Diagnosis

If the patella is still luxated, the diagnosis can be made by sole observation. In addition, the knee joint effusion and the Giving way are groundbreaking for the diagnosis. The clinical examination is the so-called Apprehension Test.

In this test, an attempt is made to slide the kneecap over the outer slide bearing in a relaxed state. The test is considered positive if an involuntary defensive movement is performed or the patella can be luxated. An x-ray of the knee joint is performed on apparatus-based diagnostics.

In addition, a special image of the kneecap is taken in three positions (patelladéfilé at 30°,60° and 90° flexion of the knee joint). This image can be used to assess patellar dysplasia (misalignment of the patella), arthrosis behind the kneecap (retropatellar arthrosis) and bony excrescences (boiling cartilage flake). If there is a strong suspicion of cartilage shearing at the back of the patella or the outer femoral condyle, a magnetic resonance tomography of the knee joint (MRI knee) should be performed to determine the extent of the damage.

In addition to the cartilage damage, ligament injury can also be assessed in magnetic resonance imaging of the knee joint, especially of the medial retinaculum of the kneecap, which often tears completely in the case of an outwardly dislocated patella. In most cases, a patellar dislocation does not require any treatment because it usually returns to its sliding bearing by itself (self-reposition), especially when the knee joint is brought into an extended position. If this does not happen, however, it is extremely important to treat a patellar dislocation quickly and adequately in order to avoid possible consequential damage.

The aim is to bring the patella back into its slide bearing permanently, since the probability of cartilage damage increases with each new dislocation. First of all, the patella must be brought back into its correct position as quickly as possible. This repositioning can be done either by a doctor or an experienced sports trainer.

Here it is important to stretch the knee slowly while keeping the kneecap firmly in place so that no sudden unwanted movements can occur. If the reduction is successful, the patient will immediately notice an improvement in pain. If possible, an x-ray or computed tomography (CT) should then be performed to confirm the correct position of the kneecap.

Depending on the extent of the damage caused, there are various treatment options to choose from.

Magnetic resonance imaging (MRI) can be used to determine whether the ligament and holding apparatus have been damaged. If this is not the case, a conservative (non-surgical) treatment is usually sufficient to repair the defect.
It is often sufficient to stabilize and immobilize the knee joint for about 6 weeks with the help of a guide rail (orthosis), a plaster sleeve or a bandage.
Accompanying medication can be prescribed to relieve pain and to counteract possible inflammation and swelling. Particularly helpful here are preparations from the antirheumatic form (non-steroidal antirheumatic drugs, NSAIDs) such as Diclofenac or Ibuprofen.
Cooling ointments can also reduce swelling and relieve pain.
In rare cases, it may be advisable to relieve a larger knee joint effusion with a puncture.
In addition to these acute measures, physiotherapy should be carried out over a longer period of time. This means that the patient should by no means allow the resting phase to become too long and should be mobilized quickly afterwards, preferably under medical or physiotherapeutic supervision.
On the one hand, this serves to prevent a regression of the musculature and stiffening of the knee joint. On the other hand, a muscle-building training should be carried out to improve strength and coordination, thus making a renewed luxation of the kneecap less likely.
However, if there is extensive cartilage damage or defects of the ligamentous apparatus or a shearing of a cartilage-bone fragment (flake), surgical therapy should be performed. Even after repeated dislocations, surgery is usually resorted to at some point to ensure long-term healing.