A 36-year-old male is taken to the emergency room after jumping from a building. Bilateral fractures to the femur were stabilized at the scene by emergency medical technicians. The patient is lucid upon questioning and his vitals are stable. Pain only at his hips was elicited. Cervical exam was not performed. What is the best imaging study for this patient?

Computed tomography (CT) scan of cervical spine, hips, and lumbar area

AP and lateral radiographs of hips

Lateral radiograph (x-ray) of hips

Magnetic resonance imaging (MRI) of hips, knees, lumbar, and cervical area

Anterior-posterior (AP) and lateral radiographs of hips, knees, lumbar, and cervical area

A 69-year-old woman presents with pain in her hip and groin. She states that the pain is present in the morning, and by the end of the day it is nearly unbearable. Her past medical history is notable for a treated episode of acute renal failure, diabetes mellitus, obesity, and hypertension. Her current medications include losartan, metformin, insulin, and ibuprofen. The patient recently started taking high doses of vitamin D as she believes that it could help her symptoms. She also states that she recently fell off the treadmill while exercising at the gym. On physical exam you note an obese woman. There is pain, decreased range of motion, and crepitus on physical exam of her right hip. The patient points to the areas that cause her pain stating that it is mostly over the groin. The patient's skin turgor reveals tenting. Radiography is ordered. Which of the following is most likely to be found on radiography?

Loss of joint space and osteophytes

Posterior displacement of the femoral head

A 40-year-old woman comes to the physician because of a 2-week history of anal pain that occurs during defecation and lasts for several hours. She reports that she often strains during defecation and sees bright red blood on toilet paper after wiping. She typically has 3 bowel movements per week. Physical examination shows a longitudinal, perianal tear. This patient's symptoms are most likely caused by tissue injury in which of the following locations?

Posterior midline of the anal canal, distal to the pectinate line

Anterior midline of the anal canal, proximal to the pectinate line

Posterior midline of the anal canal, proximal to the pectinate line

Lateral aspect of the anal canal, distal to the pectinate line

Anterior midline of the anal canal, distal to the pectinate line

A 45-year-old man is brought to the emergency department following a motor vehicle collision. He reports right hip pain and numbness along the right thigh. Physical examination shows decreased sensation to light touch over a small area of the proximal medial thigh. X-rays of the pelvis show a displaced pelvic ring fracture. Further evaluation of this patient is most likely to show which of the following findings?

Sensory deficit of the dorsal foot

A 35-year-old man comes to the physician because of a 3-month history of intermittent right lateral hip pain that radiates to the thigh. Climbing stairs and lying on his right side aggravates the pain. Examination shows tenderness to palpation over the upper lateral part of the right thigh. There is no swelling. When the patient is asked to abduct the right leg against resistance, tenderness is noted. An x-ray of the pelvis shows no abnormalities. Which of the following structures is the most likely source of this patient's pain?

Lateral femoral cutaneous nerve

A 25-year-old man presents with progressive weakness and urinary retention. MRI of the spine shows an intramedullary lesion from T10-T12 with expansion of the spinal cord and syrinx formation. The conus medullaris is identified at the L1-L2 level (normal: L1-L2). The filum terminale appears thickened at 3 mm. CSF flow study shows obstruction at the lesion site. Evaluate these radiologic landmarks and their relationships to determine the neurological level most likely affected.

Epiconus (T12-L1) with distal lower extremity and sphincter dysfunction

Cauda equina only, sparing upper motor neurons

Conus medullaris with mixed upper and lower motor neuron signs

Thoracic cord with pure upper motor neuron signs below T10

Lower thoracic nerve roots with radicular pain pattern only

A 58-year-old woman with breast cancer undergoes staging CT. The scan shows a solitary 2 cm lesion in the liver at the junction of segments IVa, V, and VIII, directly adjacent to the middle hepatic vein. PET scan shows FDG avidity. The oncologist requests evaluation for surgical resection. The radiologist notes the lesion's relationship to the portal vein bifurcation (Cantlie's line). Evaluate the radiologic anatomical landmarks to determine resectability and surgical approach.

Central hepatectomy with middle hepatic vein reconstruction

Unresectable due to middle hepatic vein involvement; systemic therapy only

Right hepatectomy with adequate future liver remnant assessment

Extended right hepatectomy including segment IV

Radiofrequency ablation given central location

Pelvic radiologic landmarks for USMLE Step 2 CK: High-Yield Anatomy Lessons

Pelvic Girdle - Bony Foundation

Composition: A basin-like ring formed by two innominate bones, the sacrum, and the coccyx.
- Each innominate bone comprises the ilium, ischium, and pubis, which fuse at the acetabulum.
Key Articulations:
- Sacroiliac (SI) Joints: Link the axial skeleton (sacrum) to the iliac bones.
- Pubic Symphysis: A cartilaginous joint that unites the pubic bones anteriorly.
Primary Function: Transfers upper body weight to the lower limbs; protects pelvic viscera.

AP Pelvic X-ray with Labeled Radiologic Landmarks

⭐ The sacroiliac (SI) joint, a diarthrodial synovial joint, is a significant source of chronic low back pain, accounting for 15-30% of cases.

Key Radiographic Lines - Connect the Dots

Annotated AP pelvis X-ray: Iliopectineal & Ilioischial lines

Shenton's Line: A smooth, continuous arc from the medial aspect of the femoral neck to the inferior border of the superior pubic ramus. Disruption is a key sign of a femoral neck fracture or developmental dysplasia of the hip (DDH).
Iliopectineal Line: Follows the pelvic brim, representing the anterior column of the acetabulum. A break suggests an anterior column fracture.
Ilioischial Line (Kohler's Line): Represents the posterior column of the acetabulum. Disruption points to a posterior column fracture.
Hilgenreiner's Line: A horizontal line drawn through the superior aspect of the triradiate cartilages. Used as a baseline in pediatric hip evaluation.
Perkin's Line: A vertical line perpendicular to Hilgenreiner's line, at the lateral acetabular margin. The femoral head should lie in the inferomedial quadrant.

⭐ A subtle break in Shenton's line can be the only radiographic evidence of an undisplaced or impacted femoral neck fracture, a frequent injury in osteoporotic elderly patients.

Acetabular Landmarks - Hip Socket Scoop

Key lines on an AP pelvis X-ray that assess the integrity of the acetabulum.
Iliopectineal Line: Represents the anterior column.
Ilioischial Line: Represents the posterior column.
Radiographic Teardrop: Formed by the medial wall of the acetabulum.
Shenton's Line: A continuous curve along the inferior border of the femoral neck and the superior pubic ramus. Disruption suggests fracture or dislocation.
Acetabular Roof (Sourcil): The weight-bearing dome.

Pelvic Radiologic Landmarks on AP Hip X-ray

⭐ Disruption of Shenton's line is a classic sign of a femoral neck fracture or developmental dysplasia of the hip (DDH).

Special Views & Signs - Beyond the AP

Judet Views (Oblique Pelvis): Used to evaluate acetabular & pelvic ring fractures. Two views (iliac and obturator oblique) named for the side rolled up.
- Iliac Oblique: Shows the posterior column and anterior rim.
- Obturator Oblique: Shows the anterior column and posterior rim.
Inlet View: Assesses anteroposterior displacement of the pelvic ring. The beam is angled 40° caudally.
Outlet View: Evaluates vertical displacement of the hemipelvis. The beam is angled 40° cephalad.

Pelvic radiograph with key anatomical landmarks highlighted

⭐ Crescent Sign: A subchondral lucency in the femoral head, often one of the earliest signs of avascular necrosis (AVN) on a plain radiograph.

High‑Yield Points - ⚡ Biggest Takeaways

Shenton's line disruption on an AP X-ray is a classic sign of a femoral neck fracture or developmental dysplasia of the hip.

The ischial spines are a crucial landmark for administering a pudendal nerve block and for determining fetal station during labor.

The sacral promontory is the posterior border of the obstetric conjugate, the narrowest fixed diameter for the fetal head.

The iliopectineal line separates the true pelvis from the false pelvis.

A pubic symphysis gap >10 mm suggests diastasis or pelvic ring trauma.

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