Medial Patellar Retinaculum (Full)

retinaculum patellae mediale (complex)

The medial patellar retinaculum is a multi-layered structure comprising the MPFL (primary medial patellar stabiliser at the femoral level), the medial patellotibial ligament (inferior constraint), and the VMO fascial expansion. All three are disrupted in acute patellar dislocation. The primary structure for reconstruction is the MPFL, but the medial retinacular complex as a whole contributes to restoration of balanced patellar tracking.

Anatomical Data

Boundaries & Contents

Location	Medial side of the front of the knee, beside the patella
Boundaries	From the medial border of the patella and patellar ligament To the medial femoral epicondyle region (through the MPFL) and the medial tibial condyle Receives the aponeurotic expansion of vastus medialis Deeper layers include the medial patellofemoral, medial patellotibial and medial patellomeniscal ligaments

Biomechanics

Function & Actions

Holds the patella against lateral displacement and helps keep it centred in the trochlear groove.

Clinical Relevance

Clinical Notes

In acute patellar dislocation, haemarthrosis from the medial retinacular tear is the primary source of effusion. MRI shows medial retinacular avulsion (most common from the patellar attachment), MPFL mid-substance tear, or femoral attachment tear (at the adductor tubercle). Acute MPFL repair for first-time dislocations is controversial. The current trend is non-operative management for first-time dislocations with MPFL reconstruction for recurrence.

Pathology

Common Injuries & Conditions

Acute Patellar Dislocation

Medial retinacular complex disruption in lateral patellar dislocation managed non-operatively for first-time events and MPFL reconstruction for recurrent instability.

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