patella

Patellar fracture: description

With only about one percent, the patella fracture is one of the rare fractures of humans. Men are about twice as likely to be affected as women. As a fractured joint, the patellar fracture requires careful examination and treatment.

The patella connects the tendon of the femoral extensor (quadriceps tendon) to the patellar tendon and prevents the quadriceps tendon rubbing directly on the knee joint. It is the largest sesamoid of the human body and integrated into the extensor of the knee joint. During movement, the kneecap slides on a corresponding groove of the femur.

The patellar fracture can be classified according to the type of fracture in:

• Polabrissfrakturen
• transverse fractures
• longitudinal fractures
• piece fractures
• comminuted fractures

Patellar fracture: symptoms

A patellar fracture is characterized by swelling and pain in the knee joint. The joint can only be raised to a limited extent or no longer actively against gravity. However, this is not a definite symptom since the knee joint can sometimes be flexed despite patellar fracture.

If the patellar fracture is postponed, you can typically feel a dent in the area. Frequently, a patellar fracture can also reveal superficial skin defects such as bump marks and abrasions. In some cases, a crunch can be heard and felt as soon as the knee joint is moved (crepitus).

Patellar fracture: causes and risk factors

The cause of a patellar fracture is usually a direct trauma to the front of the knee due to a fall or impact on the flexed knee joint. This is usually a transverse fracture. A car accident often causes a patellar fracture when the knee joint hits the dashboard violently (“dashboard injury”). The sufferers often suffer other injuries, especially on the thigh or pelvis.

Certain types of sports (such as inline skating) can also cause a patellar fracture in the event of a fall on the knee. In exceptional cases, the sudden flexion of the maximum muscular knee joint leads to a fracture of the kneecap. Since the kneecap lies directly under the skin, the patellar fracture is often one of the so-called open fractures. This means: Bone parts pass through the skin to the outside.

A patellar fracture can also occur during surgery. For example, if a transplant (VKB plastic) is removed or a knee prosthesis is implanted behind the kneecap, a patellar fracture may be a potential complication. Other procedures such as quadriceps tendon repair or reconstructions around the patella are also risky.

Patellar fracture: examinations and diagnosis

If you suspect a patellar fracture, you should consult a doctor for orthopedics and traumatology. To diagnose a patellar fracture, the doctor will first ask you exactly what happened and your medical history. Some questions from the doctor might be:

• Did you fall on the knee joint?
• Did you get a knock on the front of the knee?
• What does the exact accident happen?
• Can you still stretch and bend the knee?
• Do you have pain?
• Did you have any problems in the knee area, such as pain, restricted movement or a previous dislocation?

The doctor then examines the knee joint for swelling and pain and tests how far it can be moved. In a patellar fracture, the stretched leg can often no longer be raised against the resistance of the examiner.

Tissue fluid or blood usually enters the joint space during a patellar fracture, resulting in a so-called joint effusion or hemarthrosis (bloody joint effusion). The result of an articular effusion is the typical “dancing patella”. The examiner presses against the patella and feels like she “floats” on the joint.

The doctor will also examine the surrounding soft tissues. Superficial skin abrasions are not uncommon. Bony accompanying injuries should not be overlooked either.

Patellar fracture: Imaging examination

Whether the knee is broken or not, can finally clarify an X-ray of the knee joint. The knee is x-rayed both from the front and from the side. In a longitudinal fracture in addition an axial recording is made.

Furthermore, the patellar tendon, the thigh muscles as well as an accumulation of fluid in the joint can be demonstrated by means of ultrasound. If there are still ambiguities, a computed tomography (CT) can be performed.

Patellar fracture: treatment

The aim of treating a patellar fracture is to restore the joint and the extensor apparatus. Depending on fracture type (such as longitudinal or transverse fracture) and fracture type (displaced or not), the patellar fracture can be treated conservatively or surgically. In the case of initial care, the fracture is first provisionally splinted, the leg relieved and cooled with ice pads.

Patellar fracture: Conservative treatment

In a non-displaced longitudinal fracture, in which the knee joint can still be stretched, a conservative treatment comes into question: The patellar fracture can heal without surgery in a splint. In a transverse fracture, an operation is indicated, even if it is only slightly displaced.

The knee joint is immobilized for about six weeks with two forearm supports and an orthosis (immobilization splint, Donjoy / Mecron splint without joint). The leg may be partially loaded with a maximum of 15 kilograms. Accompanying physiotherapy supports healing, with limited range of exercise. Only after the six-week rest period has elapsed can the strain be gradually increased to full body weight.

Patellar fracture: surgical treatment

An operation is indicated for a displaced patellar fracture, where a joint has formed in the joint, as well as an open fracture. The goal is to anatomically reconstruct the patella. If this is not possible (such as in a debris fracture), the patella must be completely removed.

If the patellar fracture is only slightly displaced, the fracture can also be stabilized again in the context of joint radiography (arthroscopy). If an open surgery is necessary, the incision is made longitudinal due to the vascular supply. Drill wires or screws hold the fragments. A special tension belt absorbs the tensile forces (cerclage).

In principle, the tension belt is resistant to exercise and load. This allows the physiotherapy to begin quickly. Above all, it aims to train the thigh muscles and gait. After the patellar fracture has healed, it is sometimes necessary to remove the implants in another operation.

After the operation, the patellar fracture can be mildly treated with ice over the first few days and the leg can be stored upright. A manual lymphatic drainage can prevent swelling.

Patellar fracture: disease course and prognosis

In about 70 percent of cases, the prognosis for a patellar fracture is usually very good. The bone usually heals in six to eight weeks, and the affected leg is then fully operational again.

However, there may be a number of complications: If there is an irregularity of the cartilage at the back of the patella despite debris or transverse fractures despite surgery, threatened early osteoarthritis in the sliding bearing of the patella. To prevent this, one can completely remove the kneecap (patellectomy). As a further complication, the thigh muscle may lose strength and the knee may become more unstable. A patella also carries the risk that the knee is not as mobile afterwards as it used to be.