Updated: 6/16/2021

Knee Imaging

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https://upload.orthobullets.com/topic/3004/images/segond fx_moved.jpg
https://upload.orthobullets.com/topic/3004/images/XR - Pellegrini-Stieda_moved.jpg
https://upload.orthobullets.com/topic/3004/images/1b4a6b16-6b12-4357-a64c-66faaf6f9492_sonk..jpg
https://upload.orthobullets.com/topic/3004/images/ffd46a73-1df3-4b62-a083-7f1aac1eed60_reverse_segond..jpg
https://upload.orthobullets.com/topic/3004/images/osteochondral lesion xray.jpg
https://upload.orthobullets.com/topic/3004/images/patella altal.jpg
https://upload.orthobullets.com/topic/3004/images/patella baja.jpg
https://upload.orthobullets.com/topic/3004/images/fairbanks knee.jpg
https://upload.orthobullets.com/topic/3004/images/screen_shot_2017-10-27_at_7.30.25_pm.jpg
  • High yield findings
    • High yield findings
      Finding
      Importance
      Segond sign
      Small lateral tibial avulsion fracture that indicates a ACL tear
      Reverse Segond sign
      Small medial tibial avulsion fracture that indicates a PCL tear
      Arcuate sign
      Fibular head avulsion fracture that indicates a PLC injury
      Pellegrini Stieda sign
      Medial femoral condyle avulsion fracture that indicates a chronic MCL injury
      Patella alta
      Patellofemoral pathology
      Patella baja 
      Arthrofibrosis
      Fairbanks changes
      DJD - post meniscectomy (square condyle, peak eminences, ridging, narrowing)
      Lateral MFC lesion
      OCD
      Crescent-shaped MFC lesion
      Spontanous osteonecrosis of the knee (SONK)

      Square lateral femoral condyle, cupped lateral tibial plateau
      Discoid meniscus


      3 sagittal MRI images
      Discoid meniscus
      Bipartite patella
      Must differentiate from fracture
  • Radiographic
    • Standard Radiographs
      • Weightbearing
        • preferred for evaluation of joint space
      • 45 degree PA flexion view (Rosenberg view)
        • best for early tibiofemoral arthritis, posterior wear
        • best for early tibiofemoral arthritis, posterior wear
      • best for early tibiofemoral arthritis, posterior wear
      • Merchant or sunrise view
        • to evaluate patellofemoral space, tilt, and alignment
    • best for early tibiofemoral arthritis, posterior wear
    • 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)
        • 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

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

QID: 761
1

Non-weight-bearing AP

0%

(7/2169)

2

Weight-bearing AP

16%

(338/2169)

3

Non-weight-bearing PA in 45 degrees flexion

1%

(26/2169)

4

Weight-bearing PA in 45 degrees flexion

82%

(1776/2169)

5

Merchant

1%

(17/2169)

L 2 D

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