MPFL reconstruction

Overview

Front view of the knee showing the femur, tibia, patella, cruciate and collateral ligaments, and the medial and lateral menisci. — **Knee anatomy.** The knee is the meeting point of the thigh bone (femur), shin bone (tibia), and kneecap (patella). Four ligaments hold it together — the ACL and PCL inside the joint and the MCL and LCL on the sides — and two C-shaped menisci cushion the joint surfaces.

The medial patellofemoral ligament is the primary checkrein preventing the kneecap from sliding laterally. After a first-time or recurrent patellar dislocation, the MPFL is almost always torn. Without reconstruction, the patella often re-dislocates — especially in patients with underlying anatomic predisposition like trochlear dysplasia or elevated tibial-tubercle-to-trochlear-groove distance.

How the Procedure Works

The femoral attachment point is the most technique-sensitive part of this operation. The isometric point — where the MPFL naturally originates — sits just anterior and proximal to the medial epicondyle, and a tunnel placed even a centimeter off that landmark changes graft tension dramatically through the range of motion. We use fluoroscopic landmarks and probe the tunnel position with a trial graft before committing: the graft should show less than 3–4 mm of tension change from full extension to 90° of flexion. The graft is then passed to the medial patella and anchored at two points along its medial border to distribute load. Final tension is set at 30° of flexion with the patella reduced in the trochlea — not too tight, which restricts flexion and risks medial dislocation, not too loose, which allows lateral instability. When tibial tubercle malalignment or trochlear dysplasia is present, MPFL reconstruction alone is insufficient and a bony procedure is added.

When to Consider MPFL Reconstruction

MPFL reconstruction is generally offered when symptoms, imaging, and a trial of non-operative care together point to surgery as the next step. The typical picture includes:

Recurrent patellar dislocation
Two or more episodes of the kneecap dislocating, confirming a structural problem that won't resolve with rehab alone.
First dislocation with osteochondral injury
A loose cartilage fragment requires surgical management; MPFL reconstruction is often performed simultaneously.
Persistent instability symptoms
Episodes of the kneecap slipping or giving way that interfere with daily activity or sport.