The role of imaging in anterior cruciate ligament reconstruction

Abstract

The thesis is based on four articles examining the role of imaging after surgical reconstruction of the anterior cruciate ligament of the knee. Post-operative imaging is commonly performed to validate ACL graft tunnel locations after reconstruction, to examine underlying causes in cases with poor outcome or for planning surgery prior to revision of ACL graft. Paper I examined the differences measurements of ACL graft tunnel placements according to femoral grid measurements and tibial anterior posterior ratio on three different modalities: radiographs, CT, and MRI. Paper II was systematic review of literature to define “normal ranges” of the femoral tunnel according to Bernard & Hertel grid and tibial tunnel according to the Stäubli & Rauschning ratio. Paper III assessed the ability of the Bernard & Hertel grid and Stäubli & Rauschning ratio in tibia to indicate anatomic graft placement compared with assessment done with coronal and sagittal graft angles. Paper IV assessed the rate and types of knee pathology, including anterolateral complex pathology on MRI in ACL reconstructed knees. The thesis showed that many variations in graft tunnel evaluation exist. For assessing graft tunnel placement, CT is by far the most robust modality. The grid method in the femur and ratio in the tibia are easiest to implement into clinical practice. Graft angle measurements have no value in evaluating tunnel placements. When evaluating soft tissue structures, MRI is reliable for well-established structures such as ligaments and menisci, but currently not for anatomic structures such as anterolateral complex.