Knee joint effusion
| Classification according to ICD-10 | |
|---|---|
| M25.4 | Joint effusion |
| ICD-10 online (WHO version 2019) | |
A knee joint effusion is an increased accumulation of fluid within the knee joint capsule . The fluid is, for example, normal or pathologically altered joint fluid (synovia) , blood (hemarthrosis) or pus (empyema) .
Classification and causes
There is a causal distinction between acute (mostly traumatic) and chronic knee joint effusion.
Acute knee joint effusions
The most common traumas that result in a knee joint effusion are a cruciate ligament tear , a patellar dislocation or subluxation, an osteochondral fracture and a fracture of the tibial plateau. A significant peripheral meniscus lesion is less common, but still to be named as a possible cause of a knee joint effusion.
Chronic knee joint effusions
Chronic knee joint effusions occur when the joint mucous membrane (synovium) is irritated and as a result produces more joint fluid (synovia) . Meniscus lesions as well as patellar tendon tendinitis or the so-called plica syndrome can also be considered as the cause . There is an imbalance between fluid production and absorption, which leads to excessive fluid build-up in the knee joint capsule.
Symptoms / clinical picture and diagnosis
The knee joint swells up due to the knee joint effusion. Occur tension pain , which are routed mainly through the sensory nerve endings that are located in the joint capsule. The normal amplitude of movement is restricted.
Dancing patella
A typical diagnostic sign is the so-called "dancing patella". The examiner feels an elastic rebound with frontal pressure on the kneecap (patella) , which floats on the knee joint effusion. However, the sign is only positive with larger joint effusions of approx. 50 ml.
Second method
The examination method described below is more sensitive: The suprapatellar recess is pressed out with one hand, then the fluid-filled joint capsule is stroked along the medial side of the knee from distal to proximal and a slight protrusion can be observed on the lateral side of the knee. This sign is positive from a liquid volume of approx. 10 ml.
Other methods
Of course, a knee joint effusion can also be detected with imaging diagnostics such as ultrasound , conventional X-rays or MRI .
therapy
The swelling can decrease by itself, through resorption when the knee joint is immobilized, supported by elevation of the extremity and anti-inflammatory drugs per os and locally. Otherwise, therapeutic intervention in the form of joint puncture is required. In order to avoid recurrences , it must be treated causally. A purulent effusion (knee joint empyema) must always be relieved interventionally.
