Injury of the patellar tendon | Tendon injuries to the knee joint

Injury of the patellar tendon

The rupture of the patella tendon (also called ligamentum patellae) shows it as well as the rupture of the quadriceps tendon at an extension deficit of the knee. This is explained by the fact that the patellar ligament is ultimately only the continuation of the quadriceps tendon below the kneecap – i.e. it is responsible for transmitting the stretching force of the quadriceps in the knee. The X-ray image should ensure that there are no bony injuries.

In the lateral x-ray, a tear of the patellar tendon is diagnosed if the kneecap is elevated. In normal conditions, the patellar tendon pulls the patella caudally (bottom). In case of a tear, the patella shifts cranially (top).

The cause of a tear in the patellar tendon is, as with the quadriceps tendon rupture, a fall on the knee, which is already strongly to maximally bent. The patellar tendon can no longer be stretched and ruptures in the fall, where it would have to stretch even more. Especially in older patients with reduced ability to stretch the tendons, the tendon tends to tear.Younger patients are more likely to tear the tendon from the lower pole of the kneecap.

A more complicated rupture occurs when the tibial tuberosity is torn off – i.e. when the attachment point of the tendon tears completely or partially from the tibia (shin bone). If a rupture of the patella tendon has been diagnosed, surgical treatment is absolutely necessary. A skin incision is made along the length of the knee from the kneecap up to the level of the insertion point of the tendon (tibial tuberosity/slightly below the tibial plateau).

The rupture site is exposed and the surrounding structures and tendons are checked for possible injuries. The two stumps are connected with so-called braiding sutures. A thread is used which is sewn longitudinally through the tendon and is continued parallel to the rupture site so that a square seam is created at the end.

In addition, absorbable seams are inserted directly into the two stumps so that the two ends are pulled directly together. As a further safety mechanism, a frame seam is inserted, which is pulled through a horizontally running drilled channel through the patella so that the tendon is pulled tightly against the patella. In addition, the frame suture can also be secured by a horizontally running drilled channel through the tibial tuberosity.

This ensures that the tendon is tightly stretched between the patella and the attachment point and, above all, that it is securely fastened. In order to achieve the correct length of the patallae ligament, an x-ray of the other knee is taken and then the appropriate length is set up accordingly. As with the restoration of the quadriceps tendon, a Z-plasty can be used.

If there is insufficient functional tendon tissue, the tendon of the semitendinosus muscle can be used. Drains must be left in place after the operation to allow blood and other fluids to drain away. At the beginning a thigh cast must be worn for about 1-2 weeks.

This is split – i.e. cut open, so that swelling of the thighs in the plaster does not lead to constriction. Afterwards a normal plaster can be applied. This must be worn for a period of about one and a half months.

In the course of the follow-up treatment, careful build-up training with physiotherapy and controlled strength training is necessary. Care should be taken to ensure that no premature overloading occurs (avoidance of ruptures in the healing process).