Psoriatic Arthritis and Bone Erosion

Psoriatic arthritis (PsA) is an autoimmune disease in which the body’s immune system attacks your joints and skin. It affects up to 30% of people with psoriasis, an inflammatory skin condition.

Because PsA causes chronic inflammation, it can lead to gradual bone erosion. Bone erosion refers to bony defects that develop from excessive local bone resorption (breakdown) and inadequate bone formation.

Bone erosion is typically caused by erosive arthritis conditions like PsA and rheumatoid arthritis (RA). Conditions like PsA and RA can progress, which means worsening inflammation, and the more inflammation there is, the more damage there will be to the bones.

PsA causes joint pain, stiffness, and swelling in any of the body’s joints, including the fingers, toes, knees, shoulders, neck, and back. It can also cause severe damage to the bones. Skin symptoms caused by PsA include skin inflammation that leads to red, silvery, scaly patches.

This article will discuss bone erosion in PsA, PsA vs. RA bone erosion, and the diagnosis, treatment, and prevention of bone erosion from PsA.

Bone Erosion in Psoriatic Arthritis

PsA is a diverse condition that affects the skin, nails, peripheral joints (the joints of your arms and legs), axial joints (all the joints of the body that move), entheses (the places where a tendon or ligament meets your bone), and the fingers and toes (causing dactylitis, severe swelling of these small joints).

Up to 5% of people with PsA will develop arthritis mutilans, a rare and severe form of PsA that affects the hands and feet.

The diverse nature of PsA sometimes makes it harder for doctors to distinguish it from other types of inflammatory arthritis. The term “inflammatory arthritis” refers to diseases that, like PsA, are the result of an overactive immune system that triggers chronic inflammation.

A common type of inflammatory arthritis often mistaken for PsA is RA. RA often involves the small joints of the hands and feet but can also affect larger joints.

RA inflammation is generally focused on the synovium (soft-tissue linings of joints and tendons). In contrast, PsA targets the skin, nails, joints (especially the smallest ones located in your fingers and toes), the entheses, and the spine. 

All types of inflammatory arthritis cause inflammation of the joints that leads to joint pain and stiffness. They can also affect other connective tissue, including those of the heart, eyes, lungs, skin, and other organs. Damage to any part of the body from ongoing inflammation is irreversible.

Altered Bone Remodeling in PsA

A delayed diagnosis of PsA could mean irreversible bone and joint damage. Unfortunately, diagnoses of PsA are often delayed and many people will show signs of irreversible joint and bone damage at the time of diagnosis. Researchers believe the problem is linked to altered bone remodeling in people with PsA.

According to a 2018 journal report, there are dramatic changes in the processes that maintain “normal bone integrity” in people living with PsA. In the addition to the changes to bone remodeling, there are events that promote inflammatory proteins and inflamed synovial tissues which lead to further bone changes.

Recent research has uncovered important molecules and cellular interactions that are responsible for altered bone modeling. Specifically, there are genetic and environmental factors that increase the risk for joint damage and altered bone remodeling in people with PsA. 

Bone Damage Can Occur Early and Quickly

According to a 2020 report in the journal Arthritis Research & Therapy, persistent inflammation can lead to structural damage in PsA, which results in reduced physical function and impaired quality of life. That structural damage can occur very quickly, especially in people whose PsA is not treated early.

Long-term structural changes in PsA can also occur in people receiving long-term care and treatment. A 2019 study examined structural damage via computed tomography (CT) imaging of the second and third metacarpal heads of the finger joints in 60 PsA patients at diagnosis (baseline) and after five years.

Erosion and enthesiophyte (bony spurs forming at a ligament or tendon insertion into bone) progression were defined as “change exceeding the smallest detectable change (SDC).”

The results of the study determined damage accrual (bone erosion and enthesiophyte) was observed in many of the PsA study participants over a five-year period despite receiving routine clinical care. The researchers concluded that slowing down disease activity and progression was the only way to prevent further bone damage.

Bone Erosion of the Distal Phalanges

Bone erosion resulting from PsA is often limited to the distal phalanges (finger joints). This includes inflammation and calcification—called enthesitis—at the entheses, the connective tissue between tendon or ligament and bone and acrolysis, extensive resorption of the bones of the finger joints.

 Arthritis Mutilans

Arthritis mutilans (AM) is a rare and aggressive type of arthritis that affects the hands and feet. It is common in both PsA and RA. AM in PsA is extremely rare, and it can cause severe bone loss that leads to permanent changes in the bones of the fingers and toes.

X-rays can show whether there is damage to the bones and joints. AM often causes a pencil-in-cup deformity. With this type of damage, one side of a joint or the end of the bone might resemble the pointed end of a pencil and adjacent bone appears cuplike.

Bone Erosion in RA vs. PsA

RA causes chronic inflammation, which can lead to gradual bone erosion. Much like PsA, bone erosion can develop early in the disease’s course and impair your ability to function Similarly, RA also affects the smaller joints of the hands and feet, including the fingers and toes. Bone erosion is common in these small joints.

Bone erosion is common in RA because chronic inflammation from the condition promotes osteoclasts—cells that break down bone tissue. The increase in osteoclasts advances bone resorption. In people with RA, the resorption process becomes unbalanced. It leads to a rapid breakdown of bone tissue.

Bone erosion in RA can also result from the high levels of inflammatory proteins in the body. Excessive numbers of inflammatory proteins are the cause of chronic inflammation and swelling and eventually bone, joint, and tissue damage.

Diagnosis, Treatment, and Prevention

Preventing bone erosion from PsA starts with an accurate diagnosis and early, aggressive treatment of the condition. 

Diagnosis 

There is no single test to accurately diagnose PsA but there are different methods of testing your doctor will use to determine the cause of symptoms. The most telling signs of PsA are skin and nail changes, along with joint damage. These are often seen on imaging.

PsA is known for causing permanent damage over time, especially to the hands and feet. Imaging of the fingers and toes can show joint damage very early in the disease. An accurate and early PsA diagnosis is vital to preventing this type of damage.

In addition to imaging studies, your doctor will use other diagnostic tools, including reviewing symptoms and your medical and family history, a physical examination of joints and skin, and lab work.

PsA Healthcare Providers

Once you have a diagnosis, you might need to see different types of healthcare professionals to provide various aspects of care. These may include:

• Rheumatologists: These doctors are specialists who treat diseases of bone, joints, and muscles. Regarding PsA, a rheumatologist can help you to manage the underlying inflammation that contributes to bone and joint damage.
• Dermatologists: These specialists diagnose and treat conditions that affect the skin, nails, and hair. There will be overlaps (diagnostic methods or treatment) in your dermatologic and rheumatologic care when treating PsA.
• Podiatrists: Sometimes called foot doctors, they specialize in the treatment of the feet and ankles, including the skin, bones, joints, tendons, and nails. Because PsA often affects the feet, a podiatrist can help you to manage serious symptoms of PsA that attack your feet.
• Physiotherapists: Also called physical therapists, these specialists can help you find ways to exercise safely and correctly to keep your joints functioning properly.
• Occupational therapists: People with PsA often experience pain and fatigue that make it harder to perform activities of daily living, such as getting dressed, making meals, and driving. An occupational therapist can help you to better ways to perform these activities without pain and difficulty.

Treatment

There is no cure for psoriatic arthritis, but treatment can help manage inflammation to prevent bone and joint damage. Treatment will depend on how severe your disease is and what joints the condition has affected. You might need different treatments before you find one that best manages symptoms.

Medications used to treat PsA include nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, conventional disease-modifying antirheumatic drugs (DMARDs), and biologic DMARDs (biologics).

NSAIDs: NSAIDs can help relieve pain and reduce inflammation. NSAIDs like Advil and Motrin (ibuprofen) and Aleve (naproxen sodium) are available over the counter without a prescription. If needed, your doctor can prescribe a stronger NSAID. Side effects of NSAIDs include stomach irritation, heart troubles, and liver and kidney damage.

Corticosteroids: Corticosteroids can reduce inflammation to lessen pain and swelling. The most prescribed oral corticosteroid is prednisone and it's also the most common injectable corticosteroid. Rheumatologists only prescribe these drugs as needed because they can cause potent side effects.

Side effects include a worsening of skin symptoms from PsA or psoriasis, an increased risk for infections, weight gain, increased appetite, increased blood pressure, and increased risk for osteoporosis and diabetes.

Conventional DMARDs: These drugs can slow down PsA disease progression to save your joints and bones from permanent damage or disability. The most commonly prescribed DMARD is methotrexate. Side effects of conventional DMARDs include liver damage, bone marrow troubles, and lung inflammation and scarring.

Biologics: This class of drugs targets the parts of the immune system that trigger PsA. Examples of biologics used to treat PsA are Cimzia (certolizumab pegol), Enbrel (etanercept), Humira (adalimumab), Remicade (infliximab), and Simponi (golimumab). Biologics can increase your risk of serious infections.

Newer Therapies

Janus kinase (JAK) inhibitors and an enzyme blocker called Otezla (apremilast) are the newest therapies available for treating PsA, which work as follows:

• JAK inhibitors: JAK inhibitors are synthetic targeted DMARDs. Xeljanz (tofacitinib), for example, targets specific parts of the immune system to reduce the overactive response caused by PsA. Side effects of JAK inhibitors include an increased risk for blood clots of the lungs, serious cardiac events, and cancer.
• Otezla (apremilast): This new therapy blocks the production of an enzyme called phosphodiesterase 4 (PDE4) that is responsible for causing inflammation. It is prescribed to people with mild to moderate PsA who can’t use DMARDs or biologic drugs. Side effects may include nausea, headaches, and diarrhea.

Additional Treatment Options

Physical and occupational therapies might help you manage pain and make it easier for you to do your activities of daily living. Ask your treating physician for a referral to physical and/or occupational therapy. 

Joint replacement therapy is considered when joints and bones have severely been damaged by PsA. Surgery can replace a damaged bone or joint and replace it with artificial parts made of plastic and/or metal.

Lifestyle Therapies

Making certain lifestyle changes can help you manage PsA symptoms and prevent flare-ups (periods of high disease activity) of the condition. The prevention of flare-ups can reduce the risk for bone erosion and other bone and joint changes.

Lifestyle therapies that might help include controlling stress, eating healthy and keeping a healthy weight, not smoking, being active, and managing other health concerns.

Control stress: Stress can trigger PsA flares, so it is important to identify triggers of stress and to address those.

Eating healthy: Being overweight can make PsA worse because the extra weight adds stress to your joints. Maintaining a healthy weight can also reduce inflammation and swelling.

Not smoking: People with PsA who smoke might have a more severe disease early on and might not respond well to their treatments if they continue smoking. A 2019 study found methotrexate (a DMARD) may not be as effective for people with PsA who smoke compared to those who don’t smoke.

Smoking also increases your risk for other serious health conditions, including heart disease. Quitting smoking can help relieve PsA symptoms and reduce the number of flares you experience.

Staying active: Being active can help prevent your joints from becoming stiff and painful. Water-based exercise is one of the best exercises for managing all types of arthritis. Reach out to your doctor or a physical therapist before starting a new exercise routine to determine what activities are safest for you.

Management of other health conditions: PsA is linked to many conditions, including psoriasis, heart disease, diabetes, and depression. Gaining control of other health conditions can help to prevent PsA flares and slow down the disease’s progression.

Treating multiple conditions might require seeing several specialists, and your doctors can work together to create a treatment plan that best works to manage all of your conditions.

Summary

Psoriatic arthritis is a lifelong, inflammatory condition that can lead to bone erosion from worsening inflammation. Bone erosions can occur early in the disease’s course and lead to disability and impaired function of affected joints and bones.

Early diagnosis and aggressive treatment are vital to preventing this type of damage. Treatment includes different medicines and lifestyle therapies to manage symptoms, reduce inflammation, and slow down the disease’s progression.

Talk to your rheumatologist about what you can be done to maintain your bone health and slow down PsA bone erosions and bone and joint damage.

A Word From Verywell

Living with a chronic inflammatory disease like psoriatic arthritis can be a challenge, and PsA can have a significant effect on both your mental and physical health. Early diagnosis and treatment are vital to helping you stay mobile and continue to enjoy a good quality of life.

Take the time to understand what you can about PsA, including knowing what to expect and different ways to plan or complete daily tasks. Once you better understand and can predict how you will respond to the disease, you can use what you know to prevent disease flare-ups and ease pain, discomfort, stress, and fatigue.