Knee series

The knee series is a set of radiographs taken to investigate knee joint pathology, often in the context of trauma. It usually comprises an AP and lateral projection, although other non-standard, modified projections can be used for specific indications.

See also knee radiograph (an approach).

Indications

Knee radiographs are indicated for a variety of settings including :

• trauma
• bony tenderness at the head of the fibula
• isolated patella tenderness
• patient unable to flex the knee to 90 degrees
• if the patient is unable to weight bear
• suspected osteoarthritis
• detecting joint effusions
• infection

Projections

Standard projections

• AP view
  • demonstrates the distal femur, proximal tibia/fibula and the patella in the AP position
  • ideal projection to assess the tibial plateau and tibiofemoral alignment  
• horizontal beam lateral view
  • orthogonal projection to the AP, routinely done in trauma horizontal beam to better demonstrate any joint effusions
  • ideal projection to assess lipohemarthrosis
  • used to examine the location of the patella and the patency of the patella tendon

Additional projections

• rolled lateral view
  • often performed on bed-bound patients with suspected arthritis
  • orthogonal view of the AP projection
  • demonstrate the joint space, yet sacrifices any assessment of fluid levels
• skyline (Merchant view)
  • superior-inferior projection of the patella; this is an ideal projection for patients that are better suited in the supine position
• skyline (Laurine view)
  • inferior-superior projection of the patella; this projection is best suited to patients able to maintain a semi-recumbent position on the examination table
• knee AP weight-bearing view
  • often used in the context of orthopedic appointments to obtain images of the knees in their natural anatomical position
• knee intercondylar view
  • view utilized to demonstrate intercondylar space, often used for OA and suspected tibial plateau fractures 
• Rosenberg's view
  • weight-bearing projection used to assess joint space-related pathology such as osteoarthritis 
• oblique view
  • two views (internal and external) better demonstrating the knee joint in the absence of CT