Septic arthritis
Acute septic arthritis, infectious arthritis, suppurative arthritis, pyogenic arthritis,[4] osteomyelitis, or joint infection is the invasion of a joint by an infectious agent resulting in joint inflammation. Generally speaking, symptoms typically include redness, heat and pain in a single joint associated with a decreased ability to move the joint. Onset is usually rapid. Other symptoms may include fever, weakness and headache. Occasionally, more than one joint may be involved, especially in neonates, younger children and immunocompromised individuals.[2][3][5] In neonates, infants during the first year of life, and toddlers, the signs and symptoms of septic arthritis can be deceptive and mimic other infectious and non-infectious disorders.[5]
In children, septic arthritis is usually caused by non-specific bacterial infection and commonly hematogenous, i.e., spread through the bloodstream.[6][7] Septic arthritis and/or acute hematogenous osteomyelitis usually occurs in children with no co-occurring health problems. Other routes of infection include direct trauma and spread from a nearby abscess. Other less common cause include specific bacteria as mycobacterium tuberculosis, viruses, fungi and parasites.[3] In children, however, there are certain groups that are specifically vulnerable to such infections, namely preterm infants, neonates in general, children and adolescents with hematologic disorders, renal osteodystrophy, and immune-compromised status. In adults, vulnerable groups include those with an artificial joint, prior arthritis, diabetes and poor immune function.[2] Diagnosis is generally based on accurate correlation between history-taking and clinical examination findings, and basic laboratory and imaging findings like joint ultrasound.[5]
In children, septic arthritis can have serious consequences if not treated appropriately and timely. Initial treatment typically includes antibiotics such as vancomycin, ceftriaxone or ceftazidime.[2] Surgery in the form of joint drainage is the gold standard management in large joints like the hip and shoulder.[2][5][8] Without early treatment, long-term joint problems may occur, such as irreversible joint destruction and dislocation.[2]
Signs and symptoms[edit]
Children[edit]
In children septic arthritis usually affects the larger joints like the hips, knees and shoulders. The early signs and symptoms of septic arthritis in children and adolescents can be confused with limb injury.[5] Among the signs and symptoms of septic arthritis are: acutely swollen, red, painful joint with fever.[9] Kocher criteria have been suggested to predict the diagnosis of septic arthritis in children.[10]
Importantly, observation of active limb motion or kicking in the lower limb can provide valuable clues to septic arthritis of hip or knee. In neonates/new born and infants the hip joint is characteristically held in abduction flexion and external rotation. This position helps the infant accommodate maximum amount of septic joint fluid with the least tension possible. The tendency to have multiple joint involvements in septic arthritis of neonates and young children should be closely considered.[5]
Adults[edit]
In adults, septic arthritis most commonly causes pain, swelling and warmth at the affected joint.[2][11] Therefore, those affected by septic arthritis will often refuse to use the extremity and prefer to hold the joint rigidly. Fever is also a symptom; however, it is less likely in older people.[12] In adults the most common joint affected is the knee.[12] Hip, shoulder, wrist and elbow joints are less commonly affected.[13] Spine, sternoclavicular and sacroiliac joints can also be involved. The most common cause of arthritis in these joints is intravenous drug use.[11] Usually, only one joint is affected. More than one joint can be involved if bacteria are spread through the bloodstream.[11]
Treatment is usually with intravenous antibiotics, analgesia and washout and/or aspiration of the joint.[11][13] Draining the pus from the joint is important and can be done either by needle (arthrocentesis) or opening the joint surgically (arthrotomy).[2]
Empiric antibiotics for suspected bacteria should be started. This should be based on Gram stain of the synovial fluid as well as other clinical findings.[2][11] General guidelines are as follows:
Once cultures are available, antibiotics can be changed to target the specific organism.[11][13] After a good response to intravenous antibiotics, people can be switched to oral antibiotics. The duration of oral antibiotics varies, but is generally for 1–4 weeks depending on the offending organism.[2][11][13] Repeated daily joint aspiration is useful in the treatment of septic arthritis. Every aspirate should be sent for culture, gram stain, white cell count to monitor the progress of the disease. Both open surgery and arthroscopy are helpful in the drainage of the infected joint. During surgery, lysis of the adhesions, drainage of pus, and debridement of the necrotic tissues are done.[2] Close follow up with physical exam & labs must be done to make sure the person is no longer feverish, pain has resolved, has improved range of motion, and lab values are normalized.[2][13]
In infection of a prosthetic joint, a biofilm is often created on the surface of the prosthesis which is resistant to antibiotics.[29] Surgical debridement is usually indicated in these cases.[2][30] A replacement prosthesis is usually not inserted at the time of removal to allow antibiotics to clear infection of the region.[14][30] People that cannot have surgery may try long-term antibiotic therapy in order to suppress the infection.[14] The use of prophylactic antibiotics before dental, genitourinary, gastrointestinal procedures to prevent infection of the implant is controversial.[2]
Low-quality evidence suggests that the use of corticosteroids may reduce pain and the number of days of antibiotic treatment in children.[31]
Outcomes[edit]
Risk of permanent impairment of the joint varies greatly.[13] This usually depends on how quickly treatment is started after symptoms occur as longer lasting infections cause more destruction to the joint. The involved organism, age, preexisting arthritis, and other comorbidities can also increase this risk.[14] Gonococcal arthritis generally does not cause long term impairment.[11][13][14] For those with Staphylococcus aureus septic arthritis, 46 to 50% of the joint function returns after completing antibiotic treatment. In pneumococcal septic arthritis, 95% of the joint function will return if the person survives. One-third of people are at risk of functional impairment (due to amputation, arthrodesis, prosthetic surgery, and deteriorating joint function) if they have an underlying joint disease or a synthetic joint implant.[2] Mortality rates generally range from 10 to 20%.[14] These rates increase depending on the offending organism, advanced age, and comorbidities such as rheumatoid arthritis.[13][14][15]
Epidemiology[edit]
In children and adolescence septic arthritis and acute hematogenous osteomyelitis occurs in about 1.34 to 82 per 100,000 per annual hospitalization rates.[32][33][34][35] In adults septic arthritis occurs in about 5 people per 100,000 each year.[3] It occurs more commonly in older people.[3] With treatment, about 15% of people die, while without treatment 66% die.[2]