 The knee is the largest joint in the body.
 The knee is stabilized by the collateral ligaments.
 The lateral and medial menisci function as shock absorbers.
 The bursae decrease friction of tendons and muscles as they move over bones.
CURRENT Medical Diagnosis & Treatment 2012. www.accessmedicine.com

Am Fam Physician. 1999;60(9):2599-2608.

 Plain radiograph for:
 Fractures
 Degenerative changes
 Osteochondral defects
 Effusions
 CT for:
 Fractures in patients with knee trauma
 MRI for:
 Damage to cartilage, menisci or ligaments
Cleveland Clinic Journal of Medicine 2008;75:377-384

 To assess the patellofemoral articulation
 Femur and tibia are superimposed
 Medial condyle is more rounded and prominent

medial epicondyle medial condyle femur patella tibia fibula intercondylar notch lateral epicondyle lateral condyle

Quadriceps femoris tendon patella femur
Inferior patellar tendon
Tibial tuberosity tibia fibula intercondylar notch medial femoral condyle lateral femoral condyle

 The patella can be fractured through one of its poles or through its central body.
 Patellar fractures can be simple or comminuted.
 Transverse fractures are most common and are most likely to be displaced.
Am Fam Physician. 1999;60(9):2599-2608.

Displaced fracture of the lower pole of the patella

Where is the fracture?
What type of fracture is this?
Non-displaced patellar fracture
The Color Atlas of Family Medicine: http:accessmedicine.com

 Femoral condyle fractures account for 4% of femur fractures. Potential complications include: DVT, fat embolus syndrome, delayed union ort malunion, and osteoarthritis.
 Tibial spine and tuberosity fractures usually result in cruciate ligament insufficiency.
 Fractures of the tibial plateau are seen more commonly in the elderly. Lateral plateau is more often fractured.
Potential complications include: popliteal artery injury,
DVT and osteoarthritis.
Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e. www.accessmedicine.com

 Usually the result of low impact trauma
 Common in kids
Where is the fracture?
The Color Atlas of Family Medicine : http:accessmedicine.com

Tibial intercondylar emminence fracture
Identify the lipohemarthrosis on the radiograph
The lipohemarthrosis (composed of blood and fat from the marrow) seen above is a specific sign of an intra-articular fracture although a fracture is not visualized.

Comminuted left tibial metaphysis and lateral plateau fracture
Lateral plateau fracture left tibial metaphysis fracture

Fracture of the tibial eminence joint effusion
An additional sign of a fracture includes a joint effusion fracture lateral tibial bone depressed posteriorly
Koplas M et al. Cleveland Clinic Journal of Medicine 2008;75:377-384

 Epiphyseal plates in children can be mistaken for fractures
Child Adult http://www.dartmouth.edu/~anatomy/Lowerextremity/leg-knee/radiology/APknee-child.htm

 Often associated with a fracture of the tibial plateau
 Usually the result of motor vehicle crashes, falls, sports, and industrial injuries
 Knee dislocations are associated with popliteal artery and common peroneal and tibial nerve injuries
Anterior knee displacement
Posterior displacement of the tibia
The Atlas of Emergency Medicine: http:accessmedicine.com

The Atlas of Emergency Medicine: http:accessmedicine.com

Flow chart shows approach to radiographic evaluation of arthritis.
©2008 by Radiological Society of North America
Jacobson J A et al. Radiology 2008;248:737-747

Felson DT. N Engl J Med 2006; 354:841-848

Osteoarthritis:
 initially involves medial side
 joint space narrowing
 subchondral cysts
 osteophytes
 sclerosis
Basic Radiology, 2 nd edition: http:accessmedicine.com

Bone on bone contact
Patellar osteophyte subchondral osteophyte

Rheumatoid arthritis:
 Osteopenia
 Loss of joint space
 Ligamentous laxity
 Joint effusion
 Bone erosion

Diffuse osteopenia
Symmetric joint space narrowing
Bone erosion
Joint effusion
Tibial erosion

Osteoarthritis What radiographic features do you see? osteophyte joint space narrowing medial or lateral side? medial subchondral cyst

Felson DT. N Engl J Med 2006; 354:841-848.
Geisel School of Medicine at Dartmouth, Department of Anatomy. Introduction to Radiology. Retreived September 6, 2012 from http://www.dartmouth.edu/~anatomy/Intro-to-radiology/index.htm.
Glaspy J.N., Steele M.T. (2011). Chapter 271. Knee Injuries. In Tintinalli's Emergency Medicine: A Comprehensive Study
Guide, 7e. Retrieved September 6, 2012 from http://www.accessmedicine.com.
Gonzales R., Nadler P.L. (2013). Chapter 2. Common Symptoms. In M.A. Papadakis, S.J. McPhee, M.W. Rabow (Eds),
CURRENT Medical Diagnosis & Treatment 2013. Retrieved September 6, 2012 from http://www.accessmedicine.com.
Jacobson J, Girish G, Jiang Y, et al. Radiographic evaluation of arthritis: degenerative joint disease and variations.
Radiology. 2008; 248: 737-747.
Koplas M, Schils J and Sundaram M. The painful knee: choosing the right imaging test. Cleveland Clinic Journal of Medicine
2008;75:377-384.
Raukar N.P., Raukar G.J., Savitt D.L. (2010). Chapter 11. Extremity Trauma. In K.J. Knoop et al. (Eds), The Atlas of Emergency
Medicine, 3e. Retrieved September 7, 2012 from http://www.accessmedicine.com.
Tandeter HB and P Shvartzman. Acute knee injuries: use of decision rules for selective radiograph ordering. Am Fam
Physician. 1999 Dec 1;60(9):2599-2608.
Wasserman P.L., Pope T.L. (2011). Chapter 7. Imaging of Joints. In M.Y. Chen, T.L. Pope, D.J. Ott (Eds), Basic Radiology, 2e.
Retrieved September 7, 2012 from http://www.accessmedicine.com.