Lateral patellar dislocations are the second leading cause of traumatic knee hemarthroses, and recurrent patellar dislocations often require surgery. The medial knee structures responsible for stabilization of the patellofemoral joint are the medial patellofemoral ligament (MPFL), the medial patellotibial ligament (MPTL), and the medial patellomeniscal ligament (MPML). Although the MPFL has been identified as the main medial patellar restraint, new evidence suggests that the MPTL and MPML might also play an important role in medial patellar stability. Consequently, injury to these ligaments can lead to altered patellofemoral joint contact forces, patellar instability, and joint degeneration, highlighting the need for appropriate anatomic surgical management to restore joint kinematics.
The optimal treatment algorithm for addressing lateral patellar instability needs to be further refined. The biomechanical properties and function of the individual medial ligaments attaching to the patella must be determined to restore the native kinematics of the patella. In this regard, we were motivated to determine whether further quantification of the biomechanical properties of each individual ligament of the medial side of the patellofemoral joint would help to explain injury patterns and advance reconstruction techniques by improving the selection of appropriate grafts for each ligament.
Although an extensive body of literature on anatomic and biomechanical characteristics of the MPFL has been published, limited data exist for the MPTL and MPML. Therefore, the purpose of this study was to determine the ultimate load, stiffness, and mechanism of failure of the MPFL, MPTL, and MPML to ultimately assist with the selection of grafts for anatomic reconstruction. It was hypothesized that consistent biomechanical properties would be found for each structure.