Psoriatic arthritis is an inflammatory arthritis that occurs when someone already has psoriasis (a skin disease that causes a rash with itchy, scaly patches, most commonly on the knees, elbows, trunk and scalp).
Psoriatic arthritis (PsA) is different from “common” arthritis (osteoarthritis) in that it is inflammatory in nature and can develop quite quickly whereas osteoarthritis takes time to develop and is associated with load bearing on certain joints.
PsA is the second most common inflammatory arthropathy after rheumatoid arthritis.
Psoriatic arthritis is categorized into five types:
Asymmetric oligoarticular – affecting less than 5 joints and not occurring on both sides of the body (ie: left knee is affected but not the right)
Symmetric polyarthritis – affecting 5 or more joints in the body and symmetrical in presentation (ie: both left and right knee are affected)
Distal interphalangeal predominant – affecting the distal interphalangeal joints of the fingers or toes. Often will present long side other type of PsA and can present with nail changes such as lysis and pitting.
Spondylitis – inflammation, pain or stiffness of the joints in the spine
Arthritis mutilans – the most severe destructive type of PsA presenting in 5% of people affected resulting in marked osteolysis and deformity of finger and toes.
How is a PsA diagnosed:
As PsA shows no rheumatoid factor in blood tests; Xrays along with clinical assessment is the key for an accurate diagnosis.
Due to the variations of PsA, 6 areas of PsA have been identified to help diagnose and treat the condition:
Peripheral arthritis – Swelling, pain and/or stiffness in the extremities for example in the hands, feet, and/or knees. In the foot, affects will likely be noticed in the middle joints of the toes (interphalangeal joints) or the joint that connects that toe to the foot (metatarsophalangeal joints)
Enthesitis – Swelling, pain and/or stiffness where tendons connect to the bone.
Dactylitis – The swelling of a whole finger and/or toe.
Axial disease – Pain and/or stiffness in the joints of the spine and/or buttock region
Psoriasis – A condition that causes dry, red, scaly skin patches and chronic itch.
Nail disease – Pitting, discoloration and/or abnormal nail growth.
Not everyone will experience all six, but each person will have his or her own combination of manifestations, which will vary in severity and impact in day-to-day life.
Characteristic radiographic features of PsA include
Joint space narrowing
Bony proliferation appearing around affected joints – this leads to a fuzzy appearance on radiograph
Osteolysis including “pencil in cup” deformity
Acro-osteolysis (resorption of distal phalanges)
Ankylosis – joint fusions
How is PsA treated?
There are a number of ways that Riverside podiatry can assist PsA symptoms including:
Orthotic shoe inserts to reduce pain in joints and ligaments and to maximize your foot function
Accommodating digital deformities that develop to make footwear more comfortable