Polyarticular Arthritis

Etiology

Non-articular etiologies: hypothyroidism, depression, somatoform pain disorder

Peri-articular etiologies: bursitis, tendinitis, neuropathic pain, metabolic bone diseases, soft tissue injury, fibromyalgia 

Non-inflammatory articular etiologies: osteoarthritis

Inflammatory arthritis etiologies:

1) Bacterial (Lyme disease, endocarditis, septic arthritis)

2) Viral (hepatitis B and C, Epstein Barr virus, parvovirus, dengue, alphaviruses, rubella, human immunodeficiency virus, mumps, coxsackievirus) 

3) Collagen-vascular disease (rheumatoid arthritis, palindromic rheumatism, rheumatic fever, lupus, vasculitis, systemic sclerosis, myositis, ankylosing spondylitis, psoriatic arthritis, Behcet syndrome, relapsing polychondritis)

4) Crystal-induced arthritis (uric acid deposition of gout, calcium pyrophosphate deposition of pseudogout)

5) Post-infectious or reactive arthritis (post enteric infections, disseminated gonococcal infection)

6) Familial Mediterranean fever  

Epidemiology

Data published by arthritis foundation in 2015 suggests that there are over 100 types of arthritis. And about 91.2 million adults either have physician-diagnosed arthritis and/or report joint symptoms consistent with a diagnosis of arthritis.[2] That translates to almost 1 in 3 persons aged 18-64. After the age of 65, half the men and two-thirds of women have arthritis. The incidence is on the rise, and Hootman estimates that by 2040, almost half the population will have physician-confirmed arthritis.[3]

Arthritis, and polyarticular arthritis, in particular, are more common in females and obese patients. Age significantly increases the prevalence. One estimate puts the total costs related to arthritis (medical care, earning losses, lost time, etc.) at 1% of US gross domestic product ($304 billion) for the 2013 fiscal year.[4]

Among people with arthritis, 33% have depression or anxiety, 25% have cardiac problems, 20% have respiratory conditions, and 16% have Diabetes. It is likely that arthritis is predisposing patients to all the comorbidities through physical inactivity. 

Pathophysiology

Pathophysiology of non-inflammatory arthritis is primarily mechanical but introduced cellular and biochemical processes will also change the normal slow cartilage remodeling process. There will be excess degeneration, less regeneration, and abnormal separation of the cartilage. Progressive cartilage loss, increased thickness of the subchondral plate, and cyst formation will happen. With time the cartilage gets thinner, looser, and weaker; bone will rub against bone causing remodeling of the bone and new bone formation at joint margins (osteophytes). Friction will cause mild inflammation.[5] All these changes will make the normal movement and gliding of bones over each other with the cartilage help more difficult and uncomfortable, and eventually painful. 

Pathophysiology of inflammatory arthritis can be infectious, crystal-induced, reactive, or autoimmune. In collagen vascular etiologies, inflammatory cytokines and autoantibodies create an inflammation cascade and pannus formation which can invade the cartilage and bone, and damage them. This damage is more acute and severe, and absent immediate medical attention, joint destruction can progress quite rapidly.

History and Physical

Acute arthritis usually lasts from hours to two weeks. Chronic arthritis is an inflammation of over two weeks. Chronic symptoms can be intermittent or constant. Symmetry and the number of joints involved are important factors. Pauciarticular is two to four involved joints whereas polyarticular is over five involved joints. Size and kind of the joints matter. Inflammatory pattern versus the non-inflammatory pattern, as mentioned, is a huge dividing factor.

Rheumatoid arthritis is usually polyarticular and in hands/wrists (small joints) in a symmetric distribution. It starts slow and lasts weeks to months before we make the diagnosis. Seronegative spondyloarthropathies are usually pauciarticular with axial involvement and large joint inflammation.[6] Osteoarthritis is in weight-bearing joints, is mostly asymmetric, and is worse with movement and better with rest.[7] Inflammatory arthritis is symmetric with severe inflammatory patterns and in non-weight-bearing joints. Morning stiffness of over than an hour is pathognomonic of inflammatory arthritis such as seronegative spondyloarthropathies.

An acute presentation with a migratory pattern can be viral arthritis, rheumatic fever or disseminated gonococcal infection; although viral arthritis is much more common than either of them.[8] It is hard to prove a diagnosis of viral arthritis as the inflammation usually resolves before confirmatory diagnosis. Septic joints are generally a straightforward diagnosis with hot, swollen, red, painfully moved joints. They are typically monoarticular arthritis of a large joint and come with constitutional symptoms and rarely come in a polyarticular form. More common would be an acute infection of a joint already affected by a polyarticular process. That makes the distinction difficult.  

The pain of osteoarthritis gets worse with movement and less with rest which is the opposite of rheumatoid arthritis that is worse with inactivity (morning stiffness) and better with movement. Short periods of synovitis (4-6 weeks) are usually from viral infections as opposed to longer periods that show an underlying persistent problem. Sensory problems like paresthesia, allodynia, anesthesia indicate a neuropathy or radiculopathy. Finally, the extra-articular symptoms can be hugely helpful and make or break the diagnosis — rashes (psoriatic arthritis), oral and genital lesions (Behcet syndrome), heart murmur (endocarditis), dry mouth and eye (Sjogren syndrome) and polyserositis (lupus).

Physical examination proves or disproves synovitis and sometimes shows the chronic changes of long-standing arthritis. The clinician should examine muscles, joints, tendons, bursas, and soft tissue. One should test both passive and active range of motion (ROM). Non-articular diseases present with normal passive ROM but reduced active ROM. Tendinitis or bursitis are good examples. Palpation can further differentiate these two. Bursitis has a very localized tender area that does not change much with movement, but the tender area in tendinitis is worse with movement. Articular diseases cause both reduced active and passive ROM. 

Warmth, redness, swelling, tenderness are the cardinal signs of inflammation and make the diagnosis of inflammatory arthritis easy to make. Septic arthritis has all these in a more pronounced form. Crepitation of the joint shows possible osteoarthritis and laxity prove a damaged and unstable joint. Again, extra-articular findings in the physical exam are sometimes even more crucial than the findings of the joints.

Evaluation

Laboratory Work

Evaluation of poly-arthritis can be extensive.

Rheumatological workup usually recommended includes: Rheumatic factor (RF) and anti-citrullinated peptide antibodies (CCP) for rheumatoid arthritis (RA), antinuclear antibody (ANA) for systemic lupus erythematosus and some other entities, anti-smith and anti-double-stranded DNA for confirmation of lupus, anti-Scl-70 for systemic sclerosis, anti-Ro (SSA) and anti-La (SSB) for Sjogren syndrome, anti-U1-RNP for mixed connective tissue disease, anti-neutrophilic cytoplasmic antibody (ANCA) for granulomatosis with polyangiitis (C form) and microscopic polyangiitis (P form), Anti-Jo-1 for myositis, anti-histone for drug-induced lupus erythematosus, cryoglobulin for vasculitis and hepatitis C. 

Erythrocyte sedimentation rate and C-reactive protein are non-specific markers of inflammation but usually helpful in ruling in a pathology causing significant inflammation and also monitoring its response to treatment.[9]

Polarized microscopy of synovial fluid can help with crystal arthritis diagnoses, such as gout and pseudo-gout. Clinicians also analyze synovial fluid for cell count, gram stain and cultures. Synovial fluid leukocyte counts less than 200/mm are normal, between 200/mm and 2000/mm are associated with non-inflammatory arthritis, and over 2000/mm with inflammatory arthritis. If the cell count is over 50000/mm, physicians should treat the fluid as infectious.[10]

Work up should also rule out common infectious diseases that cause arthritis. We will achieve this with testing for hepatitis, Lyme disease, and parvovirus. 

Imaging Studies

Imaging is a costly proposition and has a low diagnostic yield. There are usually no positive findings in the cases of acute polyarthritis. There is also no need to do imaging of every single joint involved. Some joints are "high yield" and provide information essential for diagnosis and treatment; some other joints are not. 

X-rays are helpful in showing fractures, dislocations, and osteomyelitis. In advanced osteoarthritis, the x-rays are useful and show erosion, sclerosis, joint space narrowing, osteophyte formation; but usually by the time these changes are present, the disease is well advanced and easily recognizable from history and physical. Also, many aging patients have x-rays compatible with osteoarthritis without having clinical symptoms; therefore, the correlation can be tricky. Although hand, wrist and metacarpal x-rays are unnecessary for a diagnosis of RA, they occasionally do help, and the response to treatment is at times monitored based on findings on x-rays. Cervical X-rays (specifically the C1-2) is essential during follow up of RA to look for damages and help prevent a pathologic fracture of the joint which would be devastating.[11] X-rays also easily show the disposition of calcium pyrophosphate in joints, such as a knee, and make the diagnosis of pseudo-gout. X-rays can show sacroiliac joint involvement of seronegative spondyloarthropathy although magnetic resonance imaging (MRI) is more sensitive.  

Ultrasound is readily available in the clinics and hospitals and is has utility for a variety of functions, but it has a limited role in polyarticular arthritis for detecting erosions and synovitis. Clinicians can easily perform joint injection under the guidance of ultrasound.[12][13] Computed tomography has almost no role other than ruling out other etiologies, and the role of MRI is to pick very early joint inflammation or early bone/soft tissue infection. 

Radionuclide scans are rarely done but have specific purposes. Picking up metastases, Paget disease of the bone, and osteomyelitis represent several of these indications.   

Biopsy

Biopsy many times have the final word; as is in most of medicine. There are enough diagnostic modalities for polyarticular arthritis to render biopsy unnecessary, but still, biopsies are occasionally done to diagnose or confirm a clinical suspicion for different vasculitis, arteritis, infectious etiologies, or granulomatous diseases.

Treatment / Management

Diagnosis Dictates Treatment

For osteoarthritis: Correction of the biophysical abnormality, weight loss, reduction of joint stress, maintenance of heat and warmth, strengthening exercises, non-steroidal anti-inflammatory medication (NSAIDS), injection of corticosteroids, are all helpful in that sequence. Joint replacement therapy will have the final word.

For collagen vascular diseases: Biologic medication and anti-inflammatories are in use and have revolutionized the management of diseases that in the past used with gold salts as a treatment! Half a century ago, there was a therapeutic pyramid for rheumatisms that would start with NSAIDs and escalate to steroids and then penicillamine and gold salts for refractory cases. Such an approach would permit joint destruction to advance before any real attempt at treatment was initiated. Nowadays, the pyramid is reversed, and early aggressive treatment with biologic medication can prevent joint damage at an early stage.

Rheumatologists use NSAIDs as a palliative measure for advanced disease and significant damage before they consider surgical approaches. Many new biologic agents are in the market and used in oral or injectable forms for a variety of approved indications.  

For infections: Antibiotic Treatment

For crystal-induced arthritis: Chelating agents are the treatment of choice. They will reduce the level of an offending agent in blood and prevent further damages.

Differential Diagnosis

The differential diagnosis is broad, but the following common conditions need to be ruled out:

• Psoriatic arthritis
• Tophaceous Gout
• Undifferentiated seronegative polyarthritis
• Erosive inflammatory arthritis
• Enteropathic arthritis
• SLE
• Scleroderma
• Polymyalgia rheumatica

Prognosis

Prognosis depends on several factors:

Duration of symptoms, age at onset, male gender, Obesity, the number of joints involved, lower limb involvement, severity of inflammation, and elevated lab markers of inflammation.

Complications

Complications are many. Each disease can induce its own set of complications based on the severity of the pathology, location of inflammation, host factors, and treatments available.