Items tagged “knee”
122 results found
Article
Cyclops lesion (knee)
The cyclops lesion, also known as localized anterior arthrofibrosis, is a painful anterior knee mass that arises as a complication of anterior cruciate ligament (ACL) reconstruction, although has rarely been reported in patients with ACL injuries that have not been reconstructed.
Epidemiology
...
Article
Discoid meniscus
Discoid menisci are anatomical variants that have a body that is too wide, usually affecting the lateral meniscus. They are incidentally found in 3-5% of knee MRI examinations.
Epidemiology
Discoid menisci are congenital, frequently bilateral (up to 50%) and have been reported in twins, altho...
Article
Double posterior cruciate ligament sign
The double posterior cruciate ligament (PCL) sign appears on sagittal MRI images of the knee when a bucket-handle meniscal tear (medial meniscus in 80% of cases) flips towards the center of the joint so that it comes to lie anteroinferior to the posterior cruciate ligament (PCL) mimicking a seco...
Article
Extensor mechanism of the knee injuries
Extensor mechanism of the knee injuries can be subdivided into:
acute injuries
quadriceps muscle tears
quadriceps tendon rupture
patellar tendon rupture
patella fracture
patellar dislocation often with medial retinaculum tears
patellar sleeve fractures
chronic injuries
Osgood-Schlatter...
Article
Lipohemarthrosis
Lipohemarthrosis results from an intra-articular fracture with escape of fat and blood from the bone marrow into the joint, and is most frequently seen in the knee, associated with a tibial plateau fracture or distal femoral fracture; rarely a patellar fracture. They have also been described in ...
Article
Insall-Salvati ratio
The Insall-Salvati ratio or index is the ratio of the patella tendon length to the length of the patella and is used to determine patellar height.
Usage
The Insall-Salvati ratio is probably the most commonly used measurement to assess patellar height, partially based on its simplicity. It can...
Article
Meniscal flounce
Meniscal flounces refer to the "ruffled" appearance of the inner margin of knee menisci. They were initially thought to be only an arthroscopic finding, as a result of joint distension and anesthetic muscle relaxants but they are occasionally seen on MRI.
Epidemiology
Meniscal flounces are un...
Article
O'Donoghue unhappy triad
O'Donoghue unhappy triad or terrible triad often occurs in contact and non-contact sports, such as basketball, football, or rugby, when there is a lateral force applied to the knee while the foot is fixated on the ground. This produces an abduction-external rotation mechanism of injury ("pivot s...
Article
Osgood-Schlatter disease
Osgood-Schlatter disease, also known as apophysitis of the tibial tubercle, is a chronic fatigue injury due to repeated microtrauma at the patellar tendon insertion onto the tibial tuberosity, usually affecting boys between ages 10-15 years.
Terminology
Unresolved Osgood-Schlatter disease is t...
Article
Osteochondritis dissecans of the knee
Osteochondritis dissecans (OCD) most commonly affects the knee. See osteochondritis dissecans article for a general discussion.
Pathology
Location
The condition occurs bilaterally in 25% of cases, and has a characteristic distribution 2,4,6:
medial condyle: ~78.5% (range 70-85%)
"classic" l...
Article
Popliteal artery aneurysm
Popliteal artery aneurysms are the most common peripheral arterial aneurysm and the second most common aneurysm after abdominal aortic aneurysms.
Epidemiology
Overall, popliteal artery aneurysms are uncommon. They occur almost exclusively in males (up to 97%) for unknown reasons 8-9. There is ...
Article
Quadriceps tendon
The quadriceps tendon is a thick tendon extending to the patella made up of contributions from all four quadriceps muscles. It classically has a trilaminar structure:
superficial layer: rectus femoris
middle layer: vastus medialis, vastus lateralis
deep layer: vastus intermedius
It continues...
Article
Rim sign (osteonecrosis)
A rim sign can be seen in osteonecrosis and comprises a high T2 or intermediate T1 signal line sandwiched between two low signal lines, and represents fluid between the sclerotic borders of an osteochondral fragment, and implies instability (stage III).
This rim sign should not be confused with...
Article
Subchondral insufficiency fracture of the knee
Subchondral insufficiency fracture of the knee (SIF/SIFK) are stress fractures in the femoral condyles or tibial plateau that occur in the absence of acute trauma, typically affecting older adults.
Terminology
The entity subsumes that previously known as spontaneous osteonecrosis of the knee (...
Article
Anterior cruciate ligament mucoid degeneration
Anterior cruciate ligament (ACL) mucoid degeneration, along with tears and anterior cruciate ligament ganglion cysts, is a relatively common cause of increased signal within the anterior cruciate ligament (ACL). The appearance can mimic acute or chronic interstitial partial tears of the ACL. How...
Article
Anterior cruciate ligament ganglion cyst
Anterior cruciate ligament (ACL) ganglion cysts, commonly referred to simply as ACL cysts, along with ganglion cysts arising from the alar folds that cover the infrapatellar fat pad, make up the vast majority of intra-articular ganglion cysts of the knee.
Epidemiology
Anterior cruciate ligamen...
Article
Celery stalk sign (anterior cruciate ligament)
The celery stalk sign is a term given to the appearance of the anterior cruciate ligament which has undergone mucoid degeneration and has been likened to that of a celery stalk. Its low signal longitudinal fibers are separated from each other by higher signal mucinous material, best appreciated ...
Article
Pellegrini-Stieda lesion
Pellegrini-Stieda lesions refer to ossified post-traumatic lesions at (or near) the medial femoral collateral ligament adjacent to the margin of the medial femoral condyle. One presumed mechanism of injury is a Stieda fracture (avulsion injury of the medial collateral ligament at the medial femo...
Article
Absent bow tie sign (knee)
The absent bow tie sign represents the loss of the normal appearance of the menisci on parasagittal MRI images and is suggestive of meniscal injury.
Normally the medial and lateral menisci appear as low signal triangular structures linked by a thin body located between the femoral condyles and ...
Article
Fragment-in-notch sign (knee)
The fragment-in-notch sign is closely related to, can be thought of as a failed, double PCL sign, in so far as it represents a meniscal fragment lying in the intercondylar notch, but not paralleling the posterior cruciate ligament (PCL).
Although both signs are most frequently seen in the sett...
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