Fluoroscopic determination of the tibial insertion of the posterior cruciate ligament in the sagittal plane

Abstract

Background: Currently, placement of the tibial tunnel for arthroscopic transtibial posterior cruciate ligament (PCL) reconstruction relies on a limited arthroscopic view of the native insertion or the use of intraoperative imaging. No widely accepted method exists for intraoperative determination of PCL tibial tunnel placement, and current descriptions are cumbersome.

Purpose: To identify the center of the PCL's anatomic tibial insertion site as a percentage of the PCL facet length on a lateral radiograph of the knee so that it may be reliably located in the sagittal plane during surgical reconstruction.

Study design: Descriptive laboratory study.

Methods: Twenty fresh-frozen cadaveric knees were dissected and the tibial insertions of the PCL were digitized with an optical tracing system. The digitized PCL footprints were mapped onto 3-dimensional computed tomography-acquired tibial models, and their center points were determined. A K-wire was then inserted into the center of the PCL's tibial insertion under direct visualization, a direct lateral radiograph was obtained, and the center point was measured. The center locations for both methods were defined as a percentage of PCL facet length from anterior and proximal to posterior and distal, and intraobserver and interobserver reliability was tested with 4 different observers.

Results: The average location of the PCL center on the 3-dimensional bone model method was 71.7%±5.6% along the PCL facet from anterior/proximal to posterior/distal. In the lateral radiographic method, the center of the PCL was at an average of 69.7%±4.9% of the facet length. There was no significant difference between the percentage measurements of the 2 methods (P=.13). Interobserver reliability (κ=0.57) and intraobserver reliability (κ=0.71) were moderate to strong.

Conclusion: Locating the center of the tibial PCL insertion with fluoroscopy at a point that is 70% of the PCL tibial facet length on a true lateral radiograph is a reliable method for locating the PCL tibial insertion.

Clinical relevance: The method described in this study enables clinicians to identify the tibial location of the PCL insertion, which must be accurately determined during PCL reconstruction.

Keywords: PCL; anatomic; fluoroscopic; radiographic; tibial tunnel.