The anatomy and isometry of the medial patellofemoral ligament - Implications for reconstruction

Background: Several techniques have been described for reconstruction of the medial patellofemoral ligament. However, the isometry of the medial patellofemoral ligament has not been studied. Purpose: To define the anatomy and isometry of the medial patellofemoral ligament. Study Type: Cadaveric study. Methods: The authors dissected the medial patellofemoral ligament in 11 cadaveric knees and recorded its anatomic relationships. They evaluated the isometry of the medial patellofemoral ligament by obtaining measurements between various anatomic pairings at certain fixed angles of knee flexion. Results: During knee flexion from 0degrees to 90degrees, the portion of the medial patellofemoral ligament from the inferior patellar attachment to the superior femoral attachment was nearly isometric, demonstrating an average change in length of only 1.1 mm. Statistical analysis showed the superior femoral attachment to be most significant in determining isometric behavior. Conclusions: The most isometric portion of the medial patellofemoral ligament is the interior portion of its patellar attachment extending to the superior portion of its femoral attachment, with the superior femoral attachment having the most notable influences on isometry. Clinical Relevance: This study provides a detailed description of the anatomy of the medial patellofemoral ligament, as well as an evaluation of the isometric behavior of the ligament. Application of these data during reconstruction of the medial patellofemoral ligament may help to optimize patellofemoral stability.