Diagnosis
Three symptoms are very typical for a patella tendon rupture. Firstly, active knee extension is limited and the patella protrudes slightly upwards (patella elevation). On the other hand, one can feel (palpate) a dent at the site of the rupture, which is usually palpable despite the bruise that forms.
Frequently, a “wandering up” of the patella can also be observed when bending the knee or tensing the thigh muscles, since the patella is no longer fixed to the tibia by the torn patella tendon. Since the leg can no longer be actively and powerfully stretched, the affected limb is unable to bear weight. In contrast to, for example, an Achilles tendon rupture, patients with a patella tendon rupture often complain of severe pain, as there is often also a torn bony tendon.
An x-ray provides a good means of assessing the extent of the patellar tendon rupture; a bony tear can also be easily seen on an x-ray. An ultrasound examination of the tendon will confirm the diagnosis.In some cases, further imaging diagnostics (MRI, nuclear spin of the knee) may be helpful, for example, if there is a suspicion of concomitant damage to the knee joint or if only part of the patellar tendon is torn (partial rupture). The symptoms of a (rare) patellar tendon rupture can be similar to the symptoms of a much more common patella fracture (fracture of the patella), which also involves a loss of extensibility in the knee joint.
In addition, a fracture may also cause the patella to be palpable in a raised position. The reliable differentiation of the two diagnoses enables a lateral X-ray of the knee joint. This also makes it possible to rule out a quadriceps tendon rupture, which is usually manifested by a low position of the kneecap in the event of an acute extension deficit in the knee joint.
ICD-10
The pain and swelling in acute patellar tendon rupture should be treated with ice and the leg should be elevated. A complete rupture of the patellar tendon should always be treated surgically, except in the case of extensive concomitant injuries or acute danger to the life of the affected person. In these cases, surgery for patellar tendon rupture is also recommended after the affected person has been stabilized to restore good knee joint function in the long term.
Without surgery, only strains or small tears of the patellar tendon can be treated, which do not lead to any relevant weakening of the patellar tendon. The rupture can be located centrally in the tendon area as well as at the tip of the patella or at the base of the tibia. Depending on the localization, a tendon suture is performed; near the bone, it is fixed in the bone with a suture anchor.
In addition to the direct suture of the two tendon ends, a twisted wire (wire cerclage) is placed between the patella and the tibial tuberosity, the so-called McLaughlin cerclage. This wire completely relieves the suture of the patellar tendon, thus enabling early functional treatment of the knee joint after surgery. As a rule, the wire cerclage can be surgically removed after three to six months.
Very often, however, the wire cerclage already tears during the functional post-operative treatment, in which case the material should be removed early. The surgery for patellar tendon rupture is usually performed under general anesthesia and takes about 30 to 45 minutes. Complications such as bruising (hematoma) and superficial infections can occur during the operation.
The goal of surgery for a patellar tendon rupture is to completely restore the extension of the leg and the ability to bear weight. The patellar tendon consists of the end tendon of the thigh muscle (quadriceps femoris), which connects the patella with the tibia. The tendon is attached to the tibial tuberosity.
During the operation, the torn parts of the tendon are reconnected. An incision is made below the knee to expose the tendon. For optimal stability, a hole is drilled into the kneecap and the tibia each.
These holes are connected by means of different wires (cerclage or labitzke) or transosseous sutures to fix the patella in its correct anatomical position. Then the end links of the tendon are sutured together again. Once optimal stability and functionality have been ensured, the wound is closed. If necessary, a drainage is inserted to treat secondary bleeding. After the operation, a splint is put on and a weekly follow-up training is recommended.