Abstract
Background:
As the main translational and rotatory stabilizer of the knee, the anterior cruciate ligament (ACL) plays a critical role in knee biomechanics. Anterior cruciate ligament ruptures generally require surgical attention for not only restoration of knee stability but also prevention of meniscal and chondral injuries. There are countless options for both the surgeon and the patient when contemplating graft choice and surgical technique for ACL reconstruction. However, the literature assessing the outcomes following various autografts has varied with some studies citing no significant difference in clinical and patient-reported outcomes, while others showing notable advantage when using bone–patellar tendon–bone (BPTB) autograft. In addition, there have been challenges associated with femoral tunnel placement using an anteromedial portal technique.
Indications:
In this study, we present a young female patient with a history of remote mid-substance ACL tear now presenting with worsening knee instability and a bucket-handle medial meniscus tear as a sequela of the incompetent ACL. After extensive discussion regarding the treatment options, patient had decided to proceed with surgical intervention with a BPTB autograft using the anteromedial portal technique for femoral tunnel placement and compression technique with bio-absorbable interference screw fixation.
Results:
Bone–patellar tendon–bone autograft has been noted to have lower risk of revision when compared with other graft options.
Discussion:
In this surgical technique study, we underline the importance of peritenon handling. We highlight the use of a 70-degree arthroscope to improve posterolateral wall visualization during femoral tunnel placement as well as for inspection of the reamed tibial tunnel. We also provide technique commentary and solutions for management of the medial femoral condyle (MFC) articular surface and femoral tunnel placement using an anteromedial portal technique. Last, we review graft-related outcomes, postoperative management, and rehabilitation protocol.
This is a visual representation of the abstract.
Video Transcript
In this video, we describe surgical technique of an arthroscopically assisted anterior cruciate ligament (ACL) reconstruction using bone–patellar tendon–bone (BPTB) autograft. With recent increased attention on medial independent femoral tunnel placement, we discuss various medial independent femoral tunnel drilling options and provide surgical technique pearls for this approach. We also review graft-related outcomes, postoperative management, and rehabilitation protocol.
Visualization of the entire femoral ACL footprint can be challenging when using a 30-degree arthroscope from a standard anterolateral-viewing portal. We provide commentary on use of a 70-degree arthroscope to improve visualization of the femoral ACL footprint as well as the tunnel depth while reaming. In addition, medial independent femoral tunnel placement increases the risk of iatrogenic articular damage to the medial femoral condyle (MFC) and can potentially lead to a short femoral tunnel and overall tunnel malpositioning. We present 3 different options to preserve the MFC, including the use of a hammer head reamer, a retro-cutter, or an arthroscopic skid for a flexible acorn reamer. We also bring attention to the use of a flexible guide pin and reamer to improve length and position of tunnel using a 70-degree arthroscope.
In this case report, we present a 27-year-old active female patient with right knee injury with evidence of recurrent instability, mechanical symptoms, and knee effusion. Clinical examination had yielded a knee range of motion of 0-120 degrees, medial joint line tenderness to palpation, and knee effusion. She was also noted to have a Grade 2B Lachman test, positive pivot shift test, positive anterior drawer test, stable collateral ligaments, and negative posterior drawer test. Imaging results were notable for a mid-substance tear of the ACL with a tibial plateau pivot shift contusion as well as a displaced bucket-handle medial meniscus tear.
Given the patient’s age, desire to return to physical activity, the concomitant meniscal injury, and recurrent knee instability episodes, there was extensive discussion regarding the various treatment and graft options, and patient had decided to proceed with surgical intervention consisting of an ACL reconstruction with BPTB autograft. As shown in a prospective Scandinavian registry study, patient with BPTB ACL autografts had significantly lower risk of revision when compared with hamstring autografts. 4
In the operative suite, the patient is placed in a supine position on the operating room table with the use of a side post, a footrest set to 90 degrees, and a lateral pad to support the leg in 90 degrees of flexion. A thigh tourniquet is utilized.
A knee examination under anesthesia (EUA) is performed. This includes evaluation of knee range of motion, collateral ligament stability under varus and valgus stress, posterior drawer test to assess integrity of the posterior cruciate ligament (PCL), Lachman’s test, anterior drawer test, and pivot shift test to assess the ACL.
The graft is harvested and prepared using conventional technique. Of note, care is taken to develop peritenon flaps and protect for later repair. The graft is transferred using a wet sponge, limiting its contact with patient skin and the handler’s gloves.
After completing a standard 2-portal diagnostic arthroscopy with a 30-degree arthroscope, the medial meniscus tear was repaired using an all-inside technique in this case.
With the knee at 90 degrees of flexion, the femoral notch is entered. The ACL and PCL integrity is probed. The ACL is debrided back to its femoral footprint with shaver and cautery.
At this point, the 30-degree arthroscope is exchanged for a 70-degree arthroscope. The 30-degree arthroscope is maintained in the trocar until the 70-degree arthroscope is attached to the camera and light source and ready for a swift exchange. This technique is used to minimize loss of intra-articular fluid pressure. Regardless of the femoral tunnel technique, the 70-degree arthroscope provides complete visualization of the entire femoral footprint on the lateral wall, allowing for anatomic femoral tunnel placement as seen in the side-by-side comparison without switching portals as evidenced by Bedi et al 2 and Joseph et al. 6 The arthroscope placement through the anterolateral portal also avoids medial crowding from the camera.
After completion of the notchplasty, we turn our attention toward the femoral tunnel placement using an anteromedial (AM) portal technique. In 2012, Tompkins et al 10 showed the AM portal technique placed the femoral tunnel closer to the center of femoral footprint (AM: 97.7% ± 5%; TT: 61.2% ± 24%) and in a more consistent location when compared with the traditional transtibial (TT) technique. However, given the anatomy of the MFC, there is an inherent risk of iatrogenic articular cartilage damage during femoral tunnel placement from the AM portal. Previous studies have described techniques to prevent iatrogenic injury to the MFC including passing the acorn reamer and the guide pin as a composite while in knee hyperflexion or using a bio-interference screw sheath as a protective barrier for the MFC.1,3
Here, we provide 3 techniques for femoral tunnel placement via an AM portal while preserving the MFC articular cartilage integrity. The first technique utilizes a 7-mm offset guide to estimate the position of the femoral footprint. A curved awl is then used to mark the starting point and guide tunnel placement in a more anterosuperior position. A flexible guide pin is placed in the center of ACL footprint and advanced bi-cortically out of the skin. Silver et al 9 compared the use of flexible guide pin and standard rigid guide pin for femoral tunnel placement via AM portal technique and showed flexible pins allow for significantly longer femoral tunnels and safer distance from the lateral collateral ligament ensuring stable suspensory fixation while reducing risk of iatrogenic articular cartilage damage. In addition, a skid can be placed to protect the MFC articular surface prior to insertion of the reamer. A flexible acorn reamer is then used to drill a 10 mm × 25 mm tunnel, leaving a 2-mm posterior wall.
The second technique also takes advantage of the 7-mm offset guide, curved awl, and flexible guide pin, but alternatively uses a hammer head reamer as it provides a lower profile when passing the MFC, therefore reducing risk iatrogenic articular surface damage.
Last, the femoral socket can be drilled in a retrograde manner using an all-in-one retro-cutter. This method takes advantage of outside-in guide pin placement. With the arthroscope in the AM portal, the retrograde guide is placed in the center of the femoral footprint on the lateral wall. A counter incision is made on the lateral thigh. The guidewire is advanced in the bone under direct visualization. Following this, the reamer is drilled into the joint, flipped, and retro-cut to a depth of approximately 25 mm. At this point, the tunnel is inspected for appropriate position and back wall thickness.
In all 3 techniques, precautionary steps are taken to prevent any iatrogenic injury to the MFC.
An over-the-top view is utilized with the 70-degree arthroscope for direct visualization of tunnel depth while reaming as previously illustrated by Joseph et al. 6 As noted by Lubowitz, 7 the camera should be positioned superior to the reamer while looking down, a view that is reproducible by an assistant. Aggressive suctioning is performed using the shaver to remove bony debris. A passing suture is then pulled through for later graft passage.
Here, we re-demonstrate the technique for the over-the-view using a 70-degree arthroscope. While maintaining the arthroscopic view at the 9 o’clock position, the hand holding the camera is supinated 90 degrees. This allows for direct visualization of the depth while reaming.
Attention is then turned toward the tibial tunnel. The tibial stump of the ACL is shaved leaving a small remnant as a guide.
The gold guide is inserted through the AM portal and placed at the desired tibial origin of the ACL. The tibial incision is then retracted medially and inferiorly to allow the guide trocar to sit on the tibial surface inside the skin. With the tibial guide pin through the trocar, the surgeon’s hand is positioned medially and closer to the tibia. The tunnel position should be approximately 1-cm medial to the tibial graft harvest site. The pin is advanced into the joint. The gold guide is then removed from the joint. The tibial tunnel is drilled using a 10-mm cylindrical reamer over the guide pin. The bone graft from the reaming is collected for later autogenous bone grafting. It is critical for the assistant to continue to retract the skin medially to prevent entry of the intra-articular fluid into the anterior tibial compartment. Again, the advantage of a 70-degree arthroscope is seen as it allows for direct visualization of the entirety of the tibial tunnel.
The graft passage is assisted using a probe under direct arthroscopic visualization. Femoral fixation is achieved using compression technique with a biocomposite interference screw. The knee is then cycled and brought into extension under direct arthroscopic visualization to ensure no evidence of notch impingement. Tension is maintained on the graft on the tibial side, and the knee is progressively cycled, and then brought into 20 to 30 degrees of flexion. The tibial fixation is also completed with a biocomposite interference screw. The ACL graft is then probed, and an EUA is repeated to ensure stability of the graft. The knee is then lavaged and suctioned of any remaining debris.
The central one-third of the patellar tendon is then reapproximated with interrupted resorbable braided sutures with the knee in flexion to prevent over-tightening of the tendon. The patella and tibial harvest sites are bone grafted with autogenous bone graft obtained previously from the tibial tunnel reaming. The peritenon is then closed as a separate layer from the patellar tendon over the top with interrupted resorbable braided sutures, and last, a layered skin closure is completed.
One of the most commonly cited complications after an ACL reconstruction among all graft types is anterior knee pain; however, anterior knee pain with kneeling is specific to BPTB autograft. 8 Graft re-rupture, patella fracture, patellar tendon rupture, arthrofibrosis, and tunnel malpositioning are other noted complications. 8
Our postoperative rehabilitation involves a five-phase protocol approximately 24 weeks in duration. The program includes focus on initial weightbearing restrictions, active range of motion, quadriceps strengthening, return to running, sports-specific drills, and, finally, return to play testing. In general, the majority of athletes are not allowed to return to sport until 1 year postoperative.
Historically, there has been no statistically significant difference among autograft options with respect to clinical and instrumented laxity testing as well as patient-reported outcomes. 5 However, in a prospective Scandinavian registry-based study of nearly 46,000 patients, those with BPTB ACL autografts had significantly lower risk of revision when compared with hamstring autografts, and the risk decreased with increasing age at the time of surgery. 4
Footnotes
Submitted January 30, 2021; accepted February 12, 2021.
One or more of the authors has declared the following potential conflict of interest or source of funding: M.J.S. has received personal fees from Stryker and fellowship program support from Smith & Nephew, Breg, Conmed, and Arthrex. J.E.V. is a paid presenter or speaker for Arthrex. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
