The kid plants and pivots. The knee buckles inward. The kneecap slides off the front of the knee toward the outside. Instant severe pain. Sometimes the kneecap pops back into place on its own as the kid extends the leg. Sometimes it stays out, with the knee locked at 30 to 60 degrees of flexion.
This is patellar dislocation, one of the most common pediatric knee injuries. The protocol below is the on-field response and the next steps.
Recognize.
Sudden severe knee pain with a feeling of “something popped” or “the knee gave way.”
The kneecap visibly displaced (usually to the outside of the knee).
The knee held in a slightly flexed, locked position.
Inability to fully straighten the knee.
In some cases, the kneecap has spontaneously reduced (popped back) before adults reach the kid. The history (the kid says “my kneecap went out and came back”) plus typical findings (lateral knee tenderness, inability to straighten) is the diagnosis.
The protocol on the field.
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Stop activity. The kid is done for the day, regardless of how it resolves.
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Stabilize the knee in the position you find it. Do not try to force it straight if the kneecap is still out.
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If the kneecap has spontaneously reduced (popped back) and the knee can extend, splint the knee in extension if a splint or rolled-up sweatshirt is available.
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Apply ice over a cloth for 15 to 20 minutes. Reduces swelling and pain.
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For a dislocation that has not spontaneously reduced, do not try to push the kneecap back yourself. The straight-leg-lift technique used by athletic trainers and emergency room (ER) providers (gentle knee extension while encouraging the kid to relax the quadriceps) often produces spontaneous reduction. Without training, attempting it can cause additional injury.
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Transport to ER or urgent care with imaging capability. Imaging confirms the diagnosis, rules out associated fractures (osteochondral fragments), and determines the recovery plan.
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Notify the parent.
The first-time dislocator vs the repeat dislocator.
First-time. The standard workup includes X-ray (rule out fracture), MRI in many cases (assess medial patellofemoral ligament damage and osteochondral fragments), reduction in the ER if not yet reduced, immobilization in extension or a hinged brace, weight-bearing as tolerated with crutches initially.
The published recurrence rate after first patellar dislocation in adolescents is high — roughly 30 to 50 percent will have a repeat dislocation in the first 2 years. The factors that predict recurrence: younger age at first dislocation, female sex, certain anatomic factors (trochlear dysplasia, patella alta), and bilateral dislocation history.
Repeat dislocator. The kid who has had multiple patellar dislocations has a different recovery picture. Many have anatomic factors that predispose to dislocation. Surgical stabilization (often MPFL reconstruction) is increasingly the recommended path for recurrent cases in young athletes who want to continue cutting sports.
The recovery timeline.
Acute phase: 1 to 4 weeks of immobilization or hinged brace, with progressive range of motion as tolerated.
Rehab phase: 4 to 12 weeks of physical therapy. Quad-strengthening, hip-strengthening (often where the actual problem lies, at the hip controlling knee position), neuromuscular re-education.
Return to sport: typically 2 to 4 months for first-time dislocators with good recovery, longer for kids with osteochondral injuries or recurrent dislocations.
Bracing for return: most kids return with a patellar tracking brace or sleeve for at least the first season post-injury.
The “but I want to play tomorrow” reality.
For the kid whose kneecap popped back and feels mostly okay 30 minutes later, the temptation is to skip imaging and “see how it feels.”
This produces complications. Osteochondral fragments (small pieces of bone and cartilage that can break off during the dislocation) need imaging to identify. A fragment in the joint can produce locking, catching, and longer-term cartilage damage. Missing this on imaging is the most common preventable complication.
The pediatric orthopedist or sports-medicine clinician sees the X-ray, the kid, and the history together. The decision tree is theirs.
The “the kneecap shifts but doesn’t fully dislocate” pattern (subluxation).
A kid who reports the kneecap “feels like it slips” without full dislocation has patellar subluxation. The mechanism is similar to dislocation; the severity is less. The same evaluation pathway applies but with less urgency.
Patellar subluxation in adolescents often responds to physical therapy alone (quad-and-hip strengthening, neuromuscular work). Surgery is rarely needed for pure subluxation without dislocation history.
For coaches.
Recognize the mechanism. Stabilize. Sling. Transport.
Document mechanism for the receiving ER.
Do not let the kid talk you out of going to the ER even if the kneecap has popped back.
For parents.
Insist on imaging at the ER, even for spontaneously-reduced dislocations.
Engage with the rehab. The kids who skip rehab are the kids who re-dislocate.
For recurrent dislocators, the conversation with a pediatric orthopedic surgeon about MPFL reconstruction is reasonable.
The honest read. First-time patellar dislocations are common, recoverable, and have a meaningful recurrence rate that proper rehab reduces. Repeat dislocations have a different calculus, often with surgical solutions. The most common preventable complication is skipping imaging because the kneecap popped back. The cost of imaging is small. The cost of an undiagnosed osteochondral fragment is much larger.
If this content is reaching someone with a kid whose kneecap is currently displaced, splint in the position found, ice it, transport to ER. Do not try to force the kneecap back yourself.