transverse metatarsal ligament.

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Imaging

The diagnosis of Morton’s neuroma is based on the patient’s history and physical findings. Plain weight-bearing x-rays are again helpful to assess the foot in general and to identify any underlying bone or joint disease that may be causing symptoms or may coexist. Ultrasound examination may be helpful in some situations but is often operator dependent and has too high a rate of false positive and false negative results to be relied on for diagnosis.MRI may be useful in some patients to rule out other pathologies but is not warranted for establishing the diagnosis of Morton’s neuroma. There is no need for electrodiagnostic studies unless peripheral neuropathy or radiculopathy is suspected because of atypical symptoms. These include bilateral generalised numbness, numbness in the sole of the foot or neuritic pain radiating from the back or buttock down the leg to the foot.

Management

Initial management of Morton’s neuroma should be conservative and directed toward the use of accommodative footwear that does not cause compression across the forefoot. A metatarsal bar or Morton’s domed insert can be requested from the orthotist, which relieves pressure on the affected common digital nerve. Ultrasound- guided corticosteroid injections to the affected web space can be beneficial. There is good evidence supporting their benefit for short-term relief but they are unlikely to cure the patient’s symptoms in the long term.8 Ultimately, surgical excision is likely to be the solution if symptom relief cannot be achieved with nonoperative treatment. Patients should be made aware that the procedure will cause an area of numbness in the affected toes that is likely to be permanent but will likely resolve the pain.

Toe nail abnormalities

Toe nail disorders are among the most prevalent causes of foot pain in older people.9 Ingrowing toe nails (onychocryptosis), hypertrophy of the nail plate (onychauxis or onychogryphosis) and fungal nail disorders (onychomycosis) are the most common of these disorders.

Examination

The patient’s description of the nail is often enough to identify the pathology. A nail in which the side of the nail plate extends farther into the nail groove causing pain or inflammation is consistent with an ingrowing nail. A thickened nail plate or one that is thickened and has a hooked appearance is likely to represent onychauxis or onychogryphosis, respectively. A thickened nail plate with a dusty yellow or brown discolouration is likely due to fungal nail infection.

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Dr Dearden is a Postgraduate Orthopaedic Foot and Ankle Fellow at the Mater Hospital, Sydney. Dr Wines is an Orthopaedic Foot and Ankle Surgeon at Royal North Shore Hospital, North Shore Private Hospital and Mater Hospital, Sydney, and Dubbo Private Hospital, Dubbo, NSW.