Arthroscopic Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone Autograft: Pearls for an Accurate Reconstruction

Abstract

An anterior cruciate ligament (ACL) tear is one of the most common orthopaedic injuries. Optimal results are not always achieved after surgical reconstruction after a surgical technical error, namely, tunnel malposition. Understanding of the anatomy is vital, and several anatomic landmarks can be used to aid in an optimal reconstruction technique. The purpose of this Technical Note is to describe our preferred technique for an arthroscopic single-bundle anteromedial ACL reconstruction, using a bone-patellar tendon-bone autograft fixed with interference screws.

Fig 1

(A) An anatomic cadaveric dissection of the tibial plateau reveals the location of the ACL AM and PL bundles. Note that the anatomic footprint on the tibia is commonly identified arthroscopically as being approximately 9 mm posterior to the intermeniscal ligament and 7 mm anterior to the PCL. Note that the AM bundle is aligned with the anterior horn of the lateral meniscus attachment, and the PL bundle has fibrous attachments to the posterior aspect of the anterior horn of the lateral meniscus. (B) An anatomic cadaveric dissection of the lateral femoral condyle reveals the footprint locations of the AM and PL bundles. A knee flexion angle of 90° is needed to consistently identify the anatomic footprint of the ACL, as the attachment anatomy can appear to change as a function of knee flexion angle. The bifurcate ridge (BR) separates the AM and PL bundles, and the lateral intercondylar ridge (LIR), also known as resident's ridge, is more consistently identified arthroscopically and represents the anterior margin of the AM and PL femoral bundles. (ACL, anterior cruciate ligament; AM, anteromedial; PCL, posterior cruciate ligament; PL, posterolateral.)

Fig 2

Patellar tendon (bone-tendon-bone) harvest on the left knee. (A) The skin is initially marked from the patella to the tibial tubercle at the midline of the knee for a length of approximately 9 cm. (B) Sharp dissection is carried through skin and subcutaneous tissue to the paratenon layer using a scalpel. (C) The paratenon layer is separated from the underlying tendon in a thick flap, which is repaired during closure. (D) We use a surgical marker to delineate the middle one-third of the patellar tendon and mark a desired graft width of 10 mm in the center of the tendon. We then use a scalpel to mark a longitudinal incision, in line with the tendon fibers, in the center of the patellar tendon to the 10 mm desired width. (E) A Bovie electrocautery device is used to delineate the patellar and tibial bone plugs and clear soft tissue from the bone to facilitate the harvest. The patellar bone plug measures 10 mm wide by 20 mm long and the tibial bone plug measures 10 mm wide by 25 mm long from the tendinous insertion of the patellar tendon to the respective bones. (F) A sagittal saw is then used to harvest the plugs from the previously measured and established tracks created in panel E. The saw blade is angled 30° toward the midline of the patella for the lateral and medial cuts and 45° distally for the proximal cut. The saw blade is angled 20° toward midline in the tibia for the lateral and medial cuts and 45° proximally for the distal cut. (G) Thin ⅜- and ½-in. straight osteotomes are used to gently free the plug out from the patella. This process should be relatively easy if adequate saw cuts were previously made. Avoid excessive malleting and levering with the osteotomes to prevent cartilage damage and iatrogenic fracture. (H) The final step of harvest consists of sharply dissecting remaining soft tissue attachments from the graft during removal with a scalpel.

Fig 3

An arthroscope placed in the anterolateral portal on the patient's left knee is used to visualize the femoral footprint of the ACL. The anteromedial portal is used as a working portal to facilitate use of the various arthroscopic instruments including shavers, electrocautery, and burr. After soft tissue is cleared using an arthroscopic shaver and radiofrequency device, the LIR and the LBR can be identified. The LBR marks the separation between the anteromedial and posterolateral bundles of the ACL. The LIR, also known as resident's ridge, is more consistently identified arthroscopically, and this ridge represents the anterior margin of the AM and PL femoral bundles. An arthroscopic burr is used to perform a focal notchplasty to restore the anatomic shape of the intercondylar notch, which helps facilitate graft passage and prevents graft impingement, thereby ensuring full knee range of motion after reconstruction. (ACL, anterior cruciate ligament; AM, anteromedial; LBR, lateral bifurcate ridge; LIR, lateral intercondylar ridge; PL, posterolateral.)

Fig 4

An arthroscope placed in the anterolateral portal of the patient's left knee is used to visualize the tibial footprint of the ACL. The standard anteromedial portal is used as a working portal and the tibial ACL guide set to 65° is placed through this portal to the anatomic center of the ACL. The anatomic footprint on the tibia is commonly identified arthroscopically as being approximately 9 mm posterior to the intermeniscal ligament, 7 mm anterior to the PCL, and should not exit the tibial plateau posterior to the anterior horn of the lateral meniscus. The guide should engage the tibia approximately halfway down the tibial tubercle bone plug harvest site roughly 1.5-2 cm medial to the tubercle. (ACL, anterior cruciate ligament; PCL, posterior cruciate ligament.)

Fig 5

Graft passage after creation of the femoral and tibial tunnels is facilitated by the previously placed “passing suture” by retrieving the looped end through the distal tibial tunnel. The graft passage process is visualized arthroscopically through the anterolateral portal on the patient's left knee. The 4 suture ends on the patellar bone plug end of the patellar tendon graft are placed through the loop and then pulled through the joint and out the lateral aspect of the femur and skin by an assistant. The graft is pulled and positioned into the femoral tunnel under arthroscopic visualization with the aid of a 90° hemostat placed through the anteromedial portal, ensuring the graft does not twist during passage. The graft is pulled until the bone plug abuts the lateral wall of the femoral tunnel.

Fig 6

Femoral fixation of the ACL graft is performed with the patient's left knee in maximal flexion. A guide pin is inserted through the accessory medial portal with visualization from the anterolateral portal to the superior aspect of the graft and femoral tunnel junction. A 7- × 20-mm cannulated titanium interference screw is then placed under arthroscopic visualization, which is facilitated by a soft tissue, cannulated protector to prevent iatrogenic injury to the PCL and the ACL graft. The screw is placed while an assistant is pulling lateral tension on the passed graft. (ACL, anterior cruciate ligament; PCL, posterior cruciate ligament.)

Fig 7

Tibial fixation of the ACL graft is performed with the patient's left knee fully extended and the joint reduced. A guide pin is inserted to the superolateral aspect of the tunnel-graft interface. The assistant pulls the graft taut while a 9- × 20-mm cannulated titanium interference screw (Arthrex) is used for tibial fixation. Excess bone that may be present outside of the tibial tunnel can be removed with a rongeur or oscillating saw. (ACL, anterior cruciate ligament.)

Fig 8

Excess bone from the patellar tendon bone-tendon-bone autograft that was saved during graft preparation is used as bone graft at the patellar and tibial harvest sites. A priority is placed on bone graft being used to fill the patellar bone void created during harvest.