Recent concepts in patellofemoral instability

Abstract

Purpose of review: Recent patellofemoral literature on biomechanical and anatomical analyses, imaging studies, acute and chronic instability treatment, and patellar realignment procedures will be reviewed. Recent findings: A recent epidemiological study found women aged 10–17 years to be most predisposed to acute and recurrent patellar instability. Instability is experienced most readily at 20° of flexion where vastus medialis obliquus tension is also the least. A decreased Q-angle, however, improved resistance to lateral patellar tracking more than strengthening of the vastus medialis obliquus. Although conservative is still recommended for treatment primary dislocations, chronic instability is better treated with surgery. Mini-open medial reefing with lateral release, vastus lateralis tendon release, and medial patellofemoral ligament reconstruction have all showed promising results. Cadaveric studies facilitated the improved outcomes by helping us determine the isometric point of the medial patellofemoral ligament. Distal realignment procedures such as the Elmslie–Trillat and modified Roux–Goldthwait procedure have also improved outcomes in the proper population. Interestingly, patients with trochlear dysplasia benefited from proximal and distal realignment procedures more conclusively than by undergoing trochleoplasty. Summary: Understanding the anatomy and biomechanics of the patellofemoral joint will guide future testing and treatment methods. Patellar realignment procedures are successful in managing recurrent instability; arthrosis and pain, however, are less controlled.