Question 1: Slipped Upper Femoral Epiphysis (SUFE)
Stem: A 13-year-old overweight boy presents with a 3-week history of a painful limp and referred pain to his left knee. An AP radiograph of the pelvis is obtained. A line drawn along the superior surface of the left femoral neck (Klein’s line) fails to intersect the lateral part of the femoral epiphysis.
Question: What is the most likely diagnosis?
(A) Slipped Upper Femoral Epiphysis (SUFE) (B) Perthes’ Disease (C) Developmental Dysplasia of the Hip (DDH) (D) Septic Arthritis (E) Transient Synovitis
Correct Answer: (A) Slipped Upper Femoral Epiphysis (SUFE).
Explanation:
- Why (A) is correct: This is the classic clinical (obese adolescent male, knee/hip pain) and radiological presentation of SUFE (also known as Slipped Capital Femoral Epiphysis or SCFE). The abnormal Klein’s line is the key sign on an AP view, indicating the femoral epiphysis has slipped medially and posteriorly.
- Why (B) is wrong: Perthes’ disease is avascular necrosis, which affects a younger age group (4-8 years) and appears as a sclerotic, fragmented epiphysis.
- Why (C) is wrong: DDH is a congenital condition diagnosed in infancy, characterized by a shallow acetabulum.
- Why (D) is wrong: Septic arthritis is an acute, febrile illness with a joint effusion, not a growth plate slip.
- Why (E) is wrong: Transient synovitis (irritable hip) is a diagnosis of exclusion in a younger child (3-10 years) and has normal radiographs.
Key Points: Slipped Upper Femoral Epiphysis (SUFE)
- Definition: A Salter-Harris Type I fracture through the proximal femoral growth plate.
- Demographic: Typically overweight, adolescent males (10-16 years).
- Radiographic Signs:
- Klein’s Line: A line along the superior femoral neck that should intersect the lateral epiphysis; in SUFE, it fails to do so.
- “Frog-leg” lateral view: Best view to assess the degree of posterior slippage.
- Complication: High risk of Avascular Necrosis (AVN), making it a surgical emergency.
Question 2: Perthes’ Disease
Stem: A 6-year-old boy presents with a painless limp that has been present for 2 months. An AP radiograph of his right hip demonstrates that the femoral epiphysis is sclerotic, flattened, and appears fragmented.
Question: What is the most likely diagnosis?
(A) Slipped Upper Femoral Epiphysis (SUFE) (B) Developmental Dysplasia of the Hip (DDH) (C) Transient Synovitis (Irritable Hip) (D) Perthes’ Disease (E) Septic Arthritis
Correct Answer: (D) Perthes’ Disease.
Explanation:
- Why (D) is correct: This is the classic presentation. Perthes’ disease is avascular necrosis (AVN) of the femoral head epiphysis in a child. The classic age group is 4-8 years. The radiological signs are progressive sclerosis (dead bone), flattening (subchondral fracture), and fragmentation.
- Why (A) is wrong: SUFE affects older, adolescent children (10-16) and is a slip of the growth plate, not a change in bone density.
- Why (B) is wrong: DDH is a congenital abnormality of acetabular formation, not an acquired AVN.
- Why (C) is wrong: Transient synovitis is a diagnosis of exclusion and, by definition, has normal X-rays.
- Why (E) is wrong: Septic arthritis is an acute, febrile illness and would show joint space widening or destruction, not sclerosis.
Key Points: Perthes’ Disease
- Definition: Idiopathic avascular necrosis of the capital femoral epiphysis.
- Demographic: Typically boys aged 4-8 years.
- Radiological Signs:
- Early: Small epiphysis, medial joint space widening.
- Late: Sclerosis, fragmentation, and flattening (coxa plana) of the femoral head.
- Healed: A large, mushroom-shaped head (coxa magna).
Question 3: Developmental Dysplasia of the Hip (DDH)
Stem: A 6-month-old infant is referred for an ultrasound after a positive Ortolani test. The ultrasound demonstrates a shallow, bony acetabulum with an alpha angle of 45 degrees. The femoral head is subluxed superolaterally.
Question: These findings are diagnostic of:
(A) Developmental Dysplasia of the Hip (DDH) (B) Perthes’ Disease (C) Slipped Upper Femoral Epiphysis (SUFE) (D) Proximal Femoral Focal Deficiency (E) Septic Arthritis
Correct Answer: (A) Developmental Dysplasia of the Hip (DDH).
Explanation:
- Why (A) is correct: Ultrasound is the primary imaging modality for DDH in infants (< 6 months). The alpha angle (Graf classification) measures the bony acetabular roof. A normal alpha angle is > 60 degrees. An angle of 45 degrees indicates severe dysplasia.
- Why (B) & (C) are wrong: Perthes’ and SUFE are diseases of older children; the hip is structurally normal at birth.
- Why (D) is wrong: This is a rare congenital anomaly involving absence or hypoplasia of the proximal femur, which is a different pathology.
- Why (E) is wrong: Septic arthritis would present with a large, complex joint effusion and synovial thickening, not a dysplastic acetabulum.
Key Points: Developmental Dysplasia of the Hip (DDH)
- Definition: A spectrum of abnormalities of the hip joint, from mild acetabular dysplasia to irreducible dislocation.
- Imaging (<6 months): Ultrasound. Key measurement is the alpha angle (bony roof). Alpha > 60° is normal.
- Imaging (>6 months): X-ray. Look for:
- Increased acetabular angle.
- Breach of Shenton’s line.
- Superolateral displacement of the femoral epiphysis (out of the inferior-medial quadrant of Perkin’s lines).
Question 4: Femoral Neck Fracture (Garden)
Stem: An 82-year-old woman falls and presents with hip pain. An AP radiograph shows an impacted subcapital fracture of the femoral neck. The inferior trabeculae are angulated (valgus), but there is no displacement.
Question: According to the Garden classification, what type of fracture is this?
(A) Garden I (B) Garden II (C) Garden III (D) Garden IV (E) Intertrochanteric
Correct Answer: (A) Garden I.
Explanation:
- Why (A) is correct: A Garden I fracture is an incomplete or impacted fracture that is non-displaced and in a stable valgus position.
- Why (B) is wrong: A Garden II fracture is a complete fracture that is non-displaced.
- Why (C) is wrong: A Garden III fracture is a complete fracture with partial displacement (varus angulation). The trabeculae are no longer aligned.
- Why (D) is wrong: A Garden IV fracture is a complete fracture with full displacement. The femoral head is completely dissociated from the neck.
- Why (E) is wrong: This is an intracapsular fracture. An intertrochanteric fracture is extracapsular.
Key Points: Garden Classification (Femoral Neck)
- Used for subcapital fractures to predict the risk of AVN.
- Garden I: Incomplete / Impacted. (Low risk of AVN)
- Garden II: Complete, non-displaced. (Moderate risk of AVN)
- Garden III: Complete, partially displaced. (High risk of AVN)
- Garden IV: Complete, fully displaced. (Highest risk of AVN)
Question 5: Posterior Hip Dislocation
Stem: A 25-year-old unbelted driver is involved in a head-on collision, striking his knee on the dashboard. He presents with his left hip held in flexion, adduction, and internal rotation. A radiograph shows the femoral head is displaced superoposteriorly to the acetabulum.
Question: What is the most likely diagnosis?
(A) Posterior Hip Dislocation (B) Anterior Hip Dislocation (C) Femoral Neck Fracture (D) Slipped Upper Femoral Epiphysis (SUFE) (E) Acetabular Fracture
Correct Answer: (A) Posterior Hip Dislocation.
Explanation:
- Why (A) is correct: This is the classic mechanism (dashboard injury) and presentation for a posterior hip dislocation, which accounts for ~90% of all hip dislocations. The limb is characteristically held in flexion, adduction, and internal rotation.
- Why (B) is wrong: An anterior dislocation is less common and results from forced abduction. The limb is held in abduction and external rotation.
- Why (C) is wrong: A femoral neck fracture usually results in a limb that is shortened and externally rotated.
- Why (D) is wrong: SUFE is a non-traumatic (or low-trauma) process in an adolescent.
- Why (E) is wrong: An acetabular fracture (especially of the posterior wall) is often associated with a posterior dislocation, but the primary finding described is the dislocation itself.
Key Points: Posterior Hip Dislocation
- Mechanism: Axial load on a flexed knee (e.g., dashboard injury).
- Position: Limb is flexed, adducted, and internally rotated.
- Complications: Sciatic nerve injury (10-20%), Avascular necrosis (AVN), associated posterior wall acetabular fracture.
Question 6: Avascular Necrosis (AVN)
Stem: A 45-year-old man with a history of long-term steroid use for lupus presents with hip pain. An AP radiograph of his hip reveals a subchondral curvilinear lucency in the superior aspect of the femoral head, with early flattening of the articular surface.
Question: This subchondral lucency is known as the:
(A) “Crescent Sign” (B) “Rim Sign” (C) “Fleck Sign” (D) “Pelvic Brim Sign” (E) “Double-Line Sign”
Correct Answer: (A) “Crescent Sign”.
Explanation:
- Why (A) is correct: The “crescent sign” is a pathognomonic finding of AVN on radiographs. It represents a subchondral fracture through the dead bone, which is the first sign of impending articular collapse.
- Why (B) is wrong: The “rim sign” refers to enhancement in perianal fistulas, not AVN.
- Why (C) is wrong: The “fleck sign” is a finding in a Lisfranc injury of the foot.
- Why (D) is wrong: The “pelvic brim sign” (thickened iliopectineal line) is a sign of Paget’s disease.
- Why (E) is wrong: The “double-line sign” (a serpiginous T2-bright inner line and T1-dark outer line) is a sign of AVN on MRI, not radiographs.
Key Points: Avascular Necrosis (AVN) of the Femoral Head
- Causes: Steroids, alcohol, trauma (femoral neck fracture), sickle cell disease, idiopathic (Legg-Calvé-Perthes).
- Radiographic Signs (Ficat Classification):
- Stage 1: Normal X-ray (diagnosed on MRI).
- Stage 2: Sclerosis or cystic changes.
- Stage 3: “Crescent Sign” (subchondral fracture).
- Stage 4: Articular collapse and secondary osteoarthritis.
- MRI: Most sensitive; shows a focal, serpiginous line of low T1 signal.
Question 7: Osteoarthritis (OA)
Stem: A 70-year-old man presents with chronic hip pain and stiffness. A radiograph of his hip demonstrates superior joint space narrowing, subchondral sclerosis, marginal osteophytes, and subchondral cysts.
Question: This combination of findings is most characteristic of:
(A) Osteoarthritis (B) Rheumatoid Arthritis (C) Ankylosing Spondylitis (D) Septic Arthritis (E) Avascular Necrosis
Correct Answer: (A) Osteoarthritis.
Explanation:
- Why (A) is correct: This is the classic radiographic “tetrad” of osteoarthritis (OA). The joint space narrowing is typically at the superior or superolateral aspect of the joint (the main weight-bearing area).
- Why (B) is wrong: Rheumatoid arthritis causes inflammatory changes, characterized by uniform/axial joint space narrowing, erosions (not osteophytes), and periarticular osteopenia.
- Why (C) is wrong: Ankylosing spondylitis also causes inflammatory arthritis, but its hallmark is sacroiliac joint fusion and spinal changes.
- Why (D) is wrong: Septic arthritis is a rapid, destructive process with effusion and bone erosion, not the chronic changes of osteophytes and sclerosis.
- Why (E) is wrong: AVN is a primary process of femoral head collapse, which leads to secondary OA, but the findings described are of OA itself.
Key Points: Osteoarthritis (OA) of the Hip
- Definition: Degenerative “wear-and-tear” joint disease.
- The 4 Cardinal Signs:
- Joint space narrowing (asymmetric, at weight-bearing area).
- Osteophytes (bone spurs).
- Subchondral sclerosis (increased density).
- Subchondral cysts (geodes).
- Distribution: Typically superior or superolateral narrowing.
Question 8: Femoroacetabular Impingement (FAI) – Cam
Stem: A 30-year-old male athlete presents with anterior groin pain and clicking, worse on hip flexion. A CT scan with a “pistol grip” deformity is noted. An MR arthrogram confirms a labral tear and measures the alpha angle at the femoral head-neck junction to be 70 degrees.
Question: These findings are characteristic of what type of impingement?
(A) Cam-type FAI (B) Pincer-type FAI (C) Mixed Cam- and Pincer-type FAI (D) Slipped Upper Femoral Epiphysis (SUFE) (E) Acetabular retroversion
Correct Answer: (A) Cam-type FAI.
Explanation:
- Why (A) is correct: Cam-type impingement is a femoral-sided problem. It is caused by a non-spherical femoral head (a “cam” or bump) at the head-neck junction, which abuts the labrum during flexion. This is measured by the alpha angle, which is abnormal if > 55 degrees. The “pistol grip” deformity is the radiographic sign of this.
- Why (B) is wrong: Pincer-type FAI is an acetabular-sided problem due to “overcoverage” of the femoral head (e.g., coxa profunda or acetabular retroversion).
- Why (C) is wrong: While mixed is common, the findings described (alpha angle, pistol grip) are the specific signs of a Cam lesion.
- Why (D) is wrong: SUFE is a cause of Cam-type FAI, but (A) is the correct diagnostic term for the impingement.
- Why (E) is wrong: Acetabular retroversion (e.g., a “crossover sign”) would be a sign of Pincer impingement.
Key Points: Femoroacetabular Impingement (FAI)
- Cam Type: Femoral problem. Non-spherical head. Measured by alpha angle > 55°. “Pistol grip” deformity.
- Pincer Type: Acetabular problem. Overcoverage. Signs include “crossover sign” (retroversion) or coxa profunda.
- Result: Both types cause chondrolabral damage and lead to early OA.
Question 9: Paget’s Disease
Stem: A 75-year-old man presents with an elevated alkaline phosphatase. A pelvic radiograph shows thickening of the iliopectineal line, coarsening of the trabecular pattern, and expansion of the right pubic ramus.
Question: What is the most likely diagnosis?
(A) Paget’s Disease (B) Sclerotic Metastases (e.g., from prostate) (C) Fibrous Dysplasia (D) Lymphoma (E) Myelofibrosis
Correct Answer: (A) Paget’s Disease.
Explanation:
- Why (A) is correct: This combination of findings is classic for Paget’s disease. The key features are bone expansion, cortical thickening, and coarsening of the trabeculae. Thickening of the iliopectineal line (the “pelvic brim sign”) is a specific and common finding.
- Why (B) is wrong: Sclerotic prostate metastases are dense (“blastic”) but are typically not expansile, do not coarsen the trabeculae, and do not preferentially thicken the pelvic brim.
- Why (C) is wrong: Fibrous dysplasia is typically a lytic/”ground-glass” lesion seen in younger patients.
- Why (D) & (E) are wrong: Lymphoma and myelofibrosis can cause sclerosis but not the classic triad of expansion, cortical thickening, and trabecular coarsening seen in Paget’s.
Key Points: Paget’s Disease of Bone
- Pathology: A chronic disorder of accelerated, abnormal bone remodelling.
- Phases: 1. Lytic, 2. Mixed, 3. Sclerotic.
- Key Imaging Signs:
- Bone Expansion.
- Cortical Thickening (e.g., “pelvic brim sign”).
- Coarsening of Trabeculae.
- Complication: Malignant transformation to osteosarcoma (<1%).
Question 10: Sacral Insufficiency Fracture
Stem: An 82-year-old woman with severe osteoporosis presents with an acute onset of low back pain after a minor stumble. She is unable to bear weight. A radionuclide bone scan is performed, which reveals an “H-shaped” pattern of intense tracer uptake across both sacral alae and the sacral body.
Question: This finding is pathognomonic for:
(A) Sacral Insufficiency Fracture (B) Widespread Metastatic Disease (C) Spondylodiscitis (D) Bilateral Sacroiliitis (E) Spinal Canal Stenosis
Correct Answer: (A) Sacral Insufficiency Fracture.
Explanation:
- Why (A) is correct: The “H-shaped” sign (also known as the “Honda sign”) on a bone scan is the classic and pathognomonic finding for a sacral insufficiency fracture. It represents fractures of both sacral alae (the vertical bars of the H) and a horizontal component through the sacral body.
- Why (B) is wrong: Metastases would appear as multiple, focal, asymmetric hot spots, not a symmetric H-shape.
- Why (C) is wrong: Spondylodiscitis would show uptake in a disc space and adjacent vertebral bodies, not the sacrum in this pattern.
- Why (D) is wrong: Sacroiliitis would show uptake confined to the SI joints, not the sacral body.
- Why (E) is wrong: Spinal stenosis is a clinical diagnosis and would be normal on a bone scan.
Key Points: Sacral Insufficiency Fracture
- Definition: A stress fracture occurring in weak, osteoporotic bone.
- Clinical: Acute low back/buttock pain in an elderly patient, often after minor or no trauma.
- Bone Scan: “H-sign” or “Honda sign” is pathognomonic.
- MRI: The most sensitive imaging; shows vertical lines of T1-low / T2-high (oedema) in the sacral alae, often with a horizontal component.
Question 11: Pelvic Ring Fracture (APC)
Stem: A 30-year-old motorcyclist is involved in a head-on collision. The AP Pelvis radiograph reveals diastasis (widening) of the pubic symphysis to 4 cm and widening of the right sacroiliac joint.
Question: According to the Young-Burgess classification, this “open book” injury pattern is classified as:
(A) Anteroposterior Compression (APC) (B) Lateral Compression (LC) (C) Vertical Shear (VS) (D) Combined Mechanism (E) Stable Pelvic Fracture
Correct Answer: (A) Anteroposterior Compression (APC).
Explanation:
- Why (A) is correct: An Anteroposterior Compression (APC) force causes the pelvic ring to “open like a book.” This is seen radiologically as widening of the pubic symphysis and/or anterior widening of the SI joints. A symphysis >2.5 cm (as in this case) implies a severe, unstable APC Type II or III injury.
- Why (B) is wrong: Lateral Compression (LC) is the most common type and compresses the pelvis, causing impaction fractures (e.g., sacral impaction, pubic rami fractures).
- Why (C) is wrong: Vertical Shear (VS) is a high-energy injury (e.g., fall from height) and is defined by vertical displacement of one hemipelvis, seen as a “step” at the SI joint or pubic symphysis.
- Why (E) is wrong: With both the symphysis and SI joint disrupted, this is a highly unstable fracture.
Key Points: Young-Burgess Classification (Pelvic Ring)
- Anteroposterior Compression (APC): “Open book” injury. Widens symphysis/SI joints.
- Lateral Compression (LC): Most common. “Closed book” injury. Sacral/rami impaction fractures.
- Vertical Shear (VS): Vertical displacement of one hemipelvis. Highly unstable.
Question 12: Osteitis Pubis
Stem: A 28-year-old professional soccer player presents with several months of worsening, activity-related, central groin pain. An AP radiograph of his pelvis shows subchondral sclerosis, irregularity, and erosions at the pubic symphysis.
Question: What is the most likely diagnosis?
(A) Osteitis Pubis (B) Inguinal Hernia (C) Spondylodiscitis (D) Avulsion Fracture (E) Metastasis
Correct Answer: (A) Osteitis Pubis.
Explanation:
- Why (A) is correct: This is the classic presentation. Osteitis pubis is a non-infectious, chronic inflammatory condition of the pubic symphysis, typically seen in athletes who do a lot of kicking, twisting, or running (e.g., soccer, rugby). The radiographic findings of sclerosis, erosions, and widening at the symphysis are characteristic.
- Why (B) is wrong: An inguinal hernia is a soft-tissue diagnosis and would have a normal X-ray.
- Why (C) is wrong: Spondylodiscitis (infection) of the pubic symphysis is very rare (e.g., in IVDUs) and would be much more destructive and associated with systemic fever.
- Why (D) is wrong: An avulsion fracture (e.g., of the adductor insertion) would be a focal bone fragment, not a diffuse degenerative change of the joint.
- Why (E) is wrong: Metastasis would be a focal destructive lesion, not symmetric, chronic changes.
Key Points: Osteitis Pubis
- Definition: A chronic, stress-related inflammatory condition of the pubic symphysis.
- Demographic: Athletes (running, kicking).
- Radiographic Signs: Erosions, sclerosis, and widening of the pubic symphysis.
- MRI: Shows subchondral bone marrow oedema on both sides of the symphysis.
Question 13: Fibrous Dysplasia
Stem: A 20-year-old woman has an incidental finding on a hip X-ray. There is a large, well-defined, expansile lesion in the proximal femur that has a uniform “ground-glass” matrix. The lesion is causing a varus deformity of the femoral neck.
Question: This appearance, including the deformity, is most characteristic of:
(A) Fibrous Dysplasia (B) Simple Bone Cyst (C) Aneurysmal Bone Cyst (ABC) (D) Paget’s Disease (E) Osteosarcoma
Correct Answer: (A) Fibrous Dysplasia.
Explanation:
- Why (A) is correct: The “ground-glass” matrix is the pathognomonic sign of fibrous dysplasia. It is a benign, developmental anomaly where bone is replaced by fibro-osseous tissue. When it is extensive in the proximal femur, it weakens the bone and leads to a varus deformity known as a “Shepherd’s Crook” deformity.
- Why (B) is wrong: A simple bone cyst is purely lytic (dark) and centrally located, often with a “fallen fragment” sign.
- Why (C) is wrong: An ABC is lytic, expansile, and has “fluid-fluid levels,” not a ground-glass matrix.
- Why (D) is wrong: Paget’s disease affects older patients and causes bone expansion with coarse trabeculation, not a ground-glass matrix.
- Why (E) is wrong: Osteosarcoma is a malignant, aggressive lesion with ill-defined borders and a “cloud-like” osteoid matrix.
Key Points: Fibrous Dysplasia
- Definition: Benign developmental “do-not-touch” lesion.
- Hallmark: “Ground-glass” matrix (homogeneous, hazy density).
- Location: Can be monostotic (one bone) or polyostotic (multiple).
- Sign: Can cause expansion and deformity, such as the “Shepherd’s Crook” deformity of the proximal femur.
- Syndrome: McCune-Albright (polyostotic FD, café-au-lait spots, precocious puberty).
Question 14: Pelvic Ring Fracture (Lateral Compression)
Stem: A 50-year-old pedestrian is struck on the side of the hip by a car. An AP radiograph of the pelvis shows fractures of the left superior and inferior pubic rami and an impaction fracture of the left sacral ala.
Question: According to the Young-Burgess classification, this “closed book” injury pattern is classified as:
(A) Lateral Compression (LC) (B) Anteroposterior Compression (APC) (C) Vertical Shear (VS) (D) Acetabular Fracture (E) Stable Pelvic Fracture
Correct Answer: (A) Lateral Compression (LC).
Explanation:
- Why (A) is correct: A Lateral Compression (LC) injury is the most common type of pelvic ring fracture. It is caused by a side impact, which “closes the book.” This force is transmitted from the iliac wing to the sacrum, causing an impaction fracture of the sacral ala on the side of impact. The anterior ring (pubic rami) often breaks on the same side or opposite side (a “buckle” injury).
- Why (B) is wrong: An APC injury opens the pelvis, causing symphyseal or SI joint diastasis, not impaction.
- Why (C) is wrong: A VS injury involves vertical displacement, which is not described.
- Why (D) is wrong: This is a ring injury; the acetabulum may be involved, but the primary pattern is LC.
- Why (E) is wrong: With both anterior and posterior ring injuries, this is an unstable fracture.
Key Points: Lateral Compression (LC) Fracture
- Most common pelvic ring injury pattern.
- Mechanism: Side impact (“T-bone” MVA, pedestrian struck).
- Hallmark: Sacral ala impaction fracture.
- Anteriorly: Often associated with transverse pubic rami fractures.
Question 15: Transient Osteoporosis of the Hip
Stem: A 35-year-old woman in her third trimester of pregnancy presents with the acute onset of severe, non-traumatic hip pain, causing her to be unable to bear weight. An MRI of her hip (with no gadolinium) shows diffuse, high T2 signal (bone marrow oedema) throughout the entire femoral head and neck. The X-ray is normal.
Question: What is the most likely diagnosis?
(A) Transient Osteoporosis of the Hip (B) Avascular Necrosis (AVN) (C) Septic Arthritis (D) Metastatic Disease (E) Femoral Neck Stress Fracture
Correct Answer: (A) Transient Osteoporosis of the Hip.
Explanation:
- Why (A) is correct: This is the classic presentation. Transient osteoporosis is a self-limiting condition of unknown cause, most common in middle-aged men or women in the third trimester of pregnancy. It presents with acute, severe pain. The key MRI finding is diffuse bone marrow oedema throughout the femoral head and neck, without the focal subchondral defects of AVN.
- Why (B) is wrong: AVN would present as a focal, subchondral, serpiginous area of oedema/necrosis, not diffuse oedema of the entire head and neck.
- Why (C) is wrong: Septic arthritis would be associated with fever, raised inflammatory markers, and a large, complex joint effusion and synovial enhancement.
- Why (D) is wrong: Metastases are typically focal, destructive, solid lesions.
- Why (E) is wrong: A stress fracture would appear as a distinct fracture line, not diffuse oedema.
Key Points: Transient Osteoporosis of the Hip
- Definition: A rare, self-limiting condition of acute bone marrow oedema.
- Demographic: Middle-aged men OR women in the 3rd trimester of pregnancy.
- Clinical: Acute, severe, non-traumatic pain; inability to bear weight.
- MRI: Diffuse bone marrow oedema of the entire femoral head and neck.
- Note: It resolves spontaneously over 3-9 months.
