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[Conditions](https://durgical.com/en/conditions/) · [Knee](https://durgical.com/en/conditions/)

# Patellar Dislocation

A patellar dislocation is when the kneecap slips out of its groove, almost always to the outer side, after a twist or a direct blow.

Updated 2026-10-23

## Structures involved

Tap one to see what it is and open it in 3D.

- [Patella](https://durgical.com/en/anatomy/patella/)
- [Medial retinaculum](https://durgical.com/en/anatomy/medial-patellar-retinaculum/)
- [Lateral retinaculum](https://durgical.com/en/anatomy/lateral-patellar-retinaculum/)

## What it is

The kneecap moves out of its groove, usually laterally, after a twisting injury or direct blow.

## Risk factors

- [Patella](https://durgical.com/en/anatomy/patella/) alta
- Trochlear dysplasia
- Previous dislocation

## Symptoms and signs

- Sudden pain and deformity of the kneecap
- Swelling
- Inability to straighten the knee fully

## Diagnosis

**Clinical**
History and exam

**Imaging**
X-ray to rule out fracture; MRI for cartilage or soft-tissue injury

## Treatment

**Rehabilitation**
Reduction if needed, bracing, and physical therapy for first-time dislocations.

**Surgical**
[MPFL](https://durgical.com/en/anatomy/medial-patellofemoral-ligament/) repair or reconstruction for recurrent dislocations.

## Complications

- Recurrent instability
- Osteochondral fracture
- Patellofemoral osteoarthritis

## Related conditions

- [Patellar fracture](https://durgical.com/en/conditions/patellar-fracture/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Patella Dislocation](https://www.ncbi.nlm.nih.gov/books/NBK538288/) (StatPearls (NCBI Bookshelf), 2024).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/patellar-dislocation/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/patellar-dislocation/