Femoral insertion site of the graft used to replace the medial patellofemoral ligament influences the ligament dynamic changes during knee flexion and the clinical outcome

Autores de IIS La Fe

• Cristina Ramírez Fuentes

  Autor

• 

  Luis Martí Bonmatí

  Autor

Participantes ajenos a IIS La Fe

• Sanchis-Alfonso, V
• Montesinos-Berry, E
• Domenech, J

Grupos

• Investigacion Biomédica en Imagen (GIBI 2-30)

  Investigador Principal

  Leonor Cerdá Alberich

Abstract

This study's purpose was to investigate how an ideal anatomic femoral attachment affects the dynamic length change pattern of a virtual medial patellofemoral ligament (MPFL) from an extended to a highly flexed knee position; to determine the relative length and length change pattern of a surgically reconstructed MPFL; and to correlate femoral attachment positioning, length change pattern, and relative graft length with the clinical outcome. Twenty-four knees with isolated nonanatomic MPFL reconstruction were analysed by three-dimensional computed tomography at 0A degrees, 30A degrees, 60A degrees, 90A degrees, and 120A degrees of knee flexion. The lengths of the MPFL graft and a virtual anatomic MPFL were measured. The pattern of length change was considered isometric if the length distance changed < 5 mm through the entire dynamic range of motion. Knee flexion significantly affected the path lengths between the femoral and patellar attachments. The length of the anatomic virtual MPFL decreased significantly from 60A degrees to 120A degrees. Its maximal length was 56.4 +/- 6.8 mm at 30A degrees. It was isometric between 0A degrees and 60A degrees. The length of the nonanatomic MPFL with a satisfactory clinical result decreased during flexion from 0A degrees to 120A degrees. Its maximal length was 51.6 +/- 4.6 mm at 0A degrees of knee flexion. The lengths measured at 0A degrees and 30A degrees were isometric and statistically greater than the lengths measured at higher flexion degrees. The failed nonanatomic MPFL reconstructions were isometric throughout the dynamic range, being significantly shorter (27.1 +/- 13.3 %) than anatomic ligaments. The femoral attachment point significantly influences the relative length and the dynamic length change of the grafts during knee flexion-extension and graft isometry. Moreover, it influences the long-term outcome of the MPFL reconstructive surgery. A nonanatomic femoral fixation point should not be considered the cause of persistent pain and instability after MPFL reconstruction in all cases. III.

Keywords

• Patella; Medial patellofemoral ligament; Femoral attachment; Anatomic reconstruction; 3D-CT