MSK Flashcards
4 features that suggest bone malignancy?
Cortical destruction. Periostitis. Orientation or axis of the lesion. Zone of transition.
Benign periostitis features?
Thick, wavy, uniform, or dense periostitis. Due to low-grade chronic irritation that gives periosteum time to lay down thick new bone.
Aggressive periostitis features?
Lamellated (onion-skinned), amorphous, or sunburst-like. Periosteum does not have time to consolidate.
Zone of transition in bony lesions?
Border of lesion with normal bone. Narrow: Well-defined (benign). Wide: Imperceptible (aggressive).
Osteosarcoma features?
Destructive lesions with sclerosis from tumor new bone formation or reactive sclerosis. Occur almost exclusively in children and young adults (less than 30 years old).
Parosteal osteosarcoma features?
Arises from periosteum. Grows outside one, often wrapping around diaphysis without breaking cortex. Occurs in older age group than central osteosarcomas. Not as aggressive central osteosarcomas. Posterior distal femur is common location.
May mimic an early parosteal osteosarcoma of the posterior femur near the knee.
Cortical desmoid tumor. Myositis ossificans.
Ewing sarcoma features?
Permeative (multiple small holes) lesion in long bone diaphysis. May have onion-skin, sun-burst, or amorphous periostitis.
Cassic differential diagnosis for a permeative lesion in a child?
Ewing sarcoma. Infection. EG.
Chondrosarcoma features?
Bony or soft tissue mass with amorphous, snowflake calcification in an older patient (>40 years). Can’t distinguish between enchondromas and low-grade chondrosarcomas.
Malignant Giant Cell Tumor
Benign and malignant giant cell tumors appear identical. If metastasizes (often to lung) then is malignant.
Fibrosarcoma features?
Lytic tumor without osteoid or chondroid matrix. May be permeative to a fairly well-defined area of lysis. Tend to predominate in fourth decade. May have a bony sequestrum.
Malignant fibrous histiocytoma
Common soft tissue tumors. In bone, appear identical to fibrosarcomas: Variable lytic lesion. May have bony sequestrum.
Desmoid tumor
Half-grade fibrosarcoma. More common in soft tissue than bone. Usually are well defined lytic lesions when in bone. Often have benign periostitis with thick spicules.
Primary lymphoma of bone (reticulum cell sarcoma)
Similar appearance to Ewing sarcoma (permeative or moth-eaten). Occur in older age group than Ewing sarcoma.
Classic differential diagnosis for an expansile, lytic metastasis
Renal cell carinoma. Thyroid carinoma.
Two most common soft tissue tumors
Malignant fibrous histiocytoma. Liposarcoma.
Synovial sarcomas or synoviomas features?
Often adjacent to joints. Typically homogeneously T2 bright. May mimic fluid collection.
Synovial osteochondromatosis features?
Benign joint lesion. Synovial metaplasia leading to multiple calcific cartilaginous loose bodies in a joint. 20% do not calcify. May mimic pigmented villonodular synovitis.
Pigmented villonodular synovitis features?
Rare chronic inflammatory process causing synovial proliferation. Joint swelling, pain, occasionally joint erosions. No calcifications. Low T1 and T2 synovial signal (hemosiderin deposits). Rare chronic inflammatory process causing synovial proliferation.
Soft tissue Hemangioma features?
Phleboliths. Often cause cortical holes (pseudopermeative) in adjacent bone. May mimic permeative or moth-eaten pattern.
Predental space should not measure more than?
2.5 mm.
Jefferson fracture features?
Blow to top of head. C1 ring fracture, lateral masses of C1 must extend beyond margins of C2 body.
Rotatory fixation of the atlantoaxial joint?
Atlantoaxial joint becomes fixed. C1–C2 bodies move en mass, instead of rotating on one another.
Clay-Shoveler’s Fracture
Fracture of C6 or C7 spinous process, relatively innocuous.
Hangman’s Fracture
Unstable, serious fracture of posterior elements of C2 usually with C2 anterolisthesis on C3. Caused by hyperextension and distraction (head against dashboard).
Flexion-Teardrop Fracture
Disruption of posterior C-spine ligaments with anterior vertebral body compression. Usually associated with spinal cord injury.
Unilateral Locked Facets
Rupture of facet joint ligaments with dislocation due to severe flexion with some rotation. Facets are locked in an overriding position.
Seatbelt spine injury
Hyperflexion at the waist (lap belt). Distraction of posterior elements and ligaments with anterior vertebral body compression. Usually involves T12, L1, or L2.
Spondylolysis
Break or defect in pars interarticularis portion of lamina.
Kummel disease
Further collapse of an acute unprotected wedge compression fracture. Results in severe neurologic deficits. Typically occurs 1 to 2 weeks after initial trauma.
Bennett Fracture
fracture at base of thumb extending into carpometacarpal joint.
Rolando fracture
Comminuted fracture of thumb base extending into carpometacarpal joint.
Mallet finger or baseball finger
Avulsion injury at distal phalanx base where extensor digitorum tendon inserts.
Gamekeeper’s Thumb
Avulsion of thumb ulnar collateral ligament at the ulnar aspect of first metacarpophalangeal joint.
Failure to diagnose and treat lunate dislocation can result in?
Permanent median nerve impairment. Nerve can get impinged by volarly displaced lunate.
Rotary subluxation of the navicular
Rupture of scapholunate ligament. Scaphoid (navicular) rotates dorsally. Widened space between scaphoid and lunate.
__________ is often associated with Kienbock malacia.
Negative ulnar variance.
Positive ulnar variance has an increased incidence of
Triangular fibrocartilage tears.
Fracture of distal radius and ulna with dorsal angulation of distal forearm and wrist.
Colles fracture.
Monteggia Fracture
Facture of ulna with dislocation of proximal radius.
Galeazzi fracture
Fracture of radius with dislocation of distal ulna.
Bony deformities of anterior shoulder dislocation?
Hill-Sachs deformity: indentation on posterosuperior humeral head. Bankart deformity: Bony irregularity or fragment off inferior glenoid.
Permeative lesion in patient less than 30 years?
Ewing sarcoma. Infection. Eosinophilig granuloma.
Permeative lesion in patient > 40 years?
Multiple myeloma. Metastatic carcinomatosis. Primary lymphoma.
Subperiosteal bone resorption sites in hyperparathyroidism?
Radial aspect of middle phalanges. Medial aspect of proximal tibia. Sacroiliac joints. Distal clavicle.
Calcification of the sacrotuberous ligament is characteristic for
Fluorosis.
Differential for periostitis in a long bone without an underlying bony abnormality
Hypertrophic pulmonary osteoarthropathy. Venous stasis. Thyroid acropachy. Pachydermoperiostosis. Trauma.
Melorheostosis features?
Idiopathic thickening of cortical new bone. Accumulates near ends of long bones (dripping candle wax). Can affect several adjacent bones. May be symptomatic.
Common Causes of Avascular Necrosis
Trauma. Steroids. Aspirin. Collagen vascular diseases. Alcoholism. Idiopathic causes.
Don’t touch lesions?
Myositis ossificans. Avulsion injury. Cortical desmoid. Trauma. Discogenic Vertebral Sclerosis. Fracture. Pseudodislocation of Humerus.
Radiologic appearance of myositis ossificans
Circumferential calcification with a lucent center (malignancy may have calcified or ossific center).
These injuries can have an aggressive radiographic appearance and are located at ligament and tendon insertion sites
Avulsion Injury.
Cortical desmoid?
Occur only on posteromedial epicondyle of femur. May result from avulsion of adductor magnus muscle.
Geodes can occur in what conditions?
Trauma. Calcium pyrophosphate dihydrate crystal disease. Rheumatoid arthritis. Avascular necrosis.
Discogenic Vertebral Sclerosis?
Variant of a Schmoral node. Often a sclerotic lesion adjacent to endplate. Associated disk space narrowing and osteophytosis.
Dorsal Defect of the Patella?
Lytic defect in upper outer quadrant of patella. May mimic pathologic process.
Pseudocyst of the humerus
Anatomic variant of increased cancellous bone near greater tuberosity. May mimic a lytic pathologic lesion.
Os odontoideum?
Unfused dens. Smooth, often well-corticated, inferior dens border. Hypertrophied, densely corticated anterior arch of C1. May move anterior to C2 body with flexion. Can mimic a fractured dens.
Unicameral bone cysts treatment?
Curettaged and packed to prevent fracture. Those occuring in the calcaneus, however, should be left alone.
Bone infarct features?
May be patchy, mixed lytic-sclerotic or even resemble permeative process. Typically occur in metadiaphyses. Multiple bone infarcts consider sickle cell anemia or systemic lupus erythematosus.
Achondroplasia features?
Failure of endochondral bone formation. Narrowing of caudal interpedicular distances. Short long bones with normal width.
Hypertrophic Pulmonary Osteoarthropathy features?
Finger clubbing. Extremity periostitis.
Multiple Hereditary Exostosis
Multiple osteochondromas or exostoses. Nearly always involves knees. Undertubulation (widened bone diameter) present at site of exostosis.
Central beak or anterior bony projection off vertebral bodies?
Morquio Syndrome.
Inferior bony projections extending anteriorly off the vertebral bodies?
Hurler Syndrome.
Characteristic finding in all of the mucopolysaccharidoses (Hurler, Hunter, Morquio).
Notch at base of fifth metacarpal.
Osteoid Osteoma
Painful sclerotic cortical lesion with lucent centered nidus. Occurs in patients younger than 30. Nidus is surgically removed or thermally ablated. May mimic osteomyelitis. Bone scan double-density sign versus photopenic area for osteomyelitis.
Osteopathia Striata
Aka Voorhoeve disease. Multiple 2- to 3-mm-thick linear sclerotic bands aligned parallel to bone long axis. Usually affects multiple long bones. Generally is asymptomatic.
Osteopoikilosis
Hereditary, asymptomatic disorder. Multiple small (3 to 10 mm) sclerotic bony densities. Primarily involves ends of long bones and pelvis. May mimic diffuse osteoblastic metastases.
Pachydermoperiostosis
Rare, familial disease. Skin thickening of face and extremities, finger clubbing, widespread periostitis.
Sarcoidosis bony findings?
Lacelike pattern of cortical bony destruction of multiple phalanges. May affect both hands. May have skin nodules.
Transient Osteoporosis of the Hip
Painful hip osteoporosis and no other finding. Self-limited with full resolution.
Benign, bony cystic lesion differential?
FEGNOMASHIC. Fibrous dysplasia. Enchondroma, EG. Giant cell tumor. Nonossifying fibroma. Osteoblastoma. Metastases, Myeloma. Aneurysmal bone cyst. Solitary bone cyst. Hyperparathyroidism. Infection. Chondroblastoma, Chondromyxoid.
Benign lytic lesions in patients younger than 30 years?
Eosinophilic granuloma. Aneurysmal bone cyst. Nonossifying fibroma. Chrondoblastoma. Solitary bone cyst.
Benign lytic lesions that have no pain or periostitis?
Fibrous dysplasia. Enchondroma. Nonossifyuing fibroma. Solitary bone cyst.
Fibrous dysplasia discriminator(s)?
No periosteal reaction.
Enchondroma discriminator(s)?
Calcifications present (except phalanges). Painless (no periostitis).