What is patella?

The patella, commonly known as the kneecap, is a flat, triangular bone located at the front of your knee joint. The patella normally glides up and down in a groove (trochlear groove) at the lower end of the femur (thigh bone) when we bend and straighten the knee.

The main function of patella is

1) to protect the knee joint

2) to enhance the leverage that the quadriceps muscle group can exert on the knee, improving extension (straightening) of the leg

3) to reduce the friction between the quadriceps tendon and the underlying femur

What is dislocation of patella?

Patellar dislocation (also known as kneecap dislocation) is a condition where the patella slips sideways out of the vertical groove at the end of the femur. When the dislocation occurs, the kneecap moves out of this groove, typically towards the outside (lateral dislocation), and may stretch or tear ligaments, especially the medial patellofemoral ligament. There may also be associated injuries, such as cartilage damage or fracture of the patella.

How does patella dislocation happen?

Usually occurs from trauma, such as a direct blow to the knee or a twisting injury, especially during athletic activities or abrupt changes in direction.

What are the main symptoms?

1. Sudden, intense pain at the front of the knee
2. Swelling and sometimes noticeable bruising
3. Feeling of instability or that the knee “gave out”
4. Visible deformity: the kneecap appears out of place, often towards the outside of the knee
5. Locked or bent knee: difficulty straightening the leg
6. Inability to walk or put weight on the affected leg

What is recurrent patellar dislocation and patellar instability?

• Recurrent Patellar Dislocation is when the kneecap dislocates more than once. After an initial dislocation, the soft tissues that normally hold the patella in place can become stretched or torn, increasing the risk of repeated episodes.
• Patellar Instability refers to any sensation that the kneecap is “unstable,” “giving way,” or could dislocate again—even if it does not always completely dislocate.
• Causes and Risk Factors

1. Damage or laxity of the medial patellofemoral ligament (MPFL)
2. Shallow or abnormally shaped trochlear groove
3. High positioning of the patella (patella alta)
4. Leg alignment issues (e.g., knock knees)
5. Weakness of thigh muscles or overly loose ligaments
6. Repeated trauma or previous dislocation injuries

• Patellar instability often disrupts daily activities and quality of life, especially in adolescents and young adults. If left untreated, it may lead to chronic instability and long-term joint problems.

What is the management of patella dislocation?

1. Initial (Emergency) Management:

The initial management involves reduction of the dislocated knee cap. This is done by gentle manipulation of the knee. The knee is then immobilized in a knee brace for a few weeks to facilitate healing of soft tissues.

2. MRI scan: This is recommended to look for Medial patellofemoral ligament (MPFL) injury and osteochondral injuries.
3. Non-operative (Conservative) Management

Most first-time, uncomplicated acute patellar dislocations are managed non-operatively with splint for few weeks and then physiotherapy aimed at improving the strength of Quadriceps and other supportive muscles.

4. Surgical Management

Surgery is reserved for specific scenarios:

1. Osteochondral fracture or loose body requiring removal or fixation.
2. Large disruption of the medial patellofemoral ligament (MPFL) or significant retinacular injury.
3. Recurrent dislocations or persistent patellofemoral instability after non-operative treatment.

Surgical procedures include:

1. Lateral release (for mild instability).
2. MPFL reconstruction 
3. Distal realignment procedures, such as tibial tubercle osteotomy
4. Trochleoplasty