(Fig 4-A.33) Type P1: Bony Avulsion Fracture from Medial Patella

https://youtu.be/z7657-MMgvE

https://youtu.be/vzxclU_34OI?si=B88NykUJHSELzyAC

 

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📌 Bony Avulsion Fracture from the Medial Patella

 

✅ Case Analysis

• When examining the MRI, it might appear as a Medial Patellofemoral Ligament Disruption at the Patellar Attachment. However, the low signal intensity of the cortex is disrupted in the middle.
•  This indicates a bony avulsion fracture from the medial margin of the patella, which is clearly visible on the CT scan. 
• Additionally, the transverse component of the medial patellofemoral ligament midsubstance shows thickening and intraligamentous fluid, suggesting a tear.

 

✅ Injury Patterns of MPFL in Children

1️⃣ MPFL is most easily injured at its patellar insertion in children.

2️⃣ Wiberg patellar type B predisposes children to a complete MPFL tear.

3️⃣ No correlations between the injury patterns of MPFL and the other three anatomical variants.

4️⃣ Complete MPFL tear predisposes children to a higher grade patellar chondral lesion.

 

✅ Reasons for MPFL Vulnerability in Children

• The distribution of MPFL tears may be related to the ossification process of the medial patella and distal femoral epiphysis. The medial patellar border, where the patellar MPFL insertion is located, remains cartilaginous until the age of 16–18 years. In contrast, the distal femoral epiphysis, where the femoral MPFL attachment is, ossifies around the age of 13–15 years. 
• Another reason could be the anatomy of the MPFL. In children, the fibers of the MPFL and vastus medialis obliquus may not yet blend fully on the patellar side, unlike in adults. Considering these two factors, the patellar MPFL insertion is most easily injured in children.

 

References:

• Knee Surg Sports Traumatol Arthrosc (2014) 22:2414–2418
• Eur Radiol. 2017 Mar;27(3):1322-1330

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#MPFLInjury, #PatellarFracture, #ChildhoodInjuries, #MRI, #CTScan, #MedialPatella, #Orthopedics, #LigamentTear