Patella Maltracking

Anatomy and Basics

Stability is provided by Osseous and Soft tissue structures

Osseous

Patella and Trochlear groove congruency (trochlear dysplasia).
Tibial Tuberosity lateralisation.

Soft Tissue

Stabilised by 4 lateral and 4 medial stabilisers
but only 2 are important : Medial patellofemoral ligament (MPFL) and Lateral patellofemoral ligament (LPFL)

as only these 2 are visible on MR.

Retinaculum = fibrous tissue extending out from the patella
Ligaments here = Areas of thickening of the retinaculum

Radiological Assessment

Multiple different systems. He says stick to:

1. Trochlear Dysplasia
   1. Trochlear Depth
   2. Dejour Classification
   3. Lateral Trochlear Inclination
2. Patella Tilt and Subluxation
3. Patella Alta
   1. Caton-Deschamps Index
4. Tibial Tuberosity Lateralisation
   1. TT-TG

Trochlear Depth

Dejour Classification

Patella Tilt

Patella Alta

Tibial Tuberosity - Tibial Tuberosity Index

could do with writing this up in Jackdaw next time I have a case

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Patella Dislocation and Cartilage Injury

Important to realise that the best predictor of operative intervention is Cartilage Injury and not just bone bruising.
And to realise that MPFL injury is not really important to classify accurately as reconstruction is much preferred to repair.

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1. Jorge Delgardo, Lecture at SPR 2024 ↩