What is the medial patellofemoral ligament (MPFL)?
The knee is a complex joint that contains a network of soft tissues that work together to stabilize the knee. The medial patellofemoral ligament (MPFL) attaches the inside part of the patella (kneecap) to the femur (thigh bone). The MPFL plays a particularly important role in keeping the patella on track by acting like a leash that restrains the patella's movement.
How do MPFL tears occur?
When patellar dislocation occurs, soft tissues are damaged as the patella “jumps” the track and then comes forcibly back into place. Because the kneecap dislocates toward the outside of the leg, the ligament on the inside of the knee (the MPFL) gets torn. Left untreated, an injured MPFL can heal on its own. However, when left alone, the ligament heals in a loosened, lengthened position. This causes instability that makes it easier for the patella to become dislocated again in the future.
Injury to the MPFL can also occur as a result of naturally loose ligaments or due to individual variations in bony anatomy. People with these injuries are often described as having patellar instability.
What are the symptoms of an MPFL injury?
- Feeling like your knee is buckling and can no longer support your weight
- The kneecap slips off to the side of the joint and no longer feels as though it is in the proper position
- A catching sensation in the knee joint when you bend or straighten your leg
- Pain in the front of your knee that increases with activity
- Knee pain while sitting
- Stiffness or swelling in the knee
- Creaking or cracking sounds when you move your knee
How are MPFL tears diagnosed?
Patients with patellar instability undergo a thorough assessment that includes a physical examination and review of the patient's medical history. Dr. Potts may also order an MRI to help confirm the diagnosis, assess the alignment of your knee, and look at the condition of the cartilage in the patellofemoral joint.
What is the treatment for MPFL injuries?
Initially, some patients may benefit from conservative treatment, especially if the patient has experienced a single dislocation without a cartilage injury on MRI. Almost all candidates for MPFL reconstruction have dislocated their kneecap more than once, and in some cases, may have experienced numerous dislocations. MPFL reconstruction offers an excellent treatment option for patients who have recurring patellar dislocations.
