Lab and Diagnostics Final Exam

Distal radius

The most commonly fractured bone, typically resulting from a FOOSH injury.

Osteoblasts

Bone cells responsible for building new bone tissue.

Osteoclasts

Bone cells responsible for destroying or "cleaving" bone tissue.

Hydroxyapatite

The bone mineral (calcium phosphate) that provides bone with its strength.

Physis

The clinical name for the epiphyseal plate or growth plate.

Metaphysis

The region of a long bone between the physis and the diaphysis, which receives the greatest blood flow.

Orthogonal views

The radiographic axiom stating that one should always obtain at least two views at right angles to each other.

Joint above and below

The clinical rule stating you must always evaluate these two areas relative to a suspected injury.

ABCs

The mnemonic for systematic X-ray interpretation: Alignment, Bony mineralization, Cartilage, and Soft tissue.

Fracture

A break in the continuity of bone or cartilage, often considered a soft tissue injury in which a bone is broken.

Comminuted

A complex fracture pattern where the bone is broken into multiple fragments.

Open (compound)

A fracture where the overlying skin integrity is breached, carrying a higher risk for infection.

Stress (Fatigue) fracture

A break caused by abnormal activity on normal bone.

Insufficiency (Pathologic) fracture

A break caused by normal activity on abnormal bone.

Torus (Buckle) fracture

The most common incomplete fracture, characterized by the buckling of the cortex on both sides of the bone.

Greenstick fracture

An incomplete fracture where the bone is broken on one side and bent on the other.

Burst fracture

A high-energy compression fracture where a vertebral body is crushed in all directions.

Distraction

A fragment position description referring to a tensile force pulling bone ends apart.

Salter-Harris Type 2

The most common type of physeal fracture, involving the physis and a metaphyseal fragment.

Salter-Harris Type 5

The least common physeal fracture, involving compression of the growth plate.

Lipohemarthrosis

A soft tissue finding on imaging where a fat-fluid level is seen in a joint, indicating an intra-articular fracture.

Subluxation

A condition where the bones making up a joint are in partial contact but have "slipped" without full disarticulation.

Dislocation

A condition where the bones that make up a joint are completely disarticulated.

Metastases

The most common cause of bone lesions, as primary bone tumors are rare.

Transition Zone

The single most important predictor of a lesion's aggressiveness, referring to the border between normal and abnormal bone.

Pencil-in-cup deformity

The classic imaging hallmark of Psoriatic arthritis.

Osteophytes

A form of bony "buttressing" reaction commonly seen as a hallmark of Osteoarthritis.

Codman triangle

A triangular area of new bone formation deep to the periosteum, often indicating an aggressive process.

Ground glass

The classic imaging appearance of a fibrous lesion matrix.

Aggressive lesion

A bone lesion characterized by a wide transition zone, wider-than-long shape, and interrupted periosteal reaction.

Non-aggressive lesion

A bone lesion characterized by a well-defined sclerotic border and a shape that is longer than it is wide.

20-30 percent

The approximate percentage of ER visits involving musculoskeletal complaints.

Lead pipe fracture

An incomplete fracture where one side of the bone is buckled and the other side is cracked.

Osteopenia

A bone density condition characterized by a T-score between -1.0 and -2.5.

Osteoporosis

A bone density condition diagnosed when a T-score is lower than -2.5.

Diaphysis

The clinical name for the shaft of a long bone.

Epiphysis

The clinical name for the head or end of a long bone.

Mechanical forces

The primary factor that bone density responds to, with high stress leading to high density.

Apophyseal disruption

An injury affecting a bony outgrowth where tendons or ligaments attach.

Delayed union

A bone healing outcome where a fracture takes longer than expected to heal but eventually does.

Malunion

A bone healing outcome where the fracture heals in an abnormal or deformed position.

Non-union

A bone healing outcome where the fractured bone ends fail to grow back together.

Laxity vs Instability

The clinical distinction used to describe joint looseness versus a loss of functional control.

Synovium

The primary location of pathology for Rheumatoid arthritis.

Articular cartilage

The primary location of pathology for Osteoarthritis.

Punched-out erosions

The hallmark imaging finding for Gout, often featuring overhanging edges.

Sclerosis

A bony reaction where the body attempts to wall off a diseased area.

Laminated

A periosteal reaction often described as having an onion skin appearance.

Spiculated

A periosteal reaction often described as having a hair-on-end appearance.

Osteolytic

A type of bone behavior where osteoclasts destroy or cleave bone tissue.

Geographic

A non-aggressive type of bone destruction characterized by a large, well-defined lucent area.

Moth-eaten

An aggressive bone destruction pattern characterized by multiple small, scattered holes.

Permeative

An aggressive bone destruction pattern characterized by numerous tiny, pin-hole sized lucencies.

Chondroid matrix

A type of lesion production appearing as fine stippled calcification, rings, or popcorn.

Osteoid matrix

A type of lesion production appearing as fluffy, cloud, or cotton-like densities.

Fat lines

Imaging markers that indicate injury when they are lost or displaced.

Osteopetrosis

A condition of increased bone density also known as marbling.

Joint space narrowing

The hallmark radiographic feature of arthritis.

SALTR

The mnemonic used to remember the types of Salter-Harris physeal fractures.

Marginal erosions

The hallmark imaging finding of Rheumatoid arthritis.

Cortex

The compact and dense outer layer of bone visible on a radiograph.

Arthrocentesis

The procedure of obtaining fluid from a joint or bursa

Effusion

The accumulation of fluid in or around a joint

Aspirate

All fluids resulting from an aspiration procedure

Monosodium urate crystals

The type of crystals found in joint fluid that indicates a diagnosis of gout

Calcium pyrophosphate crystals

The type of crystals found in joint fluid that indicates a diagnosis of pseudogout

Cellulitis

An absolute contraindication for passing an aspiration needle through the skin

Total joint replacement

A relative contraindication for arthrocentesis unless sepsis is suspected

Quick relief

A primary therapeutic benefit of aspirating a painful joint effusion

Dry tap

A potential complication where no fluid is successfully obtained during aspiration

Fluoroscopic guidance

The imaging method mandatory for performing spinal aspiration procedures

Chlorhexidine or betadine

Common agents used to appropriately prep the skin before arthrocentesis

WBC count with differential

The best discriminator between inflammatory and non-inflammatory joint disease

Polarized light microscopy

The specific laboratory technique used for crystal analysis in synovial fluid

Gram stain and culture

Tests ordered on an aspirate specifically to evaluate for septic arthritis

Viscosity

The characteristic of fluid described as being thick and slick or thick and sticky

0.5 mL

The approximate volume of synovial fluid that can be aspirated from a normal joint

Clear to light yellow

The gross appearance of normal joint or bursal aspirate

Less than 2000 WBC per mm3

The white blood cell count range for a normal or non-inflammatory aspirate

Greater than 50000 WBC per mm3

The white blood cell count threshold generally indicating an infectious or purulent finding

Greater than 75 percent PMNs

The differential percentage that strongly indicates a bacterial joint infection

Negative birefringence

The characteristic of monosodium urate crystals under a polarized microscope

Weakly positive birefringence

The characteristic of calcium pyrophosphate dihydrate crystals under a polarized microscope

Rhomboid or rectangular

The common shapes of crystals found in pseudogout

Needle-shaped

The classic shape of crystals found in gout

Cholesterol

A type of crystal other than MSU or CPPD that may occasionally be seen in joint fluid

Eosinophils

The presence of these cells in joint fluid could indicate a parasitic infection or Lyme disease

Lipid droplets

A finding in joint aspirate that should lead to a suspicion of an articular fracture

Traumatic tap

A potential cause of blood in an aspirate that is not due to a pre-existing bleeding disorder

Straw-colored

The gross color often associated with non-inflammatory synovial fluid

Less than 25 percent

The expected percentage of neutrophils in non-inflammatory aspirate findings

Greater than 50 percent

The typical percentage of neutrophils found in inflammatory aspirates like RA or gout

Monoarticular joint pain

A common clinical symptom of a septic joint, often accompanied by erythema and warmth

Lyme disease

A condition where gram stains and cultures of joint fluid are often negative despite infection

Gonococcal infection

An infection where the gram stain of joint fluid is only positive in a minority of cases

Reactive arthritis

A sterile inflammatory arthritis that develops 1 to 6 weeks after a gastrointestinal or urogenital infection

Urethritis and conjunctivitis

Two non-articular findings that complete the classic triad of Reiter syndrome

Chlamydia trachomatis

The most common triggering organism for reactive arthritis

Mycobacterium marinum

The pathogen to suspect if a patient develops septic arthritis after cleaning a fish tank

Pasteurella multocida

The pathogen associated with septic arthritis following a dog or cat bite