Knee Anatomy 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

Knee Anatomy

Knee Joint Anatomy Am Fam Physician. 1999;60(9):

Imaging the knee 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:

AP view of the knee

Lateral view of the knee

Sunrise view of the knee To assess the patellofemoral articulation Femur and tibia are superimposed Medial condyle is more rounded and prominent

Identify the following... femur tibia fibula patella lateral condyle medial condyle lateral epicondyle medial epicondyle intercondylar notch

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

Knee injuries

Patellar fractures 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):

Patellar fractures Displaced fracture of the lower pole of the patella

Patellar fractures Where is the fracture? The Color Atlas of Family Medicine: What type of fracture is this? Non-displaced patellar fracture

Fractures 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.

Lateral condylar split fracture Usually the result of low impact trauma Common in kids The Color Atlas of Family Medicine : Where is the fracture?

Tibial intercondylar emminence fracture 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. Identify the lipohemarthrosis on the radiograph

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

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

Epiphyseal plates Epiphyseal plates in children can be mistaken for fractures ChildAdult

Knee dislocation 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 The Atlas of Emergency Medicine: Posterior displacement of the tibia Anterior knee displacement

Patellar tendon rupture The Atlas of Emergency Medicine:

Arthritis

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

Osteoarthritis of the knee Felson DT. N Engl J Med 2006; 354:

Radiographic findings Osteoarthritis: initially involves medial side joint space narrowing subchondral cysts osteophytes sclerosis Basic Radiology, 2 nd edition:

Osteoarthritis Bone on bone contact Patellar osteophyte subchondral osteophyte

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

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

Identify the type of arthritis What radiographic features do you see? joint space narrowing medial or lateral side? medial osteophyte subchondral cyst Osteoarthritis

References Felson DT. N Engl J Med 2006; 354: Geisel School of Medicine at Dartmouth, Department of Anatomy. Introduction to Radiology. Retreived September 6, 2012 from 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 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 Retrieved September 6, 2012 from Jacobson J, Girish G, Jiang Y, et al. Radiographic evaluation of arthritis: degenerative joint disease and variations. Radiology. 2008; 248: Koplas M, Schils J and Sundaram M. The painful knee: choosing the right imaging test. Cleveland Clinic Journal of Medicine 2008;75: 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 Tandeter HB and P Shvartzman. Acute knee injuries: use of decision rules for selective radiograph ordering. Am Fam Physician Dec 1;60(9): 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