SLR - February 2024 - Wisbang
Title: Do Dynamic Plantar Pressures Differ Based on Sonographic Evidence of Metatarsophalangeal Joint Synovitis in People With Rheumatoid Arthritis?Reference: Anderson L, Ihaka B, Bowen C, Dando C, Stewart S. Do Dynamic Plantar Pressures Differ Based on Sonographic Evidence of Metatarsophalangeal Joint Synovitis in People With Rheumatoid Arthritis? ACR Open Rheumatol.
2023 Dec 20. doi: 10.1002/acr2.11635. Epub ahead of print. PMID: 38117793.
Level of Evidence: Level IV
Scientific Literature Review
Reviewed By: Cassie Wisbang, DPM, PGY-1
Residency Program: Creighton University School of Medicine -Phoenix; Phoenix, AZ
Podiatric Relevance: Synovitis is central to the pathophysiology of rheumatoid arthritis (RA). The most common location of this synovitis is at the metatarsophalangeal joints (MTPJ) in the forefoot. Chronic inflammation in this area of the foot leads to digital deformities and metatarsal head plantar prominence. People with RA display altered plantar pressure patterns while weight-bearing compared to those without the disease. The relationship between ultrasound evidence of synovitis of the MTPJs and plantar pressure had not been investigated. The aim of this study was to determine whether dynamic plantar pressures differed based on ultrasound evidence of MTPJ synovitis in individuals with RA.
Methods: Participants of this study were recruited via advertising. To be included in the study, participants needed a physician diagnosis of RA, meet the American College of Rheumatology Classification for RA, be able to walk barefoot and were over the age of 20 years old. Participants were excluded if they had other inflammatory disorders. A dynamic assessment of the plantar pressure of both feet of the participants was performed using a pressure mat. The foot was divided into seven regions of interest representing the hallux, lesser toes, metatarsal one, metatarsal two, metatarsals three-five, the midfoot, and the heel. Peak plantar pressure (PP) and pressure time integrals (PTI) were obtained.
Ultrasound was used to assess the presence of synovitis in the joints of the foot. The images were analyzed and split into groups representing none/minimal synovitis and moderate/severe synovitis. Linear regression models were utilized to determine the difference in PP and PTI between MTPJs with none/minimal synovitis and those with moderate/severe synovitis.
Results: Thirty-five participants were included in the study. Tenderness was found at all regions of the foot and ankle, with the most common locations being the MTPJs and the midtarsal joint. Based on the EULAR/Outcome Measures in Rheumatology scores for synovitis, 40.9% of the joints studies exhibited none/minimal synovitis and 59.1% exhibited moderate/severe synovitis. Participants with moderate/severe synovitis at the second and fourth MTPJs had significantly reduced PP beneath the lesser digits compared to participants with none/minimal synovitis in these joints. Participants with moderate/sever synovitis at the first MTPJ and at the second/fourth MTPJ had a significant reduction in PTIs beneath the hallux and beneath the lesser digits, respectively, compared to those with none/minimal synovitis at these joints. No significant differences were observed in PP or PTIs in other joints with synovitis.
Conclusion: The results of the study showed no direct association between plantar pressure an synovitis within the same region of the foot. This suggests there may be an offloading strategy in which synovitis in the MTPJs results in reduced propulsion of the digits. People with RA may be biomechanically adapting pressure away from areas of forefoot pathology. Knowing this information could be beneficial in determining the correct footwear and orthoses for those with RA.