patellar dislocation

Patellaluxation
und Reposition - kleine Abscherung aus der medialen Facette. Typische Kontusion auch an der Anschlagstelle am lateralen Femurkondylus.
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Lateral
patellar dislocation • Transient lateral patellar dislocation - Ganzer Fall bei Radiopaedia
Knipe H, Transient lateral patellar dislocation. Case study, Radiopaedia.org (Accessed on 23 Jan 2024) https://doi.org/10.53347/rID-97218 • CC by-nc-sa 3.0 (modified)
MRI after
luxation of the patella (axial). There is bone bruise at the medial surface of the patella itself and in the corresponding surface of the lateral condyle of the femur (arrow). The medial retinaculum of the patella is disrupted.
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MRI after
luxation of the right patella. There is bone bruise at the medial surface of the patella (axial image) and in the corresponding surface of the lateral condyle of the femur (coronal). The medial retinaculum of the patella is at least partially disrupted.
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X-ray and MRI
after luxation of the patella. There is a fragment and bone bruise at the medial surface of the patella and in the corresponding surface of the lateral condyle of the femur. The medial retinaculum of the patella is disrupted.
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Patellaluxation
im Röntgenbild. Rechtes Knie.
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Patellaluxation
im Röntgenbild. Rechtes Knie, tangentiale Aufnahme. Der Femurkondylus ist nicht komplett mit abgebildet.
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Patellaluxation
im Röntgenbild ap.
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Patellaluxation
im tangentialen Röntgenbild der Patella.
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Patellaluxation
im Röntgenbild a.p. Linkes Knie, Luxation wie meistens nach lateral (aussen).
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School ager
with knee pain. AP radiographs of the knees show lateral patellar dislocation bilaterally along with bilateral gracile bones in the femurs, tibiae and fibulae.The diagnosis was Trisomy 18.
pediatricimaging.org • CC-by-nc-sa 4.0
Chronische
Patellaluxation bei Tetraspastik seit der Kindheit. Die Patella findet sich lateral des Femurcondylus. Dadurch ist auch die Tibia deutlich pathologisch nach außen rotiert.
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Lateral
patellar dislocation • Illustration for lateral patellar dislocation - Ganzer Fall bei Radiopaedia
Majumder P, Illustration for lateral patellar dislocation. Case study, Radiopaedia.org (Accessed on 05 Jan 2023) https://doi.org/10.53347/rID-27275 • CC by-nc-sa 3.0 (modified)
Radiograph of
lateral luxation of the patella. Left before treatment, right after reduction. Even after reduction, the patella is still displaced to the outside.
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Lateral
patellar dislocation • Transient lateral patellar dislocation relocation - Ganzer Fall bei Radiopaedia
Salam H, Transient lateral patellar dislocation relocation. Case study, Radiopaedia.org (Accessed on 05 Jan 2023) https://doi.org/10.53347/rID-28874 • CC by-nc-sa 3.0 (modified)
Lateral
patellar dislocation • Medial femoral condyle fracture associated with lipohemarthrosis and lateral patellar dislocation - Ganzer Fall bei Radiopaedia
Di Muzio B, Medial femoral condyle fracture associated with lipohemarthrosis and lateral patellar dislocation. Case study, Radiopaedia.org (Accessed on 05 Jan 2023) https://doi.org/10.53347/rID-45726 • CC by-nc-sa 3.0 (modified)
Lateral
patellar dislocation • Lateral patellar dislocation with avulsion fracture - Ganzer Fall bei Radiopaedia
Saber M, Lateral patellar dislocation with avulsion fracture. Case study, Radiopaedia.org (Accessed on 05 Jan 2023) https://doi.org/10.53347/rID-74308 • CC by-nc-sa 3.0 (modified)
Lateral
patellar dislocation • Transient lateral patellar dislocation with osteochondral injury - Ganzer Fall bei Radiopaedia
Marghany B, Transient lateral patellar dislocation with osteochondral injury. Case study, Radiopaedia.org (Accessed on 05 Jan 2023) https://doi.org/10.53347/rID-73675 • CC by-nc-sa 3.0 (modified)
Intra-articular
loose bodies • Patellar dislocation with chondral injury - Ganzer Fall bei Radiopaedia
Feger J, Patellar dislocation with chondral injury. Case study, Radiopaedia.org (Accessed on 23 Nov 2022) https://doi.org/10.53347/rID-76304 • CC by-nc-sa 3.0 (modified)
Teenager who
fell on their right knee and has pain. AP (above) and Merchant (below left) radiographs of the right knee show lateral displacement of the patella and a small avulsion fragment (sliver sign) medial to the patella. Merchant radiograph of the right knee post reduction (below right) shows appropriate reduction of the patella along with medial soft tissue swelling.The diagnosis was lateral patellar dislocation.
pediatricimaging.org • CC-by-nc-sa 4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Lateral patellar dislocation refers to lateral displacement followed by dislocation of the patella due to disruptive changes to the medial patellar retinaculum.

Epidemiology

Patellar dislocation accounts for ~3% of all knee injuries and is commonly seen in those individuals who participate in sports activities.

Pathology

Patellar dislocation most commonly results from a twisting motion, with the knee in flexion and the femur rotating internally on a fixed foot (valgus-flexion-external rotation) .

Radiographic features

Plain radiograph
MRI

The following features are noted:

  • medial retinacular abnormalities (ranging from strain to complete disruption) with adjacent periligamentous edema and hemorrhage
  • lateral displacement of patella (not necessarily seen in transient dislocation)
  • medial patellar contusion +/- corresponding lateral femoral condyle contusion
  • joint effusion

The presence of an abnormal medial patellar retinaculum should suggest the diagnosis of transient lateral patellar dislocation .

The images should be scrutinized for the presence of chondral or osteochondral injury, especially if displaced as an intra-articular body, as this may affect surgical management.

The trochlear groove and patella may have abnormal morphology that predisposes to patellar dislocation.

Differential diagnosis

  • acute ACL tear: no medial patellar contusion in this injury
  • direct trauma to lateral knee: normally no patellar contusion
Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu Patellaluxation:
Jägerhutpatella
 
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Patelladysplasie
 
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Patellaluxation
bei Trisomie 18
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chronische
Patellaluxation
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