Items tagged “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 ...

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 are congenital, frequently bilateral (up to 50%) and have been reported in twins, although no genetic...

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 center of the joint so that it comes to lie anteroinferior to the posterior cruciate ligament (PCL) mimicking a second smaller PCL. A double PCL ...

Extensor mechanism of the knee injuries include: 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 disease Sinding-Larsen-Johans...

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 ...

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...

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...

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...

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 ages 10-15 years. Epidemiology Osgood-Schlatter disease is seen in active adolescents, especially those who jump ...

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...

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 ...

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...

A rim sign can be seen in avascular necrosis 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...

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 (...