[Arthroscopic reconstruction of the posterior cruciate ligament. Magnetic resonance study for bone tunnel positioning and comparison with clinical results].

INTRODUCTION

The success of arthroscopic cruciate ligament reconstruction depends on several factors, such as patient selection, correct surgical execution, and postoperative rehabilitation. Technical considerations include graft choice, positioning, fixation, intercondylar notch enlargement, and new ligament tensioning. Graft acceptance is effected by all these factors. Tunnel position is of great importance both for biomechanical reasons and optimal function of the new ligament, and to avoid stress, friction, abnormal strain, and/or damage to the reconstructed ligament. Many orthopedic and radiographic literature studies discuss the exact site of anterior cruciate ligament insertion for the best possible anatomical reconstruction. In contrast, the debate over insertional area and anatomical landmarks is open for the posterior cruciate ligament (PCL), because of the difficult execution of this type of reconstruction and the smaller number of candidates.

MATERIAL AND METHODS

Fifty patients with a healthy PCL underwent MRI of the knee for other diagnostic reasons and we measured the position of PCL insertion at the tibial and femoral condyles. We also examined with MRI 20 surgical patients with a reconstructed PCL. Graft position was assessed with the same method and the results compared with physical findings of joint stability and the IKDC form score.

RESULTS

Three main landmarks were found on standard axial, coronal and sagittal MR images: T1 on the tibia, and F1 and F2 on the femur. These points refer to the fibrous ligament center and designate the medial, middle and lateral portion of the tibial plateau, as well as the anterior/posterior and high/low positions on the roof of the intercondylar notch and anteromedial side of the medial condyle, respectively. According to these data, the midline position, whether slightly medial or lateral, of tibial insertion, was clinically less important. On the contrary, correct femoral tunnel positioning was found to effect subsequent joint stability and prompt rehabilitation.

CONCLUSIONS

This method for MR measurement is easy and repeatable, and can be used for surgical planning and patient follow-up. We found it extremely useful for the correct positioning of bone tunnels, particularly the femoral condyle, in all cases.