Fracture of the patella or kneecap fracture

Kneecap fracture (fracture of the patella) is understood to mean the fracture of the foremost bone of the knee : the kneecap, also called the patella; the lesion can be mild or severe.

In the case of fractures without displacement of the fragments or with only fine crack formation in the bone, the healing process is completed more quickly and long-term consequences occur less frequently.

In the case of displaced, open or multi-fragment fractures, the prognosis is much worse and sequelae can persist in the medium to long term, eg restricted mobility.

As a rule, a kneecap fracture occurs on one side, i.e. on the right or left side.
The fracture of the kneecap leads to major limitations in the movement of the knee joint, because the pain can be felt with every attempt to walk.
Patella fractures account for approximately 1% of all broken bones, more than half of which involve the knee.
Risk factors for a kneecap fracture include:

  • Osteoporosis;
  • walking on slippery and bumpy terrain;
  • balance disorders.

The impact can also inflame the bursa beneath the kneecap , injure the menisci , and—rarely— rupture the cruciate ligament or patellar tendon .


What exactly is the kneecap?

The kneecap or patella is a sesame bone in the front of the knee, it lies in front of the femur.
Rectangular in appearance when viewed from the front, the bone is more triangular when viewed from above, with the base pointing outwards and the apex of the triangle lying between the femoral condyles.
The kneecap moves within theFossa intercondylaris, a pit lying between the two femoral condyles.
The patella is embedded in the tendon of the quadriceps muscle , which is called the quadriceps tendon above the patella and the patellar tendon, patellar tendon, or patellar ligament below.

What types of fractures occur in a kneecap fracture?

In transverse fractures, the upper fragment is pushed up by the quadriceps tendon while the lower fragment is pulled down by the patellar tendon; This creates a diastasis of the fragments, ie the fracture is displaced and the two fracture ends diverge.
The prognosis is better for longitudinal fractures because the forces pulling the bone fragments to the hip and foot are approximately equal and the fracture gap tends to be the same.
In the case of a comminuted fracture, the kneecap breaks into many individual parts.
A fragment can also detach completely from the rest of the bone.

How does a kneecap fracture occur?

The injury almost always results from direct force applied to the front part of the knee , which occurs when:

  • when falling on the knee joint, mostly happens to older people, rarely to children;
  • in a serious traffic accident, when hitting the dashboard;
  • in the event of a fall from a bicycle or motorcycle.

If the impact is very severe, the condyles of the femur or the tibial plateau may also fracture.

What are the symptoms of a kneecap fracture?

The main symptoms are anterior knee pain , swelling , bruising and severe impairment in extending the knee joint and walking, especially if the fracture is displaced.
In the first few days after the accident, the patient is unable to bear weight on the injured leg, even when standing.
The bruise is extensive and affects a large area on the inside and outside of the knee.
Kneecap injuries are often accompanied by abrasions.

How is a kneecap fracture diagnosed?

The doctor first examines the medical history of the patient in order to be able to understand how the accident happened; the subsequent physical examination checks for typical signs and symptoms. An x-ray
is taken in the emergency room to check for a fracture; after that, the patient comes to orthopedics, where the doctors specialize in this type of injury. Other imaging methods are not necessary because an X-ray is sufficient.

What is the right treatment for a patella fracture?

For an undisplaced fracture, the orthopedist will prescribe immobilization for 30 days with a cast or splint to protect the bone to allow bone healing (consolidation).
In the case of a displaced or complete fracture, the fracture must be surgically adjusted, ie the bone fragments are united and fixed (osteosynthesis); are used for this:

  • screws
  • Kirschner wires
  • Zuggurtung (Strapping)

The kneecap is wrapped with very strong metal wires that hold the bones in the correct position.
In a comminuted fracture, the largest piece of bone is preserved and the smaller fragments removed; the tendons are then connected to the remaining piece of bone.
For a particularly severe or burst fracture, a patellectomy, which is complete removal of the kneecap, may be considered; in this case, the quadriceps and patellar tendons are joined together.

If an undisplaced fracture of the kneecap is not treated, the healing process is delayed; On the other hand, not treating a displaced fracture can have serious consequences: limping, severe limitation of movement and persistent knee pain .

Rehabilitation after surgery for kneecap fracture

The patient must perform physical therapy exercises to regain range of motion, strength, and balance.
The physiotherapist must massage the scar to break adhesions.
After a month of immobilization of the knee joint with cast or orthosis, it is necessary to do strengthening exercises.
The healing prognosis for a displaced kneecap fracture is about 3 months; in the case of an undisplaced, incomplete fracture, the patient can resume professional activities after about 1 ½ months if he carries out the physiotherapeutic exercises.
If the surgeon has used a tension band, it can be removed after 6 to 12 months if the fracture is consolidated and stable.

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