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Pain in and Around a Single Joint
Patients may report "joint" pain regardless of whether the cause involves the joint itself or surrounding (periarticular) structures such as tendons and bursae; in both cases, pain in or around a single joint will be referred to as monoarticular pain. Pain originating within a joint (arthralgia) may be caused by joint inflammation (arthritis). Inflammation tends to result in accumulation of intra-articular fluid (effusion) and clinical findings of warmth, swelling, and uncommonly erythema. With effusion, prompt assessment is essential to exclude infection. Acute monoarticular pain is sometimes caused by a disorder that characteristically causes polyarticular pain (eg, RA) and thus may be the initial manifestation of a polyarthritis (eg, psoriatic arthritis, RA—see page Pain in Multiple Joints).
Pain in and around a joint may involve
The synovium and joint capsule are major sources of intra-articular pain. The synovial membrane is the main site affected by inflammation (synovitis). Pain that originates from the menisci is more likely to be a result of injury.
The most common causes of acute monoarticular pain overall are the following:
With injury, a history of trauma is usually present and suggestive. Injury can affect intra-articular and/or periarticular structures and involve direct injury (eg, twisting during a fall) or overuse (eg, repetitive motion, prolonged kneeling).
Infection most often involves the joint (septic arthritis—see page Acute Infectious Arthritis), but periarticular structures, including bursae, overlying skin, and adjacent bone, also may become infected.
Among young adults, the most common causes are the following:
Among older adults, the most common nontraumatic causes are the following:
The most dangerous cause of joint pain at any age is acute infectious (septic) arthritis. Prompt drainage, IV antibiotics, and sometimes operative joint lavage may be required to minimize permanent joint damage and prevent sepsis and death.
Rare causes of monoarticular pain include osteonecrosis, pigmented villonodular synovitis, hemarthrosis (eg, in hemophilia or coagulopathies), tumors (see page Some Causes of Pain in and Around a Single Joint), and disorders that usually cause polyarticular pain, such as reactive arthritis and enteropathic arthritis.
The most common cause of periarticular pain is injury, including overuse. Common periarticular disorders include bursitis and tendinitis; epicondylitis, fasciitis, and tenosynovitis can also develop. Periarticular infection is less common.
Sometimes, pain is referred to a joint. For example, a splenic injury may cause left shoulder pain, and children with a hip disorder may complain of knee pain.
Some Causes of Pain in and Around a Single Joint
Acute monoarticular joint pain requires rapid diagnosis because infectious (septic) arthritis requires rapid treatment.
Clinical evaluation should determine whether the joint or periarticular structures are the cause of symptoms and whether there is joint inflammation. If signs of inflammation are present or the diagnosis is unclear, symptoms and signs of polyarticular and systemic disorders should be sought.
History of present illness should focus on the location of pain, acuity of onset (eg, abrupt, gradual), whether the problem is new or recurrent, and whether other joints have caused pain in the past. Also, temporal patterns (eg, persistent vs intermittent), associated symptoms (eg, swelling), exacerbating and mitigating factors (eg, activity), and any recent or past trauma to the joint should be noted. Patients should also be asked about unprotected sexual contact (indicating risk of sexually transmitted diseases), previous Lyme disease, and possible tick bites in areas where Lyme disease is endemic.
Review of systems may provide clues to systemic disorders. Review of systems should seek extra-articular symptoms of causative disorders, including fever (infection, sometimes crystal-induced arthritis), urethritis (gonococcal arthritis or reactive arthritis), rash or eye redness (reactive or psoriatic arthritis), history of abdominal pain and diarrhea (inflammatory bowel disease), and recent diarrhea or genital lesions (reactive arthritis).
Past medical history is most likely to be helpful if pain is chronic or recurrent. Past medical history should identify known joint disorders (particularly gout and osteoarthritis), conditions that may cause or predispose to monoarticular joint pain (eg, bleeding disorder, bursitis, tendinitis), and disorders that can predispose to a joint disorder (eg, sickle cell disease or chronic corticosteroid use predisposing to osteonecrosis). Drug history should be reviewed, particularly for use of anticoagulants, quinolone antibiotics (tendinitis), or diuretics (gout). A family history should also be obtained (some spondyloarthropathies—see page Overview of Seronegative Spondyloarthropathies).
A complete physical examination is done. All major organ systems (eg, skin and nails, eyes, genitals, mucosal surfaces, heart, lungs, abdomen, nose, neck, lymph nodes, neurologic system) should be examined, as well as the musculoskeletal system. Vital signs are reviewed for fever. Examination of the head, neck, and skin should note any signs of conjunctivitis, psoriatic plaques, tophi, or ecchymoses. Genital examination should note any discharge or other findings suggesting sexually transmitted diseases.
Because involvement of other joints can be clues to a polyarthritis and a systemic disorder, all joints should be inspected for tenderness, deformities, erythema, and swelling.
Palpation helps determine the location of tenderness. Palpation also helps detect joint effusion, warmth, and bony hypertrophy. The joint can also be compressed without flexing or extending it. Range of motion is assessed actively and passively, with attention to the presence of crepitus and whether pain is triggered by joint motion (passive as well as active). For injuries, the joint is stressed with various maneuvers (as tolerated) to identify disruption of cartilage or ligaments (eg, in the knee, valgus and varus tests, anterior and posterior drawer tests, Lachman test, McMurray test). Findings should be compared with those in the contralateral unaffected joint to help detect more subtle changes. Noting whether the tenderness is directly over the joint line or adjacent to it or elsewhere is particularly helpful in determining whether pain (particularly when the knee is involved) is articular or periarticular.
Large effusions in the knee are typically readily apparent. The examiner can check for minor effusions by pushing the suprapatellar pouch inferiorly and then pressing medially on the lateral side of the patella on an extended knee. This maneuver causes swelling to appear (or be palpable) on the medial side. Large knee effusions in obese patients are best detected with ballottement of the patella. In this technique, the examiner uses both hands to push in toward the center of the knee from all four quadrants and then uses 2 or 3 fingers to push the patella down into the trochlear groove and releases it. Clicking or a feeling that the patella is floating suggests an effusion.
Periarticular structures also should be examined for point tenderness, such as at the insertion of a tendon (enthesitis), over a tendon (tendinitis), or over a bursa (bursitis). With some types of bursitis (eg, olecranon, prepatellar), swelling and sometimes erythema may be localized at the bursa.
The following findings are of particular concern:
Recent significant trauma suggests that injury is the cause (eg, fracture, meniscal tear, or hemarthrosis). However, trauma does not rule out other causes, and patients often mistakenly attribute newly developed nontraumatic pain to an injury. Testing is often necessary to rule out serious causes and establish the diagnosis.
Acuteness of onset is an important feature. Severe joint pain that develops over hours suggests crystal-induced arthritis or, less often, infectious arthritis. Previous attacks of rapid-onset monarthritis suggest recurrence of crystal-induced arthritis, particularly if that diagnosis had been confirmed previously. Gradual onset of joint pain is more typical of RA or noninfectious arthritis. Gradual onset, although uncommon in acute bacterial infectious arthritis, can occur in certain infectious arthritides (eg, mycobacterial, fungal).
Whether pain is intra-articular, periarticular, or both (eg, in gout, which can affect intra- and extra-articular structures) and whether there is inflammation are key determinations, based mainly on physical findings. Pain during rest and on initiating activity suggests joint inflammation, whereas pain worsened by movement and relieved by rest suggests mechanical or noninflammatory disorders (eg, osteoarthritis). Pain that is worse with passive as well as active joint motion on examination, and that restricts joint motion, usually indicates inflammation. Increased warmth and erythema also suggest inflammation, but these findings are often insensitive, so their absence does not rule out inflammation. Pain that worsens with active but not passive motion may indicate tendinitis or bursitis, as can tenderness or swelling localized over a bursa or tendon insertion site. Tenderness or swelling at only one side of a joint, or away from the joint line, suggests an extra-articular origin (eg, tendons or bursae); localized joint line tenderness or more diffuse involvement of the joint suggests an intra-articular cause. Compressing the joint without flexing or extending it is not particularly painful in patients with tendinitis or bursitis but is quite painful in those with arthritis.
Involvement of the first metatarsophalangeal joint (podagra) suggests gout but can also result from infectious arthritis, reactive arthritis, or psoriatic arthritis.
Symptoms indicating dermatologic, cardiac, or pulmonary involvement suggest disorders that are systemic and more commonly result in polyarticular joint pain.
Joint aspiration (arthrocentesis) for synovial fluid examination should be done in patients with joint effusion. Synovial fluid examination includes WBC count with differential, Gram stain and cultures, and microscopic examination for crystals using polarized light. Finding crystals in synovial fluid confirms crystal-induced arthritis but does not rule out coexisting infection. A noninflammatory synovial fluid (eg, < 1000/µL WBCs) is more suggestive of osteoarthritis or trauma. Hemorrhagic fluid is consistent with hemarthrosis. Synovial fluid WBC counts can be very high (eg, > 50,000/µL WBCs) in both infectious and crystal-induced arthritis.
For some patients with prior confirmed gouty arthritis, a recurrent episode may not require any testing. However, if infection is a reasonable possibility, or if symptoms do not rapidly resolve after appropriate therapy for gouty arthritis, arthrocentesis should be done.
X-rays rarely change the diagnosis in acute monarthritis unless fracture is suspected. X-rays may reveal signs of joint damage in patients with a long history of recurrent arthritis. Other imaging tests (eg, CT, bone scan, but most often MRI) are rarely necessary acutely but may be indicated for diagnosis of certain specific disorders (eg, osteonecrosis, tumor [see Table: Some Causes of Pain in and Around a Single Joint], occult fracture, pigmented villonodular synovitis).
Blood tests (eg, ESR, rheumatoid factor, anti-cyclic citrullinated peptide [anti-CCP] antibody) may help support a clinically suspected diagnosis of a systemic inflammatory disorder (eg, RA). Serum urate level should not be used to diagnose gout; because it is neither sensitive nor specific and does not necessarily reflect intra-articular urate levels.
Overall treatment is directed at the underlying disorder. IV antibiotics are usually given immediately or as soon as possible if acute bacterial infectious arthritis is suspected.
Joint inflammation is usually treated symptomatically with NSAIDs. Pain without inflammation is usually more safely treated with acetaminophen. Adjunctive treatment for pain can include joint immobilization with a splint or sling and heat or cold therapy.
Physical therapy after the acute symptoms have lessened is useful to increase or maintain range of motion and strengthen adjacent muscles.
Arthrocentesis is mandatory to rule out infection in acute monoarticular joint pain with swelling.
Infection is the most common cause of acute nontraumatic monarthritis in young adults, whereas osteoarthritis is the most common cause in older adults.
Crystals in synovial fluid confirm crystal-induced arthritis but do not rule out coexisting infection.
Do not use serum urate level to diagnose gout.
Joint pain that is still unexplained after arthrocentesis and x-ray should be evaluated with MRI to rule out uncommon etiologies (eg, occult fracture, osteonecrosis, pigmented villonodular synovitis).
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