A patellar dislocation is when the kneecap (patella) slips out of the groove at the front of the femur, almost always to the outside (lateral). It usually happens with a twisting movement on a planted foot — landing awkwardly from a jump, cutting in sport, or a direct blow.
The immediate injury
Sometimes the kneecap goes back into place on its own. Sometimes it stays dislocated until it's reduced. Either way, several important structures can be damaged:
- Medial patellofemoral ligament (MPFL) — nearly always torn
- Cartilage on the underside of the kneecap or the femoral groove
- Bone bruising
- Loose bodies within the joint from cartilage fragments
Immediate care
Get imaging early — X-ray at minimum, often MRI. Ice, rest, and a knee brace for stability in the first 1-2 weeks. See a physician for anything beyond a first-time simple dislocation.
Why re-dislocation risk is high
After a first-time dislocation, roughly 15-40% of people re-dislocate within 5 years. Risk is higher in younger patients, those with anatomical predisposition (shallow trochlea, high-riding patella, valgus knees), and those who don't fully rehab.
Rehab that reduces re-dislocation risk
VMO (vastus medialis obliquus) activation — the inner quad that pulls the patella medially. Terminal knee extensions and specific quad drills.
Glute and hip strength — weak hip abductors and external rotators let the knee collapse inward, which loads the patella laterally.
Core stability — trunk control affects lower limb alignment.
Neuromuscular retraining — landing mechanics, single-leg control, and gradual return to cutting and pivoting.
Manual therapy for the surrounding soft tissue that gets tight after any knee injury.
When surgery gets discussed
Recurrent dislocations, significant cartilage damage, or bone abnormalities may need surgical stabilization (MPFL reconstruction being most common). Most first-time simple dislocations do well with structured non-operative care.
If you've had a patellar dislocation, don't stop rehab when it stops hurting. The strength and control work is what prevents it from happening again.