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What is the significance of the bony avulsion fracture in this case?
They do not tend to heal well on conservative treatment and therefore surgical repair is recommended.
Key findings:
- bone bruises of inferomedial patella (blue arrowhead) and the anterolateral femoral condyle (blue arrows)
- medial patellar avulsion fracture (purple arrow)
- medial patellofemoral ligament oedematous and thickened (red arrow) also at the femoral attachment (red arrowheads)
- a tear of the medial retinaculum at the inferomedial patellar attachment (orange arrow)
- myotendinous tear of the vastus medialis oblique (VMO) muscle (green arrow)
Assessment for patella alta
- Insall-Salvati-ratio (blue) was > 1.5
- modified Insall-Salvati-ratio (orange) > 2
Assessment for trochlear dysplasia
- borderline lateral trochlear inclination (LTI)
- no trochlear facet asymmetry (FA)
- decreased trochlear depth (2 mm)
Lateral trochlear inclination (LTI) < 11°, medial vs lateral trochlear facet ratio of <40% 1-4, and/or a trochlear depth < 3mm 6, indicate trochlear dysplasia.
TT-TG distance (tibial tuberosity to trochlear groove distance)
- was normal (<15mm) in this case
A TT-TG distance >20mm is considered a risk factor for patellofemoral instability.