MSK Flashcards
- Which of the following correct regarding MRI of osteonecrosis (avascular necrosis) of femoral head: (T/F)
(a) Focal areas of low signal on T1W MRI suggest an alternative diagnosis.
(b) The “double line sign (adjacent high and low intensity line on T2W MRI) is virtually diagnostic.
(c) Fractures typically appear as low signal intensity lines on T1W images.
(d) Intravenous contrast should be administered routinely.
(e) MRI is less sensitive than isotope bone scan in making the diagnosis.
Answer:
(a) Not correct
(b) Correct
(c) Correct
(d) Not correct
(e) Not correct
Explanation:
Focal areas of homogeneous or inhomogeneous low signal on T1WI are commonly found. Contrast enhancement differentiates hypervascularized viable tissue from hypovascularized necrotic tissue. However it is not routinely done as it can be differentiated on other sequences. Isotope bone scan has a sensitivity of 80-85% and MRI has a sensitivity of 90-100%.
- Which of the following are correct regarding trauma to the upper limb: (T/F)
(a) Non-or delayed union of humeral fracture is common.
(b) Bilateral shoulder dislocations are usually anterior.
(c) A fixed, abducted arm on shoulder X-ray is consistent with luxatio erecta.
(d) Humeral shaft fractures are associated with axillary nerve injury.
(e) The brachial artery is injured in 1-5% of humeral shaft fractures.
Answer:
(a) Not correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
Non-union or delayed union of humeral fracture is rare and occurs in cases secondary to excessive distraction of fracture fragments. Bilateral shoulder dislocation is rare and is usually posterior, mainly due to seizures. Humeral shaft fractures are associated with radial, medial or ulnar nerve injury. Radial nerve injury is most common (5-17%).
- Which of the following are correct regarding knee trauma: (T/F)
(a) Anterior cruciate ligament (ACL) tears usually occur at the tibial attachment.
(b) “Deep lateral femoral sulcus” is a specific sign of posterior cruciate ligament (PCL) disruption.
(c) Kissing contusions at the anterior aspect of the proximal tibial and distal femur are characteristic of hyperextension injury.
(d) O’ Donoghue triad comprises complete disruption of the medial collateral ligament, ACL and posterior horn of medial meniscus.
(e) Dashboard injuries are typically associated with ACL tears.
Answer:
(a) Not correct
(b) Not correct
(c) Correct
(d) Correct
(e) Not correct
Explanation:
ACL tears usually occur in middle part of ligament followed by femoral attachment. Deep lateral femoral sulcus sign is highly specific for ACL disruption and results from impaction of the lateral femoral condyle on the posterior tibial plateau. Dashboard injuries are typically associated with midsubstance PCL tears at the genu
- Which of the following are correct regarding osteochondritis dissecans:
(T/F)
(a) Lesions in the knee are bilateral in 20-30%
(b) Lesions in the knee most commonly involve the lateral aspect of the femoral condyle.
(c) The average age of onset is within the 2nd decade
(d) A high signal intensity line around the lesions on T2W MRI images is indicative of instability
(e) A grade 2 osteochondritis dissecans lesions is characterised displaced a displaced fragment.
Answers:
(a) Correct
(b) Correct
(c) Correct
(d) Correct
(e) Not correct
Explanation:
Grading of osteochondritis dissecans:
Grade 1- focal softening/fissuring
Grade 2- defect in cartilage
Grade 3- fragment partially detached
Grade 4- displaced fragment/ loose body in the joint.
- Which of the following are correct regarding intra-articular osteoid osteoma: (T/F)
(a) Most commonly affects the hip.
(b) Typically presents with nocturnal pain.
(c) The radiolucent nidus is surrounded by extensive reactive sclerosis.
(d) MRI is more specific than CT in detecting the nidus.
(e) Plain radiograph have a sensitivity exceeding 90% in detecting the nidus.
Answer:
(a) Correct
(b) Not correct
(c) Not correct
(d) Not correct
(e) Not correct
Explanation:
Nocturnal pain is a feature of long bone osteoid osteoma and not of intra-articular lesions. It is also less responsive to NSAIDs. Extensivereactive sclerosis surrounding the nidusis a feature of long bone lesion and not of intra-articular lesion. Nidus is often overlooked on radiographs. MRI is more sensitive than CT in detecting the nidus, however CT is more specific. MRI is sensitive as it is highly sensitive in demonstrating perilesional edema.
- Which of the following are correct regarding giant cell tumours of bone (GCT): (T/F)
(a) Are typically subarticular in location.
(b) Metastasise in less than 10% of cases.
(c) Most commonly occur in the proximal humerus.
(d) Spinal GCTs affect primarily the posterior elements.
(e) Periosteal reaction is seen in 60-80% of cases.
Answer:
(a) Correct
(b) Correct
(c) Not correct
(d) Not correct
(e) Not correct
Explanation:
Most common location of GCT is around knee joint (50%-65%) with distal femur accounting for 23%-30% cases.
Proximal humerus accounts for 4-8% of the cases of GCT. Spinal GCT primarily affects the vertebral bodies with extension into the posterior elements. Vertebral body collapse is a frequent finding. Periosteal reaction is uncommon seen on radiograph only in 10-30% cases. Cortical penetration is however seen in 33-50% cases with associated soft tissue mass.
(Ped) 7. Which of the following statements are correct? (T/F)
(a) Ewing’s tumors rarely arise within flat bones.
(b) Giant cell tumors of bone are most commonly seen in the 5-15 years age group.
(c) Parosteal osteosarcomas have a peak in the 10-20 years age group.
(d) Eosinophilic granuloma usually involves one bone only.
(e) Ewing’s tumors often demonstrate calcification on CT.
Answers:
(a) Not correct
(b) Not correct
(c) Not correct
(d) Correct
(e) Not correct
Explanation:
About 60% of Ewing tumors arise in long bones, most common site is metadiaphysis of femur. About 40% arise in flat bones especially in pelvis, particularly in patients over 20 years age. Calcification is rare in Ewing’s tumor of bone. It typically presents with an onion skin periosteal reaction on radiograph. Majority of giant cell tumors occur in patients following fusion of the epiphysis. Thus usually occur after 18-20 years of age. They have a narrow zone of transition and usually abut the articular margin. Parosteal osteosarcomas occur in an older age group than the periosteal type with 50% occurring after 30 years of age.
- Which of the following are correct regarding osteosarcoma? (T/F)
(a) There is an increased incidence osteopetrosis.
(b) There an association with pineoblastoma.
(c) Telangiectatic osteosarcoma typically demonstrates fluid-fluid levels on MRI.
(d) It frequently metastasises to other bones.
(e) Parosteal osteosarcoma resembles myositis ossificans on radiograph.
Answers:
(a) Correct
(b) Correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
In osteosarcoma, metastatic spread is heterogeneous, as bones lack a lymphatic system. The lungs are the most frequent size, although bones may be involved. Lymphadenopathy occurs late in the disease and is a poor prognostic sign.
- Features of diaphyseal aclasia (hereditary multiple exostosis) include: (T/F)
(a) Malignant transformation to chondrosarcoma occurs in 35-40 %
(b) Exostoses have a cap hyaline cartilage, often with a bursa formation over the cap.
(c) Exostoses arise from the metaphysis and point towards the joint
(d) Exostoses stop growing when the nearest epiphyseal centre fuses
(e) Autosomal recessive inheritance.
Answers:
(a) Not correct
(b) Correct
(c) Not correct
(d) Correct
(e) Not correct
Explanation:
Diaphyseal aclasia is an autosomal dominant disorder presenting between 2 to 10 years of age. The exostoses arise from the metaphysis of long bones and point away from the joint. Risk of malignant transformation to chondrosarcoma is less than 5 %.
- Which of the following are correct regarding bone metastases (T/F)
(a) Metastases can be excluded in a patient with bone scintigraphy showing no abnormal uptake.
(b) Prostate metastases are always sclerotic.
(c) Metastases located in the medulla are o reduced signal on T1W and increased signal on fat suppressed T2W MRI images
(d) Identification of a ‘halo’ of high signal intensity around a lesion on T2W MRI suggests a benign lesion
(e) Melanoma metastases are usually lytic.
Answers:
(a) Not correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Correct
Explanation:
Lesions which outgrow their blood supply appear photopenic on bone scintigraphy. Small percentage of prostatic metastases can be entirely lytic. ‘Halo’ of high signal around a lesion on T2WI is highly suggestive of metastases.
- Which of the following are correct concerning enchondromas: (T/F)
(a) In the hand, diaphysis is the most common site
(b) Most frequent tumor found in the small bones of the hands.
(c) Calcification is rare
(d) MRI appearances are of low signal on T1W and high signal on T2W spine echo images
(e) Maffuci syndrome is characterised by multiple enchondromas and soft tissue cavernous haemangiomas
Answers:
(a) Correct
(b) Correct
(c) Not correct
(d) Correct
(e) Correct
Explanation:
Enchondromas are a relatively common benign medullary cartilaginous neoplasm, usually found in children or young adults which can lead to pathological fractures or undergo malignant degeneration. Mostly they are an incidental finding with benign imaging features.
Calcification especially chondroid type is common finding.
(Ped) 28. Which of the following are correct regarding features of Ewing sarcoma: (T/F)
(a) Presentation with systemic sign and symptoms is recognized.
(b) Is usually located in the epiphyses
(c) Most commonly affects flat bones in children
(d) Onion skin periosteal reaction is a rare radiological finding.
(e) MRI demonstrates a soft tissue mass in 80-90% of patient
Answers:
(a) Correct
(b) Not correct
(c) Not correct
(d) Not correct
(e) Correct
Explanation:
Majority of Ewing sarcoma are located in diaphysis of the humerus, femur, tibia and fibula. Epiphysis is a rare location. In the first two decades lesions are predominantly located in long bones. After that time lesions in flat bones are more usual. Ewing is an aggressive tumor with permeative or moth eaten appearance on radiograph with lamellated, onion skin or spiculated periosteal reaction.
- Which of the following are correct concerning aneurysmal bone cysts: (T/F)
(a) 60-80 % of aneurysmal bone cysts are found in under 20 year old.
(b) Periosteal reaction is a pathognomonic feature
(c) They demonstrate a fluid-fluid level on CT
(d) Hyper-vascularity is usually seen in the periphery of the lesion
(e) They have a recurrence rate of 20-30 % after surgical treatment
Answers:
(a) Correct
(b) Not correct
(c) Correct
(d) Correct
(e) Correct
Explanation:
Aneurysmal bone cysts are benign expansile tumour like lesion. Periosteal reaction is not seen until associated with a fracture.
(CNS) 32. Which of the following are correct about fibrous dysplasia? (T/F)
(a) Facial bones are rarely involved.
(b) Exophthalmos is a recognised feature.
(c) There is an association with Cushing’s syndrome.
(d) In the calvaria, the frontal bone is most commonly involved.
(e) It effects the maxilla more frequently than the mandible.
Answers:
(a) Not correct
(b) Correct
(c) Correct
(d) Correct
(e) Correct
Explanation:
Fibrous dysplasia typically presents before the age of 30 years. The most common sites of involvement of the ribs, cranial, facial bones and femur and tibia.
- Which of the following are correct regarding popliteal (Baker’s) cysts: (T/F)
(a) Are commonly associated with meniscal pathology in adults.
(b) Are frequently associated with osteoarthritis and rheumatoid arthritis in adults.
(c) Ultrasound can differentiate Baker’s cysts from popliteal aneurysms and ganglion cysts.
(d) Typically extends posteriorly between the tendons of semimembranosus and the medial head of gastrocnemius.
(e) Calcified loose bodies are a recognized complication.
Answer:
(a) Correct
(b) Correct
(c) Correct
(d) Correct
(e) Correct
Explanation:
Popliteal cysts are fluid filled synovial lined bursa in the popliteal fossa communication with the knee joint. They are generally located at or below the joint line. Majority of them are incidental findings. Acute rupture of Baker’s cyst resembles DVT in clinical presentation.
