Do I need surgery after my kneecap dislocated once?

Often, no. A first-time kneecap dislocation without a loose piece of cartilage or bone is usually treated without surgery, with a short period of bracing followed by a physical therapy program focused on the quadriceps, especially the inner-thigh VMO, plus hip and core strength. Surgery is considered for recurrent instability or when a dislocation knocked off a fragment.

What is MPFL reconstruction?

The medial patellofemoral ligament (MPFL) is the main soft-tissue restraint that holds the kneecap from sliding toward the outside of the knee. When it is stretched or torn and the kneecap keeps dislocating, MPFL reconstruction rebuilds that restraint, commonly with a tendon graft, to restore stability. Significant anatomic risk factors are often corrected at the same time.

Why does my kneecap keep dislocating?

Recurrent dislocation usually reflects the underlying anatomy: a shallow groove on the thighbone, a kneecap that sits too high, or the alignment of the leg, sometimes combined with a stretched medial ligament from a prior dislocation. Identifying these factors matters, because durable treatment addresses the cause rather than just the most recent episode.

When can I return to sports?

After non-surgical treatment, return to cutting and pivoting sports is graded over the first few months as strength and control improve. After MPFL reconstruction, most athletes progress through guided rehabilitation and return to sport over roughly four to six months, depending on strength, stability, and the sport's demands.

Patellar Instability, Steven J. Lee, MD

The patella, or kneecap, normally glides in a shallow groove at the end of the thighbone as the knee bends and straightens. In patellar instability, the kneecap slides partly (a subluxation) or completely (a dislocation) out of that groove, almost always toward the outside of the knee.

It happens most often in young athletes during a sudden twist, a cutting move, or a direct blow. Some people are more prone to it because of their anatomy: a shallow groove, a high-riding kneecap, or the overall alignment of the leg. Sorting out whether a first-time event or a recurring problem, and why it is happening, is what guides treatment.

Symptoms

Common findings include:

A sense of the kneecap shifting, giving way, or popping out
Sudden pain and swelling after a twist or a blow to the knee
A visible deformity if the kneecap is still dislocated at the time
Apprehension or guarding when the kneecap is pushed toward the outside

Why anatomy matters

Some kneecaps dislocate because of a single hard injury, and some dislocate because the underlying anatomy makes them prone to it. A shallow trochlear groove, a patella that sits too high, and the alignment of the thigh and shinbone all influence how stable the kneecap is. Identifying these risk factors is important, because they change both the chance of it happening again and what surgery, if needed, should correct.

How it is diagnosed

The diagnosis starts with the history and an exam that tests how easily the kneecap shifts toward the outside. X-rays and an MRI check for a piece of cartilage or bone knocked off during the dislocation and measure the anatomic risk factors, which together shape the plan.

Dr. Lee's approach

For a first-time dislocation without a loose fragment, Dr. Lee usually treats the knee without surgery: a brief period of bracing, then a structured physical therapy program focused on the quadriceps, especially the inner-thigh VMO, along with hip and core control to keep the kneecap tracking properly.

Recurrent instability, or a dislocation that knocked off a piece of cartilage or bone, is treated surgically. The most common procedure is reconstruction of the medial patellofemoral ligament (MPFL), the main soft-tissue checkrein that holds the kneecap in place. When the underlying anatomy is a significant driver, a shallow groove, a high-riding patella, or alignment, that is addressed at the same time so the repair is not left to fail against the same forces.

Non-surgical treatment

A first-time dislocation without a loose fragment is usually managed without surgery:

A short period of bracing to calm the initial injury
Quadriceps strengthening with emphasis on the VMO
Hip and core strengthening to improve kneecap tracking
A graded return to cutting and pivoting sports

Surgical treatment

Recurrent instability, or a dislocation with a displaced cartilage or bone fragment, is treated surgically. MPFL reconstruction restores the main soft-tissue restraint, and significant anatomic risk factors are corrected at the same time so the reconstruction is protected.

Recovery timeline

Recovery depends on whether treatment is non-surgical or surgical:

Non-surgical, weeks 0 to 6
Bracing as directed, then progressive quadriceps, hip, and core strengthening.
After reconstruction, weeks 0 to 6
Brace protecting the repair, with guided motion and weight-bearing as directed.
Months 3 to 6
Progressive strengthening and a graded return to cutting and pivoting sport.

What patients commonly misunderstand

What patients are often surprised by:

A first dislocation does not always mean surgery. Many first-time dislocations without a loose fragment recover well with bracing and a focused rehabilitation program. Surgery is reserved for recurrent instability or a dislocation that knocked off cartilage or bone.
The anatomy needs to be addressed. If a shallow groove, a high-riding kneecap, or alignment is driving the instability, a soft-tissue repair alone can fail against the same forces. Correcting the underlying anatomy is what makes the result durable.

This page is general educational content authored by Dr. Lee. It is not a substitute for individual medical advice. Every patient's case is different, book a consultation to discuss yours.

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Kneecap that slips, catches, or has dislocated? The cause guides the cure.

Patellar instability ranges from a single dislocation that recovers with rehabilitation to a recurrent problem driven by anatomy. A careful evaluation defines the risk factors and directs treatment, from a focused therapy program to MPFL reconstruction that corrects the underlying cause.

Patellar Instability: when the kneecap slips out of place.