Trauma & Sports

Patellar Dislocation

Kneecap dislocation in children: evaluation, conservative and surgical treatment.

Updated: September 2026·Medically reviewed by Dr. Daniele Priano

Quick Answers

After a patellar dislocation, can it happen again?
Yes, it can. The risk of a further episode rises after a second dislocation and in the presence of predisposing anatomical factors (ligamentous laxity, trochlear or patellar shape), but these figures describe group tendencies and cannot reliably predict what will happen in an individual child. This is why rehabilitation after the first episode, focused on the whole quadriceps and hip musculature and on neuromuscular control, is important.
Does my child need surgery after a dislocation?
Not automatically. After a first episode without an osteochondral injury requiring treatment, care is often conservative. Surgery may be considered earlier if a significant osteochondral fragment or another treatable injury is present, and particularly in recurrent cases or with important anatomical factors. Skeletal age, anatomy, number of episodes and sporting goals all inform the decision.
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Patellar dislocation occurs when the kneecap moves out of the femoral trochlea, almost always towards the outside of the knee. In children and adolescents it often occurs during sports involving changes of direction, but relatively minor injuries can also cause it when predisposing anatomical factors are present.

After a first episode, assessment involves more than checking that the kneecap is back in place. It is important to look for joint effusion or bleeding into the joint, possible osteochondral injuries, and features that increase the risk of recurrence, such as trochlear dysplasia, a high-riding patella, alignment changes and skeletal immaturity. A very swollen knee after dislocation, especially with a substantial effusion, locking or catching, deserves particular attention because an osteochondral fragment may be present.

Initial assessment includes clinical examination and X-rays. MRI has an important role after a first dislocation, particularly in children and adolescents, when cartilage, the MPFL, osteochondral fragments or predisposing anatomy need to be assessed. This does not mean that every first episode needs surgery: without an osteochondral injury requiring treatment or another specific indication, initial care is often conservative and includes rehabilitation.

Surgical decisions change when there are treatable osteochondral fragments, recurrent instability or important anatomical factors. There is no single technique for every child: the approach must respect skeletal age and, when indicated, address the main mechanism of instability.

Assessment and treatment

When to seek evaluation

  • A first patellar dislocation warrants specialist assessment
  • A very swollen knee or bleeding into the joint after the episode
  • Locking, catching or suspected osteochondral fragment
  • Recurrent dislocations or subluxations
  • Persistent instability or apprehension
  • Pain or limitation that does not improve during recovery

What is evaluated

  • Mechanism of injury and any previous episodes
  • Effusion or bleeding into the joint and mechanical symptoms
  • Patellar stability and the knee extensor mechanism
  • Limb alignment and general joint laxity
  • Knee X-rays, including views useful for assessing the patellofemoral joint
  • MRI to assess cartilage, osteochondral injuries, the MPFL and key predisposing factors when indicated
  • Skeletal maturity, which affects both risk and surgical options

Treatment options

  • Reduction in a healthcare setting if the patella has not returned to position spontaneously
  • Initial non-surgical treatment for most first episodes without an osteochondral injury requiring treatment
  • Temporary protection according to pain and stability, avoiding unnecessarily prolonged immobilisation
  • Rehabilitation to restore movement, strength, neuromuscular control and functional progression
  • Treatment of an osteochondral injury when present and clinically significant
  • MPFL reconstruction and/or correction of anatomical factors in selected cases of recurrent or high-risk instability
  • Return to sport guided by functional criteria rather than a date alone

Frequently Asked Questions

After a patellar dislocation, can it happen again?▼
Yes, it can. The risk of a further episode rises after a second dislocation and in the presence of predisposing anatomical factors (ligamentous laxity, trochlear or patellar shape), but these figures describe group tendencies and cannot reliably predict what will happen in an individual child. This is why rehabilitation after the first episode, focused on the whole quadriceps and hip musculature and on neuromuscular control, is important.
Does my child need surgery after a dislocation?▼
Not automatically. After a first episode without an osteochondral injury requiring treatment, care is often conservative. Surgery may be considered earlier if a significant osteochondral fragment or another treatable injury is present, and particularly in recurrent cases or with important anatomical factors. Skeletal age, anatomy, number of episodes and sporting goals all inform the decision.
How long until return to sports?▼
After a conservative path, return to sports usually occurs over a few months, when the stabilizing musculature has sufficiently recovered. After surgery, recovery is longer to allow healing of the reconstructed structures. The return is gradual and guided by clinical progress, not a fixed calendar.
What can I do to prevent recurrences?▼
Progressive strength and control rehabilitation and an assessed return to sport address modifiable factors, but cannot guarantee no recurrence. Skeletal age, anatomy, laxity and associated injuries also matter; a brace does not replace this assessment.
After dislocation the knee is swollen: is it normal?▼
Some effusion is common after a dislocation, but a very swollen knee or bleeding into the joint should not be dismissed: it may accompany an osteochondral injury. Substantial or persistent swelling, particularly with locking or catching, requires assessment and imaging to exclude an intra-articular fragment.
Are there factors that predispose to dislocation?▼
Yes, the most common are generalized ligamentous laxity, peculiarities of lower limb anatomy, conformation of the patella and femoral trochlea and, sometimes, family history. Identifying them during evaluation is important because it guides the path and allows more accurate estimation of recurrence risk.
Can my child keep playing their sport?▼
In most cases yes, especially after a good rehabilitation path. The choice depends on the type of sport (sports with cuts and contact are more demanding), the number of episodes and the presence of risk factors. The decision is made together, weighing risks, benefits and the young person's motivation.

Important Notice: The information on this page is for educational and informational purposes only and does not constitute medical advice. Each clinical case is unique: the appropriate treatment is determined during the specialist consultation, based on a thorough clinical examination and, where necessary, diagnostic imaging. For any doubts or concerns, please consult a specialist.