Sometimes, the kneecap can slip out of its groove, causing pain, swelling, and stiffness. This condition is known as patellofemoral instability (PFI). It often happens due to a sports injury, a fall, or a direct hit to the knee.

Certain conditions can make the patella more likely to dislocate:

• Patella Alta: An abnormally high sitting kneecap that does not truly sit in its groove.
• Trochlear Dysplasia: A groove that is too shallow for the patella to sit properly.
• Increased Q Angle: Misalignment of the kneecap and shin bone.
• Lateral Patellar Dislocation: Common in young, active girls and women because they tend to have looser ligaments.

Once you have a kneecap dislocation, you are at higher risk for it happening again.

Repeated dislocations are often due to:

• A shallow groove (trochlear dysplasia)
• An unusually high kneecap (patella alta)
• Weak or stretched ligaments, including a torn MPFL
• Weak thigh muscles (quadriceps)
• Tight hip muscles
• Genetic conditions that make your connective tissue looser and allow for increased mobility

People with patellar instability might experience:

• Swelling and bruising
• Pain when sitting or standing up
• Pain at the front of the knee
• Stiffness in the joint
• Knee buckling or catching
• A creaking sound when moving the knee
• Difficulty walking

To diagnose patellar instability, doctors use:

• Physical Exam: Observing how the kneecap moves.
• X-Rays: To check for bone issues like a high kneecap or shallow groove.
• MRI: To look for soft tissue damage, such as a torn MPFL, and to see if there are loose fragments in the joint or bone bruising.
• CT Scan: Sometimes used to see if the bones are not aligned properly.

We will assess these factors to determine the best treatment plan for your knee.

If patellar instability is not treated properly or if dislocations keep happening, it can lead to several long-term problems:

• Chronic Instability: The kneecap can continue to pop out leading to damaging cartilage, pain, stiffness and swelling. It can limit activities as well.
• Cartilage Damage: When the kneecap pops out the cartilage underneath it usually bangs against the cartilage of the thigh bone and can lead to damaged cartilage which can accelerate arthritis in that location of the knee.
• Persistent Pain: Ongoing instability or damage from dislocations can cause continuous pain in the knee.
• Decreased Range of Motion: Dislocations can lead to scarring, inflammation, or other damage that might reduce how much you can bend or straighten your knee.
• Soft Tissue Damage: The initial dislocation can harm ligaments, tendons, and other soft tissues in the knee. This damage can make the knee less stable and affect how it works.
• Muscle Weakness: After a dislocation, the muscles around the knee, like the quadriceps become weaker which can lead to more instability and pain. The quads help decrease dislocations, so keeping the quads strong is important.