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.

Region: Knee

Biomechanics

Function & Actions

Medial patellar constraint; dynamic VMO tension on the patella; contributes to MCP stabilisation below the level of the MPFL

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.