Can RA, PsA or JIA affect any joint in the body? 

While rheumatoid arthritis (RA), psoriatic arthritis (PsA), and juvenile idiopathic arthritis (JIA) are all types of inflammatory arthritis, they do not impact the body in the same way. Each condition has a “preferred” pattern of joint involvement, often targeting specific areas like the small joints of the hands or the larger joints of the legs. However, because these are systemic autoimmune conditions, meaning the inflammation travels through the entire bloodstream, it is clinically possible for almost any joint in the human body to be affected. Understanding these patterns is a key part of how specialists in the UK reach an accurate diagnosis. 

What We’ll Discuss in This Article 

• The typical symmetrical pattern of rheumatoid arthritis. 

• The diverse and often asymmetrical nature of psoriatic arthritis. 

• How juvenile idiopathic arthritis differs based on its specific subtype. 

• Unusual areas that can be affected, such as the jaw and the neck. 

• The difference between small joint and large joint involvement. 

• A summary table comparing common joint targets for each condition. 

Joint patterns in rheumatoid arthritis (RA) 

Rheumatoid arthritis is most frequently recognised by its symmetrical presentation. This means that if the knuckles on your left hand are inflamed, the same knuckles on your right hand are very likely to be affected as well. In the early stages, RA typically targets the small joints, particularly the middle knuckles of the fingers and the joints at the base of the toes. 

As the condition progresses without treatment, it can move to larger joints. According to the NHS, this may include the wrists, elbows, shoulders, hips, knees, and ankles. A notable characteristic of RA is that it rarely affects the joints at the very tips of the fingers (the distal interphalangeal joints), which helps doctors distinguish it from other types of arthritis. 

The varied reach of psoriatic arthritis (PsA) 

Psoriatic arthritis is much less predictable than RA. It can be symmetrical, but it is more often asymmetrical, affecting a random assortment of joints. One of the most unique features of PsA is its ability to affect the joints closest to the fingernails. This is often seen alongside the nail changes mentioned in NICE guidance. 

PsA is also known for involving the axial skeleton, which includes the spine and the sacroiliac joints in the pelvis. Furthermore, because PsA involves the entheses (where tendons meet bone), patients often feel pain in the back of the heel or the sole of the foot. Unlike RA, it is common for PsA to cause swelling of an entire finger or toe, known as dactylitis. 

Joint involvement in juvenile idiopathic arthritis (JIA) 

In children, the joints affected depend entirely on the subtype of JIA diagnosed. For instance, children with oligoarthritis usually have involvement in large joints, most commonly the knees or ankles, and typically affect four or fewer joints. In contrast, those with polyarthritis affect five or more joints, often including the small joints of the hands, mirroring the adult RA pattern. 

Systemic JIA is unique because the joint pain may be secondary to whole-body symptoms like high fevers and rashes. It is also important to note that JIA can affect the growth plates near the joints, which is why paediatric rheumatologists monitor children closely to ensure their limbs grow evenly. 

Unusual joints: The jaw, neck, and chest 

While we often think of arthritis in the hands, knees, or hips, these conditions can strike in less common areas: 

The Jaw (TMJ): 

Both JIA and RA can affect the temporomandibular joint, making it difficult or painful to eat or speak. 

The Neck (Cervical Spine): 

Rheumatoid arthritis can specifically affect the top two vertebrae of the neck. This requires careful monitoring to ensure the stability of the neck is maintained. 

The Chest Wall: 

Psoriatic arthritis can cause inflammation where the ribs meet the breastbone, leading to chest pain that can sometimes be mistaken for other issues. 

Comparison of common joint targets 

The following table provides a quick reference for the joint patterns typically seen in each condition. 

Feature	Rheumatoid Arthritis (RA)	Psoriatic Arthritis (PsA)	Juvenile Arthritis (JIA)
Symmetry	Usually symmetrical	Often asymmetrical	Varies by subtype
Hand Joints	Middle knuckles and base	Tips of fingers	Varies; often large joints
Spine/Back	Only the upper neck	Common (lower back/pelvis)	Possible in certain types
Large Joints	Knees, hips, shoulders	Knees, ankles	Knees and ankles common
Tendon Sites	Less common	Very common	Common in Enthesitis-type

The systemic nature of the disease 

It is vital to remember that because these are systemic conditions, the inflammation is not strictly confined to one joint. A person might start with pain in their wrist, but over time, the immune system may begin to target the shoulders or the balls of the feet. This is why early treatment is so important, it works on the whole body to prevent the inflammation from spreading to new joints. 

Conclusion 

While RA, PsA, and JIA have preferred targets, they can technically affect almost any joint in the body that has a synovial lining. Rheumatoid arthritis typically follows a symmetrical pattern in the hands and feet, while psoriatic arthritis is more varied and often involves the spine and finger tips. Juvenile arthritis varies significantly by subtype but often targets the larger joints of the legs. If you experience severe, sudden, or worsening symptoms, call 999 immediately. 

Authority Snapshot (E-E-A-T Block) 

This article provides an overview of how different types of inflammatory arthritis distribute across the body to help patients identify their own symptom patterns. It has been authored by Dr. Rebecca Fernandez, a UK-trained physician with experience in internal medicine and musculoskeletal assessment. All information is grounded in the clinical diagnostic criteria utilised by the NHS and NICE.