Medial Patellofemoral Ligament
The medial patellofemoral ligament (MPFL) is a key anatomical structure for knee stability, especially for the patella, also known as the kneecap, which is the disc-shaped bone located at the front of the knee.
Located on the inside of the knee, the MPFL connects the patella to the femur, playing a crucial role in preventing the patella from dislocating outward during joint movement. Here, we will explore the importance of this ligament, the causes and symptoms of injuries, and the treatment options available.
Function of LPFM
The MPFL is one of the main stabilizers of the patella, being responsible for approximately 50-60% of its internal stability in the first degrees of knee flexion. Its function is to prevent the patella from displacing outward from the knee, especially during knee flexion and extension movements. This ligament works with other knee structures, such as the quadriceps muscle and the medial patellar retinaculum, to ensure the right movement of the patella along the trochlear groove of the femur.
MPFL injuries
Injuries to the medial patellofemoral ligament are more common in active patients, especially those who play sports that involve rapid changes of direction, such as soccer, basketball, and tennis. A trauma to the outside of the knee or sudden twisting movements can also result in an MPFL injury.
When an episode of patellar dislocation occurs, or when the kneecap moves outward from the joint, losing contact with the femur, the MPFL is often injured or even completely ruptured.
The MPFL can also be loose in patients who have patellar instability, in which the patella is looser due to a series of abnormal anatomical factors (learn more here).
Symptoms after a MPFL injury
The main symptoms of an MPFL injury include pain on the inner aspect of the knee, swelling, a sensation of giving way and, in cases of patellar dislocation, difficulty in straightening the knee. Joint effusion, an increase of the synovial fluid volume, may also occur.
Diagnosis and Treatment
Diagnosis of medial patellofemoral ligament injury is usually made through a thorough physical examination and imaging exams, such as magnetic resonance imaging (MRI). MRI is especially useful for assessing the integrity of the MPFL and the presence of other associated injuries, such as cartilage injuries, bone fractures, and intra-articular loose bodies.
Treatment of this type of injury varies depending on the severity. In a first episode of an isolated medial patellofemoral ligament injury, conservative treatment is the gold standard approach, including rest, use of immobilizers or plaster splints to stabilize the knee, physical therapy to strengthen the muscles around the patella, and anti-inflammatory drugs for pain control. Physical therapy is essential to restore joint function.
In cases where conservative treatment fails or if there are associated injuries, such as fractures or intra-articular loose bodies, surgery may be necessary. MPFL reconstruction is a widely performed surgical technique in which the ligament is reconstructed using a tendon graft to restore stability to the patella.
Post-surgical rehabilitation includes a progressive program of muscle strengthening and mobility, allowing the patient to gradually return to their usual activities.
