Polyarthritis refers to the simultaneous inflammation of more than four joints and may complicate a wide variety of diseases of autoimmune, infectious, metabolic and neoplastic pathogenesis, e.g., rheumatoid arthritis, seronegative arthritis and systemic lupus erythematosus.
Symptoms of polyarthritis are those of arthritis affecting five or more joints. Frequent complaints are:
Affected joints may be in close proximity to each other or may be located in distant parts of the human body. In fact, many forms of polyarthritis compromise several joints of both hands or feet. The above listed symptoms and signs may not be noted at all times; they are likely to diminish or worsen with rest or exercise. Patients suffering from inflammatory polyarthritis may additionally report fatigue, fever, night sweats, weight loss and lymphadenopathy.
Every form of polyarthritis may severely affect the patient's ability to cope with everyday tasks.
Anamnestic data and results of physical examination should allow for the treating physician to answer the following:
Moreover, it is important to distinguish between inflammatory and non-inflammatory forms of polyarthritis. This may be achieved by assessing inflammatory markers like serum levels of C-reactive protein and the erythrocyte sedimentation rate. Both positively correlate with inflammation.
All these data should be considered when compiling a list of differential diagnoses and deciding on a target-oriented diagnostic approach . They do not yet allow for a definitive diagnosis and additional measures are required to confirm a suspicion.
Measures described herein typically reveal the following in case of RA, SNA and SLE:
If at all possible, causative treatment should be applied to cure the underlying disease. Unfortunately, causative treatment is not available for many forms of polyarthritis and only supportive therapy can be provided. In any case, therapy should be adjusted to the individual case, to present complications and comorbidities, to the patient's response to therapy, possible side effects and adverse events. The following treatment options may be considered:
This list is restricted to treatment options for articular manifestations of polyarthritis. Many diseases that cause polyarthritis are associated with extra-articular symptoms, e.g., myocarditis, pleuritis and nephritis, and these conditions require an appropriate management as well.
The patient's prognosis largely depends on the cause of polyarthritis.
Polyarthritis results from pathophysiological events that simultaneously take place in several joints of the body. In general, joints are susceptible to virtually all kinds of disturbances, e.g., to malfunction of the immune system, infection with pathogens and release of toxins, interruption of blood supply, nutrient deficiency and metabolic perturbances, carcinogenic stimuli, and trauma. Only in case of generalized disease, polyarthritis may develop. In this context, generalized may refer to systemic diseases, hematogenous or lymphogenous spread of pathogens or tumor cells. With regards to the aforegiven list, compromise of five or more joints is more likely if a patient suffers from autoimmune diseases, nutrient deficiencies and metabolic disorders. In contrast, vascular events, neoplasms and traumas commonly affect one or few joints. This classification is not irrefutable though: RA may manifest in form of monarthritis and polyarthritis may be part of a paraneoplastic syndrome  .
In detail, the following diseases may be associated with polyarthritis :
Due to the large number of differential diagnoses, epidemiological data regarding the overall incidence and prevalence of polyarthritis cannot be provided. Similarly, underlying disorders vary largely with respect to racial and gender predilection and age distribution. In general, patients of all races, both genders and all age groups may develop polyarthritis.
Furthermore, risk groups may be defined for determined forms of polyarthritis. In this context, any condition associated with immunosuppression, e.g., diabetes mellitus, infection with human immunodeficiency virus and immunosuppressive treatment, may predispose for infectious polyarthritis. This also applies to behavior favoring infection with causative pathogens, e.g., men having sex with men and intravenous drug abuse.
Differences regarding the geographic distribution of polyarthritis is also best illustrated by those pathogens causing infectious polyarthritis: Hepatitis B is a major health concern worldwide, while the above described alphaviruses are prevalent only in determined countries .
A healthy joint is formed by at least two bones whose articulating surfaces are able to move virtually frictionless against each other, whereby the joints' motion ranges differ largely. Most joints of the human body are synovial joints, i.e., the respective articulating surfaces are covered by smooth hyaline cartilage and synovial tissue that is further lubricated by synovial fluid contained in the synovial cavity, and the whole joint is surrounded by a fibrous joint capsule. Every process altering the properties of those joint-composing structures may provoke arthritis, and such processes may originate from articular or extra-articular events:
In most cases, these pathophysiological events are mutually dependent. For instance, chronic, inflammatory polyarthritis is generally associated with excess release of pro-inflammatory cytokines interleukin-1β, tumor necrosis factor-α and transforming growth factor-β by synovial cells, infiltration of inflammatory cells that further stimulate inflammation, and proliferation of synovial tissue .
In general, lifestyle decisions consistent with an overall good health, i.e., regular, moderate exercise, appropriate nutrition and maintenance of a healthy body weight contribute to joint health. Measures to prevent infectious diseases possibly associated with polyarthritis are also recommended and may comprise use of repellents, acaricides and insecticides, as well as safer sex.
As per definition, polyarthritis may be diagnosed if a patient presents with five or more inflamed joints . In contrast, patients showing an inflammation of two to four joints suffer from oligoarthritis, whereas other diseases only affect one single joint and cause monarthritis .
In general, arthritis manifests in form of arthralgia, joint swelling, reduced motion ranges and possibly crepitation. This also applies to polyarthritis, a condition that is easily diagnosed based on anamnestic data and results of physical examination. However, there is an extensive list of differential diagnoses underlying polyarthritis and often, considerable efforts are required to identify the primary disorder and to choose an appropriate treatment. Polyarthritis may be the result of a myriad of generalized disorders, e.g., of autoimmune diseases, infection, endocrinologic imbalances, and, less frequently, metastatic neoplasms. As opposed to monarthritis, traumatic lesions of five or more joints are rare.
This article aims at providing information about a general approach to polyarthritis, since it is beyond its scope to discuss clinical presentation, diagnostic workup and treatment of any one differential diagnosis. The interested reader is thus referred to the respective articles. In order to illustrate the broad spectrum of diseases possibly associated with polyarthritis, rheumatoid arthritis (RA), seronegative arthritis (SNA) and systemic lupus erythematosus (SLE) shall serve as examples in determined sections of this review.
Polyarthritis is diagnosed if a patient presents with five or more inflamed joints. This condition is typically associated with joint pain, joint swelling, joint deformity, stiffness and reduced motion ranges. The skin surrounding the affected joints may be tender and reddened.
Polyarthritis may develop within the scope of a wide variety of disorders, and the aforementioned symptoms are very unspecific. Primary diseases that may be associated with polyarthritis are rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease and psoriasis - all of which are provoked by an immune reaction against the body's own tissues -, infectious diseases like Lyme disease, hepatitis B, hepatitis C and tuberculosis, as well as thyroid disorders and cancer.
Distinct parameters will be evaluated in order to identify the underlying disorder and to choose an adequate therapeutic approach. Important clinical data are relate to the course of the disease, to affected joints, the presence of inflammation and extra-articular manifestations. Treatment may comprise dietary and lifestyle adjustments, physical therapy and medication.