Which foot joints are commonly involved in Rheumatoid Arthritis (RA)?

From the Guidelines

Rheumatoid arthritis commonly affects multiple foot joints, particularly the metatarsophalangeal (MTP) joints at the base of the toes, especially the 2nd and 3rd MTPs. The ankle joints, subtalar joints, and midfoot joints (tarsometatarsal and intertarsal) are also frequently involved, as noted in the study published in the Mayo Clinic Proceedings 1. RA typically presents with symmetrical joint involvement, meaning both feet are affected in a similar pattern. The inflammation in these joints causes synovitis (joint lining inflammation), which leads to pain, swelling, and morning stiffness, as described in the clinical features of rheumatoid arthritis 1. Over time, this chronic inflammation can result in joint deformities such as hallux valgus (bunions), hammer toes, claw toes, and flat feet due to ligament weakening and tendon dysfunction. Some key points to consider include:

• The metatarsophalangeal joints are commonly affected, leading to pain and stiffness in the toes
• The ankle and subtalar joints can also be involved, causing pain and limited mobility in the foot and ankle
• Early recognition of foot involvement is crucial as it can lead to significant disability if untreated, with more than a third of patients eventually experiencing work disability because of the disease 1. The predilection for these specific foot joints relates to RA's tendency to target synovial joints with complex movements and weight-bearing responsibilities, where the autoimmune process attacks the synovial membrane, causing progressive joint destruction if not adequately managed with disease-modifying treatments.

From the Research

Foot Joints Involved in RA

The foot joints commonly involved in Rheumatoid Arthritis (RA) include:

• Metatarsophalangeal joints, which are frequently affected both clinically and radiologically 2
• Ankle joint, which is often involved, with clinical involvement being seen more often than radiological joint damage 2
• Midtarsal joints, where radiological joint damage is more common than clinical involvement 2

Specific Joints Affected

Studies have shown that the following foot joints are affected in RA:

• 1st-5th metatarsophalangeal (MTP) joints, with the third and second MTP joints being commonly involved 3
• Ankle joint, which is the most commonly involved joint in foot and/or ankle arthritis (FAA) 3

Prevalence of Foot and Ankle Arthritis

Foot and/or ankle arthritis (FAA) is a common feature of RA, with a prevalence of 29.3% in patients with RA 3

• FAA is associated with higher disease activity scores and a lower likelihood of achieving remission 3

Other Joints Affected

While the foot joints are commonly involved in RA, other joints such as the:

• Metacarpophalangeal and proximal interphalangeal joints of the hand 4, 5, 6
• Wrist and knee joints 4, 5, 6
• Shoulder and hip joints 5, 6 are also frequently affected.