Transepicondylar distance measured on MRI can predict the length of the graft required for different anterior cruciate ligament reconstruction (ACLR) techniques useful for revision surgery

Abstract

Background The aim of this study is to find a correlation between linear measurements and the graft length required for different anterior cruciate ligament (ACL) revision techniques, to extract formulas to predict required graft length during the preoperative planning. Methods At time 0 and 30 days later, two observers measured eight linear distances on standard 2D knee magnetic resonance imaging (MRI), and nine curved distances on 3D MRI sequences, corresponding to different techniques for ACL revision, anatomic anterolateral ligament (ALL) reconstruction, and lateral extrarticular tenodesis (LET). Intra- and interobserver reliability was tested for 2D and 3D measurements. The correlation between 2D and 3D measurements was tested. The 2D measurements with highest repeatability and reproducibility, and with strongest correlation with 3D measurements were used to extract formulas to calculate the graft length from 2D values. Results Fifty MRIs acquired with both 2D and 3D sequences were used. The intra- and interobserver reliability of linear 2D measurement was high, with the transepicondylar distance (TD) showing the highest reproducibility and repeatability. The intra- and interobserver reliability of 3D measurements was lower than 2D, but acceptable for all measurements except for ALL reconstruction. The TD showed the strongest correlation with 3D measurements. The formulas extracted to calculate the graft length from the TD proved to be accurate. Conclusion Accurate formulas were created to calculate the graft length needed for different ACL revision techniques and ALL reconstruction/LET techniques from TD. These formulas can be used during preoperative planning of ACL revision cases.

Tibial Tubercle Trochlear Groove Distance Does Not Correlate With Patellar Tendon Length in Patients Who Underwent Anterior Cruciate Ligament Reconstruction

“…Additionally, many consider the intra-articular distance of the ACL, not the patellar tendon length, as the most integral parameter to when attempting to mitigate graft-tunnel mismatch. However, the ACL is an obliquely oriented structure that cannot be easily measured with a single sagittal image 31 or requires complex formulas for accurate measurement 32 ; therefore, identifying more easily measured structures such as patellar tendon length and TT-TG would be a more reproducible source of information if a correlation did exist. In addition, accurate preoperative knowledge of patellar tendon length affords the surgeon with valuable information that may indicate the need for longer tibial tunnels, rotation of the graft, or other strategies necessary to circumvent graft-tunnel mismatch.…”