Items tagged “knee”
361 results found





Article
Cyclops lesion (knee)
The cyclops lesion, also known as localised anterior arthrofibrosis, is a painful anterior knee mass that arises as a complication of anterior cruciate ligament (ACL) reconstruction.
Epidemiology
Cyclops lesions occur with an estimated frequency of ~5% (range 1-9.8%) of patients following ACL ...
Article
Discoid meniscus
Discoid menisci are those 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 condition is congenital, frequently bilateral (up to 50%) and has been reported in twins, although no ...
Article
Double PCL sign
The double 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 centre of the joint so that it comes to lie anteroinferior to the posterior cruciate ligament (PCL) mimicking a second smaller PCL.
A double PCL ...
Article
Extensor mechanism of the knee injuries
Extensor mechanism of the knee injuries include:
quadriceps muscle tears
quadriceps tendon rupture
patella tendon rupture
patella fracture
patellar dislocation often with medial retinaculum tears
patella sleeve fractures
Chronic injuries:
Osgood-Schlatter disease
Sinding-Larsen-Johanss...
Article
Lipohaemarthrosis
Lipohaemarthrosis 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 (TL) to the length of the patella (PL).
Insall-Salvati ratio
This can be measured on a lateral knee x-ray or sagittal MRI. Ideally, the knee is 30 degrees flexed.
Distance lines used to calculate Insall-Salvati rati...
Article
Meniscal flounce
Meniscal flounces refers to the "ruffled" appearance of the inner margin of the knee meniscus. They were initially thought to be only an arthroscopic finding, as a result of joint distension and anaesthetic muscle relaxants but are rarely seen on MRI.
Epidemiology
Meniscal flounces are rare, ...
Article
O'Donoghue unhappy triad
O'Donoghue unhappy triad or terrible triad often occurs in 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 the "pivot shift" mechanism.
The O'Donoghue unhappy triad comprises three t...
Article
Osgood-Schlatter disease
Osgood-Schlatter disease (OSD) is a chronic fatigue injury due to repeated microtrauma at the patellar ligament insertion onto the tibial tuberosity, usually affecting boys between 10-15 years.
Epidemiology
Osgood-Schlatter disease is seen in active adolescents, especially those who jump and k...
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 appearance:
superficial layer: rectus femoris
middle layer: vastus medialis, vastus lateralis
deep layer: vastus intermedius
See also
q...
Article
Rim sign of avascular necrosis
The rim sign of avascular necrosis (AVN) 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).
The rim sign should not be confused with the...
Article
Spontaneous osteonecrosis of the knee
Spontaneous osteonecrosis of the knee, also known as Ahlback disease, SONK or even SPONK, has similar appearances to osteochondritis dissecans of the knee but is found in an older age group.
Epidemiology
SONK is seen more frequently in women (M:F 1:3) and affects older patients, typically over...
Case
Avascular necrosis of the knee

Diagnosis certain
Published 07 May 2008
83% complete
MRIAnnotated image
Case
Discoid meniscus (degenerate)

Diagnosis certain
Published 07 May 2008
68% complete
MRI
Case
Degenerative subchondral bone cyst

Diagnosis almost certain
Published 13 May 2008
64% complete
MRIX-ray
Case
Knee joint effusion

Diagnosis certain
Published 15 May 2008
69% complete
X-ray
Case
Celery stalk sign in ACL mucoid degeneration

Diagnosis almost certain
Published 27 May 2008
46% complete
MRIDiagram
Case
Anterior cruciate ligament ganglion cyst

Diagnosis certain
Published 27 May 2008
77% complete
MRI