Joint Pain: One / Few Joints

Pain in Just One Joint — First, rule out an Emergency:

New onset of acute, single red, hot, swollen joint could be Septic Arthritis

• Bacteria in joint (usually Staph) — very destructive; can spread to blood (& be lethal)
• Almost always with fever (except the very elderly)

Conditions that may look like septic arthritis, but aren’t: Bursitis, Cellulitis, Hemarthrosis (blood in joint).  To rule-out Septic Arthritis:

• If examiner can wiggle a relaxed joint in one or another direction without pain, unlikely to be true arthritis (joint disease).  May be bursitis — see topic Musculoskeletal Pain.
• If same as above, but especially if pain with lightly scratching red, hot skin, or stretching skin without moving joint, likely Cellulitis (bacterial skin infection)
• Hemarthrosis occurs with trauma, also if bleeding disorder like Hemophilia

The vast majority of patients with Septic Arthritis have a risk factor:

* Age >80 * Rheumatoid Arthritis * Known chronic joint disease gg

* Skin Infection * Diabetes * Prosthetic (artificial) Joint gg

* Recent joint surgery * Recent steroid injection * Injection Drug Use  * Alcoholism

Diagnosis of Septic Arthritis:  aspirate fluid from joint, in ER

• If high white cell count (suggests bacteria), IV antibiotics pending results of culture
• Joint aspiration diagnoses Hemarthrosis if fluid very bloody

If no suggestion of Septic Arthritis, continue on below

Pain in just One, or a Few, Joints
(Monoarticular / Oligoarticular Arthritis

Causes of Monoarticular *** / Oligoarticular Arthritis

*** NOTE — This assumes that if only one joint is inflamed, we’ve ruled out the possibility of Septic Arthritis.

More Common	Less Common
* Osteoarthritis * Gout * Pseudogout * Psoriatic Arthritis * Lyme Arthritis * Rheumatoid Arthritis	* Reactive Arthritis * Sarcoidosis (esp. both ankles) * Behçet’s Syndrome * Still’s Disease (Adult) * Inflammatory Bowel Disease * Avascular Necrosis (hip)

Diseases Diagnosed and Treated by Generalist Clinicians

Most Common Cause  —  Osteoarthritis (a.k.a. Degenerative Joint Disease [DJD])

• Elderly (usually begins >60 y.o.)
• Develops very gradually
• Almost never causes acute pain or flares
• Mostly knees, hips, fingers, feet, and spine
• Easily diagnosed by X-Ray

Gout and Pseudogout cause recurrent Attacks (or Flares)

KNEE  —  Aspirate joint to diagnose Gout or Pseudogout.  Examine fluid for:

• Crystals  —  need special polarizing microscope to distinguish between the two
• White Blood Cell counts — in case there’s really a Septic Arthritis.
• Gram Stain & Culture — in case there’s really a Septic Arthritis.

X-Ray can sometimes identify Pseudogout

Note:  Lots of swollen knees are really bursitis, not true arthritis (joint disease).  See Monoarticular Arthritis — Full Text, see also Musculoskeletal Pains.

BIG TOE  —  Probably Gout.  Hard to aspirate.  Order blood test for Uric Acid, but beware:

• Many people who’ll never get gout have a high uric acid
• Up to 40% of Gout sufferers may have a normal uric acid during attack
• Best time to check uric acid:  >2 weeks after the attack completely gone

ANKLE  —  Same as Big Toe.

• New arthritis in both ankles together suggests Sarcoidosis (diagnose by chest x-ray)

HIP  —  Usually Osteoarthritis

• Rarely Avascular Necrosis (bone death loss of blood supply) from alcoholism, chronic steroids, Sickle Cell, Lupus, advanced HIV, others (including some just in children)
• May be seen on X-ray; MRI is better
• Refer to Orthopedist for surgery

Referral to Rheumatology

Most types of Arthritis are diagnosed by Clinical Clues, NOT by lab tests or x-rays

• Rheumatologists have the experience
• Still, same labs as for Polyarthritis (which may begin in one or few joints)
• Joint x-rays to look for destruction

Clinical Clues for diagnosing Monoarticular or Oligoarticular Arthritis

**  History of Flares  —  Patterns & duration of recurrences are key:

• First Toe, lasting 1-2 wks: Gout
• Knee:  Gout or Pseudogout
• Behcet’s Syndrome flares with ulcers in genitals &/or mouth, lasts 1-3 weeks
• Late Lyme Arthritis may occur on and off (esp. the knee)

**  Psoriasis  —  Diagnose  Psoriatic Arthritis if also has Psoriasis

• silvery-white scaly plaques (usually backs of the elbows, fronts of the knees, scalp, Achilles tendon, or sacrum), PLUS:
• Finger arthritis in the far joint
• Nail pits
• “Sausage Digits” (fingers / toes that taper at the ends)

**  Age >65 at Onset  —  Pseudogout

• Usually involves the knee
• May cause as intermittent flares
• May look like chronic osteoarthritis in joints where that disease would be very unusual (knuckles, wrists, elbows, shoulders)

**  Oral / Genital Ulcers  —  Behçet’s Syndrome

• Arthritis tends to occur during ulcer flares
• Medium-sized joints:  knees, ankles, wrists
• Turkish descent, or ancestors from the “Silk Road” (Arabic Peninsula on through Iran & the Indian subcontinent, to China-Korea-Japan)

**  History of Diarrhea (chronic / bloody)  —  Inflammatory Bowel Disease

• Arthritis / Arthralgias tends to occur early in disease

**  Recent Bacterial Diarrheal Infection or Genital Chlamydia  —  Reactive Arthritis

• Infection occurred days to weeks before arthritis
• Large / medium joints usually
• Also swelling at heel
• Keratoderma blennorrhagica — thick, scaly plaques on palms / soles

**  Lived in Lyme Disease area  —  we’d wonder about Late Lyme Disease

• Visible swelling (knee, shoulder, ankle, elbow, wrist, TMJ)
• <5 joints; NOT symmetrical
• History of attacks lasting weeks – months
• Positive blood test for Lyme Antibody IgG  [including confirmation with Western Blot].  A hard diagnosis, since many people who live in Lyme Disease areas have positive blood tests without any symptoms or complications (most people get cured on their own)

**  Eye Disease (Painful: iritis, uveitis, episcleritis, scleritis)  —  we’d consider various possibilities

• Psoriatic Arthritis
• Reactive Arthritis
• Behçet’s Syndrome
• Sarcoidosis

**  Dactylitis (“sausage digits”)  —  we think:

• Reactive Arthritis
• Psoriatic Arthritis
• Sarcoidosis chronic)

**  Enthesitis  (inflammation where tendon/ligament meets bone)  [esp. heel]  —  we think:

• Reactive Arthritis
• Psoriatic Arthritis

**  Erythema Nodosum  (painful red nodules on shins)  —  we think:

• Reactive Arthritis
• Sarcoidosis (acute)
• Behçet’s Syndrome

**  Intermittent Fevers (lasting ≥1 week)  —  we think Still’s Disease

• salmon-colored maculopapular rash may come & go during fever

See Joint Pain: Just One / Few Joints — Full Text for more in-depth explanations and discussions