Anatomy:
Retinacula:
Medial from vastus medialis and lateral from vastus lateralis
Reinforxe patellar tracking
Retinacular tears:
In patellar and quadriceps tendon tears
Medial retinacular tear:
In lateral patellar dislocation, vulgus hyperextension injuries, associated with MCL tear
Seen as free floating or mass like medial retinaculum on axial MR
Associated with edema/hemorrhage
Tight lateral retinaculum (Excessive lateral pressure syndrome):
Tilts patella in lateral direction
Associated with subluxation of patella
Treated with retinacular release
Medial patello-femoral ligament injury (MPFL):
Commonly occurs in lateral patellar dislocation.
Sprain seen as stretching of the ligament with intact fibers and surrounding soft-tissue edema.
Disruption seen as discontinuous, wavy fibers with adjacent high signal.
Avulsion of the MPFL off of the adductor tubercle seen as fluid between the MPFL and the femoral attachment site.
References:
1. Stoller DW. MRI in orthopaedics & sports medicine; Second edition; 1997. Chapter 7: the knee. Lippincott Williams & Wilkins.
