Ver el código de «Monoarticular arthritis»

==Background==
*Monoarticular arthritis (monoarthritis) refers to inflammation of a single joint<ref>Genes N, Chisolm-Straker M. Monoarticular arthritis update: Current evidence for diagnosis and treatment in the emergency department. Emerg Med Pract. 2012 May;14(5):1-19; quiz 19-20. PMID 22670394</ref>
*The critical EM question is: Is this septic arthritis?
*Septic arthritis is a joint emergency requiring urgent drainage — delay increases risk of joint destruction
*Other common causes include crystal arthropathy ([[gout]], [[pseudogout]]) and traumatic hemarthrosis<ref>Keret S, et al. Approach to a patient with monoarticular disease. Autoimmun Rev. 2021 Jul;20(7):102848. PMID 33971340</ref>
*[[Arthrocentesis]] is the key diagnostic procedure and should be performed on any hot, swollen joint without clear alternative diagnosis

==Clinical Features==
===History===
*Onset (acute vs. subacute), joint involved, trauma history
*Prior episodes (recurrent suggests crystal disease)
*Fever, chills, constitutional symptoms
*Recent infection, skin break, surgery, or injection
*Sexual history (disseminated gonococcal infection)
*History of gout, pseudogout, or autoimmune disease
*Immunosuppression, IV drug use, prosthetic joint

===Physical Exam===
*Joint warmth, erythema, effusion, decreased range of motion
*Pain with passive range of motion (highly suggestive of intra-articular process)
*Overlying skin: cellulitis, track marks, surgical scars, tophi
*Assess for signs of systemic infection
*Examine other joints (polyarticular process may present initially as monoarticular)

===Red Flags for Septic Arthritis===
*Fever with acute monoarthritis
*Recent bacteremia, skin infection, or surgical procedure
*Prosthetic joint with new pain/swelling
*Immunosuppressed patient
*IV drug use
*Non-weight-bearing or unable to flex joint

==Differential Diagnosis==
{{Differential Diagnosis Monoarthritis}}

===[[Septic Arthritis]]===
*[[Gonococcal arthritis]]
*Nongonococcal Arthritis
*Arthritis-Dermatitis Syndrome

===Crystal-Induced Monoarthritis===
*[[Gout]]
*[[Pseudogout]]

===Traumatic===
*[[Fracture]]
*Ligamentous injury
*Overuse

===Ischemic===
*[[Avascular necrosis]]
*[[Decompression sickness]]
*Spontaneous osteonecrosis
**Pain in absence of trauma
**Femoral head, medial condyle of knee

===Hemorrhagic===
*Posttraumatic
*[[Hemophilia]]
*Systemic [[anticoagulation]]

===Neoplastic===
*Metastases
*Osteochondroma
*Osteoid osteoma
*Pigmented villonodular synovitis

===Systemic Disease===
*Remote infection, infectious [[endocarditis]]
*[[Rheumatic fever]]
*Seronegative (no RF) spondyloarthropathies ([[ankylosing spondylitis]], [[IBD]], [[psoriatic arthritis|psoriatic]], [[reactive arthritis]])
*[[Rheumatoid arthritis]], [[SLE]]

===Periarticular (Non-Articular)===
*[[Bursitis]]
*[[Tendinitis]]
*[[Cellulitis]]

==Evaluation==
===Arthrocentesis (Key Diagnostic Study)===
*Perform [[arthrocentesis]] on any acute hot, swollen joint unless clear alternative diagnosis
*'''Do not delay arthrocentesis for imaging'''
*Overlying cellulitis is a relative contraindication — consult orthopedics

===Synovial Fluid Analysis===
{{Arthrocentesis diagnostic chart}}
*WBC >50,000/mm³ with >90% PMNs: highly suggestive of septic arthritis
*Crystals: negatively birefringent (gout), positively birefringent (pseudogout)
*Note: crystals and infection can coexist — always send culture even if crystals present
*Gram stain: positive in ~50% of non-gonococcal septic arthritis
*Culture: gold standard; also send blood cultures

===Laboratory===
*[[CBC]] with differential, [[ESR]], [[CRP]]
*Blood cultures (positive in ~50% of septic arthritis)
*[[Uric acid]] (may be normal during acute gout flare)
*GC/CT NAAT if disseminated gonococcal infection suspected

===Imaging===
*X-ray of affected joint: chondrocalcinosis (pseudogout), fracture, joint destruction
*Ultrasound: confirm effusion, guide arthrocentesis
*MRI if osteomyelitis or periarticular abscess suspected

==Management==
===Septic Arthritis===
*Emergent orthopedic consultation for surgical drainage/washout
*Empiric IV antibiotics after arthrocentesis:
**[[Vancomycin]] (MRSA coverage) for most patients
**Add gram-negative coverage ([[ceftriaxone]] or [[cefepime]]) for immunocompromised, elderly, or IV drug users
**[[Ceftriaxone]] alone if gonococcal arthritis suspected
*Prosthetic joint infection: orthopedic consultation for operative management

===Crystal Arthropathy===
*[[Gout]]: NSAIDs ([[indomethacin]], [[naproxen]]), [[colchicine]], or [[corticosteroids]] (PO or intra-articular)
*[[Pseudogout]]: NSAIDs, [[colchicine]], or intra-articular/systemic corticosteroids
*Avoid [[allopurinol]] initiation or changes during acute flare

===Traumatic===
*Splinting, pain management
*Orthopedic follow-up for hemarthrosis or fracture

==Disposition==
===Admit===
*Septic arthritis (for surgical drainage and IV antibiotics)
*Prosthetic joint infection
*Sepsis from joint source
*Unable to rule out septic arthritis with pending cultures in high-risk patient

===Discharge===
*Crystal arthropathy with adequate pain control
*Traumatic arthritis/hemarthrosis with orthopedic follow-up arranged
*Provide return precautions: fever, worsening pain/swelling, inability to bear weight
*Primary care or rheumatology follow-up for gout/pseudogout management

==See Also==
*[[Septic arthritis]]
*[[Gout]]
*[[Pseudogout]]
*[[Arthrocentesis]]
*[[Gonococcal arthritis]]

==External Links==

==References==
<references/>

[[Category:Orthopedics]]
[[Category:Symptoms]]
[[Category:Rheumatology]]