APEX Knee Navigating Pearls and Pitfalls-Patellar Instability (Lateral Release, MPFL Reconstruction)

Video Transcription

Video Summary

The session covers evaluation and surgical decision-making for recurrent patellar instability using a case of a 28-year-old woman with more than 10 dislocations, normal gait/alignment, positive apprehension, and minimal pain between episodes. Faculty emphasize starting with plain radiographs to assess trochlear dysplasia (crossing sign, supratrochlear spur) and degenerative change, while noting axial/sunrise views can be misleading due to variable knee flexion. Most recommend MRI for all dislocators to evaluate cartilage, loose bodies, MPFL injury, and dysplasia (e.g., lateral trochlear inclination). Common MRI measurements discussed include TT–TG, patellar height ratios, patellar tilt/overlap indices, and newer metrics, though one panelist argues TT–TG elevation often reflects rotational effects driven by dysplasia rather than true tubercle lateralization.<br /><br />Treatment discussion centers on stabilizing surgery after failed therapy. Several would perform isolated MPFL reconstruction if dysplasia is mild and cartilage is normal; others add lateral lengthening routinely or selectively. Severe/flat/convex trochlea may warrant trochleoplasty plus soft-tissue procedures. Technical pearls for MPFL include avoiding patellar anterior cortex violation (fracture risk), using small anchors, obtaining a perfect true lateral with fluoroscopy to hit Schöttle’s point, checking isometry through range of motion, avoiding overtensioning, and special care with femoral tunnel placement in pediatric patients (below the physis).

Asset Caption

Moderator: Jason L. Koh, M.D.
Panel: James Lee Pace, M.D., Nikolaos K. Paschos, M.D., Ph.D., Giovanna Medina, M.D., Ph.D., Sherwin S.W. Ho, M.D.

Keywords

recurrent patellar instability

MPFL reconstruction

trochlear dysplasia assessment

TT–TG measurement

MRI cartilage and loose body evaluation

trochleoplasty indications

Schöttle’s point femoral tunnel placement