PARIS — When it comes to psoriatic arthritis, don't forget the feet.
The burden of foot pain and deformity is high and the level of foot care provision is low, Deborah E. Turner, Ph.D., reported at the annual European Congress of Rheumatology.
A big part of the reason the feet of psoriatic arthritis patients are underassessed clinically is that the disease activity measures widely used in both clinical practice and research ignore the foot, according to Dr. Turner of Glasgow (Scotland) Caledonian University.
She reported on an unselected series of 88 consecutive psoriatic arthritis patients at Glasgow Royal Infirmary who underwent a clinical foot examination by a podiatrist. Two-thirds of the patients reported chronic foot pain; in most cases, the medical team was unaware of the problem because nobody had ever asked.
On clinical examination, 30% of the cohort had plantar fasciitis and 24% had Achilles tendonitis. These are probably marked underestimates of the true prevalence of pathology at these sites, as ultrasound studies have shown that roughly three-quarters of psoriatic arthritis patients are affected.
Interestingly, 40% of the psoriatic arthritis patients had inflammatory involvement of the posterior tibial tendon.
A striking finding in the study was the very high prevalence of flat feet in the patients with significant foot pain. The working hypothesis is that a combination of inflammation of tendons and in the joints around the ankle and rear foot leads to weakened foot ligaments, which then stretch under the stress of weight bearing, resulting in flattening of the arch, Dr. Turner said.
She added that foot problems are often one of the earliest features of psoriatic arthritis. A common scenario in young patients participating in sports is that months before they receive the diagnosis of psoriatic arthritis, they develop Achilles tendonitis and/or plantar fasciitis, which are misinterpreted solely as chronic overuse athletic injuries.
“A lot of attention is given to foot problems in rheumatoid arthritis, but we found the overall burden of foot problems in terms of how much they contribute to the patients' disability was as high for patients with psoriatic arthritis as for those with rheumatoid arthritis,” Dr. Turner said in an interview.
Nevertheless, only one-quarter of study participants had received conservative foot care.
The standard podiatric treatment for painful flat foot deformities is the use of a rigid arch support.
As part of Dr. Turner's ongoing research project funded by the Arthritis Research Campaign, she plans to see whether correcting the abnormal foot mechanics in psoriatic arthritis patients improves their inflamed lower extremity joints and tendons.