Septic Arthritis Clinical Presentation

Because joint infections are uncommon, be especially attentive to features of the patient's history that may indicate an infectious process instead of a primary rheumatologic or orthopedic process.^[5]

Pay attention to the following symptoms:

• Acuteness of onset of the joint pain
• Whether the pain is superimposed on chronic pain
• Previous history of joint disease or trauma, whether accidental or iatrogenic (eg, infection complicates 0.4% of arthrocenteses)
• Whether the process is monoarticular or polyarticular and which joints are involved
• The presence of extra-articular symptoms
• Whether the patient has had vascular invasion due to catheterizations or intravenous drug abuse

Obtain a thorough history regarding the possible presence of sexually transmitted diseases (STDs) or exposure to ticks (Lyme disease). The increase of group B streptococcal joint infections is associated with the increased prevalence of diabetes and increasing life expectancy.

Numerous conditions that adversely affect the host's defenses (eg, liver disease, diabetes mellitus, lymphoma, solid tumors, complement deficiencies [C7, C8], immunosuppressive drugs, hypogammaglobulinemia) are increasingly observed in patients with septic arthritis. Determine the possible contribution of these diseases to the clinical presentation.

The most important historical feature is the existence of underlying joint disease, especially rheumatoid arthritis. In addition, the possibility of recent injury to the joint or penetrating or blunt trauma must be explored. Ask the patient about needle aspiration of the joint or injections of corticosteroids into the joint. Elicit a history of diarrheal disease.

Symptoms

Patients with an infected joint typically present with the triad of fever (40-60% of cases), pain (75% of cases), and impaired range of motion. These symptoms may evolve over a few days to a few weeks. Fever is usually low-grade (< 102°F), with rigors present in only 20% of cases. Spiking fevers and chills are much more common with crystalline arthritis.

Lyme disease

Months after infection onset, 60% of patients with untreated Lyme disease develop swelling and pain, chiefly affecting the large joints. Usually, Lyme disease affects 1-2 joints at a time, with the knee involved most commonly. The distinguishing pattern is attacks extending from a few weeks to months and separated by periods of complete remission. The rate of recurrence lessens by about 15% per year. A small percentage of individuals develop chronic arthritis (ie, inflammation of a joint lasting ≥ 1 y). This type of relapsing course almost always precedes the chronic stage of Lyme arthritis.

Prosthetic joint infection

Compared with patients with infections of native joints, most patients with prosthetic joint infection (PJI) exhibit a prolonged low-grade course with gradually increasing pain. However, with gram-negative infections, especially with enteric organisms, PJI may be far more acute in onset.

Usually, no significant fever or swelling occurs (delayed prosthetic joint infection). However, individuals with early prosthetic joint infection present with an acute illness characterized by high-grade fever, focal swelling, and redness. Cellulitis and draining sinus tracts often develop.

Because late prosthetic joint infection is usually secondary to bacteremia, the clinical picture is often dominated by the source of the bloodstream infection.

The nature of the invading organism, the type of tissue infected, and the route of infection determine presentation. Thus, a high index of suspicion is needed for identification of bacteremic and delayed prosthetic joint infection. Because of its many pathogenic mechanisms, S aureus is usually associated with a fulminant course, as opposed to the indolent course of coagulase-negative S aureus (CoNS) that dominates delayed prosthetic joint infection. Relatively devitalized tissues (eg, wound hematomas) are conducive to rapid bacterial replication and a more acute course. Bacteremic spread allows infection with fewer organisms and leads to a more muted course.

Reactive and tuberculous arthritides

Reactive arthritis usually begins several weeks after the underlying infection has resolved. Few concurrent systemic symptoms occur.

Symptoms of tuberculous arthritis are quite indolent; the diagnosis may be delayed for several years. Usually, the purified protein derivative (PPD) results are negative, and no signs, past or present, of pulmonary tuberculous exist.

Viral septic arthritis

Table 1, below, provides a summary of the clinical features of septic arthritis caused by various viral organisms.

Table 1. Clinical Features of Viral Septic Arthritis (Open Table in a new window)

The most commonly involved joint in septic arthritis is the knee (50% of cases), followed by the hip (20%), shoulder (8%), ankle (7%), and wrists (7%). The elbow, interphalangeal, sternoclavicular, and sacroiliac joints each make up 1-4% of cases.

A thorough inspection of all joints for signs of erythema, swelling (90% of cases), warmth, and tenderness is essential for diagnosing infection. Infected joints usually exhibit an obvious effusion, which is associated with marked limitation of both active and passive ranges of motion (ROMs). Frequently, these findings are apparent but may be diminished or poorly localized in cases of infection of the spine, hip, and shoulder joints.^[14]

Signs and symptoms of infection may be muted in people who are elderly, who are immunocompromised (especially those with rheumatoid arthritis), and who abuse intravenous drugs.

Pattern of joint involvement

Nongonococcal bacterial/suppurative arthritis

The pattern of joint involvement is an extremely important diagnostic feature. Of cases of nongonococcal suppurative arthritis, 85-90% are monoarticular. If the disease affects more than one joint, S aureus is most commonly implicated. Polyarticular arthritis is usually observed in gonococcal disease, various viral infections, Lyme disease, reactive arthritis, and various noninfectious processes. Gonococcal arthritis may be part of the gonococcal arthritis/dermatitis syndrome.

Group B streptococci most commonly infect the sacroiliac and sternoclavicular joints.

Gonococcal bacterial/suppurative arthritis

Gonococcal musculoskeletal involvement may present in 1 of 2 ways, as described below.

Fever, arthralgias of multiple joints, and multiple skin lesions (dermatitis-arthritis syndrome) characterize disease that develops soon after the gonococcus disseminates from the cervix, urethra, or pharynx. Usually, this disease exhibits no clinical direct joint findings, but the process is one of tenosynovitis of asymmetric distribution. Typically, hand joints are involved most often, as well as those of the knee, wrist, ankle, and elbow. Skin lesions are multiple but seldom number more than 12, whereas lesions associated with meningococcemia may number more than 100. The lesions evolve over a few days from papular to pustular or vesicular to necrotic. This course may recur for several months. Findings on cultures of blood and mucosal surfaces are often positive; findings on cultures of joint fluid are usually negative. Sixty percent of disseminated gonococcal infections are of this type.

Monoarticular arthritis without associated systemic symptoms, tenosynovitis, or skin lesions characterizes disease that begins later after gonococcal dissemination than does dermatitis arthritis syndrome.^[7] Dermatitis-arthritis syndrome may or may not precede this phase. In a joint infected by the Lyme organism, swelling may be disproportionate to the level of pain. Baker cysts are a frequent feature of this type of infectious arthritis. Because the pain of an infected hip joint may not be localized directly and swelling of the joint is inconspicuous, perform specific maneuvers, such as the Fabere maneuver. Infection of the sacroiliac joint often presents as buttock, hip, or anterior thigh pain. Direct pressure usually elicits tenderness in the joint. Alternatively, hyperextension of the hip and leg while the patient is lying down (ie, Gaenslen maneuver) elicits pain in a suppurative sacroiliac joint.

Septic bursitis most commonly involves the olecranon and prepatellar bursae. Swelling and pain are present. However, an infected bursa does not limit the range of motion of the underlying joint the way an actual joint infection does.^[18]

Prosthetic joint infections

Physical findings are usually minimal in an infection of the prosthetic joint, and swelling is usually slight. The most distinctive finding is a draining sinus presumed to originate in the underlying infected prosthetic joint.

Reactive, viral, and tuberculous arthritides

Most cases of reactive arthritis involve a few large joints in an asymmetric fashion, whereas viral arthritis usually exhibits symmetric involvement of the smaller joints, especially the hands, with a concurrent rash. The joints of tuberculous arthritis can appear to be boggy on palpation.