Items tagged “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 ...

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 ...

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 ...

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...

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...

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 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, ...

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

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 appearance: superficial layer: rectus femoris middle layer: vastus medialis, vastus lateralis deep layer: vastus intermedius See also q...

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...

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...