The resident’s ridge as an arthroscopic landmark for anatomical femoral tunnel drilling in ACL reconstruction

Abstract

The purposes of this study were to establish the technique to arthroscopically identify the resident's ridge without bony notchplasty even in patients with chronic ACL insufficiency and to elucidate if the ridge could be used as a landmark for anatomical femoral tunnel for ACL graft. There were 50 consecutive patients undergoing arthroscopic ACL reconstruction. With the thigh kept horizontal using a leg holder, a meticulous effort was made to find out a linear ridge running proximo-distal in a posterior one-third of the lateral notch wall, after removal of superficial soft tissue with radiofrequency energy. If the ridge was found, a socket with a rectangular aperture of 5 x 10 mm was created just behind the ridge. At 3-4-weeks post surgery, three-dimensional computed tomography (3-D CT) was performed to geographically identify the location of the ridge using the socket as a reference. Arthroscopically, a linear ridge running from superior-anterior to inferior-posterior on the lateral notch wall was consistently observed 7-10 mm anterior to the posterior articular cartilage margin of the lateral femoral condyle in all of the patients. The 3-D CT pictures proved the arthroscopically identified ridge to be the resident's ridge. The resident's ridge is arthroscopically identifiable after non-mechanical removal of the soft tissues without bony notchplasty. The ridge is a useful landmark for anatomical femoral tunnel drilling in arthroscopic ACL reconstruction.

Medial portal technique for single-bundle anatomical Anterior Cruciate Ligament (ACL) reconstruction

“…The lateral intercondylar ridge ("resident's ridge") runs at approximately a 30-35°angle with respect to the long axis of the femoral shaft and represents the upper or superior limit of the ACL femoral attachment site. The lateral intercondylar ridge has been shown to be present and visible in 88-100 % of chronic ACL-deficient knees [10,11]. When present, the lateral intercondylar ridge is critical to anatomical ACL femoral tunnel placement since the ACL femoral attachment site always lies below or inferior to this ridge.…”

Radiological evaluation for conflict of the femoral tunnel entrance area prior to anterior cruciate ligament revision surgery

“…Ideal positioning of the graft in the single-bundle technique is a subject of wide debate in the current literature and may differ substantially between surgeons and their technique used [8][9][10][11][12].…”

“…The use of 3D-CT or MRI reconstruction has been reported occasionally for the visualisation of the native and the reconstructed femoral insertion on the femur [11,[23][24][25][26][27][28][29][30][31], and in patients with failed reconstruction [32,33]. This radiological tool has been validated and shown to be feasible [25].…”

Direct Visualization of Existing Footprint and Outside-In Drilling of the Femoral Tunnel in Anterior Cruciate Ligament Reconstruction in the Knee

“…The lateral intercondylar ridge can often be identified by direct arthroscopic visualization and as a tactile step-off with a probe (Fig 6). Shino et al 18 used quantitative imaging to show that the intercondylar ridge is 7 to 10 mm anterior to the posterior cartilage margin on the lateral After debridement of the ACL stump, start at the intersection of the reflection of the synovium and the proximal border of the articular cartilage and move distally, in line with the femoral shaft, to pass through the center of the ACL footprint. Use the area of the footprint above and below the swath created with the radiofrequency wand to locate the ACL footprint center in the anteroposterior and proximal-distal axes.…”