questions
1

Knee Imaging

Author:
Topic updated on 07/02/16 11:10pm
  
High yield findings

Finding
Importance
 Images
Segond sign  Small tibial avulsion fracture that indicates a ACL tear
Patella alta Patellofemoral pathology
Pellegrini Stieda Sign Medial femoral condyle avulsion fx (Chronic MCL injury)
Patella baja Arthrofibrosis
Fairbanks changes  DJD - post meniscectomy (square condyle, peak eminences, ridging, narrowing)
Lateral MFC lesion OCD
Square lateral femoral condyle, cupped lateral tibial plateau, hypoplastic lateral tibial spine Discoid meniscus
3 sagittal MRI images Discoid meniscus  
Bipartate patella
Must differentiate from fracture
 

Radiographic
  • Standard Radiographs
    • Weight-bearing 
      • preferred for evaluation of joint space.
    • 45 degree PA flexion view (Rosenberg view)
      • best for early tibio-femoral arthritis, posterior wear 
    • Merchant or sunrise view 
      • to evaluate patello-femoral space, tilt and alignment.
  • Stress Radiographs
    • Varus-valgus stress radiographs
      • two diagnostic indications
        • physeal fractures in children
        • MCL / LCL injuries
    • Posterior stress radiographs
      • isolated PCL injury (10-12 mm posterior displacement)
      • PCL and PLC injury (> 12 mm posterior displacement)
MRI
  • Views
    • sagittal  
      • evaluate menisci, cruciates, cartilage, extensor mechanism
    • coronal 
      • evaluate menisci, cruciates, collaterals, cartilage
    • axial 
      • evaluate patellofemoral joint, cruciates, popliteal fossa
  • Sequences
    • T1
      • water dark, fat bright
      • best for showing anatomy, but not pathology
    • T2 
      • fat dark, water bright
      • well suited for imaging edema and pathology  
    • STIR (Short T1 Inversion Recovery) Images 
      • fat suppression technique
      • improved quality imaging in the presence of orthopedic prostheses
  • Excellent for
    • meniscal injury
      • Medial meniscal extrusion >3mm is associated with severe meniscal degeneration, a large meniscal tear, or tear of the root
      • Radial meniscal tears are more common in patients following prior meniscal surgery (32% prevalence of radial meniscal tears in post-op knees compared to 14% in patients without prior surgery)
      • 3.0 T MRI has accuracy, sensitivity, and specificity of >90% for detecting medial and lateral meniscus tears
    • ligament tear
      • Increased signal intensity, thickening, and cysts within and adjacent to ACL are common findings, and clinically insignificant (no instability)
    • bone bruise
      • near sulcus terminalis
      • osteochondral injury
    • PLC corner injuries
      • can routinely visualize LCL and popliteus tendon with MRI, other structures are more rarely seen
      • edema posterior to popliteus tendon can indicate an injury to the underlying structures of the PLC 
 Ultrasound
  • Excellent for   
    • fluid collections
      • useful to evaluate bursae and fluid collections about the knee
    • arthrofibrosis
      • effective in detecting arthrofibrosis of the knee following TKA
      • key findings for arthrofibrosis are synovial thickening and neovascularity 

 

Please Rate Educational Value!
3.0
Average 3.0 of 30 Ratings

Qbank (1 Questions)

TAG
(OBQ07.100) Which of the following radiographic views is most sensitive for detecting knee joint degenerative changes? Topic Review Topic

1. Non-weight-bearing AP
2. Weight-bearing AP
3. Non-weight-bearing PA in 45 degrees flexion
4. Weight-bearing PA in 45 degrees flexion
5. Merchant

PREFERRED RESPONSE ▶




Evidence



Topic Comments