Joint Pain and Approaches to Arthritis

Question 1

___ are the most common type of joint in the body.

Answer 1

Synovial joints are the most common type of joint in the body.

Question 2

Three types of joints

Answer 2

Synovial

Fibrous

Cartilagenous

Question 3

The key feature that distinguishes synovial joints from fibrous and cartilagenous joints is the presence of ____.

Answer 3

The key feature that distinguishes synovial joints from fibrous and cartilagenous joints is the presence of a joint cavity.

Question 4

Articular capsule

Answer 4

Question 5

Articular cartilage is always made of ____.

Answer 5

Articular cartilage is always made of hyaline cartilage.

Question 6

Synovial fluid

Answer 6

“synovia” = thick fluid

A thick, slimy fluid that provides further lubrication in synovial joints. Also nourishes the articular cartilage, which is avascular. Essentially an ultra-filtrate of plasma with some added proteins secereted by synoviocytes, including hyaluronate.

Question 7

All synovial joints are functionally classified as ____.

Answer 7

All synovial joints are functionally classified as diarthroses.

Question 8

diarthrosis

Answer 8

A joint which permits free, unrestricted movement

Question 9

Extrinsic ligament

Answer 9

Located outside the articular capsule of the joint it holds together.

Question 10

Intrinsic ligament

Answer 10

Fused or incorporated into the articular capsule of the joint which it holds together.

Question 11

Intracapsular ligament

Answer 11

Ligament which is located inside of the articular capsule of the joint it holds together.

Question 12

Sagittal knee joint diagram

Answer 12

Question 13

Articular disc

Answer 13

Fibrocartilagenous structure located inbetween articulating bones. Generally small and oval- or meniscus-shaped. May provide shock absorption.

Sometimes unites bones together and prevents movement, such as at the sternoclavicular joint or the distal radial-ulnar joint.

Question 14

Bursa

Answer 14

Thin connective tissue filled with lubricating fluid. Located in regions where skin, ligaments, muscles, or muscle tendons can rub against each other, usually near a body joint. Classified based on location relative to the joint.

Question 15

Subcutaneous bursa

Answer 15

Located between skin and underlying bone. Allows skin to move over bone smoothly.

Question 16

Submuscular bursa

Answer 16

Found between muscle and underlying bone. Prevents rubbing of the muscle during movements.

Ex, the trochanteric bursa

Question 17

Subtendinous bursa

Answer 17

Located between tendon and underlying bone.

Question 18

Articular cartilage

Answer 18

Hypocellular, viscoelastic (due to water and proteoglycan) tissue that lines synovial joints. The articular surface is made of dense collagen of low proteoglycan content.

No basement membrane, innervation, or vascular supply.

Question 19

During gentle walking, the force experienced by the hip joint is roughly equivalent to ___.

Answer 19

During gentle walking, the force experienced by the hip joint is roughly equivalent to 4 times the body weight of the individual.

Question 20

What happens to the articular cartilage during loading?

Answer 20

Water exudes from proteoglycans and mixes with hyalonurate-rich synovial fluid.

The resulting coeffient of friction produced by this process is 1/5 that of the smooth ice-smooth ice coefficient of friction.

Question 21

The integrity of the articular cartilage matrix is maintained by ___.

Answer 21

The integrity of the articular cartilage matrix is maintained by chondrocytes.

Question 22

Articular cartilage is bound to the underlying bone through ____.

Answer 22

Articular cartilage is bound to the underlying bone through a narrow calcified zone of cartilage.

Question 23

High loading of a healthy joint is unlikely alone to ____

Answer 23

High loading of a healthy joint is unlikely alone to initiate joint disease

Question 24

Disuse of a joint leads to ___.

Prolonge ___ may even lead to ___.

Answer 24

Disuse of a joint leads to atrophy of the articular cartilage.

Prolonged atrophy may even lead to replacement of the articular cartilage with fibro-fatty tissue.

Question 25

All connective tissues, including cartilage, respond to \_\_\_.

Answer 25

All connective tissues, including cartilage, respond to **the mechanical forces placed upon them and, in general, extra use leads to hypertrophy and mechanical strengthening**

Question 26

Synovial membrane

Answer 26

1-3 cells thick. Forms the surface layer of the synovial tissue, but is otherwise not particularly distinct from it.

Question 27

Deep synovial tissue is made up of . . .

Answer 27

* Many vascular vessels * Many fat-rich cells * Low cell count outside of a discontinuous layer of synovial intimal (aka synoviocytes) cells on the internal joint surfaces * Synoviocytes line all surfaces apart from cartilage and menisci * Aspiratable volume of only 0-4 mL of fluid

Question 28

Changes in the loading-capability of one joint have effects on \_\_\_.

Answer 28

Changes in the loading-capability of one joint have effects on **the loading-capability of other joints.**

Question 29

Hyaluronate

Answer 29

Produced by synoviocytes. Present in synovial fluid. A linear, repeating disaccharide of β-D-gluconuryl-β-D-N-acetyl-glucosamine. Very high molecular weight, greater than 10 megadaltons. Forms the central axis of the proteoglycan aggregates in synovial fluid which provides integrity to articular cartilage and other extracellular matrices of the synovium. It is the main component responsible for synovial fluid's visco-elastic properties.

Question 30

How fluid accumulates in the synovium

Answer 30

The synovium has a high osmotic potential as a result of all of the proteins, proteoglycans, and carbohydrates secreted into it by synoviocytes.

Question 31

Synovium in rheumatoid arthritis

Answer 31

Undergoes massive hyperplasia to form a complex, villous structure extending into the synovial space, a thickened cell lining layer, and infiltration of many leukocytes which then form lymphoid follicles. Acute inflammation of the synovium can result in proteolytic cleavage of the articular cartilage and intracapsular ligaments. Inflammatory cytokines also activate ostoclasts to resorb bone, causing the bone erosion characteristic of RA.

Question 32

Basic clinical characterization of arthritis

Answer 32

1. Is it true arthritis? Or is it extra-articular? (Bursitis, etc) 2. Inflammatory or Non-inflammatory? 3. Duration (acute, subacute, or chronic?) 4. Number of joints (if multiple, is it symmetrical?) 5. Accurate delineation of involved joints

Question 33

Synovial fluid WBC count is ___ in non-inflammatory arthritis and ___ in inflammatory arthritis. This is evaluated by \_\_\_.

Answer 33

Synovial fluid WBC count is **\<****2000 /****μL**in non-inflammatory arthritis and**\>2000 / μL**in inflammatory arthritis. This is evaluated by**arthrocentesis**.

Question 34

Patients with an inflammatory arthritis usually complain of. . .

Answer 34

. . . **pain and stiffness** in involved joints; typically these symptoms are **worse in the morning or after periods of inactivity** and **improve with mild to moderate activity.**

Question 35

Patients with non-inflammatory arthritis have pain that \_\_\_, with ___ stiffness.

Answer 35

. . . **worsens with activity** **and improves with rest, with mild (\<30 minutes in the morning) stiffness.**

Question 36

Constitutional symptoms in arthritis

Answer 36

* **Fever**: raises **possibility of arthritis due to infection**, but is **not totally specific.** * Constitutional symptoms **rarely ever accompany non-inflammatory arthritis.**

Question 37

Family history in arthritis

Answer 37

* Positive family history increases likelihood of certain forms of arthritis * **Ankylosing spondylitis** especially (~75 fold risk of general pop.) * **Systemic lupus erythematosus** (~20-30 fold risk of general pop.) * **Less helpful** for **rheumatoid arthritis** (~3 fold risk of general pop.) * **_Osteoarthritis is often misdiagnosed as rheumatoid arthritis_** due to confounding with family history of rheumatoid arthritis.

Question 38

Extra-articular manifestations in arthritis

Answer 38

* Kidney abnormalities, pulmonary abnormalities, oral ulcerations, ocular inflammation, peripheral neuropathy * Presence of rash * May signal that the arthritis is due to systemic rheumatic disease or vasculitis

Question 39

Essential features of acute monoarthritis

Answer 39

* Septic arthritis is the marajor diagnostic concern * Arthrocentesis is the most important diagnostic test

Question 40

Acute arthritis

Answer 40

* Except in cases of trauma, acute arthritis is **usually inflammatory** * Septic and crystal arthritis have acute onset * History is very helpful differentiating

Question 41

Acute monoarthritis differential

Answer 41

* Septic arthritis * Crystal arthritis * Trauma-induced arthritis * Joint-space infection

Question 42

\_\_\_ is the foremost concern in patients with acute pain and swelling in a single joint not clearly due to trauma.

Answer 42

**Infection** is the foremost concern in patients with acute pain and swelling in a single joint not clearly due to trauma.

Question 43

Laboratory evaluation for acute monoarthritis

Answer 43

* Indicated for all unexplained cases * Arthrocentesis: Send synovial fluid for * Culture * WBC count * Gram stain * Examination for crystals by **polarized light microscopy**

Question 44

Synovial fluid WBC count \>50,000/μL

Answer 44

Likely septic arthritis, possibly crystal arthritis

Question 45

Synovial fluid WBC count \<50,000/μL, but \>2,000/μL

Answer 45

Likely crystal arthritis

Question 46

Gram stain for bacteria in arthrocentesis

Answer 46

False negatives are high (25-50%), and so false negatives **do not exclude bacterial arthritis** Also, **finding of crystals does not exclude infection**. They may occur simultaneously.

Question 47

Essential features of chronic arthritis

Answer 47

* Distinguishing inflammatory from non-inflammatory etiology is key * Rheumatoid and osteoarthritis are the leading causes * Careful delineation of joints involved is key

Question 48

Imaging for acute arthritis

Answer 48

May be useful to locate fractures in traumatic monoarticular arthritis, but of little utility with no history of trauma, **if the process is truly acute**. More likely to be misleading for acute, nontraumatic monoarticular arthritis.

Question 49

\_\_\_ is the leading cause of chronic noninflammatory monoarthritis,

Answer 49

**Osteoarthritis** is the leading cause of chronic noninflammatory monoarthritis, Especially when the **hip, knee, first carpometacarpal joint, or acromioclavicular joint** is involved

Question 50

Chronic arthritis differential

Answer 50

Question 51

Chronic polyarthritis of the hand

Answer 51

* Radiographs are indicated **at time of presentation** * May show primary generalized osteoarthritis, calcium pyrophosphate deposition (pseudogout), or chronic tophaceous gout * Delayed/late imaging of rheumatoid arthritis or spondylarthropathies may also show changes on radiograph

Question 52

Psoriatic arthritis typically involves ___ joints.

Answer 52

Psoriatic arthritis typically involves **DIP** joints.

Question 53

Factors that make laboratory tests for rheumatic disease difficult

Answer 53

* They share many characteristic inflammatory markers with other inflammatory diseases, infection, and malignancies * Prevalence of certain rheumatic diseases is low in most populations, so even if sensitivity and specificity of a test are high, positive predictive value may be low.

Question 54

Osteoarthritis and rheumatoid arthritis have \_\_\_\_.

Answer 54

Osteoarthritis and rheumatoid arthritis have **different patterns of joint involvement**. **Osteo: DIPs, PIPs, first metacarpal, but _NOT_ MCPs, wrists, elbows, ankles** **Rheumatoid: PIPs, MCPs, and the wrist, but _NOT_ DIPS or thoracid and lumbosacral spine** Both may affect large joints like the hip and knee

Question 55

Laboratory Tests for Arthritis

Answer 55

* ELISA or other immunspecific test for autoantibodies * Acute phase response-mediator measurement (CRP or ESR) * CRP: Measure serum CRP as a proxy for IL-6, IL-1, TNF, etc * ESR: erythrocyte sedimentation rate, effectively measures blood fibrinogen levels

Question 56

CRP levels

Answer 56

* Increase with infection (specifically acute phase, peaks 48 hr, declines within 18 hours following) * Increase with age * Increase with BMI * Can suggest inflammatory process, but is quite nonspecific within that category * Still, may be a useful indicator of progression of certain autoinflammatory diseases such as rheumatoid arthritis

Question 57

Erythrocyte sedimentation rate

Answer 57

* Allow anticoagulated blood to sediment for 1 hr in a glass tube * Reference range: **0-10 mm/hr in males, 0-15 mm/hr in females** * Upper limits of normal range increase with **age and BMI** * Effectively a measure of **fibrinogen** and other proteins that act as part of the acute phase response to increase sedimentation/coagulability. * Has a slower rate of increase following acute phase induction than CRP * May be influenced by conditions other than acute phase response (anything that increases coagulability: **pregnancy, anemia, kidney disease, obesity, hypercholesterolemia**)

Question 58

Likely cause of joint pain in a patient with a history of. . . Trauma: \_\_\_ Overuse: \_\_\_ Inflammation: \_\_\_

Answer 58

Likely cause of joint pain in a patient with a history of. . . Trauma: **could be any really, but this is the one case in which bone fracture may be involved** Overuse: **Bursitis or tendonitis** Inflammation: **Bursitis, synovitis, tendonitis**

Question 59

Cutaneous distribution of C5, C6, C7, and C8 spinal nerves

Answer 59

Question 60

Answer 60

**Osteoarthritic cartilage** Note: The **mechanical damage** to the cartilage (frayed surface), the **hypertrophy of the chondrocytes**, and the **lack of inflammatory cells**

Question 61

The majority of white blood cells present in rheumatoid arthritis arthrocentesis will be . . .

Answer 61

. . . **neutrophils**. This is another difference between osteoarthritis and rheumatoid arthritis.

Question 62

A parient presents with arthritis. It is unclear from history and physical exam whether it is osteoarthritic or rheumatoid arthritic in origin. You take an aspirate sample and do a WBC count. The count comes back as exactly 2,000 per μL, with 20% PMN. What is the likely diagnosis?

Answer 62

The 2,000 per μL is not particularly helpful, but the **low PMN content** suggests that this is an **osteoarthritic** process, as rheumatoid WBC infiltrate is usually neutrophil predominant.

Question 63

Findings of osteoarthritis on X-ray

Answer 63

* **Joint space narrowing** * **Sclerosis** (Increase in density of bones on articular surface) * **Osteophytes** (outcroppings of bone that are not usually there)

Question 64

Findings of rheumatoid arthritis on X-ray

Answer 64

Bone erosion

Question 65

Major clinical features that distinguish arthritis from arthralgia

Answer 65

Swelling and heat

Question 67

Ulnar styloid

Answer 67

The bony prominence of the ulna at the wrist joint

Question 68

Thresholds for non-inflammatory / inflammatory / infectious joint disease

Answer 68

Noninflammatory \< 2000 \< Inflammatory \< 50,000 \< Infectious

Question 69

Sensitivity of the ~50,000 cutoff for inflammatory vs infectious for infectious diseases

Answer 69

60% Know that these are just rules of thumb, they are not hard proof!

Question 70

Good questions for any patient presenting with idiopathic arthritis

Answer 70

1. Have you observed any rashes? (Slapped cheek for parvovirus, erythema migrans for lyme, psoriasis for psoriatic arthritis) 2. Did you have any signs of fever prior to or following your arthritic symptoms? (Screen for infectious and inflammatory arthritis) 3. Is the arthritis constant or does it flare at certain times? (Screen for crystal arthropathy) 4. Do you have any morning stiffness? If so, for how long? (Screen for and differentiate rheumatoid and osteoarthritis) 5. Have you recently had any new sexual partners? (Screen for reactive or gonococcal arthritis)

Question 71

Reactive arthritis

Answer 71

Reaction to Chlamydia resulting in autoimmune inflammation of joints and bladder

Question 73

When you say gout is "negatively birefringent," this means that it appears ____ under parallel polarized light and ____ under perpendicular polarized light.

Answer 73

When you say gout is "negatively birefringent," this means that it appears **yellow** under parallel polarized light and **blue** under perpendicular polarized light.

Question 75

When you say pseudogout is "positively birefringent," this means that it appears ____ under parallel polarized light and ____ under perpendicular polarized light.

Answer 75

When you say pseudogout is "positively birefringent," this means that it appears **blue** under parallel polarized light and **yellow** under perpendicular polarized light.

Question 76

Crepitus

Answer 76

"cracking sensation" when moving a joint. Typical symptom of osteoarthritis.

Question 77

Chondrocalcinosis

Answer 77

Radiologic finding of calcium deposition within the articular cartilage. Characteristic of pseudogout.