A novel X-ray-based theory of surgical navigation for drilling the femoral tunnel during medial patellofemoral ligament reconstruction with a function to correct aberrant lateral radiographs.

Abstract

Although surgical navigation is widely used in anterior cruciate ligament reconstruction, there are few reports on medial patellofemoral ligament reconstruction (MPFLR). To solve the inaccuracy and inconvenience of drilling the femoral tunnel during MPFLR by frequently adjusting the C-arm to get a true lateral radiograph, a surgical navigation method to correct aberrant lateral radiographs is needed. For 10 femoral specimens, imaging of the true lateral radiographs and aberrant lateral radiographs corresponding to knee rotation, valgus and varus, was performed. Anatomic geometric parameters were measured from these radiographs. Linear regression analysis was used to explore the association between parameters and the angle of rotation, valgus and varus, the relationship between parameters and the position of the Schottle point. After proposing a new method to predict the femoral tunnel, the reliability and validity of the new method were tested. Eleven anatomic geometric parameters were found to significantly predict the angle, six parameters were found to confirm the appropriate femoral tunnel site. Linear regression equations of these parameters were calculated. A theory of surgical navigation for drilling femoral tunnel in aberrant lateral radiographs was created, and the reliability and validity tests were satisfactory. A theory for a surgical navigation system for MPFLR was created, which was tested and found to be valid. It is expected to improve the efficiency of surgery, reduce the risk of surgery and improve the prognosis of patients.