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Foot, ankle OA remain ‘neglected’ without prevalence estimates
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TORONTO — Foot and ankle osteoarthritis have often gone overlooked as areas of clinical study and lacking clinical consensus on prevalence, according to Michelle Marshall, PhD, research fellow in Musculoskeletal Clinical Epidemiology & Imaging at Keele University in the UK.
In her presentation at the OARSI 2019 World Congress on Osteoarthritis, Marshall offered a comprehensive portrait of the definitions, prevalence and incidence, burden, phenotypes, risk factors, diagnosis, long-term course, and management of foot and ankle OA. “This is an area that has been relatively neglected,” she said.
Regarding prevalence, Marshall said that foot and ankle OA can be defined in different ways; however, she noted that clear estimates agreed upon by the clinical community do not exist.
Early estimates of the prevalence of the disease were based on symptoms, such as pain, aching, and stiffness. One study showed that among individuals aged 65 years or older, 24% of individuals complained of foot pain, while 15% reported ankle pain. Other data sets showed foot and/or ankle pain may exist in 10% to 15% of the population. “Symptoms alone may overestimate foot and ankle OA,” she said.
Using structural change to determine prevalence rates has also proven challenging, according to Marshall. Studies of X-ray and other radiographic evidence of foot OA have yielded prevalence estimates ranging from 18% to 39%. For the ankle, Marshall suggested that there are no true estimates. “It is difficult to estimate prevalence,” she said. “Systematic reviews showed no estimates of symptomatic radiographic OA for either the foot or the ankle.”
With this in mind, Marshall and colleagues undertook a survey of 5,109 individuals aged 50 years or older, one-third of whom experienced pain in and around the foot in the last 12 months. Estimates showed possible foot OA existed in 16.7% and possible ankle OA in 3.4%. A closer look at various foot joints showed possible OA in 4%-8% of joints.
Burden and risk factors
Prior studies have shown that foot or ankle OA can yield disabling pain in as many as 69% of patients, according to Marshall. “Pain results in functional limitations and impairment in balance, strength and locomotor ability,” she said.
Little is known about the economic burden of foot and ankle OA, but Marshall suggested that individuals who suffer from these diseases may have a reduced ability to work.
Looking at patterns of joint involvement in the feet may shed light on the burden of these diseases, according to Marshall. One study showed that 42% of patients who complained of foot pain had radiographic OA in two or more joints. These findings also demonstrated that OA was clustered across both feet.
In terms of risk factors, Marshall suggested that foot and ankle OA may be more likely in women, older individuals, and those in a lower socioeconomic class. Other possible risk factors include size and shape differences in the first metatarsophalangeal joint in the foot, or more than 5 degrees of ankle pronation. “In the midfoot joints, increased pronation and increased midfoot pressures were associated with increased risk for foot OA,” Marshall added.
Malalignment, instability and incongruity may be risk factors for ankle OA. “More than 70% of ankle OA is post-traumatic,” Marshall said.
Diagnosis and management
The signs and symptoms used to diagnose foot and ankle OA are similar to those of other joint sites, noted Marshall. “However, there are no currently accepted diagnostic criteria for foot or ankle OA,” she said, adding that these diseases are likely currently underdiagnosed.
Some attempts have been made to develop diagnostic models. Criteria that underwent analysis included clinical parameters of pain more than 25 months, dorsal exostosis of the first metatarsophalangeal joint, hard-end feel, or crepitus; or demographic criteria such as older age, female gender, or increased BMI. These models had a “poor fit” for diagnosing the disease, according to Marshall.
Management of foot and ankle OA generally starts with conservative treatments and moves through pharmaceutical options, Marshall noted. Conservative treatments include physical therapy, specialized footwear, and orthoses. “There is some evidence of some conservative, non-pharmacological interventions being beneficial in foot OA,” Marshall said. However, further studies need to be done.
Marshall stressed that there is no evidence that use of paracetamol, topical or oral NSAIDs, or capsaicin have been effective.
In terms of injections, Marshall highlighted studies comparing hyaluronic acid with placebo, corticosteroids, or saline, noting that the findings for these studies failed to draw any actionable conclusions. —by Rob Volansky
Reference:
Marshall M, et al. Concurrent Session 3. Presented at: OARSI 2019 World Congress on Osteoarthritis; May 2-5; Toronto, Canada.
Disclosure: Marshall reports no relevant financial disclosures.