MPFL Tears & Patellar Instability
Why Does My Kneecap Keep Slipping Out of Place?
Your kneecap keeps slipping out of place because the ligament that normally holds it centered, the MPFL (medial patellofemoral ligament), is torn. The MPFL is the primary ligament restraining your kneecap (patella) at the front of the knee. It's usually torn during a first dislocation, when the kneecap slides out of its groove, typically toward the outside of the knee. Once that ligament is torn, your kneecap loses much of its normal restraint, which is why further dislocations or a persistent feeling of instability become more likely afterward. Your own knee anatomy also plays a role — some people are simply born with a shallower groove for the kneecap, a kneecap that sits differently relative to the shin bone, or a kneecap that naturally rides a bit high, all of which make a dislocation more likely from a relatively minor twist or impact.
This is you if:
- Your kneecap has dislocated or shifted out of place, whether once or repeatedly
- Your knee feels like the kneecap is going to “pop out,” especially with twisting or pivoting
- You've had swelling and pain at the front of your knee following a dislocation
- You've already been told you have an MPFL tear or patellar instability and want an honest read on your real options
- Physical therapy hasn't resolved your instability and you want to know what's next
Symptoms
- A visible or felt kneecap dislocation, followed by looseness afterward
- Pain and swelling at the front of the knee
- A feeling that your kneecap is going to slip or “pop out”
- Reduced confidence or apprehension with twisting, pivoting, or going down stairs
- Weakness or a sense of instability in the front of the knee
Causes & Risk Factors
- Traumatic dislocation — often from a pivot, twist, or direct blow to the knee
- Repeat dislocation — each one increases the risk of another, and can cause additional cartilage or bone damage over time
- Anatomic factors — some people are naturally more prone to dislocation based on how their kneecap and its groove are shaped
- Younger age and sports involving pivoting or cutting — associated with higher rates of first-time dislocation
Non-surgical first.
A first-time dislocation, especially in a lower-demand patient, often responds well to physical therapy focused on strengthening the muscles that support the kneecap. Bracing and activity modification can also help reduce the risk of another dislocation. How well non-surgical treatment works depends heavily on your specific activity level and sport, pivoting and cutting sports carry a much higher risk of another dislocation than low-impact activity, as well as your own anatomy; significant alignment issues, like a shallow groove or a high-riding kneecap, make non-surgical treatment less likely to succeed on its own.
Surgical reconstruction.
When physical therapy isn't enough, especially after repeat dislocations, surgery may involve one or more of the following, depending on your specific anatomy and what's driving your instability:
- MPFL Reconstruction — Uses donor tissue (allograft) to reconstruct the MPFL, restoring the ligament's normal job of holding your kneecap in place. For most patients, this is the core procedure that addresses the instability itself.
- Tibial Tubercle Osteotomy — Addresses instability caused by misalignment between your kneecap and shin bone by repositioning where your kneecap tendon attaches, in addition to the ligament itself.
- Trochleoplasty — A procedure that deepens or reshapes the groove your kneecap glides in, addressing instability that comes from the groove itself being too shallow to keep the kneecap centered.
- Cartilage Restoration — Addresses any cartilage damage caused by the dislocation itself, repairing the joint surface alongside whichever ligament or alignment procedure your case requires.
Dr. Thon will determine which of these your knee actually needs, MPFL reconstruction alone is enough for most patients, while others benefit from addressing alignment or cartilage damage at the same time, and will walk you through exactly why.
Recovery & What to Expect
- Brace: A minimum of 6 weeks, worn at all times except during physical therapy, showering, changing, and while awake at complete rest. Locked straight while walking.
- Crutches: Typically 1-2 weeks.
- Physical therapy: Begins within 1-2 weeks after surgery, at least once weekly for the first 6-12 weeks.
- Follow-up visits: You'll be seen 6 times after surgery, spaced with gradually increasing time between visits over the following year.
- Overall timeline: Recovery is gradual — expect 1-2 months to regain normal gait and full motion, 3-4 months to feel a significant difference, and 5-6 months to return to full sports.
Every recovery is different, and depends on the extent of your injury and any other issues addressed in your knee at the same time. Dr. Thon will walk you through your personal timeline in detail.
Why Choose Orchard Orthopedics for This
You'll always see Dr. Thon personally for your initial patellar instability evaluation and surgery, not a resident or rotating provider. Recurrent kneecap instability is easy to under- or over-treat; you'll get an honest, personalized read on whether your knee actually needs surgery or whether targeted rehab is the smarter first step, paired with the direct access and unhurried follow-up care Orchard Orthopedics is built around.
Frequently Asked Questions
Understanding Your Injury
Each dislocation makes the next one more likely, and repeat dislocations can cause additional cartilage or bone damage over time. An evaluation gives you an honest picture of your actual risk.
That's a common and important signal. It usually means the torn ligament, or an underlying alignment issue, needs to be addressed surgically rather than just supported by stronger muscles around it.
Occasionally, the extent of cartilage, bone, or alignment involvement is only fully clear during surgery. If that happens, Dr. Thon will address what's actually there and explain exactly what changed and why, before, during, and after your procedure.
Deciding on Treatment
It depends on what's driving your instability. Most patients only need MPFL reconstruction, but if significant misalignment between your kneecap and shin bone, a very shallow groove, or cartilage damage is also contributing, Dr. Thon may recommend addressing that at the same time. He'll walk you through exactly what your knee needs and why.
Yes, especially before surgery. A second opinion isn't a lack of trust in your first doctor. It's a normal, expected step, and many patients return to their original surgeon with more confidence in the plan either way.
I have no insurance panel dictating my decisions and no quota to hit. I'll tell you honestly when physical therapy is a realistic path for your knee, and when surgery is the better call.
No surgery can promise zero risk of recurrence, but the right procedure, or combination of procedures, matched to what's actually causing your instability, significantly reduces your risk compared to leaving it untreated. Dr. Thon will walk you through your specific odds based on your case.
That's a completely normal reaction. Your visit is the place to ask every question you have, including ones about anesthesia, risk, and what the day of surgery actually looks like, until you feel genuinely informed, not just signed up.
Age alone doesn't rule surgery in or out. What matters more is how many times you've dislocated, your activity level, how much the instability is limiting your life, and if there is any underlying arthritis.
Access & the Orchard Model
No. You can call and schedule directly, no referral or prior authorization required.
You'll always start with Dr. Thon on your initial visit for your patellar instability evaluation and surgery. He remains closely involved in your care throughout.
Surgery & Recovery Logistics
Most patients can be seen same-day or next-day. Call the office and we'll get you scheduled quickly.
Surgery time varies depending on whether you need MPFL reconstruction alone or in combination with other procedures. It's typically an outpatient procedure, so most patients go home the same day.
A minimum of 6 weeks, worn at all times except during physical therapy, showering, changing, and while awake at complete rest.
Most people can drive again 2-6 weeks after surgery, once fully off narcotic pain medication. Return to work depends on your job — desk jobs often resume in 1-2 weeks, while jobs requiring heavy lifting may take 8-12 weeks or longer.
Most patients regain normal gait and motion around 1-2 months, feel a significant difference by 3-4 months, and return to full sports around 5-6 months, though this can vary if additional procedures like a tibial tubercle osteotomy or trochleoplasty were needed.
Get an honest answer about your kneecap instability, and a plan built specifically for you.
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