Thin Flap Trochleoplasty for High-Grade Trochlear Dysplasia

One of the most consistent pathoanatomic findings in lateral patellofemoral instability is trochlear dysplasia. Trochleoplasty is a procedure designed to deepen the trochlear groove, thus correcting trochlear pathoanatomy and improving patellofemoral tracking.

Patients with high-grade trochlear dysplasia that includes anteriorization of the floor of the trochlear groove (trochlear bump >5 mm), with lateral patellofemoral instability.

The technique described is a thin flap trochleoplasty. By an open lateral parapatellar approach, trochlear cartilage is elevated. A new groove is created by removing subchondral bone with a burr. The cartilage flap is then reduced on the subchondral bone, and gentle pressure is applied to the cartilage. Plastic deformity occurs, and the cartilage is fixed with bioabsorbable nails. This technique should be accompanied by a stabilizing procedure, such as a medial patellofemoral ligament reconstruction.

Thin-flap trochleoplasty has low redislocation rates (3%-4%) in appropriately selected patients. Multiple clinical studies and meta-analyses have shown good postoperative patient-reported outcome scores and improved postoperative knee scores. There is a high rate of patient satisfaction, return to work, and return to sports following surgery (>85%). Notable complications include patellofemoral osteoarthritis (7%-18%), knee ankylosis (4.4%), and the need for additional surgery (8%-11%). However, the risk of complications seems to be similar to other patellar-stabilizing procedure.

Trochleoplasty is a technically demanding surgical procedure but is safe, reliable, and effective in appropriately selected patients.

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