About patellar instability
The kneecap (patella) glides in a groove at the end of the thigh bone as the knee bends and straightens. In patellar instability, the kneecap slips partly out of this groove (subluxation) or fully out of it (dislocation), almost always toward the outer side of the knee.
A first dislocation often happens during a twist with the foot planted, and it commonly tears the medial patellofemoral ligament, a band on the inner side of the kneecap that holds it in place. Some people have a shallow groove, a high-riding kneecap, or loose ligaments that make it easier for the kneecap to slip.
After one dislocation, the chance of another is higher, especially in teenagers and young athletes. A careful evaluation helps decide between a rehab-first plan and an early surgical opinion.
Common symptoms
- A sense of the kneecap shifting or popping out, then back in
- Swelling and pain after a dislocation
- Feeling the knee is unstable or about to give way
- Apprehension or worry when the kneecap is pushed outward
- Pain along the inner edge of the kneecap
Common causes and risk factors
- A twisting injury with the foot planted
- A shallow groove for the kneecap or a high-riding kneecap
- Generalized loose ligaments
- Weak hip and thigh muscles that let the knee collapse inward
- Knock-knee alignment or rotation in the leg bones
How we diagnose it
Our physicians assess how the kneecap tracks, how easily it shifts, and whether the inner stabilizing ligament is tender or loose. Diagnostic ultrasound at the exam table can show swelling in the joint and injury to the soft tissues on the inner side of the kneecap. After a first dislocation, we refer for X-rays and often an MRI to look for loose pieces of bone or cartilage and to measure features such as groove depth and kneecap height that affect the risk of it happening again.
How Propel treats patellar instability
For most first-time dislocations without loose fragments, treatment starts with a short period of protection, then a rehabilitation program focused on the quadriceps, hip, and core muscles that control the knee's position. A patellar stabilizing brace or taping can provide support as you return to activity. We progress to balance, landing, and sport-specific drills before clearing a return to play.
Recurrent dislocations, a loose fragment of bone or cartilage in the joint, or instability that continues despite good rehab are reasons to see a surgeon, and we refer to trusted orthopedic surgeons for stabilization procedures. We can then guide rehab after surgery and the return to sport.
What to expect at your visit
- 1.
We listen first
Your visit opens with a real conversation: how the problem started, what you have already tried, and the activity you want back.
- 2.
Exam and in-office ultrasound
A hands-on exam, then ultrasound at the exam table, often while you move, so your physician can see the tendon, joint, or nerve involved.
- 3.
A clear diagnosis and plan
You leave knowing what is wrong and what your options are, from strength-based rehab to procedures, and why we recommend each one.
- 4.
Treatment and follow-through
Most procedures happen here in the office. We coordinate with your physical therapist and check progress against the goals you set.
Questions about patellar instability
- Do I need an MRI after my kneecap dislocated?
- After a first dislocation, an MRI is often helpful because it can show loose pieces of cartilage or bone and the condition of the inner stabilizing ligament. These findings shape whether rehab alone is reasonable or whether a surgical opinion makes sense.
- Will my kneecap keep dislocating?
- It can, particularly in younger people and those with a shallow groove or loose ligaments. Strengthening the hip and thigh muscles and using a brace for sport lower that risk for many people. When dislocations keep happening, surgery is often the better option.
- Can a knee brace stop my kneecap from slipping?
- A patellar stabilizing brace or taping can add support and confidence, especially when returning to sport. It works best as part of a strengthening program rather than on its own.